PARALLEL AND NONPARALLEL ASPECTS OF ECOLOGICAL, PHENOTYPIC, AND GENETIC DIVERGENCE ACROSS REPLICATE POPULATION PAIRS OF LAKE AND STREAM STICKLEBACK
Article first published online: 20 SEP 2011
© 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.
Volume 66, Issue 2, pages 402–418, February 2012
How to Cite
Kaeuffer, R., Peichel, C. L., Bolnick, D. I. and Hendry, A. P. (2012), PARALLEL AND NONPARALLEL ASPECTS OF ECOLOGICAL, PHENOTYPIC, AND GENETIC DIVERGENCE ACROSS REPLICATE POPULATION PAIRS OF LAKE AND STREAM STICKLEBACK. Evolution, 66: 402–418. doi: 10.1111/j.1558-5646.2011.01440.x
- Issue published online: 25 JAN 2012
- Article first published online: 20 SEP 2011
- Accepted manuscript online: 11 AUG 2011 11:25AM EST
- Received September 28, 2010, Accepted July 19, 2011, Data Archived: Dryad: doi:10.5061/dryad.k987h
- Adaptive divergence;
- adaptive radiation;
- ecological speciation;
- natural selection;
- parallel evolution
Parallel (or convergent) evolution provides strong evidence for a deterministic role of natural selection: similar phenotypes evolve when independent populations colonize similar environments. In reality, however, independent populations in similar environments always show some differences: some nonparallel evolution is present. It is therefore important to explicitly quantify the parallel and nonparallel aspects of trait variation, and to investigate the ecological and genetic explanations for each. We performed such an analysis for threespine stickleback (Gasterosteus aculeatus) populations inhabiting lake and stream habitats in six independent watersheds. Morphological traits differed in the degree to which lake–stream divergence was parallel across watersheds. Some aspects of this variation were correlated with ecological variables related to diet, presumably reflecting the strength and specifics of divergent selection. Furthermore, a genetic scan revealed some markers that diverged between lakes and streams in many of the watersheds and some that diverged in only a few watersheds. Moreover, some of the lake–stream divergence in genetic markers was associated within some of the lake–stream divergence in morphological traits. Our results suggest that parallel evolution, and deviations from it, are primarily the result of natural selection, which corresponds in only some respects to the dichotomous habitat classifications frequently used in such studies.