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.

深时扩散限制在大空间尺度上对现代生物多样性的塑造程度仍不明确。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——该类群是新近纪辐射演化的相对年轻类群，其祖先从阿拉伯半岛迁徙至非洲。研究基于当前气候、地形条件，以及晚中新世（约1000万年前）、上新世（约300万年前）和末次盛冰期（LGM，约2.1万年前）以来的气候变化，检验历史殖民事件与扩散限制（即物种地理起源区域的可及性）对现代物种丰富度的解释程度。空间与非空间多预测因子回归模型结果显示，通过干旱走廊的限时扩散是解释宏观尺度物种丰富度格局的关键预测因子。此外，当前降水季节变化、最热月均温，以及末次盛冰期和晚中新世以来的古温度变化、地形起伏，均为重要的驱动因子。本研究结果表明，除气候与造山运动之外，深时扩散限制强烈塑造了非洲干旱适应性类群的现代物种丰富度。这类历史扩散限制或暗示，物种的自然扩散速率过慢，无法响应当前及未来预估的气候与土地利用变化速率。