The effect of climate change on the timing of reproduction in Yellow-Bellied Marmots

Background/Question/Methods

With global climates changing rapidly and drastically, animals must adapt to new environmental conditions with altered weather and phenology. Adjusting the timing of reproduction to produce offspring when the conditions are optimal to maximize survival is key to adapting to new conditions. Using a long-term dataset on a wild population of yellow-bellied marmots (Marmota flaviventer) at the Rocky Mountain Biological Laboratory, we investigated how the timing of reproduction changes with varying spring conditions. Marmots are hibernators with a four-month active season. It is thus crucial to reproduce early enough in the season to have time to prepare for hibernation, but not too early so as snow cover prevents access to food. Given that adaptation to environmental conditions could arise from either micro-evolution or phenotypic plasticity, we evaluated how female marmots adjust the timing of reproduction and estimated the importance of both genetic variance and plasticity in the variation in the timing of reproduction.

Results/Conclusions

We report a positive effect of spring snowpack but not of spring temperature on the timing of reproduction. There is inter-individual variation in the timing of reproduction but not in its response to spring conditions. The genetic variance and heritability in the timing of reproduction are low. We found a negative relationship between the timing of reproduction and both the weighted proportion and total number of pups surviving their first winter. Overall, it seems that we should expect some changes in this population with changing climatic conditions, but at the population level and not due to natural selection.