Awesome Picture: Florida Panthers in the Picayune

I was just emailed this picture of a mama panther and her cubs:

The email (from a reliable source) advises that the photo was recently taken during a fly-over of the Picayune Strand near Naples in South Florida.

Looks like three wild Florida panthers - cool!

Also pictured are what looks like a recently cleared road and stands of noxious Melaleuca – could be better! (As a matter of fact it is getting better - click here for info).

In addition to dealing with us ecosystem-altering and land-lusting apes, Florida panthers must also cope with other parasites – including highly specialized trematodes that have evolved a fancy for fare of the feline sort...

Trematodes are flukes of nature (sorry, couldn’t resist) in that they've evolved an astonishing, almost incomprehensible level of developmental plasticity. Most have evolved the ability to subtly manipulate their growth rates and sexual maturation to track the resources available in their environment. For parasitic nematodes, their environment is manifested by the internal chemistry of their victims. Id est, the digestive enzymes, hormones and antibodies expressed through the physiology of their hosts help the trematodes gauge the probability of reproductive success and to tune their own developmental process accordingly. This fantastic capacity for flexibility is of survival benefit because should a trematode happen to find itself immersed in the body of an unsuitable host, it can induce a state of arrested development and shift its metabolism to complete dormancy while awaiting transmission to a more favorable chemical climate. As a natural corollary, if the trematode succeeds in locating its target host (aka, its 'definitive host') it can quickly push development into overdrive and achieve reproductive adulthood in short order, thereby maximizing the opportunity to its individual advantage. Being unrestrained by the ticking-clock of reproductive efficacy, trematodes can migrate from host-to-host and even between species with relative ease. As a case study, consider the misadventures undertaken by the trematode species named Alaria marcianae.


Alaria marcianae is a fascinating organism known to target, as definitive hosts, the kittens of the Florida Panther (Puma concolor couguar). The Florida Panther holds a critically endangered status and, as the common name strongly suggests, resides in the state of Florida. The tawny colored Florida Panther is one variety of a widely recognized group of felids that are also known by the names cougar, mountain lion and puma. The panther-intersecting life cycle of Alaria marcianae is complex with several possible vectors of transmission, but in choosing an arbitrary starting point for the purpose of description, we can assume that its convoluted journey begins within the intestines of an adult panther.

Having recently been deposited in the intestinal tract of an adult feline, members of Alaria marcianae start their lifecycle as eggs. The eggs, unembryonated germ cells, intermix with the partially digested remnants of raccoons, armadillos and other common delicacies found in the panther's system, and are then excreted with the animal's feces. On being submerged in the inundated wetlands for which south Florida – and the Picayune Strand - is renowned, water stimulates the eggs to internally develop embryos. Once these embryos have achieved sufficient maturation, sunlight triggers the eggs to hatch free swimming, cilia-driven, paramecium-looking critters called miracidia.

The miracidia are not adult Alaria marcianae, rather they represent a sexually immature stage of development that is specialized for seeking out a very specific (obligate) intermediate host. To ultimately succeed in stalking a panther, the miracidia of Alaria marcianae must first locate and infect a ram's horn snail of the genus Helisoma.

On locating a ram's horn, the miracidium attaches itself to the soft exposed flesh of the snail, and by excreting tissue-degrading enzymes, it parts ways with its cilia-bearing outer layer. It then penetrates into the snail's body cavity. Shedding its ciliated epithelium, the miracidium becomes an immature sporocyst. Although sporocysts still lack the ability to reproduce sexually, by embedding in the snail's nutrient rich organs they acquire the power to produce additional replicates of themselves - clones called 'daughter sporocysts.'


Further advancing on the panther, the new daughters promptly leave their mother's side and venture to the snail's gonads. Mollusk hormones produced by the gonads fuel special cells within the daughters as they morph into tailed, tadpole-looking larval forms called cercariae. The cercariae swim to, and exit from, the snail's shell-producing mantle. From there, they return once again to the open water as free-swimmers.

Leaving the snail behind, the cercariae swim to the water's surface and hunt down the true tadpoles of the leopard frog (Rana pipiens) - their second intermediate host. Hijacking the leopard frog's tadpoles for transport, the cercariae drop their own tail and burrow into the tadpole's skin. There's no need for self-propulsion when riding inside a tadpole. Once inside the developing frog, Alaria marcianae, then at a stage where they're referred to as mesocercaria, cease further development and undergo another round of asexual cloning. As numbers continue to multiply, they patiently rest, waiting for the tadpoles to carry them landward as adult leopard frogs.

In time, the mesocercaria-bearing tadpoles grow into leopard frogs and move their parasitic cargo to land. On terra firma the leopard frogs are hunted by a wide range of predators; occasionally falling prey to yet another preferred host (aka, a 'paratenic host') of Alaria marcianae, the raccoon. After catching an infested frog, the raccoon's digestive enzymes make short work of the frog's flesh - in the process releasing the mesocercaria. As with its previous host, the mesocercaria multiply in the raccoon, but continue to maintain a state of arrested development - they are not yet adults.

Did I mention that raccoons in south Florida happen to be a favorite prey item of the endangered panther?

Utilizing methods similar to those during the frog-to-raccoon transmission, Alaria marcianae find their way into adult panthers by contaminating raccoons - panther prey. During the process of raccoon digestion, mesocercaria are liberated from tissue and enter the bloodstream by penetrating the intestinal wall.

Now, if the panther they find themselves parasitizing, by chance, turns out to be a lactating female, her hormones will stir the mesocercaria into migrating to her mammary glands where they will transmit (trans-mammary) to the digestive system of her kittens'. The term used to describe the situation in which a mother acts as a paratenic host to her own offspring is called 'amphiparatenesis.'

Here, amphiparatenesis results in the imbibing of mesocercaria-laden milk by the kittens. As with the mesocercaria residing within their mother, the parasites in the kittens will penetrate the intestinal wall and enter the blood stream. They'll surf the blood stream until reaching the lungs where they become metacercaria; as metacercaria they harden the surrounding lung tissue forming protective cysts. Having profitably acquired housing in their definitive host, the cysts in the lungs will eventually be coughed-up the trachea and then promptly swallowed into the esophagus. Once back in the intestines, Alaria marcianae accelerates its developmental process, achieves sexually reproductive adulthood (as sequential hermaphrodites), and deposits the next generation of eggs in the intestine.

Thus the cycle comes full circle.




Reference:
Foster, G., Kinsella, J., Sheppard, B., & Cunningham, M. (2009). Transmammary Infection of Free-Ranging Florida Panther Neonates by Alaria marcianae (Trematoda: Diplostomatidae) Journal of Parasitology, 95 (1), 238-239 DOI: 10.1645/GE-1749.1

How to Study Invasive Species, a Conservation and Ecological Imperative

The January edition of The American Midland Naturalist includes an essay by Daniel Simberloff (University of Tennessee) that bears the questioning title “Invasions of Plant Communities – More of the Same, Something Very Different, or Both?” As alluded to by the interrogative title, the central theme of the piece is whether or not the ecological characteristics displayed by invasive plant species are similar to those demonstrated by native plants during the natural succession of a vegetative community. In other words, do the strategies and tactics employed by invasives during the conquest of new habitats follow similar patterns of recruitment and regeneration as those exhibited by native plants in moving a community towards maturation? Or, in contrast to natural succession patterns, do invasive species have unique biological or demographic qualities that require a novel or specialized approach to studying their dynamics?

Daniel poses great questions, because, recognizing that we live in a world of mass travel and shifting climates, the study of invasive dynamics is of critical importance to the conservation of biodiversity – protecting natural habitats and native species. In addition to conservation, by researching the interplay of native and non-native species during the establishment of ecosystems we will undoubtedly gain a wealth of knowledge in regards to the feedbacks between evolution and ecology (i.e. how do those species lacking a shared co-evolutionary history come to achieve a stable strategy for survival?).

So, with that in mind, here’s my answer to Daniel’s question: Both!


Cause’ in a nutshell: Although invasive species will exhibit some life-history strategies comparable to those of plants from the newly invaded habitat (growth pattern, time to reproductive maturity, etc…) they will also be subject to environmental factors of a temporal nature that do not influence the natives (at least to the same extent).

Said differently, because the growth, reproductive habits and resource needs of an invasive likely mirror those of at least one native plant, the invasive could theoretically replace the native with little ill effect to the ecosystem; the invasive could fill the niche left void by the out-competed native plant without disrupting the energetics of the plant community as a whole. BUT, at the same time, a newly arrived invasive species may have a distinct advantage over a native transient because it is completely foreign to the ecosystem. For example, being unrecognized by its new environment the invasive may, for a period of time, be buffered against attack by herbivores, parasites and other stressors that may be actively reducing the fitness of the locals.

Similar to the above potential advantages, the invasive could also be subject to the detrimental affects of being an outsider - brought about by a lack of co-evolved pollinators, ect…

I would also argue that the above temporal effects associated with being a novel addition to an ecosystem, though only short-lived, can be magnified greatly by stochastic events. I would suggest this because – generally – variability in initial survival rates contributes greatly to ultimate establishment; often more so than reproductive strategy, which is subject to greater phylogenetic constraint (i.e. initial survival is more important than in choosing to produce many low-quality seeds when young, or to conserve energy and produce fewer higher-quality seeds when older).


Daniel’s essay is a great read and offers plenty of real-world case studies to emphasize his points; definitely check it out!


Simberloff, D. (2010). Invasions of Plant Communities – More of the Same, Something Very Different, or Both? The American Midland Naturalist, 163 (1), 220-233 DOI: 10.1674/0003-0031-163.1.220

Fisheries in Peril: The Evolution of Exploitation

What happens when the commercial fishing industry and recreational fishers target certain species for size? Do these practices of selective harvest equate to active artificial selection for smaller fish? Do these practices reverberate in the fish DNA in such a way that humans can be said to be manipulating the evolutionary trajectory of marine life? Thanks to the journal of Evolutionary Applications, here’s your chance to find out!

A few weeks back Loren McClenachan of the Scripps Institution of Oceanography provided an overview of her recent work to the folks at Florida State University - where she’s currently doing some post doc stuff. The bulk of her research centers on the impact that historic human activities have on the populations of fish and marine mammal species. More specifically, using contemporary and historical records such as ship logs, archived photographs, newspaper articles, documented personal accounts, and similar sources, she examines the quantity, geographic distribution and individual sizes of harvested species.

For example, to look at the toll humans have taken on populations of the goliath grouper (Epinephelus itajara) in south Florida, McClenachan ventured to Key West and collected photographs from resident fishing charter services, and historical newspaper articles from the archives at the local county library. Through analyzing the information, she was able to statistically demonstrate (and pictorially illustrate) the change in species composition and individual size of fish harvested recreationally in the Florida Keys. More to the point, she was able to show that between the 1920s and 1970s the maximum size of harvested trophy fish decreased while at the same time the total number of caught fish plummeted.

Photo from McClenachanlen's below cited paper; Grouper Catch Dated 04/14/57

If interested, McClenachan’s grouper paper can be found here:
McClenachan, L. (2009). Historical declines of goliath grouper populations in South Florida, USA Endangered Species Research, 7, 175-181 DOI: 10.3354/esr00167


One has to wonder (i.e. worry) what impact humans are having on fisheries worldwide. Rather it is for recreational or commercial purposes, our fishing actively is reducing the abundance of many marine species, and one can argue that we’re even aggressively and proactively engaging in an artificial selection practice that seems to be in pursuit of smaller fish and reduced species diversity…

I’m reminded of McClenachan’s talk because the journal Evolutionary Applications has just published a special edition which makes available (FREE!) research presented during the 2008 American Fisheries Society Annual Meeting. Anyone with an interest in fisheries, oceanography, ecology, evolution or conservation should take a look – there’s something for everyone!

Included papers (All of which are free - HERE):

Life history change in commercially exploited fish stocks: an analysis of trends across studies (p 260-275)Diana M. T. Sharpe, Andrew P. Hendry


The role of experiments in understanding fishery-induced evolution (p 276-290)David O. Conover, Hannes Baumann


Comparison of demographic and direct methods to calculate probabilistic maturation reaction norms for Flemish Cap cod (Gadus morhua) (p 291-298)Alfonso Pérez-Rodríguez, Marie Joanne Morgan, Fran Saborido-Rey


Is fishing selective for physiological and energetic characteristics in migratory adult sockeye salmon? (p 299-311)Steven J. Cooke, Michael R. Donaldson, Scott G. Hinch, Glenn T. Crossin, David A. Patterson, Kyle C. Hanson, Karl K. English, J. Mark Shrimpton, Anthony P. Farrell


Life-history traits and energetic status in relation to vulnerability to angling in an experimentally selected teleost fish (p 312-323)Tara D. Redpath, Steven J. Cooke, Robert Arlinghaus, David H. Wahl, David P. Philipp


Avoidance of fisheries-induced evolution: management implications for catch selectivity and limit reference points (p 324-334)Jeffrey A. Hutchings


Quantifying selection differentials caused by recreational fishing: development of modeling framework and application to reproductive investment in pike (Esox lucius) (p 335-355)Robert Arlinghaus, Shuichi Matsumura, Ulf Dieckmann


Size-selective fishing gear and life history evolution in the Northeast Arctic cod (p 356-370)Christian Jørgensen, Bruno Ernande, Øyvind Fiksen


Propensity of marine reserves to reduce the evolutionary effects of fishing in a migratory species (p 371-393)Erin S. Dunlop, Marissa L. Baskett, Mikko Heino, Ulf Dieckmann


Implications of fisheries-induced evolution for stock rebuilding and recovery (p 394-414)Katja Enberg, Christian Jørgensen, Erin S. Dunlop, Mikko Heino, Ulf Dieckmann


Mitigating fisheries-induced evolution in lacustrine brook charr (Salvelinus fontinalis) in southern Quebec, Canada (p 415-437)Kenichi W. Okamoto, Rebecca Whitlock, Pierre Magnan, Ulf Dieckmann


Eco-genetic model to explore fishing-induced ecological and evolutionary effects on growth and maturation schedules (p 438-455)Hui-Yu Wang, Tomas O. Höök

The Metacommunity Mannerisms of Foraging Frogs

Last Saturday, snapshots of a spring peeper (see A Peeper’s Problem) were used to springboard a discussion regarding habitat fragmentation and the conservation of species that exhibit behavioral characteristics not exclusively bound to a single ecological community type. The general idea was that saving a forest from commercial harvest, or conserving a wetland, is an essential step towards preserving biodiversity; however just as important to conservation efforts is the protection of wildlife corridors and other thoroughfares used by flora and fauna. In that post, the spring peeper was forwarded as an exemplar of a species whose natural history requires spatial dispersion between differing communities; those communities used for reproduction (wetlands) and those used during non-reproductive adulthood (forests). To further delineate the “metacommunity” concept, the current post aims to look at this idea through the bulging eyes of a different, though not wholly dissimilar, species – the squirrel frog.

As fate would have it, on the very same stormy night that the peeper was victimized by the paparazzi, another frog also happened into the viewfinder – as though he knew that a herpetologically-laden week of community ecology discussions at Ecographica was eminent…

Meet Hyla squirella, the squirrel frog:


The squirrel frog is common throughout the Southeastern United States and like Pseudacris crucifer, Hyla squirella is a terrestrial tree frog that undertakes journeys from “water-to-wood and back again” during its life cycle. These travels are bound to reproduction and early development in water, with maturation and adulthood driving them to arboreal existence in the uplands.


Metamorphosis from tadpole to froglet is the starter pistil for transitioning to the trees, with seasonality - specifically the rainy season - as one of the big signals for movement water-ward. Thus, H. squirella represents a biological link between two ecologically distinct communities; a wetland with depressional geomorphological features that are awash in aquatically adapted plants, invertebrates and fish with fluctuating levels of hydrology and nutrients, VERSUS a forest system with epiphytic plants, wood boring insects and a generally more arid microclimate.

A set of distinct ecological communities that are biologically entangled through the spatial dispersion of commonly hosted, interacting species is one way of defining the term “metacommunity.” Essentially, a metacommunity is an order of ecological organization above the community level. So, moving backwards through the hierarchy, a metacommunity is a set of distinct communities, a community is a set of distinct populations and a population is a set of individuals. And, just as individuals interact and associate with each other under rules established by population dynamics, communities can interact with each other in a landscape through processes that can be described in terms of a metacommunity dynamic.

In traversing ecologically unique community structures, the niche of the squirrel frog presuppose many risks inherit to a world of pavement and progress, but Hyla squirella enters the battle well equipped and is armed with the decision making tools afforded by natural selection.

For example, during ovipositioning the squirrel frog deposits its eggs in elongate, slender strings with each egg lined-up, one after the other, like dominos made of pearls; these strings are laid in waters that have been positively selected for their ability to supply young tadpoles with the resources required for growth and development. For the herbivorous Hyla tadpoles, this means that an abundance of algae, plants and inorganics can be found attached to submersed logs, rocks and other structures. The tads are suspension feeders; this means that they scour the surface of substrates for nutrients, akin to tiny vacuum cleaners, leaving no surface un-sampled. Although food acquisition is vital to the tadpoles ultimate success, another key decision also enters into the equations of the mother frog’s evolutionarily provided calculator – predator avoidance.

In considering the processes under which metacommunal species weigh the risk of death against the benefits of nutrient availability (growth) within a given habitat, C.A. Binckley (Old Dominion University) and W.J. Resetarits (University of Southampton) examined the squirrel frog’s preferences in natal ponds. They constructed 54 experimental ponds in which they controlled nutrient availability and the occurrence of fish that prey on hylid eggs. By comparing the total eggs deposited at each artificial pond, they were able to correlate the pond preference of mother frogs for expressed nutrient availability and predatory risk. Their study demonstrated that within a variable landscape, metacommunal species display habitat choosing behaviors that are in accordance with optimization theory and predicted foraging behavior. In other words, the research showed that the squirrel frogs exhibited a pond choosing behavior which can be affectively viewed as the frog weighing the risk of death against the opportunity for growth; with the frog trying to achieve the lowest possible “mortality /growth” value.

In a similar fashion, it’s a safe bet that similar “decisions” are undertaken by H. squirella when choosing upland habitats as an adult… The decision making toolset programmed into the genes of the squirrel frog not only provides the ability to survive and excel within a variety of community types, it also is the instrument through which communities as distinctive as wetlands and upland forests are linked. Alteration of one habitat, one species, or even one gene, can have reverberations in far ranging ecosystems; this is precisely why conservation of those connections is of the utmost importance.

Binckley, C., & Resetarits, W. (2008). Oviposition behavior partitions aquatic landscapes along predation and nutrient gradients Behavioral Ecology, 19 (3), 552-557 DOI: 10.1093/beheco/arm164

The Threatened Gopher Tortoise

Sticking with the herpetological theme of the last couple of narrative posts (Diamondback Rattle Snakes and Spring Peepers), I thought that I’d share a couple snapshots and a short video clip of a gopher tortoise from a couple of weeks back.

This gopher tortoise, Gopherus polyphemus, was photographed in west-central Florida just outside of a planted slash pine plantation.

Most of the pine plantations in Florida have resident gopher tortoises; however these areas of anthropogenic alteration are far from ideal habitats. The plantations aren’t good for the tortoises primarily because of the fact that the plantations were established for commercial use (wood production) and were therefore seeded very densely to maximize the quantity of trees grown. The extreme density of the canopy trees drastically reduces the amount of light reaching the forest floor and affectively minimizes herbaceous growth and groundcover which the tortoises consume.

In addition to silvaculture (and as with the spring peepers), gopher tortoise populations are also heavily impacted by habitat fragmentation, which is one reason why they are listed as a Threatened Species by the U.S. Fish and Wildlife Service.

Here's a quick video of the above tortoise racing to his burrow:

For those that may not be familiar with the gopher tortoise, here’s a pile of info snagged from the Smithsonian Marine Station’s website:

Description:
The gopher tortoise, Gopherus polyphemus, is a large terrestrial turtle having forefeet well adapted for burrowing, and elephantine hind feet. The front legs have scales to protect the tortoise while burrowing. Body length averages approximately 25 cm (10 inches), with the shell ranging in height from 15 – 37 cm (6 – 15 inches). Body mass averages approximately 4 kg (9 pounds). Color is a dark brown to gray-black, with a yellow plastron (bottom shell). A gular projection is evident on the anterior plastron where the head projects out from the shell. Sexual dimorphism is evident, with male gopher tortoises having concave plastrons, while those of females are flat. In addition, the gular projection on male plastrons is generally longer than in females (Ernst and Barbour 1972).


Gopher tortoises dig burrows for cover and for nesting. These can be extensive, measuring approximately 4.7 - 11 m (14 – 40 feet) in length (Witz et al. 1991). Burrow depth is heavily dependent on depth of the local water table (Diemer 1986; Burke and Cox 1988).


Trophic Mode:
Gopher tortoises are primarily herbivorous, with the bulk of the diet consisting of low-growing herbs and grasses. Foods most common in the diet are grasses and legume fruits. They are also known to consume pine needles and seeds, oak mast, prickly pear cactus, asters, palm tree fruits, raspberries, black cherry, and gopher apples (Landers et al. 1980; Auffenberg and Franz 1982; Diemer 1986). Gopher tortoises have also been observed to eat mollusk shells and the bones of dead animals, possibly to supplement their diets with additional calcium.


Competitors:
Predators of gopher tortoises include various snakes, fire ants (Solenopsis saevissima), accipiter hawks, buteo hawks, raccoons, opossums, armadillos, skunks, dogs, foxes, feral cats and man all prey on gopher tortoises. Generally, eggs and hatchling tortoises are significantly more at risk for predation than older animals.


Habitats:
Gopher tortoises use a variety of habitats, including beach dunes, scrub, and pine flatwoods. In all habitat types, soils are generally dry, sandy and well-drained. While generally avoiding swampy areas, gopher tortoises in Brevard County, Florida have been observed to inhabit poorly-drained scrub and slash pine flatwoods (Breininger et al., 1991). In this county, higher densities of gopher tortoises were found in poorly-drained sites than in well-drained sites.
Individuals occupy distinct home ranges, with male home ranges typically being larger than those of females. In east-central Florida, home ranges of male tortoises averaged 1.9 ha (4.7 ac), while those of females averaged only 0.65 ha (1.6 ac). A tortoise excavates several burrows for its use within the home range. Burrows typically are dug at a 30 degree angle from the surface. In Florida studies, male tortoises dug between 8 – 35 burrows. Females tended not to use as many burrows as males, averaging between 3 – 17 burrows (Breininger et al., 1988).

Tortoise densities tend to be higher in fire-adapted communities (Auffenberg and Franz 1982; Diemer 1986). In the absence of fire, canopy trees grow large and shade out the herbaceous vegetation that gopher tortoises rely on as their primary food source.


Associated Species:
Gopherus polyphemus is considered a keystone species in that more than 80 different species live in their burrows, or are dependent on their burrows for protection. Some of these species, such as the gopher frog (Rana areolata), the pine snake (Pituophis melanoleucus) the indigo snake (Dymarchon corais), the scrub jay (Aphelocoma coerulescens) and in inland prairies, the burrowing owl (Athene cunicularia floridana) are rare (Burke and Cox 1988; Spillers and Speake 1988; Stout et al. 1988;Witz et al. 1991).

To the Woods and Back Again; the Peeper’s Problem

I photographed this “spring peeper” a few nights ago following a fairly impressive thunderstorm. The squall dumped a substantial amount of rain and provided Pseudacris crucifer with the perfect opportunity to talk-up the local ladies. His easily distinguished high pitched “peep –like” call is what brought him to my attention; though distinguished as his call was, he certainly had his work cut out for him on this particular night because the yard was alive with the chorus of his rivals.


Pseudacris crucifer is common throughout the eastern half of the United States and their range extends northward into Canada. Adults grow to a length of about three and a half centimeters, and as seen in the photos, their skin is a light olive-brown color with striped designs across the legs, a darker toned “X” pattern on their back and generally a darker brown color around the eyes (still visible but washed-out in these photos).


Being a terrestrial tree frog, the spring peepers have natural history requirements that depend on access to both water and forested areas. Their life cycle takes them from the vernal pools and road side ditches of their tadpole-hood to trees and shrubs as adult frogs. As with most frogs, water is a requirement for reproduction, however peepers don’t require permanent water bodies, and they are perfectly content to use puddles, seasonal ponds and even the water held between the boughs and stems of trees for ovipositioning. Once reaching adulthood, peepers travel to forested areas to hunt insects along the multitudes of woody tree branches, and to hide from predators amongst the leaves. Then, after obtaining sexual maturity, they make seasonal treks back to the water in order to start the cycle a new.

As briefly described above, the life cycle of Pseudacris crucifer necessitates the undertaking of a certain amount of risk… Traveling from water to wood and back again can be a perilous journey, not only because of natural predators, but also because of the increasing levels of habitat fragmentation at the hand of human productivity. More specific to the travels of the spring peeper, the removal of adult habitat through deforestation and the construction of paved roads represent tremendous hazards to species conservation.

Scientists from the Geomatics and Landscape Ecology Research Laboratory and Lakehead University weighed the effects of increased vehicular traffic against the impacts associated with deforestation relative to the life cycle of six anuran different species. The researchers conducted amphibian surveys at thirty-six ponds and then sorted their field data based on the ponds’ proximities to areas of high and low vehicle traffic as well as the nearness to varying densities of forest. What they discovered was that although some variation in the impacts of traffic-Vs-deforestation exited between species, overall both the removal of forest habitat and mortality as a result of road kill appeared to detrimentally affect anuran success. In regards to the spring peepers surveyed as part of this study, the quantity and proximity of forest cover was found to be of higher significance than was the density of roads and associated traffic – though both of these human influenced factors generated damaging impacts in the productivity of Pseudacris crucifer.

In considering the spring peeper’s natural history and the goals of conservation, organisms which are not tightly bound to a single community type, and are rather found to exist within a metacommunity dynamic, require special attention by biologists. Due to their fluctuating life requirements, that change from birth-to-adulthood and vary between wetland and forested habitats, the unique immigration and emigration patterns exhibited by the species require preservation of forest and water resources as well as protection of the wildlife corridors and resource connectivity between the two.

EIGENBROD, F., HECNAR, S., & FAHRIG, L. (2008). The relative effects of road traffic and forest cover on anuran populations Biological Conservation, 141 (1), 35-46 DOI: 10.1016/j.biocon.2007.08.025

Conservation Decisions – The General Patton Approach

It was General George Patton who originally said, “A good plan executed now is better than a perfect plan later.” Though Patton was referring to military planning, some scientists and policy makers believe that such a strategy should also be applied to ecology and conservation.

Recently, a paper from the Proceedings of the National Academy of Sciences proposes that decision making, in regards to natural resource conservation, should be undertaken with consideration to both science and social impact. More specifically, the paper proposes that climate change is hastening the need for sound conservation strategies with respect to the managed relocation of species. Furthermore, they argue that despite a past hesitation to intervene, biologists should consider human-facilitated migrations as a viable option.

A myriad of authors from a variety of universities and governmental agencies participated in the study which qualitatively examined three cases where managed relocation was conducted or considered. From these case studies, the group developed a decision-making model that considers such action from the Focal impact, Collateral impact, Feasibility, and Acceptability to both ecology and public perception.

Image from Article, 3D Evaluation of decision to Relocate Species

My opinion in the matter is that although the model may, or may not, be an adequate tool in achieving desired policy outcomes, the science of species introductions and relocations tends to demonstrate that the practice is wrought with unknown variables and is a high-risk endeavor. Because of this, I don’t like that the paper – though well intentioned – “pushes” managed relocation when it should only be “pushing” a decision making process. In my experience, those species found admirable to the public are not always the best candidates for relocation, and when public opinion enters into science, decisions can be made based on perception and misconceptions as opposed to on fact.

Just my opinion, I could be wrong…

Richardson, D., Hellmann, J., McLachlan, J., Sax, D., Schwartz, M., Gonzalez, P., Brennan, E., Camacho, A., Root, T., Sala, O., Schneider, S., Ashe, D., Clark, J., Early, R., Etterson, J., Fielder, E., Gill, J., Minteer, B., Polasky, S., Safford, H., Thompson, A., & Vellend, M. (2009). From the Cover: Multidimensional evaluation of managed relocation Proceedings of the National Academy of Sciences, 106 (24), 9721-9724 DOI: 10.1073/pnas.0902327106

Mangroves, Eutrophication and Dead Zones

Recent research from the University of Queensland, the Australian National University and the Smithsonian’s Environmental Research Center demonstrates that, contrary to previous studies, nutrient influx of Nitrogen and Phosphorous into coastal forests may contribute to mortality in mangrove trees. In a time of advancing Dead Zones, these findings hasten warnings about the dire consequences of poor-conservation efforts in regards to the world’s starkly limited water resources.


The name “mangrove tree” can refer to any number of species common to the world’s brackish habitats, however here in Florida, the term generally refers to one of three species, the “red mangrove” (Rhizophora mangle), “white mangrove” (Laguncularia racemosa) or the “Black Mangrove” (Avicennia germinans). In order to survive and prosper in the plant hostile environments found within coastal areas, natural selection has provided the mangrove trees with highly specialized morphological adaptations.


The evolutionary history of mangrove trees stretches back more than 100-million years to the Lower Cretaceous of Southeast Asia – a geographic area where they currently exhibit a species diversity and range greater than anywhere else on the planet. Having had emerged from tropical and subtropical intertidal zones with excesses of salinity, temperature and erosion - and having deficiencies of freshwater and aerobic soils - mangrove trees demonstrated tolerances and strategies that enabled them to quickly expand their range around the globe. These adaptations include a mode of viviparous reproduction in which energetically independent seedlings remain attached to the parent tree following germination; remaining there attached until sufficiently mature to drop to the waters below as propagules for dispersion to far-off localities. From the plants ability to turn its leaves away from the intense midday tropic sun, to its skill in fine filtrating sodium from available marine waters, the mangrove is a dynamo of the brackish way of life.


Another adaptation to intertidal existence was the advent of soil accumulating suberised prop roots, which elevate the tree, filter salts and permit mangroves to construct their own islands. The roots are critical to the mangrove’s ecology for several reasons. One is that being immersed in a saline hydrology requires balance of sodium between the plant’s internal environment and that of the surrounding marine waters; this is critical for maintaining osmotic pressures and nutrient uptake in a world where the potential for desiccation is omnipresent. The roots also provide physical stability and support to the tree during frequent and intense wave bombardment and during high wind events such as tropical cyclones. Though amazingly adapted, the roots of mangrove trees may have met their match in anthropogenic nutrient loading…


Nutrient enrichment of plants through the addition of Nitrogen and Phosphorus loads, rather occurring naturally - or as more common – of anthropogenic origins, leads to growth in most species. These are simply the principles of fertilization in action; “more nutrients equals more growth.” However, as an important aside, “more growth” does not necessarily mean that the entire plant from root-to-canopy grows uniformly. In fact, in most cases fertilization leads to expansion of above ground plant structures only. Thought of from the plant’s perspective, “if there is currently adequate, or more than adequate, nutrients available, why should I invest in additional nutrient up-taking roots – I already have what I need from the soil, so I’ll invest in stems and leaves instead!” Such a “plant’s perspective” appears to be the one implemented by mangroves in the presence of increasing levels of eutrophication.


Using Florida and the Gulf of Mexico as one example of many from around the world, run-off carrying excesses of fertilizer from the “Bread Basket” of the United States is finding its way into the tributaries of the Mississippi, and in turn, into the Gulf of Mexico where explosions of algae growth have resulted in hypoxic conditions and the creation of a massive Dead Zone. Surges in the growth of algae and other noxious plants resulting from Nitrogen and Phosphorous loading is called eutrophication; eutrophication leads to de-oxygenated environments, the death of all organisms requiring oxygen and the total loss of ecosystem function. To make matters worse, far from being stationary, the dead zones move or “creep” from their epicenters, corrupting ecosystems both far and wide. For Florida, the Gulf of Mexico Dead Zone may contribute to “Red Tide” and the death of everything from phytoplankton to manatees in the State’s waters. Now, in addition to all of these previously known adverse effects, eutrophication has the potential to fertilize Florida’s coastal mangrove forests, causing rapid tree growth – but only of canopy components, not of roots.


As described above, the roots of mangrove trees are essential for multiple reasons and any increase in above surface foliage that is not accompanied by a proportional increase in rooting not only makes the trees more susceptible to desiccation, but also makes them directly vulnerable to mortality by frequent onslaught of wind and wave. If the current research is accurate, additional Nitrogen in coastal aquatic ecosystems may translate to a short-term growth of tree canopy followed by a long-term increase in the rate of mangrove tree death.


Lovelock, C., Ball, M., Martin, K., & C. Feller, I. (2009). Nutrient Enrichment Increases Mortality of Mangroves PLoS ONE, 4 (5) DOI: 10.1371/journal.pone.0005600

The Blitzkrieg of Ungulates in Levant

The region of the Middle East referred to as “Levant” includes modern day Israel, Palestine and Jordon, and there are few places on earth more intensely studied by archaeologists than the birthplace of monotheistic religion. In addition to yielding a vast record of human occupation, culture and war, the archaeological sites within this region also document the decimation of several mammalian species. A couple of days ago (April 29), several Israeli scientists published an article in PLoS One in which they identified human driven overkill as the primary cause of regional extinction in several species of ungulates.

Through examination of vertebrate remains associated with the archaeological sites of Levant, scientists were able to piece together patterns of ungulate biogeography that point to over hunting and environmental degradation as the impetus for the extinction of hartebeests, aurochs, hippopotami and several species of deer. Additionally, a direct correlation was found between the body mass of the hunted species and the rate at which the animal went extinct – presumably, larger animals were of greater value (provided more meat) and were easier to hunt (bigger = slower).

Figure: Body mass of ungulates that became extinct at end of Iron Age (by 586 BCE), at end of Mamluk period (12th century CE), at end of 19th century CE, as well as body mass of extant ungulate species. Three species became extinct during the Iron Age (1,Hippopotamus amphibius; 2, Bos primigenius; 3, Alcelaphus buselaphus), one species during the 12th century CE (4, Cervus elaphus), and six species during the 19th century CE (5, Dama mesopotamica; 6, Capra aegagrus; 7, Capreolus capreolus; 8, Gazella subgutturosa; 18 9, Equus hemionus; 10, Oryx leucoryx). Four species still exist (11, Sus scrofa; 12,Gazella gazelle; 13, Capra ibex nubiana; 14, Gazella dorcas). Because only one species become extinct during the 12th century this period could not be included in the ANOVA analysis. Horizontal broken line indicates average body mass of the 14 ungulates in Natufian Period (13,000–9,500 years BCE). Letters above bars indicate a significant difference between groups (Bonferroni Multiple Comparison Test, P,0.05). doi:10.1371/journal.pone.0005316.g011

According to the researchers, “It thus appears that during the Holocene period in the southern Levant, the most important causes of ungulate extinctions were habitat destruction and uncontrolled hunting.” They further detail, “Based on the data of this study we assume that overkill in the southern Levant operated in two stages: 1) slow overkill by ancient hunting methods, that caused the disappearance of the larger species and 2) modern blitzkrieg, which was made possible by the use of modern firearms, such blitzkrieg differed drastically from the prehistoric hunting of naive large fauna in other continents and islands, where human hunters were never encountered.”

Tsahar, E., Izhaki, I., Lev-Yadun, S., & Bar-Oz, G. (2009). Distribution and Extinction of Ungulates during the Holocene of the Southern Levant PLoS ONE, 4 (4) DOI: 10.1371/journal.pone.0005316

Hyperbolic Geometry and Corals

This video relates to the coral bleaching post made yesterday - Resilience in Acropora Corals


Margaret Wertheim: The beautiful math that links coral, crochet and hyperbolic geometry

Resilience in Acropora Corals

Great news - local management of water quality and other factors may significantly contribute to the survivability of coral reefs that have been negatively impacted by climate change.

A massive bleaching event took place on the Great Barrier Reef approximately three years ago and devastated a huge number of inshore reefs, but the Acropora corals made an unprecedented comeback – in only a year’s time!

According to Guillermo Diaz-Pulido, three critical factors contributed to this unprecedented turn around, “first was exceptionally high re-growth of fragments of surviving coral tissue. The second was an unusual seasonal dieback in the seaweeds, and the third was the presence of a highly competitive coral species, which was able to outgrow the seaweed. But this also all happened in the context of a well-protected marine area and moderately good water quality.”

Sophie Dove of the Centre for Marine Studies and Australian Research Council Centre of Excellence for Coral Reef Studies points-out that, “The exceptional aspect was that corals recovered by rapidly regrowing from surviving tissue. Recovery of corals is usually thought to depend on sexual reproduction and the settlement and growth of new corals arriving from other reefs. This study demonstrates that for fast-growing coral species asexual reproduction is a vital component of reef resilience.”

Coral recovery following algal overgrowth

(Images from Artcle)

Branches of Acropora corals died after bleaching and were subsequently colonized by a variety of benthic algae. Remnant coral tissue at the base of the coral colonies regrew upward and deposited new skeleton along the old dead coral branch, overgrowing

A) algal turfs (arrows). B) fleshy seaweed Lobophora variegata.

C) crustose coralline algae. D) Coral tissue has all but completely overgrown the colonizing algae.


E) Thin section of coral showing benthic algae sandwiched between old coral skeleton and a thin layer of new skeleton. Examination using a compound microscope showed that coral tissue overgrew a range of algal types.

Ove Hoegh-Guldberg of CoECRS and The University of Queensland suggests, “...that managing local stresses that affect reefs such as overfishing and declining water quality can have a big influence on the trajectory of reefs under rapid global change.”

Read the Article from PLoS One - HERE

Diaz-Pulido, G., McCook, L., Dove, S., Berkelmans, R., Roff, G., Kline, D., Weeks, S., Evans, R., Williamson, D., & Hoegh-Guldberg, O. (2009). Doom and Boom on a Resilient Reef: Climate Change, Algal Overgrowth and Coral Recovery PLoS ONE, 4 (4) DOI: 10.1371/journal.pone.0005239

The Fire Gene Described

A lengthy introduction during the initial post on this topic (available Here) contrasted a harmonious view of nature with the perspective of nature as a series of oppositional organisms struggling to gain a competitive edge over rivals. As a model of this outlook, the ecotone boundaries between various sets of differing plant communities were offered as a case study. More specifically, the prairie, savanna and hardwood hammock ecosystems of the Big Cypress Preserve were forwarded along with the proposition that members of these communities actively challenged each other for limited resources. In staging this proposition the question was asked, “Why don’t trees invade - and take over – the prairie communities currently occupied by grasses?” After eliminating the likelihood that densely growing stands of grass crowded-out young saplings by denying them access to sunlight, cyclic wildfire were explained and presented as an alternative explanation. Moving forward with this production, a profile of one of the previously introduced characters is in order – the conifer tree Pinus elliotti.

Slash Pine Growing from a Log

Slash Pine is a 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. There are two distinct varieties of slash pine, variety elliotti and variety densa, although there are several important distinctions, for purposes here both varieties can be considered one and the same. Pine and spruce trees are grouped together with cycads, gnetophytes and ginkgo as gymnosperms, which had a 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. Unlike the 21% atmospheric oxygen present today, the carboniferous boasted 35% oxygen content, this in conjunction with an abundance of herbaceous material (remember Carboniferous = “coal age”) resulted in frequent – and intense – wildfires.

Wildfires…

So, do wildfires prevent trees, such as slash pine, from invading prairie strongholds held by grasses? Not really, some especially intense (“intensity” being a measure of a fire’s maximum temperature and duration) wildfires may destroy slash pine, but fires capable of doing so are relatively rare. The typical “fire seasons,” as described in the first post, may have sufficient intensity to kill some young saplings, but remember - slash pines also have “initial rapid growth genes” which provide a solid head start in defending themselves. Essentially, any sapling greater than two years old has a good chance of getting through the “average” wildfire. As for the periodic “non-average” wildfire, one that is of an unusually high intensity, slash pines may need to rely on evolutionary adaptations other than “initial rapid growth genes” – they may need to lean on morphological phenotypes resulting from a “fire gene.”

A fire gene is a genetic compliment possessed by an organism that is expressed in such a manner that the presence of fire improves the likelihood of that genotype being passed on to future generations. In other words, if a population of trees exists in which some members have a genotype that provides phenotypical resistance to fire, and that population is then exposed to fire, killing a certain percentage of the population, those trees with fire gene advantage will have higher survivability and greater measures of fitness than will those not possessing a fire gene. Through this process of “selection by fire,” the fire gene would become more prevalent in the population, eventually becoming so common as to be called characteristic.

This is precisely what has occurred with the pine trees of the Big Cypress. Through millennia of “trial by fire,” only those trees expressing the most fire tolerant phenotypes have survived. Morphological features such as thickly armored plates of bark shield the trunk from heat, scale plated meristems guard against flames and the pine’s reproductive strategies take into account spring fires by germinating in the fall and producing periodic mast crops. However, these products of natural selection are merely defenses, what is truly remarkable is that another aspect of the fire gene contributes to offensive maneuvers.

As a thought experiment only, image being a tree with the cognitive function of a human and the knowledge that you have an inherit resistance to fire; a resistance that many of your competitors do not posses. If locked in a battle for survival, and you had a match in hand, (or rather, a match in “branch”) would you start a fire?

Of course, matches are of little use to trees outside of thought experiments, but what if there was an adaptation that would provide not only defense, but also allow trees to harness naturally occurring fires to their advantage? Genes don’t exist in isolation; frequently they form partnerships to gain mutual advantage. Epistasis, the interaction between genes, has occurred in pine trees to accomplish the same goal. Not only do the trees have defensive morphologies, they have also adapted the chemistry of their leaves (i.e. pine needles) such that while on the tree the leaves produce flame resistant chemicals, but when wildfires are absent for extended periods of time leaf chemistry changes. In the absence of wildfires leaves are randomly shed, accumulate in the area around the tree and - as opposed to being flame retardant - they become easily ignited at low temperatures and burn at an intensity that, well… An intensity that only a slash pine would love…

Some fires do adversely affect slash pine, but the presence of a “fire gene” provides both defensive and offensive adaptations that can –and have been – utilized to survive. So, why don’t trees such as slash pines invade prairies? It’s a “one-two punch.” Through heat stressing the trees, fires slow down advancing slash pines; however it is what happens after the fire season that stops them cold in their tracks – flooding. Summer rains pile on additional stress to what has already accumulated due to fire defense investment. Grasses are in the same boat, but due to a better water tolerance they can bounce back more readily. The slash pine can survive fires or flood, but taken together these two modes of environmental disturbance overwhelm the trees and limit their prairie-ward charge. This is, however, a function of seasonality, climate and cyclic wildfires; with climate change and alteration of these natural processes all bets are off. (But that’s a topic for another time…)

Beckage, B., Gross, L., & Platt, W. (2006). Modelling responses of pine savannas to climate change and large-scale disturbance Applied Vegetation Science, 9 (1) DOI: 10.1658/1402-2001(2006)9[75:MROPST]2.0.CO;2

Nordlund, D., & Lewis, W. (1976). Terminology of chemical releasing stimuli in intraspecific and interspecific interactions Journal of Chemical Ecology, 2 (2), 211-220 DOI: 10.1007/BF00987744

Morse, A., Peterson, D., Islam-Faridi, M., Smith, K., Magbanua, Z., Garcia, S., Kubisiak, T., Amerson, H., Carlson, J., Nelson, C., & Davis, J. (2009). Evolution of Genome Size and Complexity in Pinus PLoS ONE, 4 (2) DOI: 10.1371/journal.pone.0004332

Platt, W. J., J. M. Huffman, M. G. Slocum, and B. Beckage. In press. Fire regimes and trees in Florida dry prairie landscapes. In: Noss, R. & Singh, S. (eds.) Land of fire and water: The Florida dry prairie ecosystem. Avon Park Air Force Range and Department of Defense, Avon Park, FL,

US.Kabrick, John M.; Dey, Daniel C.; Gwaze, David, eds. Shortleaf pine restoration and ecology in the Ozarks: proceedings of a symposium; 2006 November 7-9; Springfield, MO. Gen. Tech. Rep. NRS-P-15. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station: 28-32.

The Fire Gene: One Organism’s Ability to Exploit Fire

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. Here, anthropogenic throngs of sharply angled concrete and glass edifices suspend their battle for roadside dominance and yield themselves to a sea of sparsely treed savanna, rolling prairies of grass, and randomly scattered islands of thickly vegetated hammocks; the perfect environment for a relaxing stroll, a picnic, or even a quick nap. All may appear calm within this enchanting panorama; however, the perceived tranquility is but a chimera. A mere illusion of serenity resulting from shortfalls in the ability of Homo sapiens’ photoreceptors to see beyond the 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. If the sensory apparatus of Homo sapiens was keener - more finely calibrated – the landscape of the Big Cypress would appear very different.

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 on Earth. If these actions could be viewed more directly, the landscape would appear saturated with war. Even the plant community boundaries which demarcate prairie from savanna from hammock in the above described landscape are maintained by way of fierce battles waged over evolutionary time. These ecosystems, which appear stable and so pleasingly haphazardly scattered, are in fact tightly ordered armies of competing plants struggling for resources and existence. In these recurrent ecotonal conflicts one species has honed a new weapon – it has adapted to exploit the power of fire.

Naturally existing plant communities exist in a continuum of ecosystems which through evolution have adapted to almost every available habitat on the planet; from “box thorns” (Lycium pallidum) in Death Valley to fully aquatic hyacinths (Eichhornia paniculata) floating around the lakes of Brazil, genetic plasticity in plants is the product of natural selection. Although diverse habitats represent a surmountable challenge, a multitude of both biotic and abiotic factors 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 sun reaching the ground means fewer plants on the ground. Following this rationale, if the tree canopy should be opened (by a storm, hurricane or by the death of older trees) and sunlight is able to temporarily penetrate to the floor, a rapid emergence of both herbaceous plants and new saplings would be predicted. This is precisely what happens; sunlight is the limiting resource, once made available, those plants best able to take advantage of the situation (through rapid growth) will be able to literally overshadow their competitors; plants with genetic compliments favoring a period of “initial rapid growth” are at an advantage and will be positively selected.

Extrapolating this scenario to the prairies of Big Cypress begs the question – why aren’t there any trees in the prairie?

Prairies, typically found on relatively low topographical gradients in Florida, have an abundance of soil nutrients and water; at least enough to support the enormous quantity of grasses and herbaceous plants currently found there. Additionally, from the perspective of a tree, grasses present little competition for sunlight. So, what is it that prevents trees from invading the prairie?

One often suggested possibility is that because prairies are occupied by dense populations of grasses - some of which more than six feet in height - young trees are prevented from taking hold; sort of like a reverse hammock scenario in which the grasses overshadow the young trees thereby starving them of sunlight instead of vice versa… This is plausible, but why wouldn’t trees take hold after wildfires? Wildfires have been historically inevitable in Florida and have the effect of clearing grasses long enough for those trees possessing an “initial rapid growth gene” in their arsenals to stake a claim.

Slash Pine (Pinus elliotti), for example, has just such an initial rapid growth gene. This permits the tree to take advantage of any opportunity to seize real estate, whether it is in a forest or a prairie. Slash Pine is even capable of expressing secondary needles in less than six month’s time – seedlings grow rapidly. Once present, this conifer could easily out-compete grasses for sunlight.

A quick word about wildfires: Florida’s climate cycle is punctuated by alternating dry and wet periods. November to February is the dry season, with relatively little precipitation, and is followed by heavy rains and thunderstorms (particularly near the coasts) during the months of June, July and August. The spring season, February through May, represents a transition from dry to wet, but during this period lightening strikes often cause wildfires due to the parched conditions of plants – parched, having just come out of the dry season. Regularity of climate has resulted in a cyclic “fire season” arriving during the early spring.

Speaking of wildfires… Being a regular occurrence, they are often offered as another explanation for limiting the advance of trees into prairies. Although this suggestion is partially correct, it isn’t the whole story - in some instances trees have even wielded fire as a weapon to destroy its grass competitors.


4-19-09 UPDATE: The Second Half of this Post can be Viewed HERE.

Beckage, B., Gross, L., & Platt, W. (2006). Modelling responses of pine savannas to climate change and large-scale disturbance Applied Vegetation Science, 9 (1) DOI: 10.1658/1402-2001(2006)9[75:MROPST]2.0.CO;2

Nordlund, D., & Lewis, W. (1976). Terminology of chemical releasing stimuli in intraspecific and interspecific interactions Journal of Chemical Ecology, 2 (2), 211-220 DOI: 10.1007/BF00987744

Morse, A., Peterson, D., Islam-Faridi, M., Smith, K., Magbanua, Z., Garcia, S., Kubisiak, T., Amerson, H., Carlson, J., Nelson, C., & Davis, J. (2009). Evolution of Genome Size and Complexity in Pinus PLoS ONE, 4 (2) DOI: 10.1371/journal.pone.0004332

Platt, W. J., J. M. Huffman, M. G. Slocum, and B. Beckage. In press. Fire regimes and trees in Florida dry prairie landscapes. In: Noss, R. & Singh, S. (eds.) Land of fire and water: The Florida dry prairie ecosystem. Avon Park Air Force Range and Department of Defense, Avon Park, FL,

US.Kabrick, John M.; Dey, Daniel C.; Gwaze, David, eds. Shortleaf pine restoration and ecology in the Ozarks: proceedings of a symposium; 2006 November 7-9; Springfield, MO. Gen. Tech. Rep. NRS-P-15. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station: 28-32.