I don’t know who is worse, the idiot weatherman or Fox News… Give me a break!
________________________________________
Weather Channel Founder Blasts Gore Over Global Warming Campaign
John Coleman, now a weatherman at San Diego's KUSI, writes on his station's Web site that Al Gore is ignoring the faulty research behind global warming.
The founder of the Weather Channel is ridiculing Al Gore over his calls for action on global climate change, saying in a column that global warming is a "hoax" and "bad science."
John Coleman, now a weatherman at San Diego's KUSI, wrote on his station's Web site Wednesday that Gore refuses to acknowledge the faulty research on which the idea of global warming is based.
Coleman's lengthy scolding came as the former vice president and Nobel Peace Prize winner addressed the Senate Foreign Relations Committee and urged lawmakers to pass a bill that would put caps on heat-trapping gases and take the lead on a global climate treaty.
Coleman wrote that the Environmental Protection Agency is "on the verge" of naming CO2 (carbon dioxide) as a pollutant, and that seemingly all of Washington is on board with such CO2 silliness."
"I am totally convinced there is no scientific basis for any of it," Coleman wrote, describing the decades-old theory that increasing the amount of carbon dioxide in Earth's atmosphere leads to global warming.
"Global Warming. It is the hoax. It is bad science. It is a high jacking of public policy. It is no joke. It is the greatest scam in history," Coleman wrote.
Source Here.
Saturday, January 31, 2009
Sex with Flexible Partners #2
During the first installment in this series on reproductive strategy (available here) the topic of hermaphroditism was introduced and a quick summary of simultaneous hermaphroditism was provided. Moving forward from that discussion, this short essay will provide a synopsis of a category of hermaphroditism referred to as “sequential hermaphroditism.”
Recall from the first essay that simultaneous hermaphroditism refers to organisms that can function as both a female and a male during a single mating session. These individuals have the ability to produce both ova and sperm and, with social dynamics temporarily laid aside, can essentially mate with any adult member of its population. Using this abbreviated definition of simultaneous hermaphroditism, notice that the word “function” has a specific meaning in this context; not only does it imply the presence of reproductive organs, but it also requires the action of using those organs during mating - this is a minor, but important point.
For example, a “functional female” is an organism that undertakes the female role within the context of its social hierarchy and produces only ova during a single mating session; it exhibits the outward coloration and morphology of a female member of its species. If that functional female organism should then be taken into a laboratory, dissected by a biologist and found to have male gonad tissue as an addition to its female anatomy, it would still be considered a functional female, even though male tissues were found to be present. The same applies for a “functional male;” it would still be considered a functional male even if female reproductive tissues were later discovered. This is a significant delineation when discussing hermaphroditic organisms because frequently sexual characteristics are very difficult to distinguish. For example, on close examination of fishes belonging to the genus Lythrypnus they are often found to possess reproductive tissues of both females and males; this may erroneously lead some to conclude that the fish are simultaneously hermaphroditic, but in fact individuals function entirely as one of the two sexes when in the wild; it’s either a male or a female, not both. If at some point Lythrypnus changes its function from one sex to the other, it still wouldn’t be classified as a simultaneous hermaphrodite – because it still wouldn’t function as two sexes simultaneously – rather, it would be said to be “Sequentially Hermaphroditic.”
Sequential hermaphroditism can occur in one of two ways; either a functional male can change to a functional female, or vice versa, a female can change to a male. Organisms which are born male and later become female are said to exhibit “protandry.” Here, the prefix “proto-” is derived from Latin and translates as “first;” the root word “andro” refers to androgen, a steroid hormone responsible for masculine characteristics. Protandry therefore means “first a male.” Correspondingly, “protogyny,” means “first a female” and is used when describing the trait of a female undergoing sex change to a male. Both protandry and protogyny are used as reproductive strategies in a variety of hermaphroditic organisms. Sometimes sex changes occurs at a predetermined age in conjunction with the normal growth and maturation process, in other cases this change can occur as a response to environmental or social triggers. With the polychaete worm Ophryotrocha puerilis, sex change occurs as a strategy for dealing with the expense of creating ova, the same expense that lead to the compromise of egg trading in the Hamlet fish (Hypoplectius) mentioned in the first essay.
Recall from the Hamlet fish discussion that because of anisogamy - a size difference between male and female gametes - the cost of producing ova is greater than that associated with making sperm; eggs are expensive, sperm are cheap. Bearing this in mind, it follows that the females of a species with greatest access to resources will tend to grow larger and, in turn, be able to produce more eggs than females with more-limited access to resources. The larger the female, the greater fecundity she exhibits. Monogamous polychaete worms take this lesson to heart, within the male-female pair bond the female is the larger of the two annelids. The male polychaete typically develops more slowly and is normally smaller in size; therefore the assigning of burdensome egg development duties to the larger member of the duet is a better reproductive strategy. At least until the male hits a growth spurt!
[Ophryotrocha puerilis]
Although the male polychaete is a slow starter in regards to growth, at a certain point in adulthood he really hits his stride and rapidly outsizes the female. This creates a reproductive opportunity for the pair-bond. With increased size, the male is now better positioned to handle egg development. There’s only one problem – he’s a male! Not wasting any time, the male changes to a female and takes up the task of producing female gametes. In concert with this change, the old female, now the smaller of the two, changes to a male and begins to produce sperm. This double sex change improves the sexual efficacy of the pair and results in more offspring produced. However, there is one additional complication with this highly plastic stratagem…
Now that the original female has changed to male and is no longer responsible for egg production, her primed-up metabolism, which up to this point had to supply energy to both her and her eggs, causes the fish to really “pack on the pounds.” In time, the original female, which is now male, is once again larger than the egg-producing female of the pair-bond...
No worries though, the pair just change back to their original sexes – that’s what being a flexible partner is all about.
In talking about sequential hermaphroditism strategy in relation to body size, the polychaete worm exhibited a relationship known as the “size-advantage hypothesis.” The size-advantage hypothesis explains that when an organism reproduces best as one sex whilst either “young and small” or while “old and big,” sex changes can occur when transitioning between these two categories. The male worm benefited from being young and small, but as it got older and larger this benefit was reduced; in order to benefit from being older and bigger it had to change sexes – to a female.
It should be mentioned that like the sequential variety, some simultaneous hermaphrodites utilize this size-advantage relationship as well. The freshwater snail Helisoma trivolvis makes use of it every time it encounters a potential mate. Unlike the Hamlet fish, Helisoma doesn’t share in the costs of egg production, when two snails meet whichever one happens to be the larger takes on the role of the female for that particular mating period.
During the next Sex with Flexible Partners installment, the size-advantage hypothesis will be tested in situations for which the “eggs are expensive, sperm are cheap” rule doesn’t necessarily apply and the topic of hermaphroditism as a reproductive strategy will be drawn to a close.
P MUNDAY, P BUSTON, R WARNER (2006). Diversity and flexibility of sex-change strategies in animals Trends in Ecology & Evolution, 21 (2), 89-95 DOI: 10.1016/j.tree.2005.10.020
Kohei Ohta, Mayumi Hirano, Takayuki Mine, Hiroshi Mizutani, Akihiko Yamaguchi, Michiya Matsuyama (2007). Body color change and serum steroid hormone levels throughout the process of sex change in the adult wrasse, Pseudolabrus sieboldi Marine Biology, 153 (5), 843-852 DOI: 10.1007/s00227-007-0856-0
C. G. Norton, A. F. Johnson, R. L. Mueller (2008). Relative size influences gender role in the freshwater hermaphroditic snail, Helisoma trivolvis Behavioral Ecology, 19 (6), 1122-1127 DOI: 10.1093/beheco/arn099
Recall from the first essay that simultaneous hermaphroditism refers to organisms that can function as both a female and a male during a single mating session. These individuals have the ability to produce both ova and sperm and, with social dynamics temporarily laid aside, can essentially mate with any adult member of its population. Using this abbreviated definition of simultaneous hermaphroditism, notice that the word “function” has a specific meaning in this context; not only does it imply the presence of reproductive organs, but it also requires the action of using those organs during mating - this is a minor, but important point.
For example, a “functional female” is an organism that undertakes the female role within the context of its social hierarchy and produces only ova during a single mating session; it exhibits the outward coloration and morphology of a female member of its species. If that functional female organism should then be taken into a laboratory, dissected by a biologist and found to have male gonad tissue as an addition to its female anatomy, it would still be considered a functional female, even though male tissues were found to be present. The same applies for a “functional male;” it would still be considered a functional male even if female reproductive tissues were later discovered. This is a significant delineation when discussing hermaphroditic organisms because frequently sexual characteristics are very difficult to distinguish. For example, on close examination of fishes belonging to the genus Lythrypnus they are often found to possess reproductive tissues of both females and males; this may erroneously lead some to conclude that the fish are simultaneously hermaphroditic, but in fact individuals function entirely as one of the two sexes when in the wild; it’s either a male or a female, not both. If at some point Lythrypnus changes its function from one sex to the other, it still wouldn’t be classified as a simultaneous hermaphrodite – because it still wouldn’t function as two sexes simultaneously – rather, it would be said to be “Sequentially Hermaphroditic.”
[Lythrypnus]
Sequential hermaphroditism can occur in one of two ways; either a functional male can change to a functional female, or vice versa, a female can change to a male. Organisms which are born male and later become female are said to exhibit “protandry.” Here, the prefix “proto-” is derived from Latin and translates as “first;” the root word “andro” refers to androgen, a steroid hormone responsible for masculine characteristics. Protandry therefore means “first a male.” Correspondingly, “protogyny,” means “first a female” and is used when describing the trait of a female undergoing sex change to a male. Both protandry and protogyny are used as reproductive strategies in a variety of hermaphroditic organisms. Sometimes sex changes occurs at a predetermined age in conjunction with the normal growth and maturation process, in other cases this change can occur as a response to environmental or social triggers. With the polychaete worm Ophryotrocha puerilis, sex change occurs as a strategy for dealing with the expense of creating ova, the same expense that lead to the compromise of egg trading in the Hamlet fish (Hypoplectius) mentioned in the first essay.Recall from the Hamlet fish discussion that because of anisogamy - a size difference between male and female gametes - the cost of producing ova is greater than that associated with making sperm; eggs are expensive, sperm are cheap. Bearing this in mind, it follows that the females of a species with greatest access to resources will tend to grow larger and, in turn, be able to produce more eggs than females with more-limited access to resources. The larger the female, the greater fecundity she exhibits. Monogamous polychaete worms take this lesson to heart, within the male-female pair bond the female is the larger of the two annelids. The male polychaete typically develops more slowly and is normally smaller in size; therefore the assigning of burdensome egg development duties to the larger member of the duet is a better reproductive strategy. At least until the male hits a growth spurt!
[Ophryotrocha puerilis]
Although the male polychaete is a slow starter in regards to growth, at a certain point in adulthood he really hits his stride and rapidly outsizes the female. This creates a reproductive opportunity for the pair-bond. With increased size, the male is now better positioned to handle egg development. There’s only one problem – he’s a male! Not wasting any time, the male changes to a female and takes up the task of producing female gametes. In concert with this change, the old female, now the smaller of the two, changes to a male and begins to produce sperm. This double sex change improves the sexual efficacy of the pair and results in more offspring produced. However, there is one additional complication with this highly plastic stratagem…
Now that the original female has changed to male and is no longer responsible for egg production, her primed-up metabolism, which up to this point had to supply energy to both her and her eggs, causes the fish to really “pack on the pounds.” In time, the original female, which is now male, is once again larger than the egg-producing female of the pair-bond...
No worries though, the pair just change back to their original sexes – that’s what being a flexible partner is all about.
In talking about sequential hermaphroditism strategy in relation to body size, the polychaete worm exhibited a relationship known as the “size-advantage hypothesis.” The size-advantage hypothesis explains that when an organism reproduces best as one sex whilst either “young and small” or while “old and big,” sex changes can occur when transitioning between these two categories. The male worm benefited from being young and small, but as it got older and larger this benefit was reduced; in order to benefit from being older and bigger it had to change sexes – to a female.
It should be mentioned that like the sequential variety, some simultaneous hermaphrodites utilize this size-advantage relationship as well. The freshwater snail Helisoma trivolvis makes use of it every time it encounters a potential mate. Unlike the Hamlet fish, Helisoma doesn’t share in the costs of egg production, when two snails meet whichever one happens to be the larger takes on the role of the female for that particular mating period.
[Helisoma trivolvis]
During the next Sex with Flexible Partners installment, the size-advantage hypothesis will be tested in situations for which the “eggs are expensive, sperm are cheap” rule doesn’t necessarily apply and the topic of hermaphroditism as a reproductive strategy will be drawn to a close.
P MUNDAY, P BUSTON, R WARNER (2006). Diversity and flexibility of sex-change strategies in animals Trends in Ecology & Evolution, 21 (2), 89-95 DOI: 10.1016/j.tree.2005.10.020
Kohei Ohta, Mayumi Hirano, Takayuki Mine, Hiroshi Mizutani, Akihiko Yamaguchi, Michiya Matsuyama (2007). Body color change and serum steroid hormone levels throughout the process of sex change in the adult wrasse, Pseudolabrus sieboldi Marine Biology, 153 (5), 843-852 DOI: 10.1007/s00227-007-0856-0
C. G. Norton, A. F. Johnson, R. L. Mueller (2008). Relative size influences gender role in the freshwater hermaphroditic snail, Helisoma trivolvis Behavioral Ecology, 19 (6), 1122-1127 DOI: 10.1093/beheco/arn099
Thursday, January 29, 2009
Sex with Flexible Partners: Socio-Ecological Reproductive Strategy #1
Reproductive strategies and natural mating systems have long been a favorite topic of those with interests in the areas of ethology, ecology and evolution. From the call of the nightingale, which is at the same time both alluring and manipulative, to the merging of circulatory systems by the male and female anglerfish, the myriad of processes employed by organisms in bringing forth future generations are as fascinating as they are bizarre. It is because of this fascination that this short essay is written. It represents the first of several that will provide a pr̩cis of the range and disparity in sexual strategies utilized by the natural world in meeting the demands of one of its prime drivers Рsex.
In contrast to more formal literary approaches, this initial essay will move historical context to the backburner as a reserve for future conversation and jump-in headfirst by discussing one of the more unique tactics applied in promoting fecundity; a reproductive tactic that’s applied by a vast array of organisms from plants to annelids to vertebrates - hermaphroditism. More specifically, this first installment will discuss a type of hermaphroditism called “simultaneous hermaphroditism.”
Hermaphroditism, when used in the context of natural history and behavioral ecology, doesn’t hold precisely the same meaning as it does when used in popular – non scientific – conversation. In terms of reproductive strategy the term can be used to describe one of two situations.
In the first scenario, called “simultaneous hermaphroditism,” organisms exhibit both male and female genitalia – they are 50% male and 50% female – and are able to produce the gametes of both sexes, both female ova and male sperm. In this instance, although able to produce both sperm and ova, self-fertilization is avoided through production of digestive enzymes that act as a barrier, destroying one of the two gametes. This type of hermaphroditism is practiced by several species, including a variety of nudibranchs (Nudibranchia) and the Chalk Bass (Serranus tortugarum).
[Nudibranchia -top; Serranus - bottom]
Energetically speaking, simultaneous hermaphroditism as a strategy is most useful for organisms that exist in populations of very low density, where the cost of searching out a mate is greater than the expense associated with maintaining two independent reproductive systems. Ecological benefit occurs because when seeking a mate, either a male or female will serve the reproductive function, thus the chances of finding a partner are twice as good as they would be if forced to locate a member of a specific sex.
However, being two sexes simultaneously does have its difficulties, especially when negotiating with potential mates in regard to total parental investment. Although the chances of locating a mate are improved if gender isn’t a concern, the total investment in reproductive effort can be a point of discord. Like other vertebrate sex cells, the “female” and “male” gametes (here female and male refer to the sex role undertaken at the time of mating) in fish are different sizes, this is called anisogamy or heterogamy.
Female gametes (ova) are larger in size than that of the male gametes (sperm). They’re larger because they must provide not only the “female” contribution of genetic material to the developing zygote, but in addition they must also supply the zygote with all of the nutrients and protection required during embryological development. Spermatozoa by contrast are merely vehicles for delivering the male genetic compliment and are less costly to manufacture and deliver; plainly stated, sperm are cheap, eggs are expensive.
Considering the resource investment involved in gamete production, when two simultaneous hermaphrodites meet for the purpose of reproduction, which member is going to take on the extra burden of producing eggs and which is going to provide the “cheap” sperm? What’s to prevent one fish from “cheating” the system by not providing eggs and only producing sperm; thereby reserving resources while spreading his genetic compliment at the expense of another’s egg investment?
Hamlet fish (Hypoplectius) resolve the egg stand-off through a process called “egg trading.” During egg trading both fish first subdivide their egg clutches into individual parcels for ease of dispersement. As breeding commences, one fish initiates mating by releasing a single egg parcel; seeing this, the opposite fish readily fertilizes these eggs with sperm. Next, the roles reverse. The fish that initially fertilized the eggs with sperm now renders one of its egg parcels to the fish which provided eggs during the first exchange; as in, “you scratch my back, I’ll scratch yours.”
[Hypoplectius]
If the Hamlet that provided sperm during this first exchange should refuse to supply one of its parcels in return, the courtship will be broke off prematurely and mating will cease with only a few eggs fertilized. If however, the initial sperm supplier “plays fair” and then produces a parcel for the initial egg maker to fertilize with its sperm, the process will continue, back-and-forth to the mutual benefit of both fish, ultimately resulting in greater numbers of total eggs fertilized. Because of this unique dynamic, egg trading is often used as an example of reciprocal altruism and as an analogy when discussing biological “game theory” – but these are topics for other times.
The second type of hermaphroditism is called, “sequential hermaphroditism.” Sequential hermaphroditism means that an organism literally becomes a member the opposite sex! An organism is born as one gender, with the sex characteristics and reproductive organs of a single sex, but then it undergoes a “sex change” in which the full range of hormones, morphology, coloration, behavior and social position that are normally associated with the opposite sex are phenotypically expressed. Males literally become females, females literally become males.
In some instances, sequential hermaphrodites undergo a change in sex at a predetermined age in conjunction with the normal growth and maturation process, but in other cases this transition occurs in response to an environmental or social factor. Furthermore, this switching of sexes isn’t limited to a one time occurrence; a single individual can change repeatedly – back and forth, again and again.
In order to keep the length of these ramblings to a readable minimum, sequential hermaphroditism will be the topic of the next installment.
Verena S. Brauer, Lukas Schärer, Nico K. Michiels (2007). PHENOTYPICALLY FLEXIBLE SEX ALLOCATION IN A SIMULTANEOUS HERMAPHRODITE Evolution, 61 (1), 216-222 DOI: 10.1111/j.1558-5646.2007.00018.x
Eric A. Fischer (1987). Mating behavior in the black hamlet — gamete trading or egg trading? Environmental Biology of Fishes, 18 (2), 143-148 DOI: 10.1007/BF00002602
Tuesday, January 27, 2009
How can someone hate David Attenborough?
I’ve always associated my maternal grandfather with David Attenborough. Not because they look alike or even have anything in common, but because from the age of about six until I was fifteen or so, my “pap” and I spent every Saturday morning parked in front of the TV watching nature programming together on PBS.
Attenborough’s documentaries were always the best. It would definitely take a lot of “faith” to first imagine a loving and benevolent god and then to think that god has hatred for someone like Attenborough – bunch of whackaloons!
A few Attenborough quotes from the Guardian:
"They tell me to burn in hell and good riddance."
"It never really occurred to me to believe in God - and I had nothing to rebel against, my parents told me nothing whatsoever. But I do remember looking at my headmaster delivering a sermon, a classicist, extremely clever ... and thinking, he can't really believe all that, can he? How incredible!"
"They always mean beautiful things like hummingbirds. I always reply by saying that I think of a little child in east Africa with a worm burrowing through his eyeball. The worm cannot live in any other way, except by burrowing through eyeballs. I find that hard to reconcile with the notion of a divine and benevolent creator."
Similiar statements during television interview (YouTube)
"Men never do evil so completely and cheerfully as when they do it from religious conviction."
-Blaise Paschal
This quote is often attributed, in error, to Sam J. Ervin, Jr. in "Protecting the Constitution." (1984).
Wetland Plant of the Week #2
Drosera capillaris
"Sundew"
Insectivorous and Facultative Wet species with a basal rosette up to 10cm wide and 2-20 pink flowers. Michelle (my fiancé) took this snapshot while hiking in the Picayune Strand.
Sunday, January 25, 2009
Brassica oleracea: Artificial Selection is Delicious!
Just a quick post...
While reading through a few abstracts at the Journal of Insect Science - looking for information regarding introduced predators as biological controls for invasive insect species - I came across an article discussing Delphastus catalinae (ladybird beetles, image below) as a control agent for Bemisia tabaci (whiteflies).
Legaspi J, Legaspi BC, Simmons AM, Soumare M (2008). Life table analysis for immatures and female adults of the predatory beetle, Delphastus catalinae, feeding on whiteflies under three constant temperatures Journal of Insect Science
While reading through a few abstracts at the Journal of Insect Science - looking for information regarding introduced predators as biological controls for invasive insect species - I came across an article discussing Delphastus catalinae (ladybird beetles, image below) as a control agent for Bemisia tabaci (whiteflies).
Whiteflies are major pests, and have recently gained infamy for attacks in Florida.
A good description from a recent Florida news article:
“The whitefly is not a fly, but a flying insect that is very similar to some scale insects. It has sucking mouthparts and some species are known to cause sooty mold, but this species does not. Heavy feeding by the adult and the immature stages — which are immobile, flattened and translucent with red eyes — cause yellowing of the foliage and significant defoliation. The undersides of leaves are coated with a pebbly like, whitish residue, which is the empty casings or “skins” left behind by the immature stages as they molt and develop into the adult stage.”
Luckily, D. catalinae is a voracious predator and both its larval and adult stages feed on B. tabaci’s eggs, larvae and adults. A couple of courting B. tabaci are pictured below.
At any rate, moving on to the intended point of this post - although the mentioned research centered on the affects of temperature variation on Delphastus’ predatory capabilities, the article happened to mention that one of the plant species that may most benefit from Delphastus’ protection is Brassica oleracea.
Rummaging through my mental file cabinet in an attempt to reference B. oleracea, I soon came to the realization that the species has undergone a tremendous amount of artificial selection and is a mainstay of modern diets.
In its wild state B. oleracea is known as “wild cabbage” and looks rather like a common weed you might find in your backyard, here's a photo:
However, through artificial selection the plant has proven to be highly flexible and has been bred for its delicious leaves, inflorescence, stalks, leaf buds and roots. Some of the common names for varieties of B. oleracea include; broccoli, cauliflower, brussel sprouts, kale, kohlrabi and cabbage.
What an amazing variety from one species of plant!
Legaspi J, Legaspi BC, Simmons AM, Soumare M (2008). Life table analysis for immatures and female adults of the predatory beetle, Delphastus catalinae, feeding on whiteflies under three constant temperatures Journal of Insect Science
Saturday, January 24, 2009
Fire Ants Attack - Lizards Adapt
Fire ants (Solenopsis) are an invasive species in the US, and they’re a big problem here in Florida – there are no less than two nests in my backyard at any given time. Their hunger for new territory and their proclivity towards violence has resulted in conflict on more than one occasion. Although, thousands have been slain locally (and righteously, in my view) the battles are ongoing – and I have more than one scar on my legs and feet to attest to this brutal history!
I’ve battled Solenopsis not for glory, but for the safety of the other backyard fauna; massacred frogs, fledgling birds and anoles have all been discovered – Kitsune and Zita (my dogs) have also endured the wrath and sting of these imperialists…
OK, OK – I’ll stop with the war metaphor.
In all seriousness these gals are hardy to say the least. My understanding is that their rate of expansion into North America is driven by a genetic discrepancy between the invading lineages and those native to South America that has resulted in social polymorphism. In Argentina, Solenopsis queens emit a pheromone that identifies her to the colony – make way for the queen! If a foreign queen should enter the colony, workers detect the foreign pheromone and quickly dispatch her (essentially she’s drawn and quartered). In contrast, a genetic mutation in the DNA of the US invasive variety has altered a pheromone binding protein (Gp-9) to such extent that invasive queens are no longer recognized by workers. Because of this, a single colony in the US may have multiple reproductive queens (polygyny) coexisting at the same time – reproductive rates go through the roof.
{This pic shows the colony "rafting" following flooding}
The pheromone recognition behavior, when functioning, has the affect of geographically limiting the proximity of any two colonies. This results in fewer individual colonies per a given area. When, due to mutation, foreign queens aren’t recognized, inter-colony conflicts don’t occur as frequently thereby opening the door to “super colonies” and shared territories.
This mutation is positively selected in the relatively open ecosystem of the US; however as Solenopsis populations continue to raise their numbers may reach a threshold that gives advantage to the more territorial variety (monogyny), this may push the species towards more geographic balance, as is evident in the South American native type.
I bring up Solenopsis because I just read a Science Daily article discussing how native lizards in the southeastern United States are adapting to potentially fatal invasive fire ant attacks by developing behaviors that enable them to escape from the ants, as well as by developing longer hind legs, which can increase the effectiveness of this behavior. This according to Penn State Assistant Professor Tracy Lang Penn, recently published in the journal Ecology
Here’s a nifty little video from Penn’s website showing a noosed lizard flicking away attacking Solenopsis - FYI the video skips for the first couple seconds:
Better the lizard than me! Solenopsis are aggressive, they like to lock on with their mandibles and sting multiple times – with painful and skin blistering alkaloid venom, Ouch!
Tracy Langkilde (2009). Fence Lizard Bulletin of the Ecological Society of America, 90 (1), 36-37 DOI: 10.1890/0012-9623-90.1.36
M. J. B. Krieger (2005). Molecular Evolutionary Analyses of the Odorant-Binding Protein Gene Gp-9 in Fire Ants and Other Solenopsis Species Molecular Biology and Evolution, 22 (10), 2090-2103 DOI: 10.1093/molbev/msi203
Friday, January 23, 2009
Why’s Graham so Glum: Lawton Critiqued
Only 24 days into my blogging career and already I seem to have ruffled the feathers of a professional science journalist – not real sure if that’s a bad thing or not…
Well, in all modesty the feathers on this particular journalist seem to ruffle quite readily, so readily in fact that he’s been tousling them on several different science blogs during the past few hours. He’s posted comments and rebuttals on Evolving Thoughts, Evolutionary Novelties and where I happened to bump into him, at Larry Moran’s Sandwalk.
I guess a life of servitude to the public media can be stressful, at least for New Scientist writer Graham Lawton whose recent article “Why Darwin was wrong about the tree of life” graced the most recent cover of New Scientist titled “Darwin was Wrong.”
I’m really quite astonished at Lawton’s parrying and thrusting all over the blogosphere; it seems to me that any biology or science enthusiast could have predicted a little fallout resulting from the phrase “Darwin was Wrong” being placed on the cover of a popular science magazine. Indeed - I’d be shocked, if I were to discover that the generation of such hype was anything less than the premeditated goal of the magazine’s editorial staff.
In point of fact, Lawton himself states in the comments section of Sandwalk,
So, why is Graham so glum? He’s clearly aware, as are most readers, that the cover is little more than a publicity stunt aimed at selling copy. He may be missing the very important point that although everyone recognizes the pitch, not everyone approves of the tactic.
Lawton, as well as the editorial staff of New Scientist, may think that sacrificing accuracy for the sake of profit is a respectable endeavor; however I would venture to guess that much of the magazine’s readership does not. In part, it may be that readership’s response to the cover that contributed to the comparatively apologetic tone of the article’s subsequent editorial (Editorial: Uprooting Darwin's tree tone).
At any rate, regardless of the profit margins involved in misrepresenting important biological contributions through creative cover making, why does Lawton continually assert that the article’s content somehow remedies the cover page?
I’ve read the article. It seems abundantly clear to me that Lawton’s goal was to firstly create an artificial dichotomy between Darwin’s branching tree concept and genetic studies involving horizontal gene transfer (HGT) and then, after accomplishing this, to pummel Darwin’s idea through literary biased language.
A few examples of Lawton’s biased language:
1. Speaking to the Tree of life project - “But today the project lies in tatters, torn to pieces by an onslaught of negative evidence”
2. “Many biologists now argue that the tree concept is obsolete and needs to be discarded”
3. HGT - “[This] bombshell has even persuaded some that our fundamental view of biology needs to change”
4. "For a while, this allowed evolutionary biologists to accept HGT without jeopardizing their precious tree of life”
5. Darwin’s concept - “We now know that view is wrong”
“Meanwhile, those who would chop down the tree of life continue to make progress”
6. "Having uprooted the tree of unicellular life, biologists are now taking their axes to the remaining branches”
Comparing Darwin’s tree (based on natural observation and inference) to modern molecular genetics may be stretch, but I’ll refer to the above listed blogs and their accompanying comments as opposed to laying out the arguments here…
Rather my point is very simple, popular science periodicals, as well as science journalists should strive to master the arts of clarity and accuracy; they should compose and present the resultant works in a creative and informal way that is both informative and enjoyable to the science enthusiast who partakes of them. To pursue the agitation of the informed readership and to encourage fundamentalists is – plainly and simply – wrong.
Science Journalism - “Journalism tends to have a stronger bias towards sensationalism and speculative theories than science, whereas science focuses more on fact and empirical measurement.” Lawton’s balance is askew...
As to my originally posed question at Sandwalk, “So, is the title an outright media ploy - pandering for profit – or, does Lawton lack some fundamental understanding of scientific progress?” This wasn’t a personal assault; it’s a critique of the New Scientist’s pandering and the article’s inability to distinguish between historic foundations and modern remodeling.
Thanks for the disillusionment Graham, but you’ve made it abundantly clear how the media works with your comment at Evolving Thoughts,
I do have a suggestion for the next New Scientist cover:
Well, in all modesty the feathers on this particular journalist seem to ruffle quite readily, so readily in fact that he’s been tousling them on several different science blogs during the past few hours. He’s posted comments and rebuttals on Evolving Thoughts, Evolutionary Novelties and where I happened to bump into him, at Larry Moran’s Sandwalk.
I guess a life of servitude to the public media can be stressful, at least for New Scientist writer Graham Lawton whose recent article “Why Darwin was wrong about the tree of life” graced the most recent cover of New Scientist titled “Darwin was Wrong.”
I’m really quite astonished at Lawton’s parrying and thrusting all over the blogosphere; it seems to me that any biology or science enthusiast could have predicted a little fallout resulting from the phrase “Darwin was Wrong” being placed on the cover of a popular science magazine. Indeed - I’d be shocked, if I were to discover that the generation of such hype was anything less than the premeditated goal of the magazine’s editorial staff.
In point of fact, Lawton himself states in the comments section of Sandwalk,
“I'm acutely aware that it is 50% journalism, 50% sales pitch”
So, why is Graham so glum? He’s clearly aware, as are most readers, that the cover is little more than a publicity stunt aimed at selling copy. He may be missing the very important point that although everyone recognizes the pitch, not everyone approves of the tactic.
Lawton, as well as the editorial staff of New Scientist, may think that sacrificing accuracy for the sake of profit is a respectable endeavor; however I would venture to guess that much of the magazine’s readership does not. In part, it may be that readership’s response to the cover that contributed to the comparatively apologetic tone of the article’s subsequent editorial (Editorial: Uprooting Darwin's tree tone).
At any rate, regardless of the profit margins involved in misrepresenting important biological contributions through creative cover making, why does Lawton continually assert that the article’s content somehow remedies the cover page?
I’ve read the article. It seems abundantly clear to me that Lawton’s goal was to firstly create an artificial dichotomy between Darwin’s branching tree concept and genetic studies involving horizontal gene transfer (HGT) and then, after accomplishing this, to pummel Darwin’s idea through literary biased language.
A few examples of Lawton’s biased language:
1. Speaking to the Tree of life project - “But today the project lies in tatters, torn to pieces by an onslaught of negative evidence”
2. “Many biologists now argue that the tree concept is obsolete and needs to be discarded”
3. HGT - “[This] bombshell has even persuaded some that our fundamental view of biology needs to change”
4. "For a while, this allowed evolutionary biologists to accept HGT without jeopardizing their precious tree of life”
5. Darwin’s concept - “We now know that view is wrong”
“Meanwhile, those who would chop down the tree of life continue to make progress”
6. "Having uprooted the tree of unicellular life, biologists are now taking their axes to the remaining branches”
Comparing Darwin’s tree (based on natural observation and inference) to modern molecular genetics may be stretch, but I’ll refer to the above listed blogs and their accompanying comments as opposed to laying out the arguments here…
Rather my point is very simple, popular science periodicals, as well as science journalists should strive to master the arts of clarity and accuracy; they should compose and present the resultant works in a creative and informal way that is both informative and enjoyable to the science enthusiast who partakes of them. To pursue the agitation of the informed readership and to encourage fundamentalists is – plainly and simply – wrong.
Science Journalism - “Journalism tends to have a stronger bias towards sensationalism and speculative theories than science, whereas science focuses more on fact and empirical measurement.” Lawton’s balance is askew...
As to my originally posed question at Sandwalk, “So, is the title an outright media ploy - pandering for profit – or, does Lawton lack some fundamental understanding of scientific progress?” This wasn’t a personal assault; it’s a critique of the New Scientist’s pandering and the article’s inability to distinguish between historic foundations and modern remodeling.
“Oh, and Johnny: sorry to disillusion you but I've got a pretty good understanding of scientific progress. You, however, lack a fundamental understanding of how the media works.” (Lawton)
Thanks for the disillusionment Graham, but you’ve made it abundantly clear how the media works with your comment at Evolving Thoughts,
“I really ought to make a sarcastic comment here about "really bad" bloggers, but that would be an oxymoron. (Only kidding - it's soooo much fun being rude to people on the internet, isn't it, and so much easier than being rude to them in person!)”
I do have a suggestion for the next New Scientist cover:
They’ll sell like hotcakes!
Update: Also a conversation at EvolutionBlog
Update 2: also at Pharyngula
Thursday, January 22, 2009
Atheist Files Lawsuit Against Illinois School
A federal judge has ruled that a state law requiring a moment of silence in public schools across Illinois is unconstitutional, saying it crosses the line separating church and state.
"The statute is a subtle effort to force students at impressionable ages to contemplate religion," U.S. District Judge Robert W. Gettleman said in his ruling Wednesday.
The ruling came in a lawsuit designed to bar schools from enforcing the Illinois Silent Reflection and Student Prayer Act. It was filed by talk show host Rob Sherman, an outspoken atheist, and his daughter, Dawn, a high school student.
Gettleman's ruling was not a surprise. He had already ruled in favor of Sherman in two previous decisions.
As passed by the Illinois General Assembly, the law allows students to reflect on the day's activities rather than pray if that is their choice and defenders have said it therefore doesn't force religion on anyone.
But Gettleman backed critics such as the American Civil Liberties Union, who say the law is a thinly disguised effort to bring religion into the schools.
The "teacher is required to instruct her pupils, especially in the lower grades, about prayer and its meaning as well as the limitations on their 'reflection,'" Gettleman ruled.
"The plain language of the statute, therefore, suggests and intent to force the introduction of the concept of prayer into the schools," he said.
It remained unclear if Gettleman's decision would end the dispute or merely signal a fresh battle in a federal appeals court.
State Sen. Kimberly Lightford, D-Chicago, the chief sponsor of the legislation, said she hoped Illinois Attorney General Lisa Madigan would appeal.
"I strongly feel and I still believe that children should have a moment of silence at the beginning of the school day," she said in a telephone interview from Washington, D.C., where she celebrated the inauguration of President Obama.
Madigan spokeswoman Robin Ziegler said the attorney general was reviewing Gettleman's decision and would have no immediate further comment.
Adam Schwartz, senior staff counsel of the American Civil Liberties Union, said the organization was pleased with the decision "to strike down a statewide law that coerced children to pray as part of an organized activity in our public schools."
Last year, a federal court threw out a challenge to a 2003 Texas law that allows children to "reflect, pray, meditate or engage in any other silent activities" for one minute at the beginning of each school day.
U.S. District Judge Barbara Lynn upheld the constitutionality of that law, concluding that "the primary effect of the statute is to institute a moment of silence, not to advance or inhibit religion."
Source: Here
"The statute is a subtle effort to force students at impressionable ages to contemplate religion," U.S. District Judge Robert W. Gettleman said in his ruling Wednesday.
The ruling came in a lawsuit designed to bar schools from enforcing the Illinois Silent Reflection and Student Prayer Act. It was filed by talk show host Rob Sherman, an outspoken atheist, and his daughter, Dawn, a high school student.
Gettleman's ruling was not a surprise. He had already ruled in favor of Sherman in two previous decisions.
As passed by the Illinois General Assembly, the law allows students to reflect on the day's activities rather than pray if that is their choice and defenders have said it therefore doesn't force religion on anyone.
But Gettleman backed critics such as the American Civil Liberties Union, who say the law is a thinly disguised effort to bring religion into the schools.
The "teacher is required to instruct her pupils, especially in the lower grades, about prayer and its meaning as well as the limitations on their 'reflection,'" Gettleman ruled.
"The plain language of the statute, therefore, suggests and intent to force the introduction of the concept of prayer into the schools," he said.
It remained unclear if Gettleman's decision would end the dispute or merely signal a fresh battle in a federal appeals court.
State Sen. Kimberly Lightford, D-Chicago, the chief sponsor of the legislation, said she hoped Illinois Attorney General Lisa Madigan would appeal.
"I strongly feel and I still believe that children should have a moment of silence at the beginning of the school day," she said in a telephone interview from Washington, D.C., where she celebrated the inauguration of President Obama.
Madigan spokeswoman Robin Ziegler said the attorney general was reviewing Gettleman's decision and would have no immediate further comment.
Adam Schwartz, senior staff counsel of the American Civil Liberties Union, said the organization was pleased with the decision "to strike down a statewide law that coerced children to pray as part of an organized activity in our public schools."
Last year, a federal court threw out a challenge to a 2003 Texas law that allows children to "reflect, pray, meditate or engage in any other silent activities" for one minute at the beginning of each school day.
U.S. District Judge Barbara Lynn upheld the constitutionality of that law, concluding that "the primary effect of the statute is to institute a moment of silence, not to advance or inhibit religion."
Source: Here
Tuesday, January 20, 2009
Wetland Plant of the Week #1
Crinum americanum
“Southern Swamp-Lily” or “String-Lily”
Perennial herb with strap-like leaves and large white flowers distinguished by red stamen filaments. This obligate species was photographed in the Big Cypress.
“Southern Swamp-Lily” or “String-Lily”Perennial herb with strap-like leaves and large white flowers distinguished by red stamen filaments. This obligate species was photographed in the Big Cypress.
Monday, January 19, 2009
Niche Construction and Extended Phenotypes
The Extended Pheontype Concept Vs Nich Construction Theory
From Science Daily: Here
Richard Dawkins' Extended Phenotype (EP) concept is as relevant now as when it was first proposed 26 years ago and is not at odds with other evolutionary explanations. This was the conclusion of a recent workshop on the Extended Phenotype today, organized by the European Science Foundation (ESF).
The EP states that the genes of an organism can be expressed beyond its immediate biological boundary, extending for example to birds' nests, or the behaviour of hosts infected by parasites. The key point is that the EP embraces constructions, such as the dams built by beavers, whose quality is correlated with variations, or alleles, in certain of the organism's genes, so that natural selection can act upon them. A new allele that leads to better dam constructions will in turn benefit the beaver expressing it. Similarly a parasite allele that causes the behaviour of its host to change in a way that increases the parasite's chance of survival will be favoured.
Dawkins regarded EP as his single most important contribution to evolutionary biology, but since its publication in 1982, other theories have emerged and questions have arisen over its own fitness for survival. Any doubts were dispelled at the ESF conference, which resurrected EP as an important and valuable concept that helps explain evolution, even though it does not actually help predict specific outcomes.
"It was recognised that it has explanatory rather than predictive power," said David Hughes, convenor of the ESF workshop, from the Department of Biology, University of Copenhagen, now at Harvard. "It is a good way of looking at things but not necessarily the best approach when designing experiments."
The idea that niche construction, often considered as a rival theory, contradicted EP was dismissed. "It was agreed that other currently topical points of debate such as Niche Construction theory had no major conflict with the EP," said Hughes.
However there was lively debate between Dawkins and proponents of niche construction over the role of evolution within closely coupled ecosystems. Niche construction theory goes further than EP by suggesting that organisms can alter the selective pressures acting on them by modifying their environment in many ways beyond immediate constructions such as beaver dams. In niche construction theory, the link between variations in an organism's genes and in the surrounding environment is more loosely coupled with no clear mechanism for natural selection to operate.
However according to niche construction theory, there is a feedback effect, in that the genes of organisms alter the environment indirectly, for example by improving nests, that in turn modifies the selective pressures on those genes. Dawkins argued that niche construction is really a special case of EP, relating to genes of those organisms that participate in the relevant environmental construction. But he dismissed the idea that evolution can act in a broader sense across a whole ecosystem, extending to organisms not directly involved in the niche construction. He reiterated the point running through all his books, that selection can only operate against variation of replicators, which are almost always alleles (variants) of genes. The variation in genes caused by mutation generates the different phenotypes, characteristics such as animal behaviour, that allow natural selection to work.
Some advocates of niche construction have suggested that evolution can operate at longer range. For example beavers construct dams that might benefit other animals not directly associated with them. While this may be the case, Dawkins has consistently argued that this would not result in behaviour that would help select genes in beavers themselves that would lead to better dams. Only organisms whose response to better dams has a direct benefit for beavers can affect selection of beaver genes, Dawkins argues.
These points were accepted at the ESF workshop, which concluded that the EP was fine as it stood with no need of revision. Moreover, it emerged that recent research on metabolism had reinforced the EP concept, in particular by showing how closely the health of mammals including humans depends on the populations of microbes, especially bacteria, in the gut. EP might help understand how these populations have evolved in concert with mammals.
Ideas for further projects were proposed. "A follow up funding application is a great idea and it should focus on examining the parasite manipulation of host behaviour component," said Hughes. "There was also a suggestion to have a separate application for a nest construction pan-EU network." These programs would be truly European, typically involving 5-7 partners across the EU.
From Science Daily: Here
Richard Dawkins' Extended Phenotype (EP) concept is as relevant now as when it was first proposed 26 years ago and is not at odds with other evolutionary explanations. This was the conclusion of a recent workshop on the Extended Phenotype today, organized by the European Science Foundation (ESF).
The EP states that the genes of an organism can be expressed beyond its immediate biological boundary, extending for example to birds' nests, or the behaviour of hosts infected by parasites. The key point is that the EP embraces constructions, such as the dams built by beavers, whose quality is correlated with variations, or alleles, in certain of the organism's genes, so that natural selection can act upon them. A new allele that leads to better dam constructions will in turn benefit the beaver expressing it. Similarly a parasite allele that causes the behaviour of its host to change in a way that increases the parasite's chance of survival will be favoured.
Dawkins regarded EP as his single most important contribution to evolutionary biology, but since its publication in 1982, other theories have emerged and questions have arisen over its own fitness for survival. Any doubts were dispelled at the ESF conference, which resurrected EP as an important and valuable concept that helps explain evolution, even though it does not actually help predict specific outcomes.
"It was recognised that it has explanatory rather than predictive power," said David Hughes, convenor of the ESF workshop, from the Department of Biology, University of Copenhagen, now at Harvard. "It is a good way of looking at things but not necessarily the best approach when designing experiments."
The idea that niche construction, often considered as a rival theory, contradicted EP was dismissed. "It was agreed that other currently topical points of debate such as Niche Construction theory had no major conflict with the EP," said Hughes.
However there was lively debate between Dawkins and proponents of niche construction over the role of evolution within closely coupled ecosystems. Niche construction theory goes further than EP by suggesting that organisms can alter the selective pressures acting on them by modifying their environment in many ways beyond immediate constructions such as beaver dams. In niche construction theory, the link between variations in an organism's genes and in the surrounding environment is more loosely coupled with no clear mechanism for natural selection to operate.
However according to niche construction theory, there is a feedback effect, in that the genes of organisms alter the environment indirectly, for example by improving nests, that in turn modifies the selective pressures on those genes. Dawkins argued that niche construction is really a special case of EP, relating to genes of those organisms that participate in the relevant environmental construction. But he dismissed the idea that evolution can act in a broader sense across a whole ecosystem, extending to organisms not directly involved in the niche construction. He reiterated the point running through all his books, that selection can only operate against variation of replicators, which are almost always alleles (variants) of genes. The variation in genes caused by mutation generates the different phenotypes, characteristics such as animal behaviour, that allow natural selection to work.
Some advocates of niche construction have suggested that evolution can operate at longer range. For example beavers construct dams that might benefit other animals not directly associated with them. While this may be the case, Dawkins has consistently argued that this would not result in behaviour that would help select genes in beavers themselves that would lead to better dams. Only organisms whose response to better dams has a direct benefit for beavers can affect selection of beaver genes, Dawkins argues.
These points were accepted at the ESF workshop, which concluded that the EP was fine as it stood with no need of revision. Moreover, it emerged that recent research on metabolism had reinforced the EP concept, in particular by showing how closely the health of mammals including humans depends on the populations of microbes, especially bacteria, in the gut. EP might help understand how these populations have evolved in concert with mammals.
Ideas for further projects were proposed. "A follow up funding application is a great idea and it should focus on examining the parasite manipulation of host behaviour component," said Hughes. "There was also a suggestion to have a separate application for a nest construction pan-EU network." These programs would be truly European, typically involving 5-7 partners across the EU.
Friday, January 16, 2009
RE: Improbable Mountains in the Landscape
A couple days back, Chris Nedin at Ediacaran posted an excellent blog discussing Richard Dawkins’ Mt. Improbable analogy. As a means of commenting, I had cut and pasted a copy with my thoughts interdispersed here - Improbable Mountains in the Landscape.
As shown in the the comments section of that blog, Chris subsequently provided clarification and comment as a followup.
As a re-comment followup, I have posted the below thoughts as a new blog. A new blog was required because what I lack in substance I try to makeup for in shear bulk.
Chris,
I enjoy reading your writing, and many thanks for the time spent clarifying your point at my blogsite. I sincerely appreciate your patience in talking me through the analogy and your perspective of it, but – I struggle still…
POINT 1
I’m still not quite grasping the implication of the peak as an evolutionary cause rather than its consequence – or, as guiding? Do you mean that because a peak ends at a tapered point it gives the erroneous impression that the adaptation (or, increased “allele concentration”) is being filtered, dwindled or refined to a single individual as opposed to merely becoming more prevalent in the population?
[When I referred to an “end point” in my initial comment, I meant the expression in a similar sense as that used by Payne (see your “Told ya so”) when he mentioned a “pre-existing evolutionary potential.” In other words, the idea of an organism approaching a wall or limit in its available genetic range or plasticity.]
My gut feeling is that you’re viewing allele concentration as increasing towards adaptation/specialization and therefore being better symbolized by an expansion or widening as oppose to a taper? Sort of like this image:
I realize that I’ve eliminated a dimension from the landscape in this crude sketch; however from this graphic I can see a couple or your points illustrated:
1- Fitness decreases as allele concentration increases
2- Novelty would arise from the Generalists
3- Generalists exhibit the most fitness
In addition, the “pit” could be visualized as the area beneath the slope of the allele frequency (increasing towards adaptation, as you suggest); and the “peak” would be found at the maximum of the allele concentration (at the widest/deepest point of the pit).
e.g.
Beyond the images being overly simplistic and rudimentary, if the above likenesses accurately depict the fundamentals of the “pit” analogy- in terms of process only, I would only disagree with you regarding the y-axis. (I’m sure you saw that one coming.)
As an alternative, if we flipped the y-axis upside and let it represent increasing fitness (currently it’s displaying the inverse of fitness “1/Fitness”) the following would occur:
1- Novelty would rise from small populations (less fitness)
2- The “peak” would represent greater levels of specialization
3- The greater levels of adaptation would be found in the most fit populations
Such an alternative version would be more to my liking.
POINT 2
I think our disagreement regarding the peak as being “stagnant” or required as a prerequisite for adaptation is more-or-less a difference in interpretation of the intent of Dawkins’ analogy. I’m viewing the peak as occupied by an organism/population struggling to adapt to a fluctuating environment but being handicapped by genotypes inherited from ancestral lineages - a balancing act between inheritance and current selective pressures.
The organism is “handicapped” because its ancestors had struggled with a past environment that would have been different than the current one; ecologically different as measured by degree – all ecosystems undergo transition; for example a Coastal Grassland typically transitions into Flatwoods. Yes, major extinction events and catastrophes occur (with dramatic effect, often testing the breaking point of plasticity), but in terms of probability and frequency these are second to more gradual (not “slow;” rather step-by-step) changes.
In this sense, there is no pre-existing environment towards which an organism strives, it works with what’s at hand, AND, when probability succeeds in achieving sufficient “allele concentrations” (achieved through a combination of inheritance and selective pressures, mutation, etc…) adaptation occurs. With this adaptation resources become more readily available and relative fitness improves; thereby increasing the probability of greater allele concentrations (positive phenotypes) in future generations – a positive feedback. (Don’t want to get off on a tangent here, but remember that most feedbacks have delays)
Fitness must be increasing on the above y-axis! Otherwise nothing (regardless of the process that brought it to existence) becomes fixed.
POINT 3
Last point, I promise - Acquisition and loss of alleles and/or phenotypes…
Firstly, let me reemphasize that I interpret the “peak” as being representative of any given organism’s (or population’s or species’) current state of existence; the total and complete sum of its current condition. I do not interpret the peak as perfection or as a driver; it’s just a place marker.
Secondly, let me restate that “Phenotypes are not pro-actively reduced to a vestigial state; rather they’re no longer actively maintained. There’s no longer a pressure for the original phenotype to be preserved.”
If there is no active reducing, and they’re no longer actively maintained, then there is little or no “dead allele weight” to serve as baggage. Active change (adaptation) in the presence of selective pressures (of any variety) requires energy expenditure; inactivity and stasis are a bargain by comparison.
For example: Going back to the two fish example; let’s sat that there are two fish, one with well formed, fully functional eyes, the other with poorly functioning eyes. Both fish reside in a dark cave environment that has been stable for a reasonable amount of time. But then, suddenly - the environment changes!
The water temperature rises by half of a degree – that’s substantial change in an aquatic environment!
How could either fish be said to carrying extra baggage or dead allele weight? Yes, the fish with full eyesight may now need to work towards thermal tolerance, but it doesn’t need to work towards blindness or eye loss! In fact, both fish will now need to move towards thermal tolerance and I’m willing to wager that they both are under other pressures as well. They may be “working towards” elongate tactile whiskers and improved lateral line systems; they may be “working towards” the ability to produce sound (grunting) to attract mates… There could be numerous adaptations that one or both fish are “working towards.”
From this example we could say, “Given the totality of the circumstance, I think the fish with poor eyesight is better adapted to the dark warm cave.”
We couldn’t say, “The fish with poor eyesight is more evolved.”
We couldn’t say, “The goal of the fish with functional eyes is to become blind.”
Most importantly, we couldn’t say, “The better adapted fish is at an evolutionary dead end - and is doomed.”
As an alternative, if we flipped the y-axis upside and let it represent increasing fitness (currently it’s displaying the inverse of fitness “1/Fitness”) the following would occur:
1- Novelty would rise from small populations (less fitness)
2- The “peak” would represent greater levels of specialization
3- The greater levels of adaptation would be found in the most fit populations
Such an alternative version would be more to my liking.
POINT 2
I think our disagreement regarding the peak as being “stagnant” or required as a prerequisite for adaptation is more-or-less a difference in interpretation of the intent of Dawkins’ analogy. I’m viewing the peak as occupied by an organism/population struggling to adapt to a fluctuating environment but being handicapped by genotypes inherited from ancestral lineages - a balancing act between inheritance and current selective pressures.
The organism is “handicapped” because its ancestors had struggled with a past environment that would have been different than the current one; ecologically different as measured by degree – all ecosystems undergo transition; for example a Coastal Grassland typically transitions into Flatwoods. Yes, major extinction events and catastrophes occur (with dramatic effect, often testing the breaking point of plasticity), but in terms of probability and frequency these are second to more gradual (not “slow;” rather step-by-step) changes.
In this sense, there is no pre-existing environment towards which an organism strives, it works with what’s at hand, AND, when probability succeeds in achieving sufficient “allele concentrations” (achieved through a combination of inheritance and selective pressures, mutation, etc…) adaptation occurs. With this adaptation resources become more readily available and relative fitness improves; thereby increasing the probability of greater allele concentrations (positive phenotypes) in future generations – a positive feedback. (Don’t want to get off on a tangent here, but remember that most feedbacks have delays)
Fitness must be increasing on the above y-axis! Otherwise nothing (regardless of the process that brought it to existence) becomes fixed.
POINT 3
Last point, I promise - Acquisition and loss of alleles and/or phenotypes…
Firstly, let me reemphasize that I interpret the “peak” as being representative of any given organism’s (or population’s or species’) current state of existence; the total and complete sum of its current condition. I do not interpret the peak as perfection or as a driver; it’s just a place marker.
Secondly, let me restate that “Phenotypes are not pro-actively reduced to a vestigial state; rather they’re no longer actively maintained. There’s no longer a pressure for the original phenotype to be preserved.”
If there is no active reducing, and they’re no longer actively maintained, then there is little or no “dead allele weight” to serve as baggage. Active change (adaptation) in the presence of selective pressures (of any variety) requires energy expenditure; inactivity and stasis are a bargain by comparison.
For example: Going back to the two fish example; let’s sat that there are two fish, one with well formed, fully functional eyes, the other with poorly functioning eyes. Both fish reside in a dark cave environment that has been stable for a reasonable amount of time. But then, suddenly - the environment changes!
The water temperature rises by half of a degree – that’s substantial change in an aquatic environment!
How could either fish be said to carrying extra baggage or dead allele weight? Yes, the fish with full eyesight may now need to work towards thermal tolerance, but it doesn’t need to work towards blindness or eye loss! In fact, both fish will now need to move towards thermal tolerance and I’m willing to wager that they both are under other pressures as well. They may be “working towards” elongate tactile whiskers and improved lateral line systems; they may be “working towards” the ability to produce sound (grunting) to attract mates… There could be numerous adaptations that one or both fish are “working towards.”
From this example we could say, “Given the totality of the circumstance, I think the fish with poor eyesight is better adapted to the dark warm cave.”
We couldn’t say, “The fish with poor eyesight is more evolved.”
We couldn’t say, “The goal of the fish with functional eyes is to become blind.”
Most importantly, we couldn’t say, “The better adapted fish is at an evolutionary dead end - and is doomed.”
Wednesday, January 14, 2009
Original audition tape for House (Hugh Laurie)
Nothing to do with anything inparticular; I'm a fan of the show and there are some good one liners here!
Dr. House Casting Session - Funny home videos are a click away
Dr. House Casting Session - Funny home videos are a click away
Improbable Mountains in the Landscape
Chris Nedin at Ediacaran posted an excellent blog discussing Richard Dawkins’ Mt. Improbable analogy. Below I have cut and pasted a copy with my thoughts interdispersed; for the purposes of commenting only. His text is in quotes.
"In the ongoing Adaptationist v. Pluralist debate, both sides agree on a surprising amount. Both sides agree that there is more to evolution than adaptation by natural selection. However, Adaptationist would argue that adaptation by natural selection is the most important, or even the overwhelming, evolutionary process, and that evolution can be described as climbing Mt. Improbable – with adaptation to environment similar to climbing a fitness landscape peak towards optimal fitness (but please note, never, ever, reaching the top!)"
This misses the mark somewhat, and I think there are a couple of flawed inferences that would benefit from a touch of clarification. Firstly, the mountain metaphor was (and is) intended as fortification against the argument from design; or contra spontaneous materialization of “fully formed” and/or “fully adapted” organisms. When referenced in debates such as that of the “Adaptationist v. Pluralist” it can also be interpreted as being oppositional to radical saltations and other major macromutations of behavior or morphology that would result in the instantaneous generation of novel adaptations, or even a new species – such as making the leap from an individual amphibian to a reptile in a single birthing episode. In terms of fitness landscapes- peaks and mountains are only informative with respect to local genotypic values; in this way the analogy can be seen as limiting to lateral jumps between said peaks. In either the design or anti-saltation interpretations, Mt. Improbable certainly isn’t proposed as a formal hypothesis or mathematical model; it’s proposed as a mental tool to assist the lay science reader and general population in understanding the fundamental idea of change through time.
Mt. Improbable’s “peak” isn’t equivalent to “optimal fitness” or “adaptive perfection.” Indeed, adaptive perfection doesn’t exist, nor would Dawkins propose that it does; natural selection is only capable of providing a “better” solution, not a “best” solution. The mountain’s peak represents the current state and condition (inclusive of fitness) of any given organism, which when viewed from afar gives the FALSE appearance of being optimal, designed or perfectly adapted. From this point of view Mt. Improbable doesn’t detail where an organism is going or to what environmental factors it’s trying to adapt; instead it explains how the organism reached it’s current circumstance (i.e. gradually, not in a single giant leap).
The steady incline located on the opposite side of Mt. Improbable is the antithesis of a sheer cliff or rock face that would necessitate assistance from an external source or some other highly statistically unlikely event (i.e. improbable) in order to surmount or obtain it (“it,” being the before mentioned current condition). In this sense, the analogy of “climbing” wasn’t meant to represent a movement towards increased complexity, optimum fitness or some ideal form, but rather it was intended as a model for step-by-step, gradual processes in which leaps, jumps and major saltations are avoided. [To be clear - “gradual” used in this way doesn’t imply “slow,” or imperceptibly minute as may be interpreted during common use, but instead it means “graduated” as in stepwise or measured – not “slow change” but “bit-by-bit” by degrees of change.]
Regarding the statement, “but please note, never, ever, reaching the top!” – Of course it can’t be reached; as described above, a “better” solution (or increased fitness) is the only option. That said, some highly specialized organisms do get really close to the “end point” of their available genetic variation, when this occurs either the environment changes and they move in a different direction (up or down whatever mountain on which they happen to reside), or they enter a period of stasis (during stasis allele frequencies do change, but selection pressure isn’t sufficient to drive novel adaptations).
"I disagree. I think genetic drift accounts for most of the evolution that occurs, and natural selection, while very important – especially in creating diversity – accounts for a smaller percentage. However, both have worked together to produce the diversity of life on Earth."
Genetic drift absolutely serves as a source of variation within populations, and it may lead to adaptations, BUT in order for that variation or adaptation to become fixed in any meaningful way we need natural selection.
"I also have a problem with the Mt Improbable analogy . . . well, actually I have two problems.1) It perpetuates the idea that evolution is an upward striving process, and that derived or adapted groups are higher, than the less derived or less adapted and, as a consequence, fitter, advanced . . .better. (the old Tree of Life analogy problem.)"There’s a key concept being missed here. The Mt. Improbable analogy does not, and is not intended to, predict or delineate evolutionary drivers, pressures or goals. Nor does it create a continuum of higher or lesser organisms. Its perspective is from the rearview mirror, it looks backwards in time.
Question: How did this organism reach such a state of seemingly perfect environmental synchrony?
Mt. Improbable’s Answer: Through a gradual bit-by-bit process, not in a single saltation.
Furthermore, the analogy doesn’t attempt to rank or compare the vastness of the Earth’s biota; it doesn’t establish a scale in order to weigh relative fitness or adaptation between individuals or species. It’s one critter atop the mount looking backwards though ancestral lineages.
"OK, maybe it is applicable to a fitness landscape, but there is no reason that the landscape has to have the peaks pointing upwards, . . . is there? Surely it's the distance between where you are on the peak and the schmucks on the fitness plane that is important, not the direction of that distance?"
No, there isn’t any particular reason why an upward rising mountain needs to be called into play in order for this concept to be understood. However neutral language does not lend itself to memorable metaphors; simplicity, clarity and fit are far more important. If envisioning an organism gazing up from a pit is more appealing than is considering one peering from a peak, then by all means…
Unless our goal is to create an artificial value system to scale and rank levels of fitness between unrelated organisms, the inter-schmuck distances and movements (upwards or downwards) seem irrelevant.
"Plus, fitness landscapes, are not permanent, or even solid. They change with the environment. A population/species, or whatever, may be quite "high" (see how hard it is to use neutral language)on a fitness peak one minute, and find itself down on the plane, or even in a fitness trough, with hardly any change in allele frequency, but a significant change in environment. In other words the fitness landscape moved underneath it."
Unless someone is implying that landscapes, environmental conditions, allele frequencies, selective pressures or any other biologic variables are static and non-dynamic - this almost seems a non sequitur. Of course, everything is in a state of flux; does the mountain analogy suggest stagnation of ecology?
"2) The real problem with the Mt Improbable analogy though, is that it gives the impression that as hard as it is to ‘climb up’ (and it is), the analogy suggests that it is relatively easier to ‘climb down’ - and it isn’t because its actually harder. OK that might be pushing the analogy a bit far – but that’s the point, it doesn’t hold up to detailed scrutiny."
It’s an analogy used to paint a picture of a basic premise. “Hard” climbing is in the eye of the beholder; a movement “up” or “down” requires the same amount of expenditure and neither direction denotes relative superiority.
"The real problem is that adaptation, in the broader picture, is an evolutionary cul-de-sac."
Quite the contrary, adaptation is antithetical to a “dead end” – Show me a successful lineage of organisms and I’ll show you an adaptation!
"Adaptation means that certain alleles are being selected for because they confer an advantage in a particular environment. If the environment changes, then the alleles that conferred an advantage may no longer do so. Worse, the very process of selecting for certain alleles may well have stopped other alleles getting fixed through drift – alleles which might be beneficial in the new environment. Even worse, the alleles that were originally selected for may be costly to produce and maintain where they confer no advantage, and thus be deleterious."
Does this imply, or openly state, that adaptation prevents and/or hinders biological evolution?
"But the really bad thing is that, as hard as it is to gain the alleles that provided an advantage, it is even harder to loose them, as this would require specific mutations to affect those particular alleles (rather than the random process that produced them). You could reduce them to a vestigial level, provided you survived long enough to do so. Difficult though, if you are struggling to survive in a new environment where the competition does not have the adaptive dead weight (unless you have some other advantage.)"
Phenotypes are not pro-actively reduced to a vestigial state; rather they’re no longer actively maintained. There’s no longer a pressure for the original phenotype to be preserved.
Once again, this would occur in a gradual manner (up or down directionality is irrelevant): If a species of fish finds itself in a dark cave portions of its anatomy supporting eyesight may no longer be positively selected. Overtime, sub-portions of this vision complex may undergo mutation, or be selected for another biological function. This may result in a slow degeneration of the complex through time. The eye will not disappear in its entirety overnight – it will be phased out. This however says nothing about complexity or the direction of evolution; the fish isn’t “more evolved” it’s better adapted to a given environment.
"The more adapted a group becomes, the more imbedded it is in a particular environment, and the more sensitive it is to changes to that environment."
Yes! This is the keystone of resource conservation – Save the Environment!
"Eventually all strategies lead to extinction, but during environmental change, it’s the generalists that survive, not the specialists. Adaptation generally leads to extinction. Highly adapted groups/species and ecosystems delicately balanced on a web of interconnected adaptations, will crash once environments change."
Seems a bit redundant here, everything leads to extinction + adaptation leads to extinction. My understanding is that some strategies improve fitness; others do indeed lead to extinction. And, generalists sometimes go extinct; specialists sometimes survive an environmental change.
Ecosystem’s “crash” is relative to which organisms are becoming extinct and which are becoming more specialized (adapted) to use (or better use) what resources remain.
"Adaptation is not climbing up Mt Improbable, it’s climbing down Pit Improbable!The pits are hard to find, but once in, it’s easier to go down than it is to back out, and if you adapt too far, you are trapped in a cul-de-sac with no way out when the environment changes. The generalists that flirt with the rim of the pit, or on the fitness plane have a better chance of surviving to become the stem stock for new adaptations. "
"It may well be that some species or groups of species in a pit break through to new fitness landscapes and produce new groups (e.g. birds and mammals from reptiles) because fitness landscapes are not flat, but curved.But for most populations/species, adaptation is a pit of no return."Speciation, radiation, variety and biodiversity represent the consequences of specialization regardless of the drivers that push them to existence. “Ultimate survival” is a test to which we are all doomed to fail; however local survival in a given habitat, microhabitat or niche can be achieved and, in fact, is achieved more frequently than one should expect mathematically. This, in its majority, is due to specialization. From hyperthermophiles to lemurs – it’s adaptation that pushes life to the extremes, providing opportunity and prospect to the full range of creatures on the planet today. As the world’s climates continue to change, adaptation to the Arctic environment may eventually remove polar bears from existence; however it’s that same specialization and adaptation that put them there in the first place.
PS- It has just been pointed out to me that the Mt Improbable analogy was blogged (back in July) by Larry Moran at Sandwalk; with a counter argument by Jason Rosenhouse from EvolutionBlog.
Monday, January 12, 2009
"Today is a great day for America's public lands"
After several years of resource conservation shortfalls, it appears as though the tides are beginning to turn in Washington. Good News!
Keep your mimics close, but your mutualists closer: Mutualism and competition among Ithomiinae
While contentedly paddling around the river PLoS this morning, I happened upon a paper discussing niche convergence in the rainforest butterfly Family Nymphalidae . Diving into the article, I was pleasantly surprised to discover that Marianne Elias (et al), having been discontent with examining Müllerian mimicry from the usual perspectives, decided to study not only wing patterns and ring species dynamics but also the convergence of microhabitat in several neotropical species of butterfly;
"We showed that mutualism drives convergence in flight height and forest habitat, and that these effects outweigh common ancestry (which should lead related species to be more similar) and competition (which promotes ecological divergence). Our findings imply that species that benefit from one another might evolve to form more tightly knit local communities, suggesting that adaptation is a more important process affecting community composition than is commonly suspected."
That any two species, rather they be model and mimic species or co-mimic, should converge in terms of a behavior (such as flight pattern) didn’t seem all too surprising, nor did mentioning that adaptations could outweigh common ancestry; this at a very fundamental level would seem reasonable considering that biodiversity could be defined in terms of moving from, and breaking, the bonds of ancestral characteristics. However, a finding that co-mimics can converge to occupy the same microhabitat - now that’s something worthy of a second look!
Perhaps it’s a personal bias favoring competitive evolutionary drivers (which is by no means impossible) or some other inexplicable and diabolical thought process, but for some unknown reason, I found myself reminded of Sun Tzu’s advice (or was it Don Corleone’s?) regarding long term partnerships, “Keep your friends close, but your enemies closer.” In other words, I find myself harboring doubt as to just how deep this mutualism runs, and I’m curious as to the potential for apparent friends to become realized enemies; figuratively speaking of course.
Although certainly not in a position to argue to the contrary (or for that matter to even suggest it, wait…nevermind.), the idea that two genetically distinct species would develop a mutually beneficial mimicry (+,+) while occupying the same niche, the same microhabitat and while sharing (tough not reading as “competing for”) the same ecological resources seemed… Well it seems extraordinary.
Assuming that;
- they live in the same place (microhabitat)
- they’re converging morphologically (wing patterns)
- they’re converging behaviorally (flight characteristics)
- their larvae feed on the same plants (Solanaceae, almost exclusively)
- almost all males seek the same pyrrolizidine alkaloids for protection (bad bug taste)
- almost all males use the same alkaloids for use in pheromone signaling (come hither smell)
AND assuming that the only (recognized) mutual benefit is that they have the same predators (insectivorous birds; thereby sharing the cost of local predation)… Well it’s tough for me to wrap my head around… It’s as though some lepidopteran lawyers sat down and drew up a contract –
IN EXCHANGE FOR A 50% DECREASE* IN LOCAL MORTALITY, I HEREBY RENDER THE FOLLOWING TO THE INCOMING POPULATION OF POTENTIAL MUTUALISTS:
½ OF MY FOOD SUPPLY
½ OF MY LARVAE HOST PLANTS
½ OF MY CHEMICAL/ALKALOID SUPPLIES
FURTHERMORE, I RECOGNIZE AND ACKNOWLEDGE THAT THE POTENTIAL MUTUALISTS ARE NOT LIABLE FOR DAMAGES INCURRED FOR ANY TIME, ENERGY OR RESOURCES MISAPPROPRIATED ON MY BEHALF IN PURSUING PHEROMONE TRAILS, FLIGHT BEHAVIORS, WING COLORS OR WING PATTERNS OF WHAT I MISTAKENLY PERCEIVE TO BE POTENTIAL MATES, OR POTENTIAL RIVALS.
*VALUE BASED ON A “BAD DAY” FOR INCOMING MIMIC. YOUR ACTUAL PERCENT OF DECREASED MORTALITY MAY BE LESS.
There may be a light sarcasm effervescing from the text here, but I am sincerely having some difficulty in understanding why these habitat converging mutualists aren’t bunting heads and/or getting their antennae tied in knots?
Is there perhaps a temporal factor that I missed? If the mutualists utilize the same resource base, but only did so through varied circadian rhythms or timings, perhaps conflict (competition) could be minimized to the point of obscurity? It shouldn’t take much scheduled variance to make it worthwhile for both parties; does one species or the other prefer the early bird (or butterfly) special to evening seating? (On second thought, meals would be served on the providing plant’s timeline – which I would guess to be ecologically/adaptively linked to a specific species in order to maximize pollination or other benefit.)
Or, maybe there is some other unmentioned (or unnoticed by me) misfiring of apparent parsimony somewhere? Just because two species undergo convergence doesn’t necessarily require that they do so in a precise and complete manner. “Eye spot” patterns on the wings of mimics, for example, may appear as unappetizing as those of the model species and serve equally as well to dissuade would be predators – even if the spots aren’t the exact shade of brown, or of precisely the same shape, size or dimensions.
I realize that this blog is turning into an essay, but before closing there’s just one more minor note to be made - At the start, the article takes a markedly clear, and easily read look into the compounding effects of convergence by moving from homologies of wing pattern, through comparisons of flight height and then onto microhabitat convergence, but then in closing,
Perhaps it’s a personal bias favoring competitive evolutionary drivers (which is by no means impossible) or some other inexplicable and diabolical thought process, but for some unknown reason, I found myself reminded of Sun Tzu’s advice (or was it Don Corleone’s?) regarding long term partnerships, “Keep your friends close, but your enemies closer.” In other words, I find myself harboring doubt as to just how deep this mutualism runs, and I’m curious as to the potential for apparent friends to become realized enemies; figuratively speaking of course.
Although certainly not in a position to argue to the contrary (or for that matter to even suggest it, wait…nevermind.), the idea that two genetically distinct species would develop a mutually beneficial mimicry (+,+) while occupying the same niche, the same microhabitat and while sharing (tough not reading as “competing for”) the same ecological resources seemed… Well it seems extraordinary.
Assuming that;
- they live in the same place (microhabitat)
- they’re converging morphologically (wing patterns)
- they’re converging behaviorally (flight characteristics)
- their larvae feed on the same plants (Solanaceae, almost exclusively)
- almost all males seek the same pyrrolizidine alkaloids for protection (bad bug taste)
- almost all males use the same alkaloids for use in pheromone signaling (come hither smell)
AND assuming that the only (recognized) mutual benefit is that they have the same predators (insectivorous birds; thereby sharing the cost of local predation)… Well it’s tough for me to wrap my head around… It’s as though some lepidopteran lawyers sat down and drew up a contract –
IN EXCHANGE FOR A 50% DECREASE* IN LOCAL MORTALITY, I HEREBY RENDER THE FOLLOWING TO THE INCOMING POPULATION OF POTENTIAL MUTUALISTS:
½ OF MY FOOD SUPPLY
½ OF MY LARVAE HOST PLANTS
½ OF MY CHEMICAL/ALKALOID SUPPLIES
FURTHERMORE, I RECOGNIZE AND ACKNOWLEDGE THAT THE POTENTIAL MUTUALISTS ARE NOT LIABLE FOR DAMAGES INCURRED FOR ANY TIME, ENERGY OR RESOURCES MISAPPROPRIATED ON MY BEHALF IN PURSUING PHEROMONE TRAILS, FLIGHT BEHAVIORS, WING COLORS OR WING PATTERNS OF WHAT I MISTAKENLY PERCEIVE TO BE POTENTIAL MATES, OR POTENTIAL RIVALS.
*VALUE BASED ON A “BAD DAY” FOR INCOMING MIMIC. YOUR ACTUAL PERCENT OF DECREASED MORTALITY MAY BE LESS.
There may be a light sarcasm effervescing from the text here, but I am sincerely having some difficulty in understanding why these habitat converging mutualists aren’t bunting heads and/or getting their antennae tied in knots?
Is there perhaps a temporal factor that I missed? If the mutualists utilize the same resource base, but only did so through varied circadian rhythms or timings, perhaps conflict (competition) could be minimized to the point of obscurity? It shouldn’t take much scheduled variance to make it worthwhile for both parties; does one species or the other prefer the early bird (or butterfly) special to evening seating? (On second thought, meals would be served on the providing plant’s timeline – which I would guess to be ecologically/adaptively linked to a specific species in order to maximize pollination or other benefit.)
Or, maybe there is some other unmentioned (or unnoticed by me) misfiring of apparent parsimony somewhere? Just because two species undergo convergence doesn’t necessarily require that they do so in a precise and complete manner. “Eye spot” patterns on the wings of mimics, for example, may appear as unappetizing as those of the model species and serve equally as well to dissuade would be predators – even if the spots aren’t the exact shade of brown, or of precisely the same shape, size or dimensions.
I realize that this blog is turning into an essay, but before closing there’s just one more minor note to be made - At the start, the article takes a markedly clear, and easily read look into the compounding effects of convergence by moving from homologies of wing pattern, through comparisons of flight height and then onto microhabitat convergence, but then in closing,
"Finally, our findings further support the idea of mimicry as a driver of speciation through ecological adaptation [59]. The implications of mimicry evolution extend far beyond the evolution of warning signals, with links to microhabitat use, including flight height and forest structure [24–26], but also to mate choice [60], flight physiology [61], and larval host plant use [24,27]. "
This seems to fit with the research and presented evidence, at least up to the “…but also...”
The last minute throwdown of mate choice, flight physiology and other “implications of mimicry” as inferred from various referenced studies, although quite possibly both legitimate and accurate, put my already swirling head into vertigo. If this process is indeed as I understand it to be, then I can’t help but think that such drives could only be found in localities exhibiting extremes of biodiversity, an excess of resources and a vast assortment of overlapping ranges and intermediary species; for example biodiversity hotspots such as those found in the Amazon where this study was conducted. How prevalent is this flavor of ecological convergence? And at what tempo and frequency does it operate? Is such a driver an Evolutionarily Stable Strategy – or does it possess a well concealed competitive underpinning?
In several places within the article, the authors state that this mode of adaptation “…is a more important process affecting community composition than is commonly suspected.” In regards to “common expectations” I readily concur, though admittedly if I were a model lepidopteran species, I wouldn’t be taking the Don up on his advice, rather I’d be keeping my recent mutualists closer than my closest of mimics.
Update: Please read George Beccaloni’s comment for additional clarification
Marianne Elias, Zachariah Gompert, Chris Jiggins, Keith Willmott (2008). Mutualistic Interactions Drive Ecological Niche Convergence in a Diverse Butterfly Community PLoS Biology, 6 (12) DOI: 10.1371/journal.pbio.0060300
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