Abstract
South-western Europe has a rich diversity of lacertid lizards. In this study, we evaluated the occupancy patterns and niche segregation of five species of lacertids, focusing on large-bodied species (i.e., adults having >75 mm snout-vent length) that occur in south-western Europe (Italian to the Iberian Peninsula). We characterized the niches occupied by these species based on climate and vegetation cover properties. We expected some commonality among phylogenetically related species, but also patterns of habitat segregation mitigating competition between ecologically equivalent species. We used multivariate ordination and probabilistic methods to describe the occupancy patterns and evaluated niche evolution through phylogenetic analyses. Our results showed climate niche partitioning, but with a wide overlap in transitional zones, where segregation is maintained by species-specific responses to the vegetation cover. The analyses also showed that phylogenetically related species tend to share large parts of their habitat niches. The occurrence of independent evolutionary lineages contributed to the regional species richness favored by a long history of niche divergence.
Highlights
Climate is a powerful environmental factor driving the process of niche diversification in reptiles [1,2]
The second axis described a transition between habitats having different vegetation cover, typically distinguishing habitats having a relatively high enhanced vegetation index (EVI) and a low seasonal coefficient of variation (CV) from those having a relatively low EVI and a high seasonal CV
The genus Timon was separated from the genus Lacerta mainly along the first axis, the former showing a positive association with dry-warm climates (Figure 2)
Summary
Climate is a powerful environmental factor driving the process of niche diversification in reptiles [1,2]. Tolerance to maximum temperatures in reptiles is evolutionarily constrained, possibly because of the importance of external heat sources in maintaining activity and for bodily water balance [3,4]. South-western Europe encompasses a relatively rich reptile fauna, favored by its topographic heterogeneity, insularity and mild climate conditions [9]. In this region, several groups of phylogenetically related species display complex patterns of overlap structured by environmental gradients or by interspecific interactions [10,11,12]. The target species in this study included one species having a broad circumboreal distribution, Lacerta agilis
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