The Impact of Maternal Effects on Social Plasticity and Fitness Variation in a Long-Lived Mammal

Georgetown University, Washington DC

Investigators

Abstract

Studies of long-lived social mammals such as primates, elephants and dolphins repeatedly show that individual social behavior is linked to survival and reproduction. Yet, few have examined what factors contribute to individual variation in social behavior within a species or population. For instance, it has yet be to determined why some individuals are more gregarious than others. In mammals, it is known that mothers have a pervasive influence on offspring behavioral development, not just through genetic inheritance, but also through social learning (maternal effects). Here, the research team will focus on how maternal effects influence offspring social development, a key contributor to individual variation in social behavior. Dolphins in Shark Bay, Australia, are an excellent empirical system for examining these questions because they live in a large open and dynamic social community with over one hundred potential associates to choose from. Long-term data on this social system spans 35+ years and enables this team of scientists to quantify: 1). how a dolphin changes its social behavior in space and time throughout its development, 2). the extent to which this is influenced by maternal and non-maternal effects, and 3). the extent to which maternal effects provide fitness benefits to offspring. This study will have broad reach, appeal, and implications well beyond the scientific community because it will contribute to wildlife policy, management, and conservation as well as train multiple undergraduate and graduate students and early-career stage researchers in STEM. While several studies link sociality to fitness in long-lived mammals, maternal influence on inter- and intra-individual variation in sociality (e.g. dynamic social patterns) and fitness outcomes is relatively unexplored. This study investigates how sociality evolved, not just why. Recent computational advances allow this project to incorporate multi-level, dynamic variation to advance understanding of how sociality evolved, i.e., transmission pathways. This study system, a 35-year longitudinal study of wild bottlenose dolphins, provides a unique opportunity to address these questions because of species characteristics, and the size, detail, and long-term nature of the dataset. This project will use: 1). novel quantitative genetics methodologies to unravel the importance of maternal effects on social behavior while accounting for both additive genetic variation and the mothers' social environment; 2). next-generation sequencing combined with demographic data to construct accurate pedigree information from high- density single nucleotide polymorphisms; 3). dynamic social network modeling (social association/interaction matrices) to account for changing social attributes of individuals rather than just static traits. As such, this study will be a comprehensive exploration of how maternal effects impact social traits over the lifespan and across more than one generation within an evolutionary framework. In addition, this is the first study to do so in wild long-lived mammal with extensive maternal social transmission, while accounting for additive genetic variation. The results will provide significant advances by extending our study of the genetic and non-genetic mechanisms of inheritance, which play critical roles in evolution and responses to environmental change. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.