Health and fitness consequences of group size variation in Verreauxs sifakas (Propithecus verreauxi)

• Applicant: Professor Dr. Peter M. Kappeler
• Subject Area: Sensory and Behavioural Biology ; Evolution, Anthropology
• Term: from 2014 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 244372499

A fundamental assumption in behavioral ecology posits that intraspecific variation in group size impacts individual health, condition, and ultimately fitness. The costs and benefits of living in groups of different sizes have not been comprehensively evaluated yet, however. The overall aim of this study is therefore to examine correlations between group size and ecological, social, physiological and health variables in a wild primate population. Specifically, this is the first comprehensive study to examine group size effects of ranging, feeding, parasite infection, stress levels and microbiome composition on individual fitness simultaneously. Because we will collect behavioral data and samples of neighboring groups of variable size, which will be combined with more than 20 years of demographic data, we will be able to assess the fitness consequences of group size variation. This study will therefore address a key link in the sociality-health-fitness nexus and additionally create potential for synergetic analyses. Moreover, this study will also contribute much needed comparative data across small group sizes for comparative studies, and it will provide the first test of the ecological constraints hypothesis in an independent primate radiation.

• DFG Programme: Research Units
• Subproject of: FOR 2136: Sociality and Health in Primates
• Co-Investigators: Professor Dr. Rolf Daniel; Dr. Michael Heistermann