Data from: Dietary specialization is linked to reduced species durations in North American fossil canids

How traits influence species persistence is a fundamental question in ecology, evolution, and paleontology. We test the relationship between dietary traits and both species duration and locality coverage over 40 million years in North American canids, a clade with considerable ecomorphological disparity and a dense fossil record. Because ecomorphological generalization--broad resource use--may enable species to withstand disturbance, we predicted that canids of average size and mesocarnivory would exhibit longer durations and wider distributions than specialized larger or smaller species. Second, because locality coverage might reflect dispersal ability and/or survivability in a range of habitats, we predicted that high coverage would correspond with longer durations. We find a non-linear relationship between species duration and degree of carnivory: species at either end of the carnivory spectrum tend to have shorter durations than mesocarnivores. Locality coverage shows no relationship with size, diet, nor duration. To test whether generalization (medium size, mesocarnivory) corresponds to an adaptive optimum, we fit trait evolution models to previously generated canid phylogenies. Our analyses identify no single optimum in size or diet. Instead, the primary model of size evolution is a classic Cope's Rule increase over time, while dietary evolution does not conform to a single model.

性状如何影响物种存续，是生态学、演化生物学与古生物学领域的核心科学问题。本研究以北美犬科（Canidae）这一具有显著生态形态分异度且化石记录极为丰富的支系为研究对象，在4000万年的时间尺度下，探究食性性状与物种存续时长、分布位点覆盖度之间的关联。鉴于生态形态泛化——即宽泛的资源利用策略——可帮助物种抵御外界扰动，本研究提出假设：体型处于中等水平、兼具中肉食性的犬科物种，相较于特化的大型或小型犬科物种，将拥有更长的存续时长与更广的分布范围。其次，由于分布位点覆盖度可反映物种的扩散能力与/或在多样生境中的存活能力，本研究进一步假设：较高的位点覆盖度将对应更长的物种存续时长。研究结果显示，物种存续时长与肉食性程度呈非线性关联：处于肉食性谱系两端的物种，其存续时长普遍短于中肉食性物种。而分布位点覆盖度则与体型、食性以及物种存续时长均无显著关联。为验证生态形态泛化（中等体型、中肉食性）是否对应适应性最优表型，本研究将性状演化模型拟合至此前已构建的犬科系统发育树数据中。本研究的分析并未发现体型或食性存在单一的适应性最优表型。具体而言，体型演化的主流模型符合经典的柯普法则（Cope's Rule），即随时间推移体型逐渐增大；而食性演化则不符合单一的演化模型。