Details of sampling locations and numbers of M. antarctica individuals collected, including 240 individuals previously sampled by Hoffman et al.[46].

The three spatial scales investigated were as follows (i) Fine-scale (within Anchorage Island) comprising samples from Rose Garden, Anchorage North and Trolval; (ii) Medium-scale (among islands within Ryder Bay) comprising samples from Anchorage Island, Rothera Point and Leonie Island; (iii) Large scale (along the Antarctic Peninsula) comprising samples from Ryder Bay, Galindez Island, Dobrolowski Island, Snow Island and Signy Island.