Orthology inference
We performed the phylogenomic and comparative genomics analyses including information from 12 species with an available genome assembly: eight Procellariiformes (P. mauretanicus , Thalassarche chlororhynchos , Hydrobates tethys , Oceanites oceanicus ,Fregetta grallaria , Pelecanoides urinatrix , Fulmarus glacialis and Calonectris borealis ), and four outgroups,Aptenodytes forsteri , Pygoscelis adeliae(Sphenisciformes); Egretta garzetta , Phalacrocorax carbo(Pelecaniformes). We inferred orthologous genes across the proteomes of these 12 species using OrthoFinder 2.3.8 (Emms & Kelly, 2019) with default parameters.