Trait evolution and historical biogeography shape assemblages of annual killifish

Aim: Different species assemblages of annual killifish possess replicated body size distributions yet have unique sets of species in each area of endemism. Here, we use models of trait evolution and historical biogeography to discover how size variation originated and has been restructured.

Location: South America.

Taxon: Austrolebias (Cyprinodontiformes).

Methods: We sampled 63 individuals from 26 Austrolebias species. Using phylogenetic trees (BEAST2), data on environmental variables at sampling locations and size data we compare different models for trait evolution (SURFACE, l1OU) of body size and niche traits. We model the historical biogeography of the areas of endemism (BioGeoBEARS) and use both analyses in combination to reconstruct the history of four species assemblages.

Results: We present new phylogenetic trees for Austrolebias and use them to show that large size principally arose within a single area driven by a shifted selection optimum for a subset of the spec...