Data from: Out of the dark: 350 million years of conservatism and evolution in diel activity patterns in vertebrates

Many animals are active only during a particular time (e.g. day vs. night), a partitioning that may have important consequences for species co-existence. An open question is the extent to which this diel activity niche is evolutionarily conserved or labile. Here, we analyze diel activity data across a phylogeny of 1914 tetrapod species. We find strong phylogenetic signal, showing that closely related species tend to share similar activity patterns. Ancestral reconstructions show that nocturnality was the most likely ancestral diel activity pattern for tetrapods and many major clades within it (e.g. amphibians, mammals). Remarkably, nocturnal activity appears to have been maintained continuously in some lineages for ~350 million years. Thus, we show that traits involved in local-scale resource partitioning can be conserved over strikingly deep evolutionary time scales. We also demonstrate a potentially important (but often overlooked) metric of niche conservatism. Finally, we show that diurnal lineages appear to have faster speciation and diversification rates than nocturnal lineages, which may explain why there are presently more diurnal tetrapod species even though diurnality appears to have evolved more recently. Overall, our results may have implications for studies of community ecology, species richness, and the evolution of diet and communication systems.诸多动物仅在特定时段（如昼间与夜间）活跃，这种资源分区模式可能对物种共存产生重要影响。当前存在一项悬而未决的科学问题：这种昼夜活动生态位（diel activity niche）在进化层面究竟具有保守性，还是易变性？本研究针对涵盖1914种四足动物（tetrapod）的系统发育树，对其昼夜活动数据展开分析。我们检测到显著的系统发育信号（phylogenetic signal），表明亲缘关系较近的物种往往拥有相似的活动模式。祖先特征重建结果显示，夜行性（nocturnality）是四足动物及其多数主要演化支（如两栖类、哺乳类）最可能的祖先昼夜活动模式。值得注意的是，部分演化支的夜行性活动模式已连续维持了约3.5亿年。据此，我们证实参与局域尺度资源分区的性状，可在极深的进化时间尺度上得以保守保留。本研究同时揭示了一项具有潜在重要意义（却常被忽视）的生态位保守性量化指标。此外，我们发现昼行演化支的物种形成与分化速率似乎高于夜行演化支，这或可解释为何尽管昼行性（diurnality）的演化出现时间更晚，但当前昼行四足动物的物种数量更为丰富。综上，本研究结果可为群落生态学、物种丰富度研究以及饮食与通讯系统的演化研究提供理论启示。