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Stress-related hormones and genetic diversity in sea otters (Enhydra lutris)

Marine Mammal Science

By:
, , , , and
DOI: 10.1111/j.1748-7692.2008.00260.x

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Abstract

Sea otters (Enhydra lutris) once ranged throughout the coastal regions of the north Pacific, but were extirpated throughout their range during the fur trade of the 18th and 19th centuries, leaving only small, widely scattered, remnant populations. All extant sea otter populations are believed to have experienced a population bottleneck and thus have lost genetic variation. Populations that undergo severe population reduction and associated inbreeding may suffer from a general reduction in fitness termed inbreeding depression. Inbreeding depression may result in decreased testosterone levels in males, and reduced ability to respond to stressful stimuli associated with an increase in the stress-related adrenal glucocorticoid hormones, cortisol and corticosterone. We investigated correlations of testosterone, cortisol, and corticosterone with genetic diversity in sea otters from five populations. We found a significant negative correlation between genetic diversity and both mean population-level (r2 = 0.27, P < 0.001) and individual-level (r2 = 0.54, P < 0.001) corticosterone values, as well as a negative correlation between genetic diversity and cortisol at the individual level (r2 = 0.17, P = 0.04). No relationship was found between genetic diversity and testosterone (P = 0.57). The strength of the correlations, especially with corticosterone, suggests potential negative consequences for overall population health, particularly for populations with the lowest genetic diversity. ?? 2009 by the Society for Marine Mammalogy.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Stress-related hormones and genetic diversity in sea otters (Enhydra lutris)
Series title:
Marine Mammal Science
DOI:
10.1111/j.1748-7692.2008.00260.x
Volume
25
Issue:
2
Year Published:
2009
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Marine Mammal Science
First page:
351
Last page:
372
Number of Pages:
22