RAPID EVOLUTION AND POPULATION DIVERGENCE IN RESPONSE TO ENVIRONMENTAL CHANGE IN COLIAS BUTTERLIES

Higgins, Jessica

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March 19, 2019

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Higgins, Jessica
- Affiliation: College of Arts and Sciences, Department of Biology

Abstract

My dissertation focuses on how environmental change, specifically in temperature and host plants, can drive physiological and morphological differences. I took advantage of historical studies with the Colias system of butterflies to assess adaptation and plasticity in larval performance in response to climatic change and changing host plant abundance. I have found that changing temperatures have affected the adaptation of some larval traits but not others. Specifically, as temperature variability has increased in both California and Colorado populations of Colias, the larval feeding rate has shifted to correspond to the new environmental conditions. Next, I studied how two Colorado populations of Colias eriphyle cope with repeated exposures to sub-lethal high temperatures simulating multi-day heat waves. I found that the higher elevation population suffered less detrimental fitness effects than the lower elevation population in regards to both short term (heat shock gene expression) and long term (overall growth rate) fitness effects. Building on my interest of how temperature and temperature variation affects multiple life stages I studied the effects of temperature during the pupal life stage on survival, growth and the resultant adult wing morphology. Generally, high temperatures decreased pupal time and less melanic adult wings. Finally, I used the two populations of C. eriphyle to quantify thermal performance differences of fitness when larvae consume different host plants at two temperatures. I found that cooler temperatures increased the difference in performance between populations consuming different host plants and that thermal performance differs between populations. My research shows that temperature can affect fitness across many life stages and organisms have responded to these changes in temperature over time by adaptation.

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