Phylogeny of Procellariiformes
The study of the evolutionary relationships within the order Procellariiformes had until recently been based mainly in the phylogenetic analyses of a single gene, the mitochondrial cytochrome b or on supertree approaches combining life history, morphological and sequence data (Kennedy & Page, 2002; Nunn & Stanley, 1998; Penhallurick & Wink, 2016). However, these approaches did not show enough resolution for this group, leaving several open questions. The main points that remain contentious are: 1) which family is the sister to the rest of the Procellariiformes (Diomedeidae or Hydrobatidae), 2) which is the phylogenetic position of the diving petrels (Pelecanoides sp. ) and whether they should be placed on their own family, 3) the monophyly of the storm petrels as well as the phylogenetic relationships among the speciose Procellariidae (J. J. Austin, Bretagnolle, & Pasquet, 2004; Brown et al., 2011; Obiol et al., 2020; Welch, Olson, & Fleischer, 2014). More recently, the first study to use genomic data to resolve the backbone Procellariiformes phylogeny (Estandía et al., 2021) reported a well-resolved phylogeny of 51 species using 4,365 ultraconserved elements (UCEs). This phylogeny recovered the albatrosses (Diomedeidae) as the sister group to the rest of Procellariiformes, the diving petrels included within Procellariidae, and the storm petrels constituting a paraphyletic group with Oceanitidae and Hydrobatidae being two separate monophyletic groups, and Hydrobatidae as sister group of Procellariidae. Our phylogenomic results using a smaller taxon sampling but a more extensive phylogenomic dataset (of up to 6,172 genes), agrees with those of (Estandía et al., 2021), supporting that these phylogenetic relationships are definitive.