Abstract
Spatial gradients of species richness can be shaped by the interplay between historical and ecological factors. They might interact in particularly complex ways in heterogeneous mountainous landscapes with strong climatic and geological contrasts. We mapped the distribution of 171 lizard species to investigate species richness patterns for all species (171), diurnal species (101), and nocturnal species (70) separately. We related species richness with the historical (past climate change, mountain uplifting) and ecological variables (climate, topography and vegetation). We found that assemblages in the Western Zagros Mountains, north eastern and north western parts of Central Iranian Plateau have the highest number of lizard species. Among the investigated variables, annual mean temperature explained the largest variance for all species (10%) and nocturnal species (31%). For diurnal species, temperature change velocity shows strongest explained variance in observed richness pattern (26%). Together, our results reveal that areas with annual temperature of 15–20 °C, which receive 400–600 mm precipitation and experienced moderate level of climate change since the Last Glacial Maximum (LGM) have highest number of species. Documented patterns of our study provide a baseline for understanding the potential effect of ongoing climate change on lizard diversity in Iran.
Highlights
Spatial gradients of species richness can be shaped by the interplay between historical and ecological factors
The 171 lizard species belonged to ten families and 47 genera
Nocturnal species hotspots occur in Western Zagros Mountains with 17 species, north of Persian Gulf and Oman Sea with 13 species, while we found that central parts of Iran with 1–6 species, Kopet-Dagh Mountains and Elburz Mountains with 0–4 species have much lower number of nocturnal species across the country (Fig. 1c)
Summary
Spatial gradients of species richness can be shaped by the interplay between historical and ecological factors. Beyond the Quaternary, mountain uplifting might be associated to the formation of biodiversity gradients, shaping an association between habitat heterogeneity and species r ichness[10,11] Together, it appears there is no single driver of species distribution across broad geographical range and species distributional patterns are shaped by the interplay between different historical and ecological factors[2,3,11,12,13]. Reptiles are characterized by low dispersal ability and narrow ecological n iches[17] They are suitable biological models to assess the role of historical factors in shaping spatial distribution of b iodiversity[18,19]. The influence of Quaternary climatic oscillations and mountains uplifting was observed on individual species, using genetic data and species distribution m odelling[32,33,34,35,36,37]
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