Evolutionary consequences of habitat loss for Pacific anadromous salmonids

• Published in: Evolutionary applications Vol. 1; no. 2; pp. 300 - 318
• Main Authors: McClure, Michelle M., Carlson, Stephanie M., Beechie, Timothy J., Pess, George R., Jorgensen, Jeffrey C., Sogard, Susan M., Sultan, Sonia E., Holzer, Damon M., Travis, Joseph, Sanderson, Beth L., Power, Mary E., Carmichael, Richard W.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.05.2008; John Wiley & Sons, Inc
• Subjects: Adaptation; Anadromous species; Aquaculture; Aquatic sciences; Creeks & streams; dams; Developmental biology; differential habitat loss; Ecology; Ecosystem biology; Evolution; evolutionary trajectory; Fish; Fisheries; Fishing; Genetic diversity; genetic variation; Growth models; Habitats; Heritability; Land use; Life history; Morphology; Natural selection; Oncorhynchus; Original; Quantitative genetics; Salmon; Salmonidae; Trout; Water resources; Watersheds; Zoology; Canada; Sacramento California; New York; United States > US; British Columbia Canada; Snake River; California; Columbia River; Idaho; genetic variation; dams; differential habitat loss; evolutionary trajectory; Oncorhynchus
• ISSN: 1752-4571; 1752-4571
• DOI: 10.1111/j.1752-4571.2008.00030.x

Large portions of anadromous salmonid habitat in the western United States has been lost because of dams and other blockages. This loss has the potential to affect salmonid evolution through natural selection if the loss is biased, affecting certain types of habitat differentially, and if phenotypic traits correlated with those habitat types are heritable. Habitat loss can also affect salmonid evolution indirectly, by reducing genetic variation and changing its distribution within and among populations. In this paper, we compare the characteristics of lost habitats with currently accessible habitats and review the heritability of traits which show correlations with habitat/environmental gradients. We find that although there is some regional variation, inaccessible habitats tend to be higher in elevation, wetter and both warmer in the summer and colder in the winter than habitats currently available to anadromous salmonids. We present several case studies that demonstrate either a change in phenotypic or life history expression or an apparent reduction in genetic variation associated with habitat blockages. These results suggest that loss of habitat will alter evolutionary trajectories in salmonid populations and Evolutionarily Significant Units. Changes in both selective regime and standing genetic diversity might affect the ability of these taxa to respond to subsequent environmental perturbations. Both natural and anthropogenic and should be considered seriously in developing management and conservation strategies.