Diversification of South American Vespertilionidae (Chiroptera) is not constrained by evolutionary priority effects

Abstract According to diversity-dependent diversification (DDD) theory, diversification slows down as niches are gradually filled by cladogenesis. A corollary of DDD is to assume a richness ceiling, a contentious topic for continental clades. Evolutionary priority effect is a related phenomenon whereby secondary colonizers have their diversification constrained owing to pre-emption of niches by incumbent groups. South American aerial insectivorous bats are composed of incumbent, non-Vespertilionidae groups (SA non-vesper) and the later immigrant Vespertilionidae (SA vesper). We investigated whether DDD and priority effects explain SA vesper diversification history, while also comparing it with North/Central American vespertilionids (NA vesper), an incumbent lineage in that region. Diversification analysis supported a single regime of diversification rates across all groups, with little decrease through time. Geographical state diversification of vespertilionids selected a best-fitting model with different speciation rates for NA endemics, SA endemics and widespread species, but equal extinction. The model presented higher speciation for SA endemics over NA endemics. Thus, DDD and priority effects are inconsistent with the diversification of South American aerial insectivorous bats. We discuss how SA vesper are comparatively depauperate, probably because of a shorter evolutionary history and/or cryptic diversity when compared with NA vesper, instead of niche conservatism.