SFB-TRR 212

Genetic and epigenetic mechanisms of niche choice and niche conformance in a declining fur seal population

NC³-mechanisms such as niche choice and niche conformance alter the match between an individual’s phenotype and its environment, giving rise to individualised niches. However, the ecological and evolutionary consequences of individualisation remain poorly understood, particularly in wild populations where genetic variation and environmental heterogeneity often interact to produce complex fitness landscapes with multiple local optima. An outstanding opportunity to investigate the fitness consequences and mechanistic underpinnings of niche choice and niche conformance in a natural population is provided by an exceptionally detailed long-term study of Antarctic fur seals at Bird Island, South Georgia. Antarctic fur seals feed predominantly on Antarctic krill (Euphausia superba), a shrimp-like crustacean that is strongly dependent on sea ice for both shelter and food. However, temperatures around the Antarctic peninsula have been steadily increasing over the past four decades, leading to a systematic decline in the amount of sea ice and hence the amount of krill available to the seals. Overall, this trend is reflected in a 48 % decline in the number of breeding females and an 11 % decline in average birth weight since 1982. However, female numbers also fluctuate substantially from year to year in response to shorter term climatic fluctuations and associated changes in krill abundance.

We propose to investigate how niche choice and niche conformance shape individualised phenotypes and fitness variation in Antarctic fur seals using an integrative approach combining life-history and environmental data with high density SNP genotyping and epigenetic profiling. This project will produce uniquely detailed and multi-faceted insights into both the causes and consequences of individualisation in a highly heterogeneous environment. We aim to address the following questions:

1.  What are the long-term fitness consequences of niche choice and conformance?
2.  How does genetic quality (inbreeding) influence niche choice and conformance?
3. Are niche choice and conformance mediated by epigenetic effects?

Overall, this project will provide a novel evolutionary (epi)genetic perspective on individualised niches while also generating detailed insights into how NC3-mechanisms feed into long-term fitness variation and ultimately population persistence.