geometric morphometrics, life history, morphology, predation, trade-off


Predation can drive morphological divergence in prey populations, although examples of divergent selection are typically limited to nonreproductive individuals. In livebearing females, shape often changes drastically during pregnancy, reducing speed and mobility and enhancing susceptibility to predation. In the present study, we document morphological divergence among populations of nonreproductive female livebearing fish (Brachyrhaphis rhabdophora) in predator and nonpredator environments. We then test the hypothesis that shape differences among nonreproductive females are maintained among reproductive females between predator and nonpredator environments. Nonreproductive females in predator environments had larger caudal regions and more fusiform bodies than females in nonpredator environments; traits that are associated with burst speed in fish. Shape differences were maintained in reproductive females, although the magnitude of this difference declined relative to nonreproductive females, suggesting morphological convergence during pregnancy. Phenotypic change vector analysis revealed that females in predator environments became more similar to females in nonpredator environments in the transition from nonreproductive to reproductive. Furthermore, the level of reproductive allocation affected shape similarly between predator environments. These results suggest a life-history constraint on morphology, in which predator-driven morphological divergence among nonreproductive B. rhabdophora is not maintained at the same level during pregnancy.

Original Publication Citation

J.S. Wesner, E.J. Billman, A. Meier, and M.C. Belk. 2011. Morphological convergence during pregnancy among predator and non-predator populations of the livebearing fish Brachyrhaphis rhabdophora (Teleostei: Poecilidae). Biological Journal of the Linnean Society. 104:386-392.

Document Type

Peer-Reviewed Article

Publication Date


Permanent URL


Biological Journal of the Linnean Society




Life Sciences



University Standing at Time of Publication

Full Professor

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Biology Commons