RAPID: Testing for hurricane-induced natural selection that reverses the direction of morphological adaptation in Anolis lizards

University Of Rhode Island, Kingston RI

Investigators

Abstract

Hurricanes are extreme weather events that are predicted to increase in frequency and magnitude because of increasing global temperatures. These intense storms may result in strong natural selection for organisms living in vulnerable populations in the path of the hurricane. The goal of this research is to determine whether hurricanes are a source of natural selection acting on the morphology of lizards, favoring lizards with longer limbs to better cling to vegetation during high winds. To test this hypothesis, this work will study anole lizard populations that experienced hurricane-force winds during Hurricane Irma. It will determine whether lizard morphology differed before and after the hurricane and if this results in an evolutionary response in the next generation. This research will help to establish whether extreme weather events like hurricanes can be a source of evolutionary change. It is critically important to understand the consequences of extreme events to better manage and predict patterns of persistence for vulnerable populations and communities. The objective of this project is to determine whether hurricane-force winds are a source of natural selection on the morphology of Anolis lizards. During normal periods, selection favors shorter limbs to enhance locomotion on narrow vegetation. Biomechanical studies show lizards with relatively longer limbs run faster on broad substrates, whereas lizards with shorter limbs for a given body size move more adeptly on narrow surfaces. However, during hurricanes, the relevant aspect of performance becomes clinging,instead of running, and selection should favor longer limbs for better clinging ability during high winds. Lizards with longer limbs can more easily wrap them around vegetation, which generates more force when clinging and should better counteract the forces generated by strong winds during hurricanes. Immediately after Hurricane Irma, Anolis lizard populations are predicted to have longer mean limb lengths and higher survival for individual lizards with longer limbs. During the post-hurricane period, individual lizards with shorter limbs will survive better because selection will favor morphology better suited for locomotor performance. By combining mark-recapture and genetic analyses, this study will evaluate morphological shifts, estimate selection, and determine the cross-generational response to selection. The goal is to understand whether hurricanes reverse the direction of selection on the limb length of lizards by changing patterns of selection on biomechanical function, from selection for short limbs that are better suited biomechanically for navigation on narrow surfaces to selection for longer limbs that are better for clinging on the same substrates under high winds.