Clustered fineRADstructure co-ancestry matrix. A Full dataset including U. antarctica collected on the Antarctic Peninsula in addition to U. antarctica and U. aurantiacoatra collected on King George Island and Elephant Island B Reduced dataset with all U. antarctica and U. aurantiacoatra collected on King George Island and Elephant Island. Two major clades are corresponding to the two species U. antarctica (top-left) and U. aurantiacoatra (bottom-right). The top and left trees were calculated from the co-ancestry matrix to sort the individuals by their population structure. The matrix is diagonally split into the top-right half showing raw data and the bottom-left half displaying aggregated data.