Evidence for Rapid Evolution

Last week I blogged about the Cane Toad and briefly touched upon the effects that this non-native species can have or has had locally here in Australia.  While reading through the information I had looked up I also came across information that pointed to studies that have been done or are currently being done showing that one of the effects the Cane toad has had on native species is that some have adapted to better survive he deadly toxin the Cane Toad contains (Australian Government Department of the Environment 2010).

Ben Phillips is an Evolutionary Biologist at the University of Sydney working on his PhD under Richard Shine and in his interview with ABC Science he notes that the Cane Toad is a great selective pressure in regards to evolutionary biology and that through his research he believes the changes he has documented is a sign of rapid evolution (Salleh, 2004).

Phillips studied four different species of snakes through preserved specimens; “Pseudechis porphyriacus (red-bellied black snake) and Dendrelaphis punctulatus (green tree snake)” and “Hemiaspis signata (swamp snake) and Tropidonophis mairii (keelback snake)” (Salleh, 2004).  In his interview he notes that through his research of these snakes he found clear evidence that over the past 70 years since the Cane Toad had been introduced the two more sensitive snakes the red-bellied black snake and the green tree snake had increased in their length while the other two had not changed and he claims this “morphology” is a direct result of the presence of the Cane Toad (Salleh, 2004).

This is just one example of a species not going extinct due to the presence of the Cane Toad but rather adapting.  However, after doing some more research on this topic I've come across quite a few papers written by Richard Shine and his colleagues which contain scientific data to back up their claims they make contradicting popular belief  about the effects of the introduced Cane Toad.  Those papers can be found on Shines webpage, http://sydney.edu.au/science/biology/sites/Shinelab/index.html (SBI, 2012).

For example, contrary to popular belief, and as mentioned in one of my previous comments on the last blog, the Cane Toad has not driven a single species into extinction.  It is true that numbers of specific species have dwindled upon the invasion of the Cane Toad into their area but after time those numbers begin to come back up as they learn to adapt to the Cane Toad in their environment even if it is just learning to not have them for dinner (SBI, 2012).  

This is not to say that having an introduced species slowly move in and spread out over the landscape, competing with native species for space and other resources is a good thing but there is more we can learn from it at the same time.

References:

Anna Salleh, 2004, Cane toads make snakes adapt to survive, ABC Science, viewed 19 March 2014, <http://www.abc.net.au/science/articles/2004/11/30/1250708.htm>

Can Toads in Oz 2011, SBI, viewed 21 March 2014, <http://www.canetoadsinoz.com/debunkingcanetoadimpactmyths.html>

Department of the Environment 2010, Australian Government, viewed 18 March 2014,

 <http://www.environment.gov.au/node/14576>