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Peter B. S. Spencer Alan B. Horsup Helene D. Marsh 《Behavioral ecology and sociobiology》1998,43(1):1-9
The reason why a female who is socially paired to one particular male seeks extra-pair copulations (EPCs) with others has
important implications in life history models and to the study of behaviour. The Allied rock-wallaby, Petrogale assimilis, lives in spatially isolated colonies in tropical north Queensland, Australia. Extensive observations of a colony at Black
Rock showed that intense behavioural bonding occurs between pairs of adult males and females; about two-thirds of males paired
with one female, the remainder paired with two females simultaneously. Single-locus microsatellite profiling determined the
paternity of 63 offspring from 21 females for which long-term behavioural data were available. One-third of the young were
fathered by males which were not paired socially with the mother. The mating system was heterogeneous: (1) all offspring of
11 females were fathered by the mother's partner, (2) all young of 5 females were fathered by extra-pair males, and (3) only
some of the young of 5 females were fathered by their regular consort. Analysis of individual longitudinal demographic records
showed that females whose young were always fathered by their consort had higher reproductive success than those whose young
were always fathered as a result of (EPCs). However, females with some offspring fathered by their regular consort and others
via EPCs had the highest probability of raising young to independence. These females were significantly more likely to have
an offspring fathered as a result of an EPC if their previous young had failed to survive to pouch emergence. These results
are consistent with the hypothesis that females choose mates for their genetic quality. Comparison of the males with which
these females sought EPCs and the regular consorts suggested that arm length rather than body weight or testes size was used
as the index of genetic quality. Results from a second colony of rock-wallabies in which the reproductive rate was accelerated
were also consistent with the genetic-quality hypothesis. These results imply that by choosing better-quality fathers irrespective
of social pairing, females are able to maximise their overall lifetime reproductive success, and presumably, those of their
offspring.
Received: 8 June 1997 / Accepted after revision: 28 February 1998 相似文献
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