Sympatric Divergence and Performance Trade-Offs of Bluegill Ecomorphs

• Published in: Evolutionary biology Vol. 38; no. 4; pp. 422 - 433
• Main Authors: Ellerby, David J., Gerry, Shannon P.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01-12-2011; Springer; Springer Nature B.V
• Subjects: Animal Genetics and Genomics; Biomedical and Life Sciences; Developmental Biology; Divergence; Ecology; Evolutionary Biology; Glacial lakes; Habitats; Human Genetics; Lakes; Life Sciences; Locomotion; Morphology; New species; Phenotypic plasticity; Research Article; Speciation; Swimming; Sympatric populations; Swimming; Bluegill sunfish; Polyphenism; Adaptation
• ISSN: 0071-3260; 1934-2845
• DOI: 10.1007/s11692-011-9130-y

Phenotypic plasticity in response to environmental cues can create distinct morphological types within populations. This variation in form, and potentially function, may be a factor in initiating population divergence and the formation of new species. Here we show the translation of sympatric, habitat-specific morphological divergence into performance differences in energy economy, maneuverability and steady-state locomotion. Littoral and pelagic bluegill sunfish ecomorphs show differences in performance that appear adaptive within their respective habitats: greater maneuverability in the heavily vegetated littoral; greater steady-state swimming speed and economy in the open-water pelagic. This represents a trade-off in unsteady versus steady swimming performance, likely because morphological features associated with maximizing maneuverability are incompatible with enhancing steady-swimming performance. This may constrain the direction of adaptive change, maintaining the divergence created by phenotypic plasticity. The combination of habitat specific sympatric adaptation and constraints imposed by performance trade-offs may be an important factor underlying the high rate of speciation in freshwater fishes from post-glacial lakes.