Rapid Life History Evolution in an Invasive Butterflies

Seiter, Sarah

Download PDF

Request Version for Screen Reader

Last Modified

March 20, 2019

Creator

Seiter, Sarah
- Affiliation: College of Arts and Sciences, Department of Biology

Abstract

Invasive species are ideal for studying rapid evolution because by definition they are able to successfully adapt to new environments. Species which have been introduced to multiple regions are particularly useful because they are replicated natural experiments; by comparing several invasive populations we can learn if evolution follows a consistent pattern in new habitats, or whether it is context specific. My first two chapters compare the North American and Japanese populations of the cabbage white butterfly (Pieris rapae), a European invasive species. These experiments demonstrate that the butterfly has evolved differences in body size and growth rate in both North America and Japan, but that some traits (development time) evolve in a consistent pattern in response to climate, while others (body size, immune function) are evolve in response to other regional factors. I also tested whether selection on life history traits varied between spring and summer, and whether there was a correlation between body size and development time. I found that while there was stronger selection for rapid development in spring rather than in summer, we also found that development time and body size were largely decoupled, indicating that these traits may be able to evolve in relative independence. In my fourth chapter, I compared how two components of diet (lipids and protein) affected thermal reaction norms in two wild and one domestic population of P. rapae. I found that reducing protein disrupted reaction norms in the domesticated population but not the wild population. These results indicate that reaction norms may be disrupted by protein reduction, particularly in populations that are adapted to high quality diets. In my 5th chapter, I conducted a meta-analysis to develop new ways of measuring phenotypic plasticity and to evaluate whether phenotypic plasticity was related to mean trait value. We measured plasticity in several ways (range or traits produced, slope of the reaction norm, angles of the reaction norm), and found that relationship between trait and plasticity was dependent on the metric used to measure plasticity. These results indicate that some aspects of reaction norms may evolve independently of trait values

Date of publication