Habel Jan Christian, Borghesio Luca, Newmark William D, Day Julia J, Lens Luc, Husemann Martin, Ulrich Werner
Terrestrial Ecology Research Group Department of Ecology and Ecosystem Management School of Life Sciences Weihenstephan Technische Universität München D-85354 Freising Germany.
C. Re Umberto 42 I-10128 Torino Italy.
Ecol Evol. 2015 Oct 12;5(21):4849-62. doi: 10.1002/ece3.1735. eCollection 2015 Nov.
The moist and cool cloud forests of East Africa represent a network of isolated habitats that are separated by dry and warm lowland savannah, offering an opportunity to investigate how strikingly different selective regimes affect species diversification. Here, we used the passerine genus Zosterops (white-eyes) from this region as our model system. Species of the genus occur in contrasting distribution settings, with geographical mountain isolation driving diversification, and savannah interconnectivity preventing differentiation. We analyze (1) patterns of phenotypic and genetic differentiation in high- and lowland species (different distribution settings), (2) investigate the potential effects of natural selection and temporal and spatial isolation (evolutionary drivers), and (3) critically review the taxonomy of this species complex. We found strong phenotypic and genetic differentiation among and within the three focal species, both in the highland species complex and in the lowland taxa. Altitude was a stronger predictor of phenotypic patterns than the current taxonomic classification. We found longitudinal and latitudinal phenotypic gradients for all three species. Furthermore, wing length and body weight were significantly correlated with altitude and habitat type in the highland species Z. poliogaster. Genetic and phenotypic divergence showed contrasting inter- and intraspecific structures. We suggest that the evolution of phenotypic characters is mainly driven by natural selection due to differences in the two macro-habitats, cloud forest and savannah. In contrast, patterns of neutral genetic variation appear to be rather driven by geographical isolation of the respective mountain massifs. Populations of the Z. poliogaster complex, as well as Z. senegalensis and Z. abyssinicus, are not monophyletic based on microsatellite data and have higher levels of intraspecific differentiation compared to the currently accepted species.
东非潮湿凉爽的云雾森林是由干燥温暖的低地稀树草原分隔开的孤立栖息地网络，为研究截然不同的选择机制如何影响物种多样化提供了契机。在此，我们将该地区的雀形目绣眼鸟属（白眼鸟）作为我们的模型系统。该属物种分布情况各异，地理上的山脉隔离推动了物种多样化，而稀树草原的连通性则阻止了物种分化。我们分析了：（1）高地和低地物种（不同分布情况）的表型和遗传分化模式；（2）研究自然选择以及时间和空间隔离（进化驱动因素）的潜在影响；（3）严格审查该物种复合体的分类法。我们发现，无论是在高地物种复合体还是低地分类群中，三个重点物种之间以及内部都存在强烈的表型和遗传分化。海拔高度比当前的分类学分类更能预测表型模式。我们发现所有三个物种都存在纵向和横向的表型梯度。此外，在高地物种纯色绣眼中，翅长和体重与海拔高度和栖息地类型显著相关。遗传和表型分歧呈现出种间和种内结构的差异。我们认为，表型特征的进化主要是由云雾森林和稀树草原这两种宏观栖息地的差异导致的自然选择驱动的。相比之下，中性遗传变异模式似乎更多地是由各个山脉的地理隔离驱动的。基于微卫星数据，纯色绣眼鸟复合体以及塞内加尔绣眼鸟和阿比西尼亚绣眼鸟的种群并非单系的，并且与目前公认的物种相比，种内分化水平更高。
