Female Reproductive Strategies and the Ovarian Cycle in Hamadryas Baboons

<p>This thesis examines the relationship between sexual behaviour and the ovarian cycle in a group-living primate, Papio h. hamadryas. Of particular interest is whether females modify their ovarian cycle in a manner that is expected increase their reproductive success. The study was conducted on a captive colony where the resident males (RM) had been vasectomised prior to start of the study resulting in all mature females undergoing repeated ovarian cycling throughout the study period. This made the analysis of sexual behaviour relative to fine scale changes in the ovarian cycle possible. One year of ovarian cycle data and 280 hours of behavioural data was collected via observational sampling during the study. RM vasectomisation did not alter the archetypal one male unit social structure nor the typical socio-spatial organisation of wild hamadryas populations. Females were found to be more promiscuous than in wild populations, however, presumably because of the confounding effect that the high number of simultaneously cycling females had on RM herding (Chapter 1). RMs dominated copulations over the optimal conceptive period of the ovarian cycle, while the majority of extra-OMU copulations occurred outside this period and were rarely solicited by females. This pattern supports a dual paternity concentration/paternity confusion strategy, and not female choice or fertility insurance strategies (Chapter 2). Females were not found to synchronise or asynchronise their cycles over the 1 year study period, although a review of the literature on hamadryas breeding patterns suggests that they may be able to do so over shorter periods (Chapter 3). Females did, however, appear to regulate the length of the turgescent phase of their ovarian cycle in a manner that would facilitate a paternity confusion strategy and maximise their expected fitness payoff (Chapter 4). Consequently, this study provides empirical evidence that female hamadryas baboons manipulate their ovarian cycle in a manner that is expected to increase their reproductive success.</p>

Female Reproductive Strategies and the Ovarian Cycle in Hamadryas Baboons

<p>This thesis examines the relationship between sexual behaviour and the ovarian cycle in a group-living primate, Papio h. hamadryas. Of particular interest is whether females modify their ovarian cycle in a manner that is expected increase their reproductive success. The study was conducted on a captive colony where the resident males (RM) had been vasectomised prior to start of the study resulting in all mature females undergoing repeated ovarian cycling throughout the study period. This made the analysis of sexual behaviour relative to fine scale changes in the ovarian cycle possible. One year of ovarian cycle data and 280 hours of behavioural data was collected via observational sampling during the study. RM vasectomisation did not alter the archetypal one male unit social structure nor the typical socio-spatial organisation of wild hamadryas populations. Females were found to be more promiscuous than in wild populations, however, presumably because of the confounding effect that the high number of simultaneously cycling females had on RM herding (Chapter 1). RMs dominated copulations over the optimal conceptive period of the ovarian cycle, while the majority of extra-OMU copulations occurred outside this period and were rarely solicited by females. This pattern supports a dual paternity concentration/paternity confusion strategy, and not female choice or fertility insurance strategies (Chapter 2). Females were not found to synchronise or asynchronise their cycles over the 1 year study period, although a review of the literature on hamadryas breeding patterns suggests that they may be able to do so over shorter periods (Chapter 3). Females did, however, appear to regulate the length of the turgescent phase of their ovarian cycle in a manner that would facilitate a paternity confusion strategy and maximise their expected fitness payoff (Chapter 4). Consequently, this study provides empirical evidence that female hamadryas baboons manipulate their ovarian cycle in a manner that is expected to increase their reproductive success.</p>

Are multiple gametocyte infections in malarial parasites an adaptation to ensure fertility?

Multiple infections, those by more than one parasite in the same erythrocyte, may be adaptive for the malarial parasite as a means to ensure fertility. Alternatively they may simply be the consequence of a non-adaptive process forcing several parasites to compete for resources in one host cell. Avian hosts infected withHaemoproteuswere medicated with primaquine or injected with saline solution and the density of infection and number, maturity and sex of mature multiple infections counted. Multiple infections depend on density of infection, and maturity is attained rarely and usually by gametocytes of the same sex. The role of multiple infections for fertility insurance is not supported by these results.

Extrapair Fertilizations in Red Bishops (Euplectes Orix): Do Females Follow Conditional Extrapair Strategies?

Although many studies have revealed differences in patterns of extrapair paternity between species and between populations of the same species, possible differences in female extrapair behavior within populations have received far less attention. Here, we propose and test the hypothesis that females of the highly polygynous Red Bishop (Euplectes orix) follow two different extrapair strategies, with benefits of extrapair copulations depending on the quality of their social mate (”conditional-extrapair-strategy hypothesis”). In particular, we propose that females mated to low-quality males enhance the genetic quality of their offspring by performing extrapair copulations with males of higher quality than their social mate (in accordance with the good-genes hypothesis), whereas females mated to high-quality males perform extrapair copulations as insurance against temporary infertility of their social mate caused by sperm depletion due to frequent copulations (in accordance with the fertility-insurance hypothesis). Several predictions derived from our hypothesis, regarding differences in frequency and distribution of both unhatched eggs and extrapair young between high-quality and low-quality males, are tested and shown to be supported. Most importantly, hatching failures occurred more often in territories of high-quality males than in those of low-quality males, and the proportion of unhatched eggs within the territory was positively correlated to breeding synchrony for high-quality males only. Those results suggest that sperm depletion is a risk for females mated to high-quality males with many mating opportunities. The fact that broods of high-quality males without unhatched eggs had a significantly higher proportion of extrapair young than broods of high-quality males with unhatched eggs is consistent with the hypothesis that females mated to high-quality males were successful in performing EPCs as insurance against temporary infertility of their social mates. Furthermore, genetic fathers of extrapair young hatched in territories of low-quality males were found to be of higher quality than the corresponding social fathers, whereas no difference in quality was found between genetic and social fathers of extrapair young hatched in territories of high-quality males. Although we cannot exclude the possibility that the observed pattern was a result of females mating randomly from within the available pool of extrapair males, it is in accordance with our prediction that females mated to low-quality males perform extrapair copulations with males of higher quality than their social mate to enhance offspring fitness. Overall, the data presented here suggest that females within our study colony adjusted their extrapair behavior to the quality of their social mate, even if we cannot entirely rule out alternative explanations for some of the results obtained. Thus, the study provides support for the conditional-extrapair-strategy hypothesis, which states that within populations, females may follow different extrapair strategies to gain different benefits. Fertilizaciones Extra-pareja en Euplectes orix: ¿Siguen las Hembras Estrategias Extra-pareja Condicionales?