Potential for anthropogenic disturbances to influence evolutionary change in the life history of a threatened salmonid
Date
2008-05
Authors
Williams, John G.
Zabel, Richard W.
Waples, Robin S.
Hutchings, Jeffrey Alexander
Connor, William P.
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Abstract
Although evolutionary change within most species is thought to occur slowly, recent studies have
identified cases where evolutionary change has apparently occurred over a few generations.
Anthropogenically altered environments appear particularly open to rapid evolutionary change over
comparatively short time scales. Here, we consider a Pacific salmon population that may have
experienced life-history evolution, in response to habitat alteration, within a few generations.
Historically, juvenile fall Chinook salmon (Oncorhynchus tshawytscha) from the Snake River migrated
as subyearlings to the ocean. With changed riverine conditions that resulted from hydropower dam
construction, some juveniles now migrate as yearlings, but more interestingly, the yearling
migration tactic has made a large contribution to adult returns over the last decade. Optimal
life-history models suggest that yearling juvenile migrants currently have a higher fitness than
subyearling migrants. Although phenotypic plasticity likely accounts for some of the change in
migration tactics, we suggest that evolution also plays a significant role. Evolutionary change
prompted by anthropogenic alterations to the environment has general implications for the recovery
of endangered species. The case study we present herein illustrates the importance of integrating
evolutionary considerations into conservation planning for species at risk.
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Citation
Williams, John G., Richard W. Zabel, Robin S. Waples, Jeffrey A. Hutchings, et al. 2008. "Potential for anthropogenic disturbances to influence evolutionary change in the life history of
a threatened salmonid." Evolutionary Applications 1(2): 271-285.