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...hoice, secondary sexual traits, sexual selection, testosterone. [Behav Ecol] Male ornaments and courtship displays are thought tohave evolved as honest indicators of quality to females seeking mates (=-=Andersson 1994-=-). In some species, females receive only sperm from males and no direct resources, so male ornaments may advertise indirect genetic benefits to females, including resistance to parasites and pathogens...

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...positive control. After incubation and 4 washes in TBS and 0.05% Tween 20, rabbit antipasserine plasma was added (diluted 1:2000, produced against red-winged blackbird Agelaius phoeniceus antibodies, =-=Hasselquist et al. 1999-=-). After incubation and wash, a commercial horseradish peroxidase–conjugated goat antirabbit 2 Behavioral Ecologysat Pennsylvania State U niversity on Septem ber 16, 2016 http://beheco.oxfordjournals....

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...ween producing or advertising an ornament and maintaining their immune system. This trade-off could occur for 2 reasons: 1) limited resources (e.g., energy or limiting nutrients) are needed for both (=-=Wedekind and Folstad 1994-=-; von Schantz et al. 1999; Blount et al. 2003) and (2) androgens, such as testosterone (T), may mediate this trade-off because they play a role in ornament development and breeding behavior, but they ...

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...tionship remains unclear (reviewed in Roberts et al. 2004). In contrast, experimental studies indicate that there is often a negative trade-off between ornament production and immune system function (=-=Verhulst et al. 1999-=-; Faivre, Grégoire, et al. 2003). There are only a handful of avian species in which a sexually selected male ornament is associated with both female choice of social mates and male immunocompetence ...

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...ty was measured as the local inflammatory response to a subcutaneous injection of PHA. The PHA skin test has been considered a condition-dependent indicator of an individual’s cell-mediated immunity (=-=Goto et al. 1978-=-; Cheng and Lamont 1988), and it is correlated with survival in the wild (Navarro et al. 2003; reviewed in Norris and Evans 2000). However, recent papers have shown that the swelling response involves...

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...m. This trade-off could occur for 2 reasons: 1) limited resources (e.g., energy or limiting nutrients) are needed for both (Wedekind and Folstad 1994; von Schantz et al. 1999; Blount et al. 2003) and =-=(2)-=- androgens, such as testosterone (T), may mediate this trade-off because they play a role in ornament development and breeding behavior, but they also inhibit the immune system (e.g., immunocompetence...

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...rations of all samples were within the sensitivity range of the assay. Validation tests of this commercial immunoassay have demonstrated accurate measures of T in house finches (Carpodacus mexicanus, =-=Deviche and Cortez 2005-=-). T concentrations were natural log transformed to achieve a normal distribution. Statistical analysis We used multiple regression to test the prediction that male ornaments were related to immune sy...