Predicting future changes in habitat-associated fitness traits is an important step in understanding the ecological and evolutionary consequences of environmental change in freshwater systems. However, models of phenotypic responses to future climate change typically assume populations will respond similarly across the range of a species, while local adaptation and spatial variation in environmental changes are rarely considered. In this study, we examine whether among-population phenotypic variability, coupled with geographic variation in anticipated environmental change, can produce patterns of phenotype-environment mismatching within species. We quantified phenotype-environment associations between body shape and streamflow variables among populations of six species of minnows (Cyprinidae) to generate models of phenotypic responses to future environmental change. We then used future streamflow estimates to predict the body shape within populations from 2070-2099, assuming the same phenotype-environment relationship.
Results/Conclusions
We found phenotype-environment associations between body shape and flow regimes in all species. However, the nature of these relationships was not consistent among all six species, and opposing patterns were found among species occupying similar habitat types. When these phenotype-environment relationships were projected into future streamflow conditions, spatial patterns of divergence indicate that populations are not expected to respond uniformly across their range. Our findings demonstrate that species-specific ecology and spatial variation in environmental change underlies differences in the magnitude and directionality of phenotype-environment associations, and responses to climate change may vary markedly at both the species and population level.