Abstract
BackgroundMuch debate has focused on how transitions in life history have influenced the proliferation of some clades. Rodents of the subfamily Sigmodontinae (family Cricetidae) comprise one of the most diverse clades of Neotropical mammals (~400 living species in 86 genera). These rodents occupy a wide range of habitats and lifestyles so that ecological context seems relevant to understand the evolution of this group. Several changes in the landscape of South America through the Neogene might have provided vast resources and opportunity to diversify. The aim of this study was to examine whether transitions between i) lowland and montane habitats, ii) open vegetation and forest, and iii) distinct molar architectures are correlated with shifts in diversification rates and to characterize the general pattern of diversification.ResultsBased on a dense taxon sampling of 269 species, we recovered a new phylogeny of Sigmodontinae that is topologically consistent with those of previous studies. It indicates that the subfamily and its major lineages appeared during the Late Miocene. Analyses suggest that vegetation type and elevational range are correlated with diversification rates, but not molar architecture. Tropical lowlands accumulated more lineage diversity than other areas and also supported high speciation rates. Across the radiation the subfamily Sigmodontinae appear to have experienced a decline in diversification rate through time. We detected mixed evidence for lineage-specific diversification rate shifts (e.g., leading to the clades of Akodon, Bibimys, Calomys and Thomasomys).ConclusionWe report that the evolution of habitat preference (considering vegetation type and elevational range) was associated with diversification rates among sigmodontine rodents. We propose that the observed diversification slowdown might be the result of ecological or geographical constraints. Our results also highlight the influence of the tropical lowlands -which might have acted as both “a cradle and a museum of species.” The tropical lowlands accumulated greater diversity than the remainder of the group's range.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-015-0440-z) contains supplementary material, which is available to authorized users.
Highlights
Much debate has focused on how transitions in life history have influenced the proliferation of some clades
Given that the phylogenies obtained are topologically in agreement with those recovered in previous studies, here we will focus on the general pattern of diversification
Our results indicate that the pentalophodont condition is derived; this result is somewhat questionable because support is lacking for relationships at the more basal nodes of the Oryzomyalia
Summary
Much debate has focused on how transitions in life history have influenced the proliferation of some clades. Rodents of the subfamily Sigmodontinae (family Cricetidae) comprise one of the most diverse clades of Neotropical mammals (~400 living species in 86 genera). These rodents occupy a wide range of habitats and lifestyles so that ecological context seems relevant to understand the evolution of this group. Several changes in the landscape of South America through the Neogene might have provided vast resources and opportunity to diversify. Changes in the landscape of South America during the course of the Neogene and colonization of new areas might have provided ample ecological opportunity [12, 13] -i.e. It has been proposed that the appearance of a molar with four lophs, known as tetralophodont (usually high crowned or hypsodont), facilitated the access to grazing pastures and allowed the colonization of open or “pastoral” habitats, while the plesiomorphic type of five lophs, or pentalophodont plan (usually low crowned or brachydont), remained associated with taxa from forested habitats [18]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
