Biodiversity Research Center, Academia Sinica, Taipei, Taiwan.
Department of Environmental Science, University of Tehran, Karaj, Iran.
Mol Ecol. 2019 Feb;28(4):803-817. doi: 10.1111/mec.14980. Epub 2019 Feb 4.
Ecological niche evolution can promote or hinder the differentiation of taxa and determine their distribution. Niche-mediated evolution may differ among climatic regimes, and thus, species that occur across a wide latitudinal range offer a chance to test these heterogeneous evolutionary processes. In this study, we examine (a) how many lineages have evolved across the continent-wide range of the Eurasian nuthatch (Sitta europaea), (b) whether the lineages' niches are significantly divergent or conserved and (c) how their niche evolution explains their geographic distribution. Phylogenetic reconstruction and ecological niche models (ENMs) showed that the Eurasian nuthatch contained six parapatric lineages that diverged within 2 Myr and did not share identical climatic niches. However, the niche discrepancy between these distinct lineages was relatively conserved compared with the environmental differences between their ranges and thus was unlikely to drive lineage divergence. The ENMs of southern lineages tended to cross-predict with their neighbouring lineages whereas those of northern lineages generally matched with their abutting ranges. The coalescence-based analyses revealed more stable populations for the southern lineages than the northern ones during the last glaciation cycle. In contrast to the overlapping ENMs, the smaller parapatric distribution suggests that the southern lineages might have experienced competitive exclusion to prevent them from becoming sympatric. On the other hand, the northern lineages have expanded their ranges and their current abutting distribution might have resulted from lineages adapting to different climatic conditions in allopatry. This study suggests that niche evolution may affect lineage distribution in different ways across latitude.
生态位进化可以促进或阻碍分类群的分化，并决定它们的分布。在不同的气候条件下，生态位介导的进化可能会有所不同，因此，跨越广泛纬度范围的物种提供了检验这些异质进化过程的机会。在这项研究中，我们考察了：(a)欧亚五子雀（Sitta europaea）的多少个谱系在整个大陆范围内进化；(b)谱系的生态位是否明显发散或保守；以及 (c)它们的生态位进化如何解释它们的地理分布。系统发育重建和生态位模型（ENMs）表明，欧亚五子雀包含六个近缘谱系，它们在 200 万年内发生分歧，并且没有共享相同的气候生态位。然而，与它们的分布范围之间的环境差异相比，这些不同谱系之间的生态位差异相对保守，因此不太可能驱动谱系分歧。南部谱系的 ENMs 倾向于与相邻谱系交叉预测，而北部谱系的 ENMs 通常与它们的相邻范围相匹配。基于合并的分析表明，与北部谱系相比，南部谱系在末次冰期循环中具有更稳定的种群。与重叠的 ENMs 相反，较小的近缘分布表明南部谱系可能经历了竞争排斥，以防止它们成为同域的。另一方面，北部谱系已经扩展了它们的范围，它们目前的相邻分布可能是由于谱系在异地适应不同的气候条件所致。本研究表明，生态位进化可能以不同的方式影响谱系在纬度上的分布。
