Comparative study of the relationship between genetic mating system, testes size, and body size dimorphism in swallows (Fam. Hirundinidae).

LOPEZ, ALDANA S.; FERRETTI VALENTINA

Puerto Iguazu

Congreso; Ornithological Congress of the Americas; 2017

Aves Argentinas, Association of Field Ornithologists y Sociedade Brasileira de Ornitologia

Sexual selection can occur in two ways: it can favor the competitive ability of theindividuals of one sex to gain access and fertilize individuals of the other, or it can favorthe development of characters in individuals of one sex that are attractive to the othersex. The objectives of this work are: 1) to compare testes size (gonadal volume as aprimary sexual character that might be an indicator of intrasexual competition) andbody size (a secondary sexual character of males competition) in swallows (Fam.Hirundinidae) that differ in their extra-pair paternity (EPP); and, 2) to analyze ifgonadal volume and body size dimorphism are good predictors of the level of EPP inthe species studied. We found information for a total of nine species from the ?MuseoArgentino de Ciencias Naturales? and in the database VertNet. Overall, species differedin their body size dimorphism and gonadal volume. However, this difference did notseem to be related to their level of EPP. When we looked at the relationship betweenEPP and gonadal volume and sexual dimorphism in body size we did not find theexpected relationship between intensity of sexual selection (measured in terms ofEPP), and these variables. It is possible that the relationship between these charactersdoes not exist, or that it exists but with these data we could not detect it. Anatomicalchanges might respond to sustained ecological differences in mating systems, anddifferences in reproductive anatomy might become visible at deeper evolutionaryrelationships.