Do turtles with more powerful predators have stronger shells?
Over the last year, Biology professor Tristan Stayton used GIS and finite element analysis methods to explore this question. During Summer 2010, Prof. Stayton participated in a Library & IT workshop designed to give faculty hands-on experience using GIS for academic research and teaching. Over the course of the summer, Prof. Stayton and his student researchers used ArcGIS to georeference and digitize turtle species ranges to convert them from image files into GIS data that could be used as input in Prof. Stayton’s analysis. The same techniques were also used to digitize the ranges of 25 known turtle predators.
During the 2010-11 academic year, Prof. Stayton used the GIS datasets created during summer 2010 to calculate range sizes and range overlaps of turtles and their predators – and then to derive measures of turtle predation pressure. Prof. Stayton presented his conclusions last month at the Evolution 11 conference in Norman, Oklahoma and has a paper in the works as well.
The answer to the question? The short answer is that no, turtles with more powerful predators do not have stronger shells – in fact, they appear to have evolved weaker shell shapes. But be sure to look at the poster below for a full presentation of the methodology, results and possible explanations for the findings.
Students involved in this project: Christine Vega ’11, Patrick Caloz ’13 and Joe Budzinski ’11 (georeferencing & vectorizing species ranges); Dan Ladd, GIS Student Assistant, Middlebury College ’14 (created turtle species density map shown in poster)