Neotropical diversification seen through glassfrogs

Castroviejo-Fisher, S., Guayasamin, J. M., Gonzalez-Voyer, A., Vilà, C. 2014. Neotropical diversification seen through glassfrogs. Journal of Biogeography. 41: 66–80

Aim:

We used frogs of the clade Allocentroleniae (Centrolenidae + Allophrynidae; c. 170 species endemic to Neotropical rain forests) as a model system to address the historical biogeography and diversification of Neotropical rain forest biotas.

Location:

Neotropical rain forests.

Methods:

We used an extensive taxon (109 species) and gene (seven nuclear and three mitochondrial genes) sampling to estimate phylogenetic relation- ships, divergence times, ancestral area distributions, dispersal–vicariance events, and the temporal pattern of diversification rate.

Results:

The Allocentroleniae started to diversify in the Eocene in South Amer- ica and by the early Miocene were present in all major Neotropical rain forests except in Central America, which was colonized through 11 late range expan- sions. The initial uplifts of the Andes during the Oligocene and early Miocene, as well as marine incursions in the lowlands, are coincidental with our esti- mates of the divergence times of most clades of Allocentroleniae. Clades with broad elevational distributions occupy more biogeographical areas. Most dis- persals involve the Andes as a source area but the majority were between the Central and the Northern Andes, suggesting that the Andes did not play a major role as a species pump for the lowlands. The diversification of glassfrogs does not follow a south-to-north pattern of speciation for Andean clades, and the establishment of a transcontinental Amazon drainage system is coincidental in time with the isolation of the Atlantic Forest glassfrogs. Diversification analyses indi- cated that a model of constantly increasing diversity best fits the data, compatible with the ‘evolutionary museum’ hypothesis or ‘ancient cradle’ hypothesis.

Conclusions:

Our work illustrates how the different geological and climatic historical events of the Neotropics shaped, at different levels of the phylogeny, the diversity of a species-rich clade, highlighting the importance of studying large evolutionary radiations at a continental scale.