In a recent review, Westneat and Stewart (2003) compiled evidence that extra-pair paternity results from a three-player interaction in which sexual conflict is a potent force. Sequentially polyandrous species of birds appear to fit this idea well. Earlier breeding males may attempt to use sperm storage by females to obtain paternity in their mate's subsequent clutches. Later-breeding males may consequently attempt to avoid sperm competition by preferring to pair with previously unmated females. Females may bias events one way or the other. We examined the applicability of these hypotheses by studying mating behavior and paternity in red-necked phalaropes (Phalaropus lobatus), a sex-role reversed, socially polyandrous shorebird. Male red-necked phalaropes guarded mates more strongly than other shorebirds. Males increased within-pair copulation attempts during their mate's fertile period, and maintained or further increased attempts towards the end of laying, suggesting an attempt to fertilize the female's next clutch; these attempts were usually thwarted by the female. Paired males sought extra-pair copulations with females about to reenter the breeding pool. Multilocus DNA fingerprinting showed that 6% of clutches (4/63) each contained one chick sired by a male other than the incubator, producing a population rate of these events of 1.7% (n=226 chicks). Male mates had full paternity in all first clutches (n=25) and 15 of 16 monogamous replacement clutches. In contrast, 3 of 6 clutches of second males contained extra-pair young likely fathered by the female's previous mate. Previously mated female phalaropes may employ counter-strategies that prevent later mating males from discriminating against them. The stability of this polyandrous system, in which males provide all parental care, ultimately may depend on females providing males with eggs containing primarily genes of the incubating male, and not a previous mate.
|Number of pages
|Behavioral Ecology and Sociobiology
|Published - Dec 2004
Bibliographical noteFunding Information:
Acknowledgements This manuscript has been improved by the useful comments of J. Dale, F. Cooke, L. Dill, R. Butler, J.D. Reynolds, W. Stein, P.D. O’Hara, and five anonymous reviewers. We thank D. Matkin, P. Klein, R. Gronquist, K. Oakley, L. Johnson, J. Cole, A. Swingley, C. Acevedo, Y. Zharikov, J. Schamel, and J.T. Schamel for field assistance. K. Wohl and B. Andres of US Fish and Wildlife Service, and D. Spirtes, R. Harris, L. Selig, and L. Dalle-Molle of Bering Land Bridge National Preserve provided logistical and financial support. We thank D. Blomqvist and co-workers for providing pre-publication paternity data on western sandpipers. Our paper is based upon work supported by the National Science Foundation, Office of Polar Programs, (grant OPP-9812841) through funding to process and analyze DNA samples; H. Mays, R. Hanschu, and T. Roush expedited that process. Additional funding came from Simon Fraser University, NOAA–OCSEAP, University of Alaska Natural Resources Fund, USGS–BRD, and the Frank M. Chapman Memorial Fund. This study was conducted under permits provided to D.S. and in accordance with the laws and ethical guidelines of the United States and Canada.
- DNA fingerprinting
- Sex role reversal
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Animal Science and Zoology