High rates of infidelity in the Grey Fantail Rhipidura albiscapa suggest that testis size may be a better correlate of extra-pair paternity than sexual dimorphism

Date

2010

Authors

Hoffman, Joseph I.
Munro, Kat
Kilner, Rebecca
Amos, W.

Journal Title

Journal ISSN

Volume Title

Publisher

British Ornithologists Union

Abstract

The Grey Fantail Rhipidura albiscapa is a socially monogamous passerine endemic to Australia. Behavioural and morphological clues point to opposing conclusions as to its breeding system; sexual monomorphism and monochrome colorations suggest monogamy, whereas relatively large testes and a prominent cloacal protruberance are more indicative of multiple mating and sperm competition. We used five highly variable microsatellite loci to investigate the genetic breeding system of this species. Paternity was assigned to 49 of 69 (71%) offspring tested and the overall rate of partner infidelity was high, with 55% of offspring being sired by an extra-pair male and 64% of all clutches containing extra-pair young. This puts the Grey Fantail amongst the most promiscuous socially monogamous species yet studied. Where extra-pair fathers were identified, these were invariably in neighbouring territories, and although larger males did not gain more paternities overall, extra-pair offspring tended to be fathered by larger males than expected by chance. We interpret our findings in light of some of the potential costs and benefits associated with extra-pair paternity.

Description

Keywords

Keywords: behavioral ecology; clutch size; endemic species; functional morphology; genetic marker; mate choice; passerine; paternity; reproductive strategy; sexual dimorphism; sperm competition; Australia; Passeriformes; Rhipidura Mate choice; Microsatellite; Monogamy; Passerine; Testis size

Citation

Source

Ibis

Type

Journal article

Book Title

Entity type

Access Statement

License Rights

Restricted until

2037-12-31
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