Evol Ecol Res 7: 595-606 (2005)     Full PDF if your library subscribes.

Viability selection against highly ornamented males

Amber J. Keyser1* and Lynn M. Siefferman2

1Prescott Bluebird Recovery Project, 5838 SW Vermont Street, Portland, OR 97219 and  2Department of Biological Sciences, Auburn University, 331 Funchess Hall, Auburn, AL 36830, USA

Author to whom all correspondence should be addressed.
e-mail: keyser@vancouver.wsu.edu

ABSTRACT

Hypothesis: Variation in ornamental traits, such as plumage coloration, is maintained by the opposing forces of sexual selection (increased ornamentation) and natural selection (decreased ornamentation).

Organisms: A wild population of western bluebirds (Sialia mexicana) in northwestern Oregon which has been the subject of longitudinal population studies since 1988.

Methods: We necropsied 47 adult birds recovered dead in 2002. We measured their plumage coloration with an Ocean Optics S2000 reflectance spectrophotometer. Using Mann-Whitney U-tests with Bonferroni correction, we compared these data to measurements collected from 43 adults recaptured alive.

Results: Necropsies suggested that birds died of an epidemic during 2002. Dead females did not differ from survivors in morphology or plumage. Dead males were significantly more highly ornamented (darker, redder breast patch) than males that survived the epidemic.

Keywords: natural mortality, natural selection, sexual selection, Sialia mexicana, western bluebird, wildlife disease.

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        © 2005 Amber J. Keyser. All EER articles are copyrighted by their authors. All authors endorse, permit and license Evolutionary Ecology Ltd. to grant its subscribing institutions/libraries the copying privileges specified below without additional consideration or payment to them or to Evolutionary Ecology, Ltd. These endorsements, in writing, are on file in the office of Evolutionary Ecology, Ltd. Consult authors for permission to use any portion of their work in derivative works, compilations or to distribute their work in any commercial manner.

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