• Endocrine correlates of reproductive status in breeding and nonbreeding wild female Moustached Tamarins

      Löttker, Petra; Huck, Maren; Heymann, Eckhard W.; Heistermann, Michael; Abteilung Soziobiologie, Deutsches Primatenzentrum, Göttingen, Germany; Institut für Neuro- und Verhaltensbiologie, Abteilung Verhaltensbiologie, Westfälische Wilhelms-Universität Münster, Germany; Lehrstuhl für Verhaltensforschung, Universität Bielefeld, Germany; Abteilung Reproduktionsbiologie, Deutsches Primatenzentrum Göttingen, Germany (2004-08)
      In callitrichid primates, reproduction is usually restricted to a single female per group. Reproductive rate is high and the occurrence of a postpartum estrus can lead to simultaneous lactation and pregnancy. In contrast, nonreproductive females often show ovarian inactivity. However, most studies on callitrichid reproductive physiology have been conducted in captivity, where conditions differ considerably from those in the wild, so that reproductive conditions may be strongly modified. Using fecal estrogen and progestogen measurements to monitor female reproductive status in 2 groups of wild moustached tamarins (Saguinus mystax), we examined 1) whether reproductive females in free-ranging groups also show postpartum estrus and 2) whether nonreproductive females demonstrate signs of ovarian activity. In both reproductive females, clear changes in the excretion pattern of progestogen and estrogen metabolites over time in combination with information on parturition dates allowed us to differentiate between pregnancy, a period of postpartum ovarian inactivity lasting for 54 and 64–82 days, and a period of ovarian activity before conception. Nonreproductive females demonstrated temporal fluctuations in hormone concentrations and absolute hormone levels that were similar to ones in the breeding females during the phase of ovarian activity. The results suggest that, in contrast to most captive female tamarins, reproductive females in wild groups of moustached tamarins do not have a postpartum estrus and that nonreproductive females show ovarian activity despite the presence of a breeding female.We therefore conclude that findings from captivity should be only carefully compared to the situation in the wild.
    • The many faces of helping: possible costs and benefits of infant carrying and food transfer in wild moustached tamarins (Saguinus mystax)

      Löttker, Petra; Huck, Maren; Heymann, Eckhard W.; Abteilung Soziobiologie, Deutsches Primatenzentrum, Göttingen, Germany; Lehrstuhl für Verhaltensforschung, Universität Bielefeld, Germany; Institut für Neuro- & Verhaltensbiologie, Abt. Verhaltensbiologie, Westfälische Wilhelms-Universität Münster, Germany (2004-07-01)
      Various hypotheses about adaptive and non-adaptive mechanisms of non-parental infant care have been put forward for different taxa (Emlen et al., 1991). The Neotropical callitrichid primates are renowned for their cooperative care of the twin litters. None of the studies conducted in the wild included information on genetic relationships within groups. This, however, is indispensable to evaluate the relevance of competing hypotheses concerning direct or indirect fitness gains. We studied two groups of wild moustached tamarins with known genetic relationships over a one-year period to examine individual time-budgets and contributions to infant carrying and food-transfer. With these data we tested whether helping behaviour might be a non-adaptive trait and, if not, whether indirect benefits via kin-selection could be excluded as an evolutionary force maintaining it. Other hypotheses on direct fitness benefits were discussed as far as (anecdotal) data permitted. Changes in time-budgets suggest costs, thus clearly refuting hypotheses assuming non-adaptivity. High within-group relatedness suggests kin-selection to be one driving force of maintaining the trait. However, non-parental individuals may help despite low relatedness. Data were not sufficient to decide which possible direct benefits most likely play a role in inducing non-relatives to help. Yet, two (non-exclusive) explanations seem to be the most probable ones: The chance to inherit the main-breeding position, and a certain chance of own direct reproductive success (the latter only for male helpers) due to polyandrous mating by the female. Other adaptive mechanisms may enhance benefits but are unlikely to be major selective forces since fitness gains are presumably rather small or uncertain.
    • Paternity and kinship patterns in polyandrous moustached tamarins (Saguinus mystax)

      Huck, Maren; Löttker, Petra; Böhle, Uta-Regina; Heymann, Eckhard W.; Abteilung Soziobiologie, Deutsches Primatenzentrum, Göttingen, Germany; Abteilung für Verhaltensforschung, Universität Bielefeld, Germany; Institut für Neuro- & Verhaltensbiologie, Abt. Verhaltensbiologie, Westfälische Wilhelms-Universität Münster, Germany; Arbeitsgruppe Primatengenetik, Deutsches Primatenzentrum (DPZ), Göttingen, Germany (2005)
      We studied patterns of genetic relatedness and paternity in moustached tamarins, small Neotropical primates living in groups of 1–4 adult males and 1–4 adult females. Generally only one female per group breeds, mating with more than one male. Twin birth are the norm. In order to examine the genetic consequences of this mating pattern, DNA was extracted from fecal samples collected from two principal and six neighboring groups. DNA was characterized at twelve microsatellite loci (average: seven alleles/locus). We addressed the following questions: Do all adult males have mating access to the reproductive female of the group? How is paternity distributed across males in a group? Can polyandrous mating lead to multiple paternity? Are nonparental animals more closely related to the breeders than to the population mean? And, are mating partners unrelated? Breeding females mated with all nonrelated males. In at least one group the father of the older offspring did not sire the youngest infant although he was still resident in the group. We also found evidence for multiple paternity in a supposed twin pair. Yet, within each group the majority (67–100%) of infants had the same father, suggesting reproductive skew. Relatedness within groups was generally high (average R 0.31), although both nonrelated males and females occurred, i.e., immigrations of both sexes are possible. Mating partners were never found to be related, hence inbreeding seems to be uncommon. The results suggest that while the social mating system is polyandry, paternity is often monopolized by a single male per group.