title: Sexing a sex-role-reversed species based on plumage: potential challenges in the red phalarope.
abstract: Sex-role reversal, in which males care for offspring, can occur when mate competition is stronger between females than males. Secondary sex traits and mate attracting displays in sex-role-reversed species are usually more pronounced in females than in males. The red phalarope (Phalaropus fulicarius) is a textbook example of a sex-role-reversed species. It is generally agreed that males are responsible for all incubation and parental care duties, whereas females typically desert males after having completed a clutch and may pair with new males to lay additional clutches. The breeding plumage of female red phalaropes is usually more brightly colored than male plumage, a reversed sexual dichromatism usually associated with sex-role reversal. Here, we confirm with PCR-based sexing that male red phalaropes can exhibit both the red body plumage typical of a female and the incubation behavior typical of a male. Our result, combined with previous observations of brightly colored red phalaropes incubating nests at the same arctic location (Igloolik Island, Nunavut, Canada), suggests that plumage dichromatism alone may not be sufficient to distinguish males from females in this breeding population of red phalaropes. This stresses the need for more systematic genetic sexing combined with standardized description of intersexual differences in red phalarope plumages. Determining whether such female-like plumage on males is a result of phenotypic plasticity or genetic variation could contribute to further understanding sex-role reversal strategies in the short Arctic summer.
authors.affiliation: Canada Research Chair in Polar and Boreal Ecology, Université de Moncton, Moncton, Canada; Centre d'Études Nordiques, Université du Québec à Rimouski, Rimouski, Canada; Canada Research Chair on Northern Biodiversity, Université du Québec à Rimouski, Rimouski, Canada.
authors.forename: Marie-Andrée
authors.initials: MA
authors.lastname: Giroux
authors.affiliation: Molecular Biology Unit, Fisheries and Oceans Canada , Moncton , Canada.
authors.forename: Delphine
authors.initials: D
authors.lastname: Ditlecadet
authors.affiliation: Département de Biologie, Université de Moncton , Moncton , Canada.
authors.forename: Luc J
authors.initials: LJ
authors.lastname: Martin
authors.affiliation: Migratory Bird Management, US Fish and Wildlife Service , Anchorage, AK , USA.
authors.forename: Richard B
authors.initials: RB
authors.lastname: Lanctot
authors.affiliation: Canada Research Chair in Polar and Boreal Ecology, Université de Moncton, Moncton, Canada; Centre d'Études Nordiques, Université du Québec à Rimouski, Rimouski, Canada; Département de Biologie, Université de Moncton, Moncton, Canada; Québec Center for Biodiversity Science, Université du Québec à Rimouski, Rimouski, Canada.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Lecomte
keywords: Charadriiformes; Phalaropus fulicarius; Secondary sexual traits; Sexual dichromatism; Shorebirds