Niche divergence and diversification in South American freshwater turtles of the genus Acanthochelys (Chelidae)

Abstract

Abstract Species distribution models (SDMs) are increasingly used to assess how ecological factors shape species distributions and diversification. Chelid turtles represent the richest family of chelonians in South America. Given the distributional disjunction and distinct habitats of four Acanthochelys species, we explored SDMs and niche overlap metrics between species pairs to evaluate the extent to which niche divergence or conservatism may have contributed to their geographic distribution patterns. None of the species pairs presented patterns consistent with niche conservatism suggesting that these species have different environmental requirements. However, when comparing species pairs co-occurring in the same watershed, results were conflicting. Niche divergence detected among Acanthochelys species indicate an interaction between ecological niche preference and geographical barriers for allopatric speciation. This interaction implies that ecological differentiation contributed to the diversification of Acanthochelys side-necked turtles that occur in South American freshwater environments.