Reconstructing the evolutionary history of the seabird order Procellariiformes

Abstract

The seabird order Procellariiformes, comprising the albatrosses, storm-petrels, petrels, and shearwaters, are the truly oceanic birds of the world, spending most of their lives at sea and returning to land only to breed. Despite the constraints of life in the inhospitable marine ecosystem, Procellariiformes are remarkably diverse in morphology, ecology, and life history. The order is amongst the most threatened of all bird groups, facing a range of threats at sea and at breeding colonies. Despite the intriguing diversity presented and imminent conservation concern, a modern phylogenetic hypothesis for the evolution of Procellariiformes has not yet emerged. This thesis aimed to address this by applying a dataset of thousands of genome-wide markers to a taxonomically comprehensive sample set to investigate the evolutionary history and systematics of Procellariiformes. The evolutionary relationships among species, subspecies, and populations were resolved to a fine scale with few areas of conflict, allowing new taxonomic insights. As part of the phylogenetic process, marker selection and filtering techniques have become critical, yet highly debated, steps. With growing evidence of the important roles of sex chromosomes in divergence and speciation in a wide variety of taxa, the novel genome-wide dataset was used to investigate the utility of sex-linked loci in phylogenetic reconstruction of Procellariiformes, with valuable insights for further work employing similar methods. In addition to the nuclear genome, the evolution of the mitochondrial genome in Procellariiformes was investigated, with particular relevance to the rearrangements and duplications that have been identified in birds and other animals. Mitogenomic duplications were common across Procellariiformes, with an ancient origin inferred that offers insights into this trait across bird evolution. The phylogeny presented in this thesis provides a useful resource for defining relationships in conservation management of Procellariiformes, and an evolutionary context for further comparative exploration of this remarkable order of birds.