Data from: Increasing temperature weakens the positive effect of genetic diversity on population growth

Genetic diversity and temperature increases associated with global climate
change are known to independently influence population growth and
extinction risk. Whether increasing temperature may influence the effect
of genetic diversity on population growth, however, is not known. We
address this issue in the model protist system Tetrahymena thermophila. We
test the hypothesis that at temperatures closer to the species’ thermal
optimum (i.e., the temperature at which population growth is maximal, or
Topt), genetic diversity should have a weaker effect on population growth
compared to temperatures away from the thermal optimum. To do so, we grew
populations of T. thermophila with varying levels of genetic diversity at
increasingly warmer temperatures and quantified their intrinsic population
growth rate, r. We found that genetic diversity increases population
growth at cooler temperatures, but that as temperature increases, this
effect weakens. We also show that a combination of changes in the amount
of expressed genetic diversity (G), plastic changes in population growth
across temperatures (E), and strong GxE interactions, underlie this
temperature effect. Our results uncover important but largely overlooked
temperature effects that have implications for the management of small
populations with depauperate genetic stocks in an increasingly warming
world. --