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Dominance and fertility among female primates
Author(s) -
Harcourt A. H.
Publication year - 1987
Publication title -
journal of zoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.915
H-Index - 96
eISSN - 1469-7998
pISSN - 0952-8369
DOI - 10.1111/j.1469-7998.1987.tb03721.x
Subject(s) - fertility , biology , offspring , dominance (genetics) , cooperative breeding , competition (biology) , reproductive success , demography , reproduction , seasonal breeder , breed , ecology , population , pregnancy , biochemistry , sociology , gene , genetics
Under some circumstances dominant females in social groups of primates start to breed significantly earlier in life than do subordinate ones, produce significantly more offspring per year, and mate significantly earlier in the breeding season, if there is one. Thus, competition appears to influence fertility. Observations that dominant individuals sometimes feed on better quality foods, expend less energy or time in obtaining food, or are interrupted less often when feeding, indicate that the effects of competition on fertility could be working through nutrition. In addition, subordinate animals usually suffer more threats and have to avoid others more frequently than do dominants, which may result in ‘stress’ causing lowering of fertility. Whilst ‘stress’ might explain the total suppression of reproduction in subordinate female tamarins in the wild, a correlation between ‘stress’ and fertility has yet to be conclusively demonstrated in wild Old World primates. Evidence that competitive ability might influence a female's rate or timing of copulation is sparse, and nobody has shown that subordinate females mate so infrequently that their fertility is compromised. The situation in which dominant animals are especially likely to produce more offspring than subordinates is seen when resources are so clumped that the dominants can exert their greater competitive ability with sufficient frequency to obtain preferential access to the resources and maybe to influence levels of ‘stress’. The effects of belonging to a large group seem to be very similar to those of being a subordinate, and might operate through the same mechanisms of nutrition and ‘stress’. If so, analysis of the relationship between competitive ability and fertility could be confounded. Whatever the social correlates of variance in fertility, most stages of reproduction appear to be influenced by nutrition and ‘stress’. Finally, in the wild, where mortality rates are often high, a female's reproductive success might be determined more by characteristics that promote survival of offspring than by those that favour production of them.