Data from: Historical colonization and dispersal limitation supplement climate and topography in shaping species richness of African lizards (Reptilia: Agaminae)

To what extent deep-time dispersal limitation shapes present-day biodiversity at broad spatial scales remains elusive. Here, we compiled a continental dataset on the distributions of African lizard species in the reptile subfamily Agaminae (a relatively young, Neogene radiation of agamid lizards which ancestors colonized Africa from the Arabian peninsula) and tested to what extent historical colonization and dispersal limitation (i.e. accessibility from areas of geographic origin) can explain present-day species richness relative to current climate, topography, and climate change since the late Miocene (~10 mya), the Pliocene (~3 mya), and the Last Glacial Maximum (LGM, 0.021 mya). Spatial and non-spatial multi-predictor regression models revealed that time-limited dispersal via arid corridors is a key predictor to explain macro-scale patterns of species richness. In addition, current precipitation seasonality, current temperature of the warmest month, paleo-temperature changes since the LGM and late Miocene, and topographic relief emerged as important drivers. These results suggest that deep-time dispersal constraints — in addition to climate and mountain building — strongly shape current species richness of Africa’s arid-adapted taxa. Such historical dispersal limitation might indicate that natural movement rates of species are too slow to respond to rates of ongoing and projected future climate and land use change.

深时扩散限制在多大程度上塑造大空间尺度下的当代生物多样性，这一问题仍未明确。本研究整合了一套涵盖非洲鬣蜥亚科（Agaminae）蜥蜴物种分布的大陆尺度数据集——该类群为新近纪（Neogene）时期较为年轻的演化辐射类群，其祖先从阿拉伯半岛迁徙至非洲。本研究以此为基础，对比当前气候、地形以及晚中新世（约10百万年前）、上新世（约3百万年前）和末次冰盛期（Last Glacial Maximum, LGM，约0.021百万年前）以来的古气候变化，检验历史定居事件与扩散限制（即物种从其地理起源区域的可及性）在多大程度上能够解释当代物种丰富度格局。空间与非空间多预测因子回归模型结果显示，通过干旱廊道的限时扩散是解释大尺度物种丰富度格局的关键预测因子。此外，当前降水季节格局、最暖月均温、末次冰盛期与晚中新世以来的古温度变化，以及地形起伏均为重要的驱动因子。上述结果表明，除气候与造山运动外，深时扩散限制强烈塑造了非洲适应干旱类群的当代物种丰富度。这类历史扩散限制或表明，物种的自然扩散速率过慢，无法跟上当前及预测中未来的气候与土地利用变化速率。