Changing Only Slowly: The Role of Phylogenetic Niche Conservatism in Caviidae (Rodentia) Speciation

The dynamics of species diversification have attracted significant scientific attention in recent decades. Many lineages tend to maintain their niche characteristics over evolutionary time, a phenomenon known as phylogenetic niche conservatism (NC), which can slow the processes of ecological speciation by diversification selection. NC can, however, promote speciation through neutral evolution, favoring the geographic isolation of populations. Among the mega-diverse Rodentia group, the low species richness of the family Caviidae stands out. Here, we analyzed if the processes of climatic NC are related to the slow diversification observed in the Caviidae family. Locality data for 13 species and nine climatic variables were used to generate ecological niche models. Niche similarity was quantified using the Schoener D index and used to examine correlations between the times of species divergence and niche similarities, thus characterizing their niche occupation profiles (NOP). The NOP were subsequently used to perform phylogenetic niche reconstructions for these species. Niche models accurately described known distributions of species. The greatest niche overlap documented was between Kerodon rupestris and Galea spixii (0.86). The niche and species divergence times showed a negative correlation (beta = -0.013; p = 0.01). These results support the existence of NC, with phylogenetically closer species occupying similar niches, and emphasize the importance of NC in diversification processes at continental scales in a slowly diversifying group.