Population divergence associated with spatial asynchrony in precipitation in neotropical frogs

Aim: To test the role of asynchrony in precipitation patterns among populations –a proxy for asynchronous breeding– as a driver of intraspecific genetic divergence across 38 species of Neotropical frogs. In addition, to examine whether regions with more asynchronous precipitation regimes across space have higher frog species richness and have experienced greater speciation rates than regions with more spatially synchronous precipitation regimes.

Location: Central and South America

Taxon: Anurans

Methods: For microevolutionary analyses, we assessed the relationship between spatial asynchrony in precipitation and mtDNA genetic divergence accounting for ecological connectivity using multiple regression and phylogenetic meta-analyses. For macroevolutionary analyses, we assessed the relationship between species richness, speciation rates estimated from a comprehensive molecular phylogeny, and the degree of spatial asynchrony in precipitation using generalized linear models.

Results and Main conclusions: Beyond a generalized effect of ecological connectivity on intraspecific genetic divergence, we found that spatial asynchrony in precipitation is positively associated with genetic differentiation in 39% of the species tested, resulting in a weak cross-species effect. However, the effect of asynchrony in precipitation on population divergence seems not to scale to macroevolutionary patterns because spatial asynchrony in precipitation was not associated with geographical patterns of species richness nor present-day speciation rates. Our results indicate that asynchronous breeding may promote genetic divergence even in the absence of geographic barriers in species where breeding is associated with water availability, but such effects may not be stable enough through time to influence macroevolutionary patterns.