Exploring intraspecific climatic niche conservatism to better understand species invasion: the case of Trachemys dorbigni (Testudines, Emydidae)

Abstract

Niche conservatism at distinct levels of biological hierarchy is still a highly debated topic in ecology. The general evaluation of niche shifts is mainly addressed to species level, with few explorations at lower or higher hierarchical levels. The freshwater turtle Trachemys dorbigni (Black-Bellied Slider) has recently been divided into two subspecies that occur in very different climatic conditions and is also considered to be an invasive species in parts of eastern and southeastern regions in Brazil. Here, we aimed to explore the effects of evaluating climatic niche conservatism at subspecific levels during the invasive process of T. dorbigni. We evaluated niche conservatism based on similarity (whether niches are more similar than expected by chance) and also measured expansion, stability, and unfilling in the invaded niche. We found that the climatic niches of the T. dorbigni recognized subspecies are very different, but when they are merged, the environmental condition created is more similar to the invasive niche of the subspecies T. dorbigni dorbigni. We also found consistent evidence of niche conservatism in invaded areas, which enables the effective use of ecological niche models to forecast T. dorbigni dorbigni invasion in other geographic regions.