Social mating system affects the frequency of extra-pair paternity in house wrens
We tested two hypotheses regarding the effect of the social mating system on extra-pair paternity in an Illinois population of house wrens, Troglodytes aedonAccording to the genetic-quality hypothesis, polygynous males are of higher quality than monogamists, and monogamously paired females, in an attempt to obtain high-quality genes, should have a greater proportion of extra-pair nestlings in their nests than polygynously paired females. According to the trade-off hypothesis, polygynists, with temporally overlapping nests, will have a greater proportion of extra-pair nestlings in their nests than monogamists, because polygynists have difficulty guarding one or both of their social mates. DNA fingerprinting revealed that extra-pair paternity was most frequent in secondary nests of polygynists. The proportion of secondary broods with extra-pair nestlings increased with the temporal overlap of polygynists' nests, although this trend was not significant. Both results are consistent with the trade-off hypothesis but not with the genetic-quality hypothesis. We did not address the effects of genetic quality on male success at siring nestlings in the nests of other males. Although the trade-off hypothesis focuses on male mate guarding, female behaviours may also affect frequencies of extra-pair paternity. Secondary females may compensate for reduced male defence by engaging in extra-pair copulations with neighbours to reduce the likelihood that neighbours destroy their nests. Thus, in house wrens, female participation in extra-pair copulations in combination with male mate-guarding constraints may generate higher levels of extra-pair paternity in secondary broods than in primary polygynous or monogamous broods.Copyright 1997 The Association for the Study of Animal Behaviour1997The Association for the Study of Animal Behaviour
Soukup
SS
Ecology Group, Department of Biological Sciences, Illinois State University
Thompson
CF