Publication
Title
Latitudinal distribution, migration, and testosterone levels in birds
Author
Abstract
Tropical bird species usually have lower testosterone (T) levels during breeding than temperate species. However, the potential mechanisms behind the positive interspecific correlation between T and latitude remain unexplored. In a comparative study of more than 100 bird species, we examined whether social constraints during male-male competition arising from migration and breeding synchrony are responsible for the latitude effects. Species that breed at higher latitudes are more likely to migrate and experience more intense intrasexual competition upon spring arrival than nonmigrant species from lower latitudes. Additionally, species from higher latitudes cope with shorter breeding seasons and thus with more synchronous breeding, which selects for high T titers via increased male-male conflicts. Accordingly, peak T levels were associated with migration and the duration of the egg laying period that reflects breeding synchrony. Because migration and breeding synchrony were related to latitudinal distribution, they appear to be important components of the latitude effects on T. A multivariate model controlling for covariation of predictor variables revealed that latitude remained the strongest predictor of peak T. Therefore, selection due to migration and breeding synchrony may partially cause the latitude effect, but other geographically varying factors may also play a role in mediating peak T levels at different latitudes.
Language
English
Source (journal)
American naturalist. - Chicago, Ill., 1867, currens
Publication
Chicago, Ill. : 2008
ISSN
0003-0147
Volume/pages
172:4(2008), p. 533-546
ISI
000259213600008
Full text (Publisher's DOI)
UAntwerpen
Faculty/Department
Research group
Publication type
Affiliation
Publications with a UAntwerp address
External links
Web of Science
Record
Identification
Creation 08.10.2008
Last edited 23.11.2017
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