Data_Sheet_8_The Tracking of Moist Habitats Allowed Aiphanes (Arecaceae) to Cover the Elevation Gradient of the Northern Andes.PDF

The topographic gradients of the Tropical Andes may have triggered species divergence by different mechanisms. Topography separates species’ geographical ranges and offers climatic heterogeneity, which could potentially foster local adaptation to specific climatic conditions and result in narrowly distributed endemic species. Such a pattern is found in the Andean centered palm genus Aiphanes. To test the extent to which geographic barriers and climatic heterogeneity can explain distribution patterns in Aiphanes, we sampled 34 out of 36 currently recognized species in that genus and sequenced them by Sanger sequencing and/or sequence target capture sequencing. We generated Bayesian, likelihood, and species-tree phylogenies, with which we explored climatic trait evolution from current climatic occupation. We also estimated species distribution models to test the relative roles of geographical and climatic divergence in their evolution. We found that Aiphanes originated in the Miocene in Andean environments and possibly in mid-elevation habitats. Diversification is related to the occupation of the adjacent high and low elevation habitats tracking high annual precipitation and low precipitation seasonality (moist habitats). Different species in different clades repeatedly occupy all the different temperatures offered by the elevation gradient from 0 to 3,000 m in different geographically isolated areas. A pattern of conserved adaptation to moist environments is consistent among the clades. Our results stress the evolutionary roles of niche truncation of wide thermal tolerance by physical range fragmentation, coupled with water-related niche conservatism, to colonize the topographic gradient.

热带安第斯山脉的地形梯度可能通过多种不同机制驱动了物种分化。地形可分隔物种的地理分布范围，并营造气候异质性，这或可促进物种对特定气候条件的局地适应，最终形成狭域分布的特有物种。这一模式在以安第斯山脉为分布中心的棕榈属（Aiphanes）中有所体现。为探究地理屏障与气候异质性在多大程度上可解释棕榈属（Aiphanes）的分布格局，我们采样了该属当前已确认的36个物种中的34个，并通过桑格测序（Sanger sequencing）和/或靶向序列捕获测序完成了序列测定。我们构建了贝叶斯、最大似然及物种树系统发育树，并基于物种当前的气候生境数据探究了气候性状的演化历程。此外，我们还构建了物种分布模型，以检验地理分化与气候分化在该属物种演化中的相对作用。研究结果显示，棕榈属（Aiphanes）起源于中新世的安第斯环境中，其起源生境大概率为中海拔区域。该属的物种分化与占据相邻的高、低海拔生境相关，此类生境具备高年降水量与低降水季节变率的特征，即湿润生境。在不同地理隔离区域内，不同演化支的物种会反复占据海拔梯度0至3000米范围内的所有温度生境类型。各演化支均呈现出对湿润环境的保守适应性演化模式。本研究结果强调：通过地理范围碎片化导致的宽泛热耐受生态位收缩，结合与水分相关的生态位保守性，共同推动了该属物种对地形梯度的定植与演化。