Ecological niche modelling and climate change in two species groups of huntsman spider genus Eusparassus in the Western Palearctic

The huntsman spiders’ genus Eusparassus are apex arthropod predators in desert ecosystems of the Afrotropical and Palearctic ecoregions. The Eusparassus dufouri and E. walckenaeri clades are two distinct taxonomic, phylogenetic, and geographic units concerning morphology, molecular phylogeny, and spatial data; but little is known about their ecological niche. We applied the maximum-entropy approach and modelled ecologic niches of these two phylogenetically closely related clades. Ecological niches of the two clades were compared using identity and background tests and two different metrics, the Schooner’s D and Warren’s I. We also predicted the impacts of climate change on the distribution of the two clades. The results of the identity test showed that the ecological niches of the two clades were different in geographic space but were similar in environmental space. While results of the background test revealed that the ecological niches of the two clades were similar in geographic and environmental space. This indicated that “niche conservatism” had an important role over the evolutionary time of allopatric diversification. However, the normalized difference vegetation index vs. topographic heterogeneity had influenced the niches of the dufouri and walckenaeri clades, respectively. The analyses recovered that the two clades’ climatically suitable habitats will increase under future climate (the year 2070). However, since the two clades are characterized by the narrow range of environmental optimum and the accordingly high limits of tolerance, they are vulnerable to climate change.