Data from: Tempo of trophic evolution and its impact on mammalian diversification

Mammals are characterized by the complex adaptations of their dentition, which are an indication that diet has played a critical role in their evolutionary history. Although much attention has focused on diet and the adaptations of specific taxa, the role of diet in large-scale diversification patterns remains unresolved. Contradictory hypotheses have been proposed, making prediction of the expected relationship difficult. We show that net diversification rate (the cumulative effect of speciation and extinction), differs significantly among living mammals, depending upon trophic strategy. Herbivores diversify fastest, carnivores are intermediate, and omnivores are slowest. The tempo of transitions between the trophic strategies is also highly biased: the fastest rates occur into omnivory from herbivory and carnivory and the lowest transition rates are between herbivory and carnivory. Extant herbivore and carnivore diversity arose primarily through diversification within lineages, whereas omnivore diversity evolved by transitions into the strategy. The ability to specialize and subdivide the trophic niche allowed herbivores and carnivores to evolve greater diversity than omnivores.

哺乳类以其齿系的复杂适应性为典型特征，这表明食性在其演化历史中发挥了关键作用。尽管学界已针对特定类群的食性及其适应性开展了大量研究，但食性在宏观演化辐射模式中所扮演的角色仍未明晰。此前提出的诸多假说彼此相悖，使得对二者预期关联的预测颇具难度。本研究表明，现生哺乳类的净物种分化率（net diversification rate，即物种形成与灭绝的累积效应）存在显著差异，且这一差异与其营养策略直接相关：植食性类群的分化速率最快，肉食性类群居中，杂食性类群则最慢。不同营养策略间的转换速率同样存在显著偏向性：从植食性或肉食性向杂食性转换的速率最快，而植食性与肉食性之间的转换速率最低。现生植食性与肉食性类群的多样性主要源自类群内部的物种分化，而杂食性类群的多样性则通过向该营养策略的转换演化而来。对营养生态位的特化与细分能力，使得植食性类群与肉食性类群能够演化出较杂食性类群更为丰富的多样性。