Evolution 2016: Rapid Morphological Evolution in Urban Environments

IMG_2376We as a species are rapidly changing the global environment. The changes that get the most press are those related to climate, but we are also changing the structure of environments through land development. This leads to many important questions, one of which is whether or not the novel environments that we construct can drive evolutionary change. Kristin Winchell, a graduate student in Liam Revell’s lab at UMass Boston, has been addressing this question in the Puerto Rican lizard Anolis cristatellus, which is common in urban settings. Kristin hypothesized that urban environments should select for longer legs and greater surface area of lamellae (the morphological structures on anole toes that let them grip flat surfaces). Her reasoning was that long legs should allow animals to run faster, which should be beneficial in cities where perches and refuges are further apart than in dense natural forests. Greater surface area of lamellae should be beneficial for better grip of smooth man-made surfaces. Kristin compared morphological traits of multiple pairs of urban/natural environment populations and her hypotheses were supported. Not only that, but differences between populations were maintained in individuals developed under common garden conditions, consistent with a genetic basis of the differences. You can see these results in Kristin’s excellent recent paper in Evolution. Kristin also presented some new preliminary results that directly link the morphological changes she has observed to performance on man-made surfaces. Overall, Kristin’s work indicates that urban environments can be a potent force of rapid microevolutionary change and highlights that we are not only changing the abiotic landscape of the globe, but the evolutionary landscape as well.

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