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Variation in Testosterone and Corticosterone in Amphibians and Reptiles: Relationships with Latitude, Elevation, and Breeding Season Length

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dc.contributor.authorEikenaar, Casen
dc.contributor.authorHusak, J.en
dc.contributor.authorEscallón, C.en
dc.contributor.authorMoore, Ignacio T.en
dc.contributor.departmentBiological Sciencesen
dc.date.accessed2014-06-26en
dc.date.accessioned2014-06-27T14:45:36Zen
dc.date.available2014-06-27T14:45:36Zen
dc.date.issued2012-11en
dc.description.abstractLatitudinal variation in life-history traits has been the focus of numerous investigations, but underlying hormonal mechanisms have received much less attention. Steroid hormones play a central role in vertebrate reproduction and may be associated with life-history trade-offs. Consequently, circulating concentrations of these hormones vary tremendously across vertebrates, yet interspecific geographic variation in male hormone concentrations has been studied in detail only in birds. We here report on such variation in amphibians and reptiles, confirming patterns observed in birds. Using phylogenetic comparative analyses, we found that in amphibians, but not in reptiles, testosterone and baseline corticosterone were positively related to latitude. Baseline corticosterone was negatively related to elevation in amphibians but not in reptiles. For both groups, testosterone concentrations were negatively related to breeding-season length. In addition, testosterone concentrations were positively correlated with baseline corticosterone in both groups. Our findings may best be explained by the hypothesis that shorter breeding seasons increase male-male competition, which may favor increased testosterone concentrations that modulate secondary sexual traits. Elevated energetic demands resulting from greater reproductive intensity may require higher baseline corticosterone. Thus, the positive relationship between testosterone and corticosterone in both groups suggests an energetic demand for testosterone-regulated behavior that is met with increased baseline glucocorticoid concentrations.en
dc.description.sponsorshipNational Science Foundation IOS 0545735en
dc.format.mimetypeapplication/pdfen
dc.identifier.citationCas Eikenaar, Jerry Husak, Camilo Escallón, and Ignacio T. Moore. "Variation in Testosterone and Corticosterone in Amphibians and Reptiles: Relationships with Latitude, Elevation, and Breeding Season Length," The American Naturalist, Vol. 180, No. 5 (November 2012), pp. 642-654. DOI: 10.1086/667891en
dc.identifier.doihttps://doi.org/10.1086/667891en
dc.identifier.issn0003-0147en
dc.identifier.urihttp://hdl.handle.net/10919/49124en
dc.identifier.urlhttp://www.jstor.org/stable/10.1086/667891en
dc.language.isoenen
dc.publisherUniversity of Chicago Pressen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjecttestosteroneen
dc.subjectcorticosteroneen
dc.subjectlatitudeen
dc.subjectelevationen
dc.subjectamphibiansen
dc.subjectreptilesen
dc.subjectbreeding seasonen
dc.subjectgreen anole lizardsen
dc.subjectside-blotched lizardsen
dc.subjectmating systemsen
dc.subjectimmunocompetence handicapen
dc.subjectchallenge hypothesisen
dc.subjectsocial modulationen
dc.subjectuta-stansburianaen
dc.subjectbase-lineen
dc.subjectbirdsen
dc.subjectbehavioren
dc.subjectecologyen
dc.subjectevolutionary biologyen
dc.titleVariation in Testosterone and Corticosterone in Amphibians and Reptiles: Relationships with Latitude, Elevation, and Breeding Season Lengthen
dc.title.serialAmerican Naturalisten
dc.typeArticle - Refereeden
dc.type.dcmitypeTexten

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