Relationships of diversity,disparity, and their evolutionary rates in squirrels (Sciuridae) |
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Authors: | Miriam L. Zelditch Jingchun Li Lucy A. P. Tran Donald L. Swiderski |
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Affiliation: | 1. Museum of Paleontology, University of Michigan, Ann Arbor, Michigan;2. Museum of Zoology, University of Michigan, Ann Arbor, Michigan;3. Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan;4. Kresge Hearing Research Institute, University of Michigan, Ann Arbor, Michigan |
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Abstract: | Several theories predict that rapidly diversifying clades will also rapidly diverge phenotypically; yet, there are also reasons for suspecting that diversification and divergence might not be correlated. In the widely distributed squirrel clade (Sciuridae), we test for correlations between per lineage speciation rates, species richness, disparity, and a time‐invariant measure of disparity that allows for comparing rates when evolutionary modes differ, as they do in squirrels. We find that species richness and speciation rates are not correlated with clade age or with each other. Disparity appears to be positively correlated with clade age because young, rapidly diversifying Nearctic grassland clades are strongly pulled to a single stable optimum but older, slowly diversifying Paleotropical forest clades contain lineages that diverge along multiple ecological and morphological lines. That contrast is likely due to both the environments they inhabit and their phylogenetic community structure. Our results argue against a shared explanation for diversity and disparity in favor of geographically mediated modes of speciation and ecologically mediated modes of phenotypic evolution. |
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Keywords: | Adaptive radiation macroevolution morphology Rodentia shape size |
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