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information, materials and readings for A501: Techniques in
Reproductive Diversity Photo
Gallery - MLBS Field Crews Our research group takes an experimental approach to questions of adaptation and constraint in life-history evolution. By treating birds with hormones, documenting the phenotypic consequences of hormonal treatment, and relating these consequences to fitness, we hope to understand how natural selection shapes organisms as integrated units. Our study animal is the dark-eyed junco, and we have found that testosterone affects numerous aspects of the phenotype in free-living male juncos, including song, parental behavior, home range size, attractiveness to females, immune capacity, corticosteroid responses to stress, regulation of body mass, and timing of molt. With respect to fitness, males treated with testosterone are less successful at rearing offspring with their social mates but more successful at siring offspring by means of extra-pair fertilizations. Our current goals include investigation of the extended phenotypic effects of testosterone on a male's associates, including his mate and offspring, and the role of testosterone in females. We are particularly interested in the interaction between natural and sexual selection and whether selection on hormonally mediated traits in one sex may constrain evolution of the other through correlated selection. Other studies have also focused on the relative importance of a series of selective factors (dominance status in winter, arrival time at breeding areas in spring, risk of mortality during migration) in shaping the distance an individual migrates. Current and recent graduate students have studied the role of
maternal steroids in early development in red-winged blackbirds,
European starlings, and dark-eyed juncos; seasonal profiles of
testosterone and prolactin in red-eyed vireos and solitary vireos; the
influence of testosterone on the pre-basic molt in dark-eyed juncos,
mate choice across subspecific boundaries in dark-eyed juncos; genetics
of variation in sexually selected traits in orioles; transmission of
passive immunity in Japanese quail and pied flycatchers, ageing and the
stress response in common terns, correlational selection on body size
and an attractive plumage trait in dark-eyed juncos; testosterone,
aggression, nest defence, and immune function in female dark-eyed
juncos; hormonal correlates of dominance in female dark-eyed juncos;
causes of variation among female dark-eyed juncos in extra-pair
fertilizations; hormones and social behavior in the phainopepla;
regulation of seasonal reproduction by novel peptides in dark-eyed
juncos, climate change, migratory behavior, and winter sex ratios in
dark-eyed juncos; multiple ornaments and male mate choice in cardinals. Last Updated: 15 January 2008 |