Alfred Russel Wallace, a Conspicuous Caterpillar and David Bowie

Prior to yesterday morning I had never contemplated the linkages between rock’n roller David Bowie and the co-founder of Natural Selection Alfred Russel Wallace. It turns-out that these famous Brits hold at least two things in common; the first and most obvious of which is the already mentioned fact that both Wallace and Bowie were born in the U.K. The second linkage between the two, as strange as this may sound, is caterpillars!

Yes, caterpillars!

The Bowie-Wallace-caterpillar connection became apparent to me yesterday morning as I was heading off to work. While stepping outside in route to the car, I noticed a rather strange looking creature attached to the exterior of the door frame (no, it wasn’t David Bowie!). In trying to figure-out what the creature was, my brain struggled to match its distinctive shape, color and pattern to familiar morphological templates filed away in the dark recesses of my memory. Then it hit me! Although the overall proportions of the beastie seemed diminutive in comparison to the model held in my head, its overall appearance reminded me of something from my adolescence back in the late 1980s – it reminded me of a mullet!

For those with a functional fashion sense (or a selective memory), Wikipedia defines a “mullet” as a “hairstyle that is short at the front and sides, and long in the back. Often ridiculed as a lowbrow and unappealing hairstyle, the mullet began to appear in popular media in the 1960s and 1970s but did not become generally well-known until the early 1980s.”

The tiny creature (which fortunately turned-out to be a caterpillar, not an outdated and free-living hairstyle) looked exactly like a mouse-sized mullet! In fact, it looked like a miniaturized version of the very mullet sported by David Bowie just a few decades ago.

Check it out:


As evidenced by the images shown above, both Bowie and the caterpillar exhibited a conspicuous, yet strangely similar, appearance. It’s this conspicuous appearance that brings us to Alfred Wallace; because, Wallace knew a thing or two about conspicuous caterpillars.

In 1889 Alfred Wallace published a book titled, “Darwinism: an Exposition of the Theory of Natural Selection with Some of its Applications.” In this work, Wallace expanded on one of his theories - a theory that he had previously presented to Charles Darwin and to members of the Entomological Society of London - the evolutionary phenomena now known as ‘aposematism.’

Aposematism refers to signaling adaptations exhibited by prey species that serve to dissuade would be predators from attacking. In other words, aposematic species are those organisms that intimidate, scare, or warn predators of their ‘unprofitability’ as potential prey items. Aposematic species are considered ‘unprofitable’ because in addition to the signaling adaptation, they also bear an underlying secondary defensive mechanism. For example, a coral snake could be considered an aposematic species because in addition to its secondary defense mechanism (a venomous bite), it also warns predators of this lethal capacity through the use of visual cues; in this case, warning coloration via strongly contrasting yellow, red and black colored bands along the length of its body.

Speaking to warning displays, Wallace wrote, “…instead of serving to conceal the animals that posses them or as recognition marks to their associates, they are developed for the express purpose of rendering the species conspicuous. The reason of this is that the animals in question are either possessors of some deadly weapons, as stings or poison fangs, or they are uneatable, and are thus so disagreeable to the usual enemies of their kind that they are never attacked when their peculiar powers or properties are known.” (Chapter IX of Alfred Wallace’s 1889 book; my emphasis added)

As an alternative to Wallace’s quoted learned avoidance of prey due to ‘known’ risks (learned through prior bad/unprofitable encounters), predators could also facilitate the evolution of conspicuous prey by practicing dietary conservatism. By simply avoiding prey items that look weird or unusual, predators could thin populations of normal looking individuals, thereby contributing to a reproductive boom for the remaining strange-looking conspecifics. In the case of a predator of caterpillars, for example, by eating ‘normal’ hairless caterpillars a predator could open the door for a surge in ‘strange-looking’ caterpillars - like those caterpillars that flaunt mullets.

In fact, Wallace frequently used conspicuous caterpillars as examples in explaining the phenomena of warning signaling - caterpillars not dissimilar to the venomous Megalopyge opercularis found on the frame of my door yesterday morning.

Megalopyge opercularis, the asp caterpillar, is the larval form of the southern flannel mouth. Its range extends from the southern United States through tropical South America. Though its retro hairstyle may look cute and harmless, it packs a painful punch. The ‘hairs’ of the asp moth aren’t really even hairs at all; they’re actually bundles of venom injecting spikes! The spikes are the caterpillar’s secondary defensive mechanism, and its conspicuousness serves as its primary defense – it sends a warning signal to predators.

Looking strange can sometimes be advantageous - just ask David Bowie!




Wallace, A. R. 1889. Darwinism: an Exposition of the Theory of Natural Selection with Some of its Applications. London: MacMillan.

Lee, et al. (2010). Can dietary conservatism explain the primary evolution of aposematism? Animal Behaviour, 79 (1), 63-74 DOI: 10.1016/j.anbehav.2009.10.004

Online Recommendations for Darwin Day

It’s Darwin’s birthday!

Linked below are a few videos, a website and a paper that I plan to enjoy today in celebration of the greatest scientist to have ever lived!

Charles Darwin (Born February 12, 1809)

"Thus, from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows. There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved. "


Webpage
A biographical sketch of Darwin by John van Wyhe (Darwin Online)


Videos
E.O. Wilson on ‘Darwin’s Four Great Books’ (FSU Mediasite)

Richard Dawkins on 'There is grandeur in this view of life' (YouTube)

Sean Carroll on ‘Endless Forms Most Beautiful’ (Google Video)


Paper (Free, PDF)
Spencer C. H. Barrett. Darwin's legacy: the forms, function and sexual diversity of flowers. Phil. Trans. R. Soc. B February 12, 2010 365:351-368; doi:10.1098/rstb.2009.0212

Buffalos and Birds: Flightless Wings from the KT Extinction to Darwin’s Dinner Plate

Although not an aficionado of fine cuisine by any measure, through persistence and voluminous sampling I have refined my palate to appreciate the delicate subtleties of several dishes. And, while I would admittedly be lost at a wine tasting, when it comes to cheeseburgers, pizza or Buffalo wings, I consider myself a gourmet of the highest standard. In calibrating my sophisticated taste buds, Friday night has been officially dubbed as ‘wing night’ with consumption of the deep-fried, cayenne laden morsels a matter of established ritual. This past Friday as my fiancé and I were blindly obliging our delectable dogma we were taken aback when our usual wing-purveyor served such diminutive wings that we jested they must have been taken from hummingbirds or from an assuredly flightless species. Luckily, the chicken wings’ lack of robustness was mitigated by an ice cold pitcher of beer and a nerd-ish banter about the evolutionary history of flightless birds and their place at the dinner tables long passed.

The current scientific “consensus” is that the vertebrate group we now refer to as birds had origins in the late Jurassic Period more than 145-million years ago. Having evolved from bipedal dinosaurs belonging to the theropod clade into an Archaeopteryx-type winged flyer, birds had conquered the air long before the infamous mass extinction event at the end of the Cretaceous Period. Often referred to as the ‘KT Extinction Event,’ a massive environmental upheaval approximately 65-million years ago wiped-out the majority of animal life on the planet, including what at that time was the dominant vertebrate group, the non-avian dinosaurs. The exact cause of the KT Extinction is still a topic for debate with asteroid impacts and volcanic activity viewed as the likely leading contributors, but what is absolutely certain is that the resulting mayhem collapsed the Earth’s ecosystems into complete chaos. Birds, the only members of the dino-clan to survive the cataclysm, emerged from the ruin to occupy a world in disarray but non-the-less rife with newly revealed opportunity.

In addition to leaving behind a ravaged planet, the KT Extinction also instigated the abandonment of numerous ecosystems that had previously been ruled over by the dinosaurs during their Mesozoic habitation. Though left in shambles, these ecosystems had also been vacated by many of the predators and competitors that initially pushed the theropods to the sky during the Jurassic Period. In the absence of rivalry, birds had been granted access to ‘open ecosystems’ and presented with the option to undertake a second conquest of the land. Several species of birds seized on the prospect of life on terra firma and through evolutionary time traded their wings for the physiology of sure-footedness. One modern grouping of these ground dwelling, flightless dinosaurs is called the ‘ratites’ and boasts the South American rheas among its extant members.

There are two species of rhea; the ‘Greater rhea and the ‘Darwin’s rhea,’ which is also known as the ‘Lesser rhea.’ Despite their flightless status, both the Greater (Rhea americana) and the Darwin’s (Rhea pennata) display wings as identifying anatomical features; however, due to the lack of a ‘keeled’ sternum to anchor to their already reduced breast muscles, as well as the presence of a diminished wishbone (furcula) to provide skeletal support, these South American natives are bound to a grounded existence. As an alternative to employment in the aviation industry, the process of natural selection has resulted in enhanced legs that have been optimized for a life on the run. While rhea’s legs have undergone adaptation for speed and agility, they have not yet evolved the ability to avoid entanglement by humans, or for that matter, to steer clear of the occasional dinner table.

On a more historical time scale, one of the most widely used implements of rhea leg entanglement were hunting weapons called ‘bolas.’ Bolas, derived from the Spanish word for ‘ball,’ refers to a weapon constructed with lengths of rope or braided cord with a weighted ‘ball’ attached on each end. The bolas are swung to build-up momentum and then thrown at the legs of fleeing game, tended cattle, or - more to the topic - a running rhea. The momentum of the weighted ends entangles the targeted animal by wrapping the adjoining ropes around its legs; this causes the animal to fall to the ground immobilized, or at least to be sufficiently slowed as to permit dispatch by other means (i.e. gun, knife or club).

Bolas are favorite tools of the South American ‘gauchos,’ which hold a societal role not unlike that of the North American cowboy; they work as ranch hands, hunters, and when the chance presents itself, as wilderness guides. In the year 1833 several South American gouchos were working as rhea-wrangling wilderness guides at the behest of a touring young naturalist from England. In August of that year, the naturalist Charles Darwin documented in his journal a humorous set of circumstances that lead to the dinner table identification of a new species of rhea – the bird now known as Darwin’s rhea.

Rendering of Darwin's rhea by John Gould.

Gould also identified 'Darwin's finches.'

While traversing South America during the voyage of the HMS Beagle, Darwin had observed Greater Rheas in the wild on many occasions. In fact, with the aid of a few gaucho guided bolas, the abundant Greater Rheas had become a mainstay of his diet.

In conversing with the gauchos in regards to habits of these ratites, Darwin had learned that there was a second variety of rhea roaming the continent. This second type, which the gauchos called ‘Avestruz Petise’ was reportedly a smaller version of the Greater and exhibited a darker plumage and skittishness behavior that made it readily distinguishable from the ones he had seen in the wild. Unfortunately, following Darwin’s discussion neither he nor the gauchos were able to collect a specimen of this “lesser” flightless bird for formal description, and in time it faded from Darwin’s attention. The lesser rhea went unspoken of until finally one evening Darwin was enjoying a quiet dinner with Mr. Marten, the Beagle’s contracted artist, who had shot and killed what they believed was a medium sized Greater rhea. As it turned out, the fully cooked ‘medium rhea’ that graced their plates as entrée on closer examination turned-out to be something else entirely; as Darwin himself detailed on pages 108 and 109 of Voyages of the Adventure and Beagle, Volume III:


“When at Port Desire, in Patagonia, Mr. Martens shot [a rhea]; and I looked at it, forgetting at the moment, in the most unaccountable manner, the whole subject of the Petises, and thought it was a two-third grown one of the common sort. The bird was cooked and eaten before my memory returned.”

Fortunately not all was lost. Recognizing the blunder, Darwin quickly gathered the table scraps and remaining carcass from the garbage. He continued,

“…the head, neck, legs, wings, many of the larger feathers, and a large part of the skin, had been preserved. From these a very nearly perfect specimen has been put together, and is now exhibited in the museum of the Zoological Society.”

Phillips, M., Gibb, G., Crimp, E., & Penny, D. (2009). Tinamous and Moa Flock Together: Mitochondrial Genome Sequence Analysis Reveals Independent Losses of Flight among Ratites Systematic Biology, 59 (1), 90-107 DOI: 10.1093/sysbio/syp079

Image from Wikipedia - Public Domain

Conclusion: Darwins Dilemma, Creationist Propaganda and Corrupt Christians

This post is the conclusion of a four-part series. The preceding post can be found here, the introductory 1st post is linked here.




According to “many published scientists,” there is a “story being told by Darwinists” that DNA and genetics play a role in evolutionary development, protein synthesis and the ontogeny of the physical characteristics displayed by animals. In hopes of edifying the masses of wayward “Darwinists,” these same “many published scientists” point out in Darwin’s Dilemma that DNA lacks the potency and mechanical know-how required to undertake these tasks. In actuality - according to “many published scientists” - all of life is derived from non-genetic “information” that is harbored within each irreducibly complex cell. Furthermore, this “information” does not arise from earthly processes, rather these “blue prints” are “preordained” by an “intelligent source.”

Many published scientists, many published scientists and many published scientists.

At this point in the science ‘doctrine-mentry,’ piles and piles of cover pages from published articles are shown on screen. Included with these publications are those to be found in THE JOURNAL OF MOLECULAR BIOLOGY, which is visually emphasized in the film.

So, the bestowment of consecrated ‘information’ from the heavens has reportedly been shown to be a fact? Who are these “many published scientists?”

As introduced in the film, the ranks of these scientists are held by not only the Discovery Institute’s scientists, but also those from the world acclaimed Biologic Institute in Washington State. Among the “many” – which I counted as three – are Dr. Stephen Meyer, Dr. Richard Sternberg and Dr. Douglas Axe. Incidentally, did I mention that the world acclaimed Biologic Institute, like Discovery Media (the producers of Darwin’s Dilemma), is funded by the Discovery Institute? But unlike Discovery Media, the Biologic Institute is tax exempt as it is a chartable organization!

Regardless of their employers and obvious unscientific motives, if these three ‘esteemed scientists’ have conducted valid research there is no reason to discredit their work. Their individual publications should be evaluated on the merits of established protocol and peer review. For example, just because the intelligent design article credited to Meyer was published to the journal of the Proceedings of the Biological Society of Washington by then editor RICHARD STERNBERG during his last day on post doesn’t mean that the research is necessarily invalid… Of course, the subsequent statement released by the Biological Society of Washington’s Council doesn’t help Meyer’s or Sternberg’s case very much:

“The origin of biological information and the higher taxonomic categories, in vol 117, no 2, pp 213-239 of the Proceedings of the Biological Society of Washington, was published at the discretion of the former editor, Richard Sternberg. Contrary to typical editorial practices, the paper was published without review by any associate editor; Sternberg handled the entire review process. The Council…would have deemed the paper inappropriate… subject matter represents a significant departure from the nearly purely systematic content…”

As for the momentous work by Douglas Axe that was published in THE JOURNAL OF MOLECULAR BIOLOGY… Well, it doesn’t actually say anything about intelligent design, or divinely driven biological processes. The paper, titled Estimating the Prevalence of Protein Sequences Adopting Functional Enzyme Folds, essentially reports that mutational rates found in an enzyme that breaks down penicillin (beta-lactamases) are very rare. The exact rarity of these mutations, as estimated by Axe, is determined to be in a range with a high-end value of about 10 to the 74th power- very rare indeed. From this estimation of a rare mutation rate, Axe makes inferences (far reaching) to the evolution of proteins. Once these findings are sifted through the god-filter of creationists, the end result is a pronouncement in Darwin’s Dilemma that the chance of mutation is so rare as to prohibit the process of evolution from occurring. So rare, that in fact the only possible explanation for life is divine creation. Wow, now that’s an impressive leap! The total destruction of modern biology in a single paper; I’m curious as to why thousands of independent researchers the world over continue to study evolution… Must be a conspiracy!

And then, having decimated the fossil record, slandered Darwin, Simon Conway Morris, Richard Dawkins, and Stephen J Gould, AND having misrepresented the whole of modern scientific understanding, the tale of Darwin’s Dilemma comes to an end. Fin.

To draw this novel length critique of Darwin’s Dilemma to a close, let me re-emphasize that although lacking historical accuracy, scientific legitimacy and professional integrity the film’s production value and underlying truth-manipulating strategy make it a dangerous opponent to education and reason. The people behind the film are dishonest, unethical and immoral; they lie, doctor evidence and misrepresent science as a whole. In the process of attacking evolution, they falsify history and tear down the sciences of geology and chemistry.

Though they are fundamentalists and propagandists, they are also cunning and well funded… Take caution.






Axe, D. (2004). Estimating the Prevalence of Protein Sequences Adopting Functional Enzyme Folds Journal of Molecular Biology, 341 (5), 1295-1315 DOI: 10.1016/j.jmb.2004.06.058

Part 2 - Darwins Dilemma, Creationist Propaganda and Corrupt Christians

Before picking up with the Richard Dawkins quote used to close yesterday’s post (Part 1 Available Here), I’d like to provide a little more background on some of the nefarious figures that contributed to bringing the fundamentalist film Darwin’s Dilemma to my living room.

The movie was produced by the Discovery Institute’s associate organization ‘Illustra Media.’ In this instance I use the phrase ‘associate organization’ very loosely because for all practical purposes Illustra Media is synonymous with the group known as ‘Discovery Media.’ Both media groups, Illustra and Discovery, receive the bulk of their funding from the Discovery Institute and both have Stephen Meyer as a lead consultant. Meyer is one of the Discovery Institutes original founders, and a key organizer of the intelligent design faction. For those readers unfamiliar with the Discovery Institute itself, I’d strongly encourage you to view Judgment Day: Intelligent Design on Trial, which details a 2004 federal court case in Dover, Pennsylvania. The NOVA documentary is provided free online by the Public Broadcast Service and very accurately summarizes the Discovery Institute’s deceitful and underhanded attacks on science education. To provide a little insight as to the Institute’s shameless objectives, consider that their mission statement outright states that the “point of view Discovery brings to its work includes a belief in God-given reason;” and that Discovery Media includes in its mission “to utilize every form of available media to present the reality of God's existence through compelling scientific evidence and academic research". Irrespective of one’s personal religious beliefs, sound scientifically minded inquiry can not be born of blatant biases and preconceived notions of causation. This is simply not how science works. To say that the Discovery Institute may be susceptible to high rates of confirmation bias is giving them too much credit. Speaking of biases, yesterday I reported that my in-home showing of Darwin’s Dilemma was courtesy of the Trinity Broadcast Network (TBN). Although you might be inclined to think that TBN suffers from the same religious biases as the Discovery Institute, that doesn’t appear to be the case; TBN has an altogether different bias – one that favors cold hard cash.

The Trinity Broadcast Network is the largest Christian television network provider in the United States and has media holdings in more than 70 other countries. I can sum up TBN credentials in six words- “It was founded by Jim Bakker.” Yes, Jim Bakker the televangelist, Jim Bakker the accused rapist, and yes Jim Bakker the convicted felon. If more evidence of the TBN’s ill repute is needed ponder that they are proud proponents of the religious practice known as the ‘prosperity gospel.’ Basically, the prosperity gospel teaches that a sinner can be forgiven for her/his wrongs if she/he donates money to the network. Yes, TBN is selling admission into heaven! I’m not sure what the price is though… And unfortunately, I can’t tell you how much income TBN makes from selling moral amnesty, because they refuse to disclose financial information for public inspection, or for that matter to Christian watchdog groups. So, in addition to dumbing-down its adherents with fake-science, TBN also steals their cash. In the science community this is referred to as a positive feedback cycle; the more dumberest you become, the more money you lose.

Getting back to the science…

Yesterday, I described how the high production quality of Darwin’s Dilemma allows for a visually exciting and even captivating viewing experience. As scary as this may be to admit, it’s absolutely true. The film is by far the ‘best’ anti-science propaganda film I’ve ever seen. The animation, narration and scene transitions are smooth and coherent; pseudo-science and misinformation aside, the film is good enough to rival most any that would appear on National Geographic or the History Channel. In regards to the science content presented in the film, at least up to the Richard Dawkins quote, a skeptic with some understanding of evolution and paleontology will see it for what it is – creationism; however, if seen through an uncritical eye it would appear wholly informative. Indeed, even those with a general understanding of science may at first be drawn to accepting the film’s premise; this in large part due to the awe and wonder inherent to the Cambrian Radiation itself. However, at about forty minutes into the feature the film takes a creationist turn; this happens right around the Dawkins quote. After Simon Conway Morris’s critique of the pre-radiation fossil record, the screen gives itself to the quote;


“It is as though they were just planted there without any evolutionary history”

-Richard Dawkins


In my assessment, this snippet is the first serious indicator of the film’s underlying evil purpose. Not only does the above Dawkins line – while out of context - seem to suggest the existence of a ‘planter’ and a shortfall in evolutionary knowledge, but it also happens to be one of the most frequently ‘abused’ evolution quotes in existence. It has been used and reused by creationists and fundamentalists the world over. This assertion can be verified by simply copying and pasting the whole sentence into a Google search engine; undertaking this exercise, I got back more than 10,000 hits. Incidentally, the quote itself has been clipped from page 229 of Dawkins’s 1996 book The Blind Watchmaker; when in context the quote is used in explaining that both he (Dawkins) and Stephen Gould agree that one, the pre-radiation fossils are few, and two, that the thin fossil record is no way indicative of divine intervention. Far from an admission of divine creation, the quote is used in The Blind Watchmaker to affirm that even biologists with differing perspectives on evolutionary mechanisms (see the citation below for an independent assessment of their incompatibilities) wholeheartedly endorse evolutionary agents as instigators of the Cambrian Explosion. At any rate, in Darwin’s Dilemma the Dawkins quote is used simply as a cap to Simon Conway Morris’s testimony, from there the film moves on to Creationism’s most hated of scientists – Charles Darwin. There we learn about the origins of Darwin's 'dilemma.'


ONCE AGAIN, CONTINUED - HERE's Part 3


Reference:
Shanahan, T. (2001). Methodological and contextual factors in the Dawkins/Gould dispute over evolutionary progress Studies in History and Philosophy of Science Part C: Studies in History and Philosophy of Biological and Biomedical Sciences, 32 (1), 127-151 DOI: 10.1016/S1369-8486(00)00025-X

Beetles and Darwin's On the Origin of Species

Good video to watch on the 150th Anniversary of the Origin's publication.

The story starts with beetles and then moves to Darwin's acclaimed work.



QUEST on KQED Public Media.

Fire Ecology Marathon; Nature Red in Tooth and Flame Part-4

The savannas of the southeastern United States are inimitable natural communities that have undergone ecological assembly in the presence of seasonal fire cycles and, as discussed during the first three installments on this topic (available here; Part-1, Part-2, Part-3), are rich in organisms capable of manipulating the regularity, movement and intensity of these wildfires. During the preceding post (Part-3) the phenotypes of two such fire-born species, the longleaf and slash pines, were detailed as exemplars of organisms with traits that not only aid in defending against heat and flame, but also as species that exhibit specific physical structures, chemicals and behaviors that could intrinsically promote fire. In closing that previous discussion, consideration was given to the possible motives behind the longleaf and slash pine’s ability to deliberately provoke fire.

Though it may initially seem to be counterproductive or even a hindrance to survival, through promoting fires the savanna pines obtain benefits that directly enhance their inclusive fitness. Because of the processes that drove the organismal evolution of the longleaf and southern slash pines in geological time, and the processes that propelled community assembly in savannas, the presence of wildfires effectively created a duality in the character of potential pine competitors and that of would-be savanna inhabitants - either they can tolerate fire, or they can’t tolerate fire.

In the absence of wildfires over extended periods of time (i.e. fire suppression) several ecological changes can occur in savannas. Most profoundly, without regular wildfires not only would the already present fire-tolerant plant species survive, but in addition, fire-intolerant species would experience greater fecundity. Without the deterrence provided by fire, resource-rich savannas can quickly become the envy of plants from surrounding hammocks and mixed hardwood forests, thus encouraging invasion and recruitment from these neighboring communities. Such movement of new species into the savannas would contribute to substantial ecological alteration of the natural processes that maintain the system’s predictable boundaries, ecotones and makeup.

Recall from Part-1 of this post that the plants found in hammocks have undergone selection for initial rapid growth and direct competition for sunlight. Just as the natural history of the pines has been shaped by fire, the history of dense-canopy species have evolved to fight for radiance. If unobstructed access to the abundant savanna sun is tantalizingly flaunted, these species would quickly invade, rapidly recruit and hurriedly regenerate to overtake all biologically available space. What was initially a patchwork of invasive species would spread to encompass and overcrowd the savanna, in the process reducing the diversity of appropriate groundcover plants, and adversely impacting the reproductive success of the native inhabitants – slash and longleaf fitness would decline.

In addition to increasing interspecific competition in the savannas, invasive species also create positive feedbacks in the wildfire cycle - magnifying fire suppression. The presence of abundant shrubs and woody species in a normally open savanna formulate densely vegetated landscapes that reduce fine fuel loads on the ground and decrease the likelihood of fire propagation. The lack of fire - in turn - facilitates further invasions, which increases vegetative densities even more, which reduces fire even more, which allows for yet greater invasive proliferation, etcetera…

With continued fire suppression, what was once a savanna, characterized by thinly distributed trees, would transition towards a densely canopied hammock with an impenetrable thicket understory. Growing populations of invasive species would amplify competition for resources, thus pushing the fitness experienced by the longleaf and southern slash pines to dangerously low values. This is precisely why the ‘fire gene’ is so critically important to the pine’s genotype. As crowding increases in this scenario, and essential resources dwindle, hormonal stress responses within the pines intensify. The hormones drive physiological changes in the trees causing leaves to drop and internal hydrocarbon chemistry to move toward increased combustibility. The probability for fire is increased. And, when fire does return, the stems, branches, leaves and roots from newly arrived invasives will serve as kindling for augmented wildfire intensity - to such extremes that only the hardiest of the fire-tolerant will be able to survive.

For clarification, conceptual genes (like the ‘fire gene’) aren’t confirmed as actual chromosomal localities for which variable alleles compete. Rather, conceptual genes are offered as thought-tools for understanding the premise that natural selection operates on phenotypical traits that are the products of genotypical coding. In regards to the ‘fire gene’ specifically, it is a hypothetical genetic compliment that is expressed in such a manner that the physical presence of fire improves the likelihood of that genotype being passed on to future generations. In other words, if a population of trees exist in which some members have a genotype that provides increased fitness in the presence of fire, AND that population is then exposed to fire - ultimately killing a certain percentage of the population - those trees with fire gene advantage will experience higher survivability and greater measures of fecundity compared to those not possessing a fire gene.

Returning to the savanna pines expressly, irregardless or not if there is literally a single gene that provides for all of the phenotypical adaptations to fire described throughout this post, or if these traits are the result of a cooperative epistasis, or if the characters are disparate and independent, it remains likely that their occurrence and continued propagation through evolutionary time has provided a significant advantage.

Through 300 million years of natural selection, wildfires have propelled the savanna defending pines to levels of adaptation in which they are capable of wielding fire. ‘Nature, red in tooth and flame’ has fashioned a true ecosystem engineer, one that is capable of establishing and defending the ecotonal boundaries between natural communities.


Beckage, B., Platt, W., & Gross, L. (2009). Vegetation, Fire, and Feedbacks: A Disturbance‐Mediated Model of Savannas The American Naturalist, 174 (6), 805-818 DOI: 10.1086/648458

Stevens, J., & Beckage, B. (2009). Fire feedbacks facilitate invasion of pine savannas by Brazilian pepper New Phytologist, 184 (2), 365-375 DOI: 10.1111/j.1469-8137.2009.02965.x

Ecosytem Engineering and Fire Ecology, Part 3

The closing paragraph of ‘Nature, Red in Tooth and Flame Part-2’ mentioned how extrinsic factors in the environment, such as the presence of increased atmospheric oxygen and an abundance of herbaceous plants to serve as fuel, collectively worked to generate frequent and intense wildfires during the Pennsylvanian Period approximately 300 million years ago. It was the presence of these Carboniferous wildfires that positively selected fire-tolerant gymnosperm species for continued development, and initiated their adaptive radiation towards the representative pine trees that occupy the modern-day savannas in the southeastern United States. It is within contemporary savannas that the longleaf pine (Pinus palustris) and the southern slash pine (Pinus elliottii var. densa) express their fiery ancestry; however, the fire ecology observable in these natural communities isn’t limited to wildfires born of purely extrinsic factors. Through, evolution the longleaf and slash pines have developed the ability to intrinsically influence the movement of fire, and they have learned to use this powerful tool as an instrument for customized ecosystem engineering.

During the description of savanna communities in Part-2, it was detailed that the canopies of these systems exist in an open condition that allows for ample access to sunlight by a diverse range of groundcover plants. Ample sunlight, water and soil nutrients can all be found in savannas. So, considering the occurrence of these botanical prerequisites, compounded with the highly competitive, almost war-like, tendencies of nature (as elaborately described in Part-1), one might wonder why trees from the hammocks don’t advance to occupy the promising and resource-rich savannas… The reason for the limited progress of hammock trees in moving to the savannas is that invasions are tightly controlled by the few trees already inhabiting the systems – the few trees usually being longleaf and slash pine.

An open canopy is a characteristic physiognomy of savannas precisely because the ground gaining charge of closed-canopy trees is impeded by the heirs of the Carboniferous gymnosperms. Said differently, the trials-by-fire endured by the antecedents of the modern-day conifers have shaped the phenotypes of the savanna-defending longleaf and southern slash pines. Furthermore, the phenotypes shown by the longleaf and slash pine reach outward to encompass the savanna as a whole, where these phenotypes serve as catalysts for engineering ecosystem towards one purpose – making more pine trees.

The longleaf and southern slash pine exhibit a host of morphological features that facilitate their continued manipulation of fire. For instance, both of these trees have thickly armored plates of bark on the exterior of their trunks; like fire-retardant shields, the plates guard the tree's interrior tissues against excessive heat and all but the most intense of wildfires. Similarly, the undifferentiated cells (meristematic cells) found within the trees, the ones that make-up the growth tissue found in meristems, are safeguard by a casing of heat resistant scales. And, as opposed to a pattern of wide lateral spreading, the roots of the slash and longleaf trees penetrate perpendicularly downward, where they are sheltered from harsh surficial temperatures. These are but a small number of the morphological – anatomical – traits displayed by the fire-scaping pines; their reproduction and growth habits give additional clues as to their natural history.



The reproductive cycle of the longleaf and southern slash pine include strategies that take into account the recurring spring fires described in Post-2; by germinating in the fall and occasionally producing periodic mast crops, young pines are afforded several months of growth before the first ravages of wildfire arrive. In spite of the head start gained through fall germination, the longleaf and slash pine don’t approach growth from a mere lackadaisical standpoint, quite the contrary, both trees posses the ability to quickly establish themselves. Just as the most successful plants of a closed canopy hammock battling for access to solar radiation (see the ‘competition for sunlight’ example provided in Part-1), the savanna pine trees – in addition to a ‘fire gene’ – also hold in their genetic arsenal a ‘rapid growth gene.’ Slash pine, for instance, has a genetic compliment that permits the tree to take advantage of every opportunity to seize real estate; once germinated, it rapidly shoots upward expressing secondary needles in less than six month’s time, and by the time it is two-years old, it is able to survive a wildfire of ‘average' intensity.

The above characteristics depict but a few of the intrinsic phenotypes that improve the survivability and reproduction of the savanna dwelling pines in the presence of fire; but what is truly remarkable is the trees’ ability to channel fire directly – the trees’ ability to shape their ecosystem through offensive tactics.

In addition to the defensive phenotypes of the savanna pines, the chemistry of their leaves (i.e. pine needles) have undergone adaptation such that while on the tree, the leaves produce flame resistant chemicals, but when the leaves are shed, their chemical consistency changes to achieve an altogether different effect - they become flammable and easily ignited. As the leaves are shed from branches, they fall to the ground where they accumulate around the circumference of the trees. The piled pine needles are composed of cellulose-laden fibers, which unlike the fire-resistant lignin that evolved during the Paleozoic, serve as excellent fuel for fires. So when on the tree, the pine needles are similar to the armored plates found on the trunks, they help defend against tissue damage when exposed to wildfire; but, in the absence of recurrent fire, the leaves are quickly dropped and their chemistry changes to promote fire. Moreover, pine leaves aren’t the only fire stoking property of the savanna pines. The very structure of the pine’s thin and supra-numerous branches can facilitate the spreading of fire (horizontally and vertically) through increasing the surface area of exposed tissues to flame. And, the flammable hydrocarbons produced in the plant’s resins can incite wildfires or encourage lightening strikes to take hold (for example, the terpenes produced by the conifers in question; think ‘turpentine’).

Though it may initially seem to be counterproductive, or a hindrance to survival, through promoting fires the savanna pines obtain benefits that actually enhance inclusive fitness….

[Continue HERE, PART-4.]


Beckage, B., Platt, W., & Gross, L. (2009). Vegetation, Fire, and Feedbacks: A Disturbance‐Mediated Model of Savannas The American Naturalist, 174 (6), 805-818 DOI: 10.1086/648458


Stevens, J., & Beckage, B. (2009). Fire feedbacks facilitate invasion of pine savannas by Brazilian pepper New Phytologist, 184 (2), 365-375 DOI: 10.1111/j.1469-8137.2009.02965.x

Fire Ecology and Cutthroat Ecosystem Engineering, Part 2

The phrase ‘ecosystem engineer’ refers broadly to the ability of an organism to change or modify the physical characteristics of its surroundings. When these environmental modifications resultantly impact the fitness of the engineering organism itself, the feedbacks created can be thought of as functioning like an extended phenotype. In other words, the feedbacks generated between the engineer and the ecosystem contribute to the reproductive success of the organism, and often (directly or indirectly) affect the life history of nearby competitors. In the closing line of ‘Nature Red in Tooth and Flame - Part 1’ the organisms adapted to use fire are personified as ‘cutthroat’ because they possess a genetic compliment that facilitates the shaping of their environment through a two-fold process that could easily be categorized as self-interested. Firstly, through harnessing fire these engineers are able to create a pattern of ecological disturbance that promulgates increased fitness; and secondly, the application of fire eliminates resource pilfering opposition via direct incineration. But, prior to detailing the precise methods in which ecosystem engineering plants employ fire, it is important to set the stage with a description of the battlefield – the savanna community.

In the southeastern United States savannas are typically found on relatively low topographical gradients with poorly drained soils and ample soil nutrients. Similar in biological composition to hydric flatwoods communities, savannas characteristically differ in regards to tree abundance and exhibit a relatively open canopy with a thin understory and a lavish herbaceous groundcover. Both savannas and hydric flatwoods rely on seasonal rain and fire cycles in order to maintain their soil chemistry, floral diversity and faunal components. Yes, these communities depend on fire cycles…

Prior to modern anthropogenic intervention, and the suppression of natural, seasonally occurring fire cycles, the forests, prairies and savannas of the southeastern United States experienced regular ecological disturbance by means of fire. Using Florida as an example, the annual climate cycle here is punctuated by alternating periods of relatively dry and wet weather. More specifically, the months of November through February represent the dry season and accordingly receive comparatively little precipitation. This dry season is followed by dramatically increased amounts of precipitation during summer with heavy rains and thunderstorms (particularly near the coasts) for the period including June, July and August. The spring season, February-through-May represents a transitional period from dry to wet; however the forthcoming summer brings with it thunderstorms; during this period lightening-strikes often ignite wildfires. The wildfires feed on the parched condition of desiccated plants – the wildfires thrive on the fuels remaining behind from the departing dry season. The regularity of this annual climate has resulted in a cyclic ‘fire season’ that has been recurrent for several millennia. The persistence of the fire cycle has thus contributed greatly to the structuring of local natural communities; however to understand the organismal biology of some of the fire adapted plant species a deeper gaze into evolutionary time is required. So, now that a cursory look at the battlefield has been made, a review of the actual players is in order.



Two exemplars of the fire wielding and ecosystem engineering life style are the longleaf pine (Pinus palustris) and the southern slash pine (Pinus elliottii var. densa). These trees both maintain genetic compliments – fire genes – that enable them to prosper in the flame frequented savannas of the southeastern United States. In order to appreciate the natural history of these organisms, a look at their evolutionary past is obligatory.

The longleaf pine (Pinus palustris) and the slash pine (Pinus elliottii) are two species of the genus Pinus (pine tree) which branched from genus Picea (spruce tree) during the Cretaceous Period, somewhere between 87 and 193 million years ago.


NOTE: There are two distinct varieties of slash pine, variety elliotti and variety densa, both of which can be found in southeastern U.S. and although there are several important distinctions, for purposes here both varieties can be considered one and the same, though the southern slash pine (var. densa) displays slightly greater levels of adaptation to fire.



Pine and spruce trees are grouped together with cycads, gnetophytes and ginkgo as gymnosperms, which had an initial start back in the Pennsylvanian Period of the Carboniferous more than 300 million years ago. The long history of the pine trees, and the slash pine in particular, is significant because these trees have one of the largest and most complex genomes of any organism on the planet today – a result of varied evolutionary forces. Of specific interest in regards to evolutionary history is that gymnosperms arose from the Carboniferous swamps during a period of rapid plant adaptation. In addition to the advent of the bark fiber “lignin,” plants during that period underwent a multitude of morphological changes - many of these changes were adaptations to wildfire. This was the case because unlike the 21% atmospheric oxygen present today, the carboniferous boasted 35% oxygen content, this in conjunction with an abundance of herbaceous material resulted in frequent – and intense – wildfires. Here, ‘intensity’ can be interpreted as being the ratio of a wildfire’s maximum temperature and duration; both of which can vary. The wildfires positively selected for those plant traits that phenotypically exhibited fire-tolerance, and the wildfires also actively worked to eliminate those plants that displayed fire-intolerant characteristics. Through this dualistic mechanism of natural selection, a long passed Paleozoic ecosystem worked to shape and mold the longleaf and the slash pines into masters of pyrogenic manipulation.


[This blog post continues here with installment Number 3.]



Beckage, B., Platt, W., & Gross, L. (2009). Vegetation, Fire, and Feedbacks: A Disturbance‐Mediated Model of Savannas The American Naturalist, 174 (6), 805-818 DOI: 10.1086/648458


Stevens, J., & Beckage, B. (2009). Fire feedbacks facilitate invasion of pine savannas by Brazilian pepper New Phytologist, 184 (2), 365-375 DOI: 10.1111/j.1469-8137.2009.02965.x

Nature Red in Tooth and Flame: Fire Ecology and Cutthroat Ecosystem Engineering

Renowned journalist, publisher and geologist Robert Chambers spent the majority of his 19th Century life actively engaged in two - often antagonistic - worlds, the world of science and that of the high-society Scottish elite. It may have been his struggle to maintain balance between these two worlds, one that valued rationality and meticulous observation, the other preferring political correctness and adherence to theological dictates, which helped guide him to the decision to anonymously publish his 1844 work ‘Vestiges of the Natural History of Creation.’ The work was truly progressive by almost any measure and it would go on to influence such diverse individuals as the scientifically minded Charles Darwin and the poetically endowed Alfred, Lord Tennyson.

It was a combination of Vestiges’ theological implications and the loss of a dear friend that motivated Lord Tennyson to pen the following stanza:

Who trusted God was love indeed
And love Creation's final law
Tho' Nature, red in tooth and claw
With ravine, shriek'd against his creed
(In Memoriam A.H.H., Canto 27)

‘Nature, red in tooth and claw’ is an often quoted metaphor for natural selection, and as such, it has been a recurrent theme here at Ecographica. During several previous posts, a harmonious – ‘all is in balance’ - view of nature was contrasted with the perspective of nature as a series of oppositional organisms struggling to gain a competitive edge over rivals. During these comparisons, the ‘red in tooth and claw’ view was the hands-down victor in all cases; being both more analytically accurate, and the more observationally sound perspective. As a case in point, two recently published articles, one appearing in the December edition of The American Naturalist, the other in the July New Phytologist have compelled the issuance of an update to a post made back in April; a post that emphasized the above described contrasting views of nature. Both of the published articles lend further credence to the conceptual “fire gene,” an idea coined in the April blog. One article supports the fire gene concept through development of ecological disturbance feedback models; the other tells the story of an invasive plant with a contrasting and adversarial phenotype to the one detailed in the original post, a phenotype that suppresses fire – it bears what can be called an “anti-fire gene.” As with the original blog post, the re-write begins in the Big Cypress Preserve, with a somewhat overly embellished lead-in…

Nature Red in Tooth and Flame
Gazing across the tranquil landscape of the Big Cypress Preserve, nature seems to be in balance, unchanging and at peace - picturesque beyond any poetic description. Within this serene setting, anthropogenic throngs of sharply angled concrete and glass edifices suspend their battle for roadside commercial dominance and yield themselves to a sea of sparsely treed savannas, rolling prairies of grass, and randomly scattered islands of thickly vegetated hammocks. It’s the perfect environment for a relaxing stroll, a picnic, or, an inquiry into the natural world...

All may appear calm within this enchanting panorama with its diverse array of plants, animals and abiotic ornamentation; however, this perceived tranquility is but a chimera. It is a mere illusion of serenity resulting from shortfalls in the ability of the observer’s photoreceptors to see beyond that narrow range of the electromagnetic spectrum called visible light, an inability to hear sound outside of 22000 Hertz, and the failure of the human olfactory system to nose its way into the vast chemo-landscape of pheromones and other volatile chemicals in which it is continuously assailed. Indeed, if only the sensory apparatus of Homo sapiens was keener – if only it was more finely calibrated – the landscape of the Big Cypress would be seen for what it truly is… How very different it would seem.

Picture taken from Turner river Rd - Big Cypress Preserve

Very different indeed; imagine the ecological interplay that could be interpreted if humans could see ultraviolet light through the eyes of a bee, smell pheromones from six-miles’ distance like a moth, or interpret chemical stimuli through soil like a plant… Far from serene, if viewed through time, adaptive maneuvers, survival strategies and arms races would be manifest in every action undertaken by the immense diversity of organisms in the landscape. If these actions could be viewed more directly, if they could be seen in greater detail, the landscape would appear saturated with war; from the birds in the sky to the millions of soil bacteria underfoot, mortal conflict - not harmony - would be identified as the prime mover. Even the distribution of the apparently benign flora, the very plant community boundaries that demarcate prairie-from-savanna-from-hammock in the above described landscape, is maintained by way of fierce battles waged over evolutionary time. These ecosystems, which appear stable and so pleasingly haphazardly scattered, are in fact hordes of competing plants, all struggling for limited resources and their continued existence. It is in these contested boundaries that conflicts incessantly rage, and it is within these envied ecotones that one species has honed a new weapon – it has undergone adaptation to exploit the power of fire.

Before getting to the exploitation of fire, it is important to understand that natural plant communities exist in a continuum of environments and have adapted to inhabit almost every available niche on the planet; from “box thorns” in Death Valley to fully aquatic hyacinths floating around the lakes of Brazil, genetic plasticity in plants is clearly evidenced as a product of natural selection. And although the conquest of diverse habitats represent a surmountable challenge, a multitude of both biotic and abiotic factors conspire to determine the overall abundance (density), composition (diversity) and ultimate success of plant communities at any given location.

For example, looking across the landscape of the Big Cypress, densely concentrated hardwood trees form hammocks which, due to the broad area of their collective canopies, limit the amount of sunlight available to underlying herbaceous groundcover. This is a straight forward relationship, no sunlight reaching the ground means fewer plants on the ground. Following this rationale, if the tree canopy should be opened, say by a storm, hurricane or by the death of older trees, this would permit sunlight to temporarily penetrate to the floor and a rapid emergence (recruitment) of both herbaceous plants and new saplings would be predicted. This is precisely what happens; in this example sunlight is the limiting resource and once made available those plants best able to take advantage of the situation through rapid growth will be able to quite literally overshadow their competitors. Stated differently, plants with genetic compliments favoring a period of ‘initial rapid growth’ are at an advantage and will be positively selected if positioned to compete for sunlight with a species lacking such a genetic compliment.

Similar to the botanical quarrels described for wooded hammocks - those in which plants have undergone selection for rapid growth - plants also engage in conflict to secure access to the resources offered by prairies and savannas. And, just as with the battles for sunlight on the forest floor, contenders occupying hammock-savanna ecotones have evolved specific defensive and offensive phenotypes to aid in their advance; as alluded to earlier, a few have even acquired the ability to harness the power of fire. Like the genetic compliment that allows a plant to undergo a period of initial rapid growth when a break in the hammock’s canopy becomes manifest, some plants possess a genetic compliment that allow for direct modification of local ecology. In short, the genetic compliment allows the plant to apply heat and flame in a cutthroat effort to destroy competitors, and to assert themselves as ecosystem engineers.


[The second installment of this post is available HERE.]



Beckage, B., Platt, W., & Gross, L. (2009). Vegetation, Fire, and Feedbacks: A Disturbance‐Mediated Model of Savannas The American Naturalist, 174 (6), 805-818 DOI: 10.1086/648458


Stevens, J., & Beckage, B. (2009). Fire feedbacks facilitate invasion of pine savannas by Brazilian pepper New Phytologist, 184 (2), 365-375 DOI: 10.1111/j.1469-8137.2009.02965.x