Environmental variation predicts patterns of phenotypic and genomic
variation in an African tropical forest frog
Abstract
Central African rainforests are predicted to be disproportionately
affected by future climate change. How species will cope with these
changes is unclear, but rapid environmental changes will likely impose
strong selection pressures. Here we examined environmental drivers of
phenotypic and genomic variation in the central African puddle frog
(Phrynobatrachus auritus) to identify areas of elevated
environmentally-associated turnover where populations may have the
greatest capacity to adapt. We also compared current and future climate
models to pinpoint areas of high genomic vulnerability where allele
frequencies will have to shift the most in order to keep pace with
future climate change. Analyses of body size, relative leg length, and
head shape suggest that seasonal aspects of temperature and
precipitation significantly influence phenotypic variation, whereas
geographic distance and precipitation seasonality are the most important
drivers of SNP allele frequency variation. However, neither landscape
barriers nor the effects of past Pleistocene refugia had any influence
on genomic differentiation. Most phenotypic and genomic differentiation
coincided with key ecological gradients across the forest-savanna
ecotone, montane areas and a coastal to interior rainfall gradient.
Areas of greatest vulnerability were found in the lower Sanaga basin and
southeastern region of Cameroon. In contrast with past conservation
efforts that have focused on hotspots of species richness or endemism,
our findings highlight the importance of preserving environmentally
heterogeneous landscapes to preserve putatively adaptive variation and
ongoing evolutionary processes in the face of climate change.