Trait-Specific Processes of Convergence and Conservatism Shape Ecomorphological Evolution in Ground-Dwelling Squirrels: Trait-Specific Evolutionary Processes

Document Type

Article

Publication Date

3-1-2018

Keywords

Convergence, covariance ratio, ecomorphology, macroevolution, morphological integration, phenome

Abstract

Our understanding of mechanisms operating over deep timescales to shape phenotypic diversity often hinges on linking variation in one or few trait(s) to specific evolutionary processes. When distinct processes are capable of similar phenotypic signatures, however, identifying these drivers is difficult. We explored ecomorphological evolution across a radiation of ground‐dwelling squirrels whose history includes convergence and constraint, two processes that can yield similar signatures of standing phenotypic diversity. Using four ecologically relevant trait datasets (body size, cranial, mandibular, and molariform tooth shape), we compared and contrasted variation, covariation, and disparity patterns in a new phylogenetic framework. Strong correlations existed between body size and two skull traits (allometry) and among skull traits themselves (integration). Inferred evolutionary modes were also concordant across traits (Ornstein‐Uhlenbeck with two adaptive regimes). However, despite these broad similarities, we found divergent dynamics on the macroevolutionary landscape, with phenotypic disparity being differentially shaped by convergence and conservatism. Such among‐trait heterogeneity in process (but not always pattern) reiterates the mosaic nature of morphological evolution, and suggests ground squirrel evolution is poorly captured by single process descriptors. Our results also highlight how use of single traits can bias macroevolutionary inference, affirming the importance of broader trait‐bases in understanding phenotypic evolutionary dynamics.

Journal Title

Evolution

Volume

72

Issue

3

First Page

473

Last Page

489

DOI

https://doi.org/10.1111/evo.13422

First Department

Biology

Link to Full Text

@ the James White Library

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