Institut für Organismische und Molekulare Evolutionsbiologie, Johannes Gutenberg-Universität, Anselm-Franz-von-Bentzelweg 9a, 55099, Mainz, Germany.
Department of Biochemistry, University of Stellenbosch, Private Bag X1, Matieland, 7602, South Africa.
BMC Evol Biol. 2019 Dec 5;19(1):222. doi: 10.1186/s12862-019-1545-6.
The coincidence of long distance dispersal (LDD) and biome shift is assumed to be the result of a multifaceted interplay between geographical distance and ecological suitability of source and sink areas. Here, we test the influence of these factors on the dispersal history of the flowering plant genus Erica (Ericaceae) across the Afrotemperate. We quantify similarity of Erica climate niches per biogeographic area using direct observations of species, and test various colonisation scenarios while estimating ancestral areas for the Erica clade using parametric biogeographic model testing.
We infer that the overall dispersal history of Erica across the Afrotemperate is the result of infrequent colonisation limited by geographic proximity and niche similarity. However, the Drakensberg Mountains represent a colonisation sink, rather than acting as a "stepping stone" between more distant and ecologically dissimilar Cape and Tropical African regions. Strikingly, the most dramatic examples of species radiations in Erica were the result of single unique dispersals over longer distances between ecologically dissimilar areas, contradicting the rule of phylogenetic biome conservatism.
These results highlight the roles of geographical and ecological distance in limiting LDD, but also the importance of rare biome shifts, in which a unique dispersal event fuels evolutionary radiation.
长距离扩散（LDD）和生物区系转移的巧合被认为是地理距离和源区与汇区生态适宜性之间多方面相互作用的结果。在这里，我们测试这些因素对非洲温带开花植物属 Erica（Ericaceae）在整个非洲温带的扩散历史的影响。我们使用物种的直接观测来量化每个生物地理区域的 Erica 气候生态位的相似性，并通过参数生物地理模型测试来估计 Erica 进化枝的祖先区域，同时测试各种殖民化情景。
我们推断，Erica 在整个非洲温带的总体扩散历史是由地理接近性和生态位相似性限制的不频繁殖民化的结果。然而，德拉肯斯堡山脉是一个殖民汇，而不是作为较远距离和生态差异较大的开普和热带非洲地区之间的“踏脚石”。引人注目的是，Erica 中最显著的物种辐射例子是在生态差异较大的地区之间进行的单次独特的长距离扩散的结果，这与系统发育生物群落保守性的规则相矛盾。
这些结果强调了地理和生态距离在限制 LDD 中的作用，但也强调了稀有生物群落转移的重要性，其中独特的扩散事件为进化辐射提供了动力。
