Ostner Julia, Chalise Mukesh K, Koenig Andreas, Launhardt Kristin, Nikolei Julia, Podzuweit Doris, Borries Carola
Department of Anthropology, Stony Brook University, Stony Brook, New York, USA.
Am J Primatol. 2006 Jul;68(7):701-12. doi: 10.1002/ajp.20260.
In species with a high risk of infanticide, a conflict of interest exists between the sexes over the amount of paternity information that is available to males. While females are expected to keep males unaware of their reproductive status in order to confuse paternity, selection should favor those male traits that enhance the males' assessment of female status and consequently of paternity probability. In Hanuman langurs (Semnopithecus entellus), a species that is extremely vulnerable to infanticide, females have been shown to successfully conceal the exact timing of ovulation from males--perhaps because they exhibit no sexual swelling and mate during all reproductive phases, including gestation. Nevertheless, it remains unclear whether males have hitherto unrecognized information about females' reproductive condition on a broader level that could still enhance male reproductive success. We investigated male assessment of female reproductive states in a population of wild Hanuman langurs as indicated by changes in male behavior, such as rates of copulations, anogenital inspections, and consortships, in relation to different female receptive periods (pregnant, fertile-nonconceptional, and conceptional). Our data indicate that males were able to discern qualitatively distinct reproductive states. Males were more interested in fertile than pregnant females, as indicated by higher copulation rates. Based on consortships, males distinguished fertile from nonfertile phases, as well as fertile, nonconceptional receptive periods from conceptional ones. Hanuman langur males are thus not as unaware of female reproductive condition as previously thought, supporting the idea of an ongoing battle of the sexes over paternity information. However, granting some knowledge while at the same time concealing the exact day of ovulation may also reflect a pure female strategy of balancing paternity concentration with paternity confusion, which is the most likely strategy in this system with high infanticide risk and male defense of infants.
在存在杀婴高风险的物种中，雄性可获取的父权信息数量方面，两性之间存在利益冲突。虽然预计雌性会让雄性对其生殖状态不知情，以便混淆父权，但自然选择应会青睐那些能增强雄性对雌性状态进而对父权概率评估的雄性特征。在叶猴（食叶猴属）中，这是一种极易遭受杀婴行为的物种，研究表明雌性能够成功向雄性隐瞒排卵的确切时间——或许是因为它们没有性肿胀现象，且在包括妊娠期在内的所有生殖阶段都会交配。然而，目前尚不清楚雄性在更广泛层面上是否拥有关于雌性生殖状况的未被认识到的信息，而这些信息仍可能提高雄性的繁殖成功率。我们通过观察雄性行为的变化，如交配率、肛门生殖器检查率和伴游情况，来研究野生叶猴种群中雄性对雌性生殖状态的评估，这些行为变化与不同的雌性受孕期（怀孕期、可育非受孕期和受孕期）相关。我们的数据表明，雄性能够辨别出性质上不同的生殖状态。如较高的交配率所示，雄性对处于可育期的雌性比怀孕雌性更感兴趣。基于伴游情况，雄性区分出了可育期和非可育期，以及可育非受孕期和受孕期。因此，叶猴雄性并非像之前认为的那样对雌性生殖状况一无所知，这支持了在父权信息方面两性持续斗争的观点。然而，在给予一些信息的同时又隐瞒排卵的确切日期，也可能反映了雌性在平衡父权集中与父权混淆方面的纯粹策略，这是在这种存在高杀婴风险且雄性保护幼崽的系统中最有可能的策略。
