This project tests the effects of gene flow, the movement of genes from one population to another by immigrants, on local adaptation and population dynamics in Trinidadian guppies. On the one hand, gene flow may break down local adaptation and reduce fitness by introducing maladapted genes. On the other hand, gene flow may increase fitness by adding genetic variation to small, inbred populations. Moreover, gene flow may have important effects on population growth and dynamics. The researchers will test the effects of gene flow using experiments in wild populations and in controlled mesocosms (experimental pools). First, they will determine how immigration of fish adapted to a different environment affects traits and fitness in wild populations. Next, they will test how these changes in traits and fitness affect population dynamics. Lastly, they will experimentally test how the effects of gene flow vary with the degree of adaptive differentiation between populations and the level of inbreeding.
This study takes advantage of a rare opportunity to examine populations before and after the onset of gene flow in the wild and in mesocosms. Results of this project will inform conservation programs since a commonly used, but rarely tested, conservation strategy is to artificially increase gene flow. Alongside the research, the investigators will expand their innovative "guppy kit" program to expose elementary and middle school students to experimental evolutionary biology using guppies in the classroom in both the US and in Trinidad. The research will also provide training in field, experimental, and molecular research for underrepresented minorities and Trinidadian undergraduate students. Co-funding for the international component of the research has been provided by OISE.