The evolution of sexual dimorphism in diurnal birds of prey: resource sharing or mate choice?

GRANDE, J.M,; FIGUEROLA, J.

Sevilla, España

Congreso; 4th Eurasian Congress on Raptors; 2001

Raptor Research Foundation

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:ES; mso-fareast-language:ES;} @page Section1 {size:612.0pt 792.0pt; margin:72.0pt 90.0pt 72.0pt 90.0pt; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Diurnal raptors are among the few avian groups with females larger than males. We used comparative methods to test eight different hypotheses for the evolution of female-biased size dimorphism. Univariate and multivariate analyses indicate that increased female biased dimorphism in body mass and wing length predominate in species with bird based diets and those with aerial sexual display with large acrobatic components. Migratory species were less dimorphic in wing length than sedentary species. Univariate analyses also identified incubation length and incubation roles as associated to female biased dimorphism in wing length although these effects dissapeared in multivariate analyses. Overall, evolution of acrobatic sexual displays and bird based diets were correlated. Results support the hypothesis that sexual selection has driven the evolution of females biased dimorphism in birds of prey with resource sharing in any case having a secondary importance.