Behavioral determinants and consequences of the natural spread of a sexually transmitted disease in wild olive baboons (Papio anubis)

Dr. Sascha Knauf, Göttingen
Dr. Dietmar Zinner, Göttingen

PhD Student: Filipa Paciência


Sexually transmitted diseases (STDs) represent a major ecological force in shaping the evolution of mammalian immune defences and additionally might have an impact on the evolution of mating systems. Whereas the spread of STDs in a population largely depends on the mating behaviour of a species, i.e. the number of mating partners and the number of matings per partner, it remains largely unknown whether animals, such as nonhuman primates have developed adaptive counterstrategies in response to increased STD-risk or acquisition. Such counterstrategies can involve hygienic behaviours, such as post-copulatory self-cleaning of genitals or urination, change in mate choice with a preference for non-infected mating partners, which might, in case of gregarious primates lead even to a migration into noninfected groups.
In our project we will investigate a population of olive baboons (Papio anubis) at Lake Manyara National Park (LMNP) in Tanzania. Olive baboons live in relatively large social groups and show, in principle, a promiscuous mating behaviour. The LMNP-population is infected by the bacterium Treponema pallidum which causes several diseases in humans (e.g. syphilis) and in baboons massive, highly conspicuous genital ulcerations in males and females. These ulcerations signal that such individuals are infected. Most likely T. pallidum is transmitted by sexual contacts. To test whether mate choice and post-copulatory behaviour are altered by visible sign of infection in potential mating partners, we will quantitatively analyse mating behaviour (e.g. number of mating partner, number of sexual contacts), postcoital self-grooming, post-copulatory urination in relation to the health status of the respective mating partner. As possible co-factors influencing mate choice and mating strategies, we will include dominance rank, age (males and females) and in females also reproductive state.
The data will be used to construct a mating network that represents potential routes for STD spread. In a simulation model, which incorporates network and STD avoidance behaviour and baboon demographic data, which we will gather from baboon population surveys in LMNP and additional general baboon life history data from the literature, we will be able to assess longterm disease dynamics. Using outputs from simulation model we will identify key social and demographic characteristics of superspreaders in the observed baboon population, and notably, this model could ultimately be used to predict the minimum number of baboons to treat in order to bring the population below epidemic threshold.

Karte1 Tanzania google

© google maps

Olive baboon 6