Abstracts (first author)
Maternal effects on offspring growth, survival and social status in spotted hyenas
We have studied two processes of non-genetic inheritance in a social mammal with linear dominance hierarchies. Firstly, in such species, the social status of an offspring at adulthood is often similar to the social position held by their mother; a phenomenon termed “rank inheritance”. Mothers may influence the rank obtained by their offspring at adulthood in at least three distinct ways: 1) the direct genetic inheritance of maternal traits that influence resource holding potential might predispose offspring to obtain a rank similar to that held by their mother, 2) the pre-natal maternal environment might influence offspring rank if foetal exposure to maternal androgens is related to maternal status and affects offspring competitiveness, and 3) maternal behavioural support, a component of the post-natal maternal environment, may help offspring to dominate those individuals that are subordinate to their mother, thereby assisting offspring to acquire a rank similar to that of their mother. We simultaneously test predictions derived from these three potential maternal effects on offspring rank acquisition at adulthood, using rare cases of offspring adoption detected by microsatellite profiling. We demonstrate that adopted offspring acquire a rank at adulthood similar to that of their surrogate mother and that the competitive ability of offspring at adulthood was best explained by post-natal maternal behavioural support. Secondly, we use long-term data to also show that high-born offspring have higher growth rates, are more likely to survive to adulthood and start reproduction at an earlier age than offspring of lower ranking mothers – thereby demonstrating a maternal ‘silver spoon effect’ in spotted hyenas.