Friday, April 23, 2010

Warning Sounds

Researchers at Cornell University have published a paper in Conservation Biology that used modelling to investigate population-level responses of timber rattlesnakes to habitat fragmentation. In general, habitat fragmentation reduces the ranges of many species, limits resources, increases competition, alters community structure, decreases species diversity and abundance, increases edge effects, and has many other consequences. Anthropogenic habitat fragmentation can result from a variety of things such as roads, farming, buildings, cities, etc -- basically anything that prevents or severely hinders a species' ability to move across the landscape to favorable areas to live. The results of the model show that habitat fragmentation caused by roads have a significant effect on the genetic structure of these rattlesnakes, they are barriers to gene flow and decreasing genetic diversity. This decrease in diversity has its own set of problems, not the least of which is making the population more susceptible to illness and less adaptable to environmental changes.

Additionally, the researchers looked at these rattlesnakes in 19 different hibernacula (shared wintering quarters) at four regions of New York. Using microsatellite markers they tracked the dispersal patterns of these populations as they left their hibernacula, also tracking their reproductive patterns. They compared these data to the layout of roads and to natural barriers in the areas and found that the roads altered gene flow, effectively isolating these populations. These results were seen in each of the regions and were not affected by road type or age.

The article:
Clark, Rulon W., et al. (2010) Roads, Interrupted Dispersal, and Genetic Diversity in Timber Rattlesnakes. Conservation Biology: published online. (DOI: 10.1111/j.1523-1739.2009.01439.x)

p.s. Don't run over snakes with your car, its bad for the snakes and bad for the environment (not to mention its just plain mean).

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