Patiño Jairo, Wang Jian, Renner Matt A M, Gradstein S Robbert, Laenen Benjamin, Devos Nicolas, Shaw A Jonathan, Vanderpoorten Alain
Island Ecology and Evolution Research Group, Instituto de Productos Naturales y Agrobiología (IPNA-CSIC), Astrofísico Francisco Sánchez 3, La Laguna, Tenerife, Canary Islands 38206, Spain; Department of Biology, Ecology and Evolution, Institute of Botany, University of Liège, Liège, Belgium; Azorean Biodiversity Group (GBA, CITA-A) and Platform for Enhancing Ecological Research & Sustainability (PEERS), Universidade dos Açores, Angra do Heroísmo, Terceira, Açores, Portugal.
Bryology Laboratory, School of Life Sciences, East China Normal University, Shanghai 200241, China.
Mol Phylogenet Evol. 2017 Jan;106:73-85. doi: 10.1016/j.ympev.2016.09.020. Epub 2016 Sep 21.
Why some species exhibit larger geographical ranges than others, and to what extent does variation in range size affect diversification rates, remains a fundamental, but largely unanswered question in ecology and evolution. Here, we implement phylogenetic comparative analyses and ancestral area estimations in Radula, a liverwort genus of Cretaceous origin, to investigate the mechanisms that explain differences in geographical range size and diversification rates among lineages. Range size was phylogenetically constrained in the two sub-genera characterized by their almost complete Australasian and Neotropical endemicity, respectively. The congruence between the divergence time of these lineages and continental split suggests that plate tectonics could have played a major role in their present distribution, suggesting that a strong imprint of vicariance can still be found in extant distribution patterns in these highly mobile organisms. Amentuloradula, Volutoradula and Metaradula species did not appear to exhibit losses of dispersal capacities in terms of dispersal life-history traits, but evidence for significant phylogenetic signal in macroecological niche traits suggests that niche conservatism accounts for their restricted geographic ranges. Despite their greatly restricted distribution to Australasia and Neotropics respectively, Amentuloradula and Volutoradula did not exhibit significantly lower diversification rates than more widespread lineages, in contrast with the hypothesis that the probability of speciation increases with range size by promoting geographic isolation and increasing the rate at which novel habitats are encountered. We suggest that stochastic long-distance dispersal events may balance allele frequencies across large spatial scales, leading to low genetic structure among geographically distant areas or even continents, ultimately decreasing the diversification rates in highly mobile, widespread lineages.
为什么有些物种的地理分布范围比其他物种大，以及分布范围大小的变化在多大程度上影响物种分化速率，仍然是生态学和进化领域一个基本但基本上未得到解答的问题。在这里，我们对一种起源于白垩纪的叶苔属植物进行系统发育比较分析和祖先分布区估计，以研究解释不同谱系间地理分布范围大小和物种分化速率差异的机制。在分别以几乎完全分布于澳大拉西亚地区和新热带地区为特征的两个亚属中，分布范围大小受到系统发育的限制。这些谱系的分化时间与大陆分裂之间的一致性表明，板块构造可能在它们目前的分布中起了主要作用，这表明在这些高度可移动生物的现存分布模式中，仍然可以发现明显的间断分布印记。从扩散生活史特征来看，无蒴叶苔属、具边叶苔属和后叶苔属物种似乎没有表现出扩散能力的丧失，但宏观生态位特征中显著系统发育信号的证据表明，生态位保守性解释了它们有限的地理分布范围。尽管无蒴叶苔属和具边叶苔属分别极大地局限于澳大拉西亚地区和新热带地区，但与物种形成概率随分布范围大小通过促进地理隔离和增加遇到新栖息地的速率而增加这一假设相反，它们的物种分化速率并不显著低于分布更广的谱系。我们认为，随机的长距离扩散事件可能会在大空间尺度上平衡等位基因频率，导致地理上遥远的地区甚至各大洲之间的遗传结构较低，最终降低高度可移动、分布广泛的谱系的物种分化速率。
