Habitat Use, Movement Patterns, and Spatial Population Structure of Polyphenic Sunfish

Abstract

Populations are often spatially structured such that phenotype distributions reflect adaptive phenotype-habitat associations. I investigated two questions about how environmental heterogeneity contributes to spatially structured phenotypic variation in a polyphenic population of sunfish. 1) How does sunfish habitat use in exposed lake shorelines influence spatial population structure? I found that sunfish from exposed shoreline habitat varied in diet and phenotype among sites but were more similar in body form to sunfish from shallow littoral habitat than to sunfish from open water pelagic habitat. 2) How do patterns of connectivity between habitat patches likely influence spatial population structure? Using a between year mark-recapture study, I found rates of movement between habitats sufficient for gene flow to homogenize any genetic differences. Understanding patterns of habitat use and connectivity in polyphenic sunfish populations will generate hypotheses about how spatial population structure is generated and maintained in the initial stages of adaptive diversification.