Conclusions
Our study highlights the utility of the hybrid assembly strategy using Illumina and ONT at recovering high quality genome assemblies, especially regarding contiguity and completeness. Comparative genomics analyses identified candidate genes under selection to have played a major role in the adaptation of the Procellariiformes to a pelagic lifestyle such as changes in sensory perception, navigation, natriuresis and physiological adaptations. Regarding the phylogeny of Procellariiformes, our results gave full support to recent genomic based hypotheses in which albatrosses (Diomedeidae) are sister to the rest of Procellariiformes, storm petrels are paraphyletic and diving petrels are included within Procellariidae. The high-quality genome presented in this work will be a great tool for future population genomic analyses, that will reveal with more precision the genetic variability of the species, its recent demographic history and the potential introgression with its sister species, the Mediterranean shearwater (P. yelkouan ). The data obtained will be of great help in future proposals of conservation and management plans for the species.