Endemic species are of pivotal importance in biogeography and conservation biology, because they are exclusively distributed in a given area. The regions where several endemic species occur are called centres of endemism and are expected to be characterised by stable and often singular climatic conditions that have enable divergence to accumulate over time. In particular, four non-mutually exclusive hypotheses have been proposed to explain accumulation of endemics in the centres of endemism. In general, areas rich in endemics are expected to have climates that are unusual in the region, to have low intra-annual climatic variation, to have high topographic heterogeneity resulting in a high array of local climatic conditions or to have been climatically stable over time. However, within these regions, endemics accumulate in given areas that consequently have an exceptional concentration of endemic species. Several studies aimed at identifying areas rich in endemism, but relatively few studies have attempted to analyse the environmental determinants behind this richness. Here, we aim at identifying the determinants of endemism richness within a centre of endemism, the Southwestern European Alps. We used distributional data for the endemic plants of SW Alps to explore the patterns of endemism richness to assess how environmental factors contribute to explain these patterns. Our results suggest that near all hypotheses adequately account for patterns of plant endemics richness in SW Alps. In fact, most of the relationships are statistically significant (Table 2) and the explained variance ranges from weak to substantial. In particular, temperature seasonality, velocity of climate change and the standard deviation of slope have the highest effect. Overall, no macro-ecological hypothesis fully accounts for species richness, suggesting that, within endemism centres, factors related to species dispersal ability (e.g., the rate of climate change and the standard deviation of slope) as well as region-specific historical factors combine to influence the distributional pattern of endemism richness.
Local refugia and environmental heterogeneity: a case study in a Mediterranean mountain system (Southern Alps)
GUERRINA M.;DAGNINO D.;MINUTO L.;CASAZZA G.
2023-01-01
Abstract
Endemic species are of pivotal importance in biogeography and conservation biology, because they are exclusively distributed in a given area. The regions where several endemic species occur are called centres of endemism and are expected to be characterised by stable and often singular climatic conditions that have enable divergence to accumulate over time. In particular, four non-mutually exclusive hypotheses have been proposed to explain accumulation of endemics in the centres of endemism. In general, areas rich in endemics are expected to have climates that are unusual in the region, to have low intra-annual climatic variation, to have high topographic heterogeneity resulting in a high array of local climatic conditions or to have been climatically stable over time. However, within these regions, endemics accumulate in given areas that consequently have an exceptional concentration of endemic species. Several studies aimed at identifying areas rich in endemism, but relatively few studies have attempted to analyse the environmental determinants behind this richness. Here, we aim at identifying the determinants of endemism richness within a centre of endemism, the Southwestern European Alps. We used distributional data for the endemic plants of SW Alps to explore the patterns of endemism richness to assess how environmental factors contribute to explain these patterns. Our results suggest that near all hypotheses adequately account for patterns of plant endemics richness in SW Alps. In fact, most of the relationships are statistically significant (Table 2) and the explained variance ranges from weak to substantial. In particular, temperature seasonality, velocity of climate change and the standard deviation of slope have the highest effect. Overall, no macro-ecological hypothesis fully accounts for species richness, suggesting that, within endemism centres, factors related to species dispersal ability (e.g., the rate of climate change and the standard deviation of slope) as well as region-specific historical factors combine to influence the distributional pattern of endemism richness.
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