Data from: Testing for differences in rates of speciation, extinction, and morphological evolution in four tribes of cichlids endemic to Lake Tanganyika, East Africa

Patterns of morphological disparity yield important insight into the causes of diversification and adaptive radiation in East African cichlids. However, comparisons of cichlid disparity have often failed to consider the effects that differing clade ages or stochasticity may have on disparity before making interpretations. Here, a model of branching morphological evolution allows assessment of the relative contributions of differing turnover and morphological change rates, clade ages, and stochastic variation to the observed patterns of disparity in four endemic tribes of Lake Tanganyika cichlids. Simulations compare the likelihood of generating the observed disparity of the four tribes using 200 parameter combinations and four model conditioning variations, which allows inference of evolutionary rate differences among clades. The model is generally robust to model conditioning, the approach to data analysis, and model assumptions. Disparity differences among the first three cichlid tribes, Ectodini, Lamprologini, and Tropheini, can be explained entirely by stochasticity and age, whereas the fourth tribe, Cyprichromini, has likely experienced lower rates of turnover and morphological change. This rate difference is likely related to the low dietary diversity of the Cyprichromini. These results highlight the importance of considering both clade age and stochastic variation when interpreting morphological diversity and evolutionary processes.

形态歧异度（morphological disparity）模式可为东非慈鲷的物种分化与适应性辐射的成因提供重要研究见解。然而，过往开展相关解读时，慈鲷形态歧异度的比较分析往往未提前考量支系（clade）年龄差异或随机性（stochasticity）对形态歧异度的潜在影响。本研究构建的分支形态演化模型，可量化评估物种更替速率、形态变化速率、支系年龄以及随机变异对坦噶尼喀湖（Lake Tanganyika）四个特有慈鲷族观测到的形态歧异度模式的相对贡献；本研究通过200组参数组合与4种模型条件变体，模拟生成该四族慈鲷观测形态歧异度的可能性，借此推断不同支系间的演化速率差异。该模型对模型条件设置、数据分析方法以及模型假设均具备较好的稳健性。前三类慈鲷族：Ectodini、Lamprologini与Tropheini，其形态歧异度差异可完全由随机性与支系年龄解释；而第四族Cyprichromini的物种更替与形态变化速率显著更低，该速率差异或与其较低的食性多样性密切相关。本研究结果凸显了在解读形态多样性与演化过程时，同时考量支系年龄与随机变异的重要性。