Environmental and social correlates of yellow-bellied marmot life history and behavioral plasticity
Individuals in a population may adjust their phenotypic response to varying environmental conditions. Such plastic responses often entail changes in an individual’s behavioral, morphological or physiological traits and may affect population dynamics. Here we investigate the extent to which individuals in a population express plastic responses of life history and behavioral traits to environmental variation in a yellow-bellied marmot (Marmota flaviventris) population. Our aim was to identify the proximate mechanisms that shape the pattern of plasticity and how these mechanisms respond to changes in different aspects of the biotic and abiotic environments. We used data on female body mass at emergence and before hibernation, juvenile body mass at emergence, weaned litter size, and a biologically important social network trait—embeddedness. We analyzed phenotypic plasticity using a reaction norm approach, for a period between 1975 and 2011. We fit mixed-effect linear models to estimate the parameters of the reaction norm as well as the between individual variation.
At the population level we identified different patterns of the plastic responses to environmental change. At the individual level, we found individual variation in how female marmots body mass responded to early season conditions. Our findings support the idea that plasticity contributes to the maintenance of individual phenotypic variation in our population and that individuals can adjust their phenotypes to novel environmental conditions. Furthermore, since the studied traits are known to affect survival and reproduction, such phenotypic variation may affect the population’s dynamics and its responses to environmental fluctuations.