Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK.
Florida Museum of Natural History, University of Florida, Dickinson Hall, 1659 Museum Road Gainesville, FL 32611, USA.
Syst Biol. 2018 May 1;67(3):428-438. doi: 10.1093/sysbio/syx084.
Evolutionary dynamics of abiotic ecological niches across phylogenetic history can shed light on large-scale biogeographic patterns, macroevolutionary rate shifts, and the relative ability of lineages to respond to global change. An unresolved question is how best to represent and reconstruct evolution of these complex traits at coarse spatial scales through time. Studies have approached this question by integrating phylogenetic comparative methods with niche estimates inferred from correlative and other models. However, methods for estimating niches often produce incomplete characterizations, as they are inferred from present-day distributions that may be limited in full expression of the fundamental ecological niche by biotic interactions, dispersal limitations, and the existing set of environmental conditions. Here, we test whether incomplete niche characterizations inherent in most estimates of species' niches bias phylogenetic reconstructions of niche evolution, using simulations of virtual species with known niches. Results establish that incompletely characterized niches inflate estimates of evolutionary change and lead to error in ancestral state reconstructions. Our analyses also provide a potential mechanism to explain the frequent observation that maximum thermal tolerances are more conserved than minimum thermal tolerances: populations and species experience more spatial variation in minimum temperature than in maximum temperature across their distributions and, consequently, may experience stronger diversifying selection for cold tolerance.
生物群落生态位在系统发生历史上的进化动态可以揭示大规模的生物地理格局、宏观进化率变化，以及谱系对全球变化的相对响应能力。一个悬而未决的问题是，如何最好地在时间上通过粗尺度空间来表示和重建这些复杂特征的进化。研究人员通过将系统发育比较方法与从相关和其他模型推断出的生态位估计相结合来解决这个问题。然而，生态位的估计方法通常会产生不完整的特征描述，因为它们是从目前的分布中推断出来的，而这些分布可能由于生物相互作用、扩散限制以及现有的环境条件集，而无法充分表达基本的生态位。在这里，我们使用具有已知生态位的虚拟物种的模拟来测试，在大多数物种生态位估计中固有的不完整生态位特征是否会偏向于生态位进化的系统发育重建。结果表明，特征描述不完整的生态位会夸大进化变化的估计，并导致祖先状态重建的误差。我们的分析还提供了一个潜在的机制来解释一个常见的观察结果，即最大热耐受度比最小热耐受度更保守：在分布范围内，种群和物种在最小温度方面经历的空间变化比最大温度更大，因此，可能会经历更强的耐寒性分化选择。
