Data from: Minimal effects of latitude on present-day speciation rates in New World birds

The tropics contain far greater numbers of species than temperate regions, suggesting that rates of species formation might differ systematically between tropical and non-tropical areas. We tested this hypothesis by reconstructing the history of speciation in New World (NW) land birds using BAMM, a Bayesian framework for modelling complex evolutionary dynamics on phylogenetic trees. We estimated marginal distributions of present-day speciation rates for each of 2571 species of birds. The present-day rate of speciation varies approximately 30-fold across NW birds, but there is no difference in the rate distributions for tropical and temperate taxa. Using macroevolutionary cohort analysis, we demonstrate that clades with high tropical membership do not produce species more rapidly than temperate clades. For nearly any value of present-day speciation rate, there are far more species in the tropics than the temperate zone. Any effects of latitude on speciation rate are marginal in comparison to the dramatic variation in rates among clades.热带地区的物种数量远多于温带区域，这提示热带与非热带区域的物种形成速率可能存在系统性差异。我们借助BAMM这一用于在系统发育树（phylogenetic trees）上建模复杂演化动力学的贝叶斯框架，通过重构新大陆（New World, NW）陆鸟的物种形成历史，对该假说开展了检验。我们针对全部2571种鸟类，分别估算了其现今物种形成速率的边际分布。新大陆陆鸟的现今物种形成速率跨度可达约30倍，但热带与温带类群（taxa）的速率分布并未呈现显著差异。通过宏观演化队列分析（macroevolutionary cohort analysis），我们证明热带物种占比高的演化支（clade）的物种形成速率并未显著快于温带演化支。几乎在所有现今物种形成速率的取值下，热带地区的物种数量都远多于温带区域。相较于演化支间物种形成速率的显著差异，纬度对物种形成速率的影响微乎其微。