An explorative RNA-seq analysis of Antarctic fur seal mother-pup pairs from low and high density breeding populations

The interaction between an individual’s phenotype and its environment can provide insights into the origin and extent of local adaptation. Understanding how an individual may adapt and match its phenotype to a particular environment is therefore a key objective of molecular ecology. Here, we will use an RNA-sequencing approach to compare the blood mRNA levels of Antarctic fur seals from two colonies of contrasting population density (low and high) at two seasonal time points (shortly after birth and shortly before weaning). Samples were collected from mother-pup pairs during two subsequent breeding seasons (2018-19 and 2019-20) on the sub-Antarctic island of Bird Island, South Georgia. This is an exploratory study to better understand (a) how gene expression profiles differ among individuals experiencing low and high density conditions, (b) how gene expression profiles change throughout the season (from birth to weaning), (c) how gene expression profiles reflect differing pressures on mothers and pups, and (d) how gene expression profiles reflect inter-annual variation. This amounts to four key pair-wise comparisons in our differential gene expression design matrix (low vs high density, birth vs weaning, mother vs pup, 2018-19 vs 2019-20) and interaction terms thereof.