Delimiting shades of gray: phylogeography of theNorthernFulmar,Fulmarus glacialis

Abstract

The Northern Fulmar (Fulmarus glacialis) is a common tube-nosed seabird with a disjunct Holarctic range. Taxonomic divisions within the Northern Fulmar have historically been muddled by geographical variation notably including highly polymorphic plumage. Recent molecular analyses (i.e., DNA barcoding) have suggested that genetic divergence between Atlantic and Pacific populations could be on par with those typically observed between species. We employ a multigene phylogenetic analysis to better explore the level of genetic divergence between these populations and to test an old hypothesis on the origin of the modern distribution of color morphs across their range. Additionally, we test whether mutations in the melanocortin-1 receptor gene (MC1R) are associated with dark plumage in the Northern Fulmar. We confirmed that mitochondrial lineages in the Atlantic and Pacific populations are highly divergent, but nuclear markers revealed incomplete lineage sorting. Genetic divergence between these populations is consistent with that observed between many species of Procellariiformes and we recommend elevating these two forms to separate species. We also find that MC1R variation is not associated with color morph but rather is better explained by geographical divergence.

The multiple applications of DNA barcodes in avian evolutionary studies

“…They found deep divergence in all mitochondrial markers but little differentiation in nuclear markers and shared nuclear sequences between the Atlantic and Pacific populations, suggesting an early-stage divergence. The MCR1 gene showed many variable sites, but its genetic diversity seemed to be more associated with geographic distance than with plumage morph (Kerr and Dove 2013). Based on these results, the authors recommended that the Atlantic and Pacific populations of northern fulmar be considered separate species (Kerr and Dove 2013).…”

“…However, these studies only included one specimen from the Pacific population, and this species possesses highly variable plumage colouration, with dark, light, and intermediate morphs present in both populations with varying frequencies and distributions, which confused their taxonomic treatment (Kerr and Dove 2013). To determine if the genetic divergence between these allopatric populations extends to other loci, Kerr and Dove (2013) studied nuclear and mitochondrial markers, including the melanocortin-1 receptor gene (MCR1) that has been associated with melanin colour variation in the plumage (Mundy 2005), with an extensive sampling of both populations.…”

“…The MCR1 gene showed many variable sites, but its genetic diversity seemed to be more associated with geographic distance than with plumage morph (Kerr and Dove 2013). Based on these results, the authors recommended that the Atlantic and Pacific populations of northern fulmar be considered separate species (Kerr and Dove 2013). Efe et al (2009) studied the genetic divergence among subspecies of Sandwich terns (Thalasseus sandvicensis) that breed in the Mediterranean and Atlantic coasts of Europe as well as the Atlantic coasts of southern North America south to the Argentine Patagonia.…”

“…Low or null genetic divergence in COI with noticeable phenotypic differentiation between different species has been linked to events of recent radiations (Liebers et al 2004;Campagna et al 2010Campagna et al , 2012aCampagna et al , 2015. In turn, some cases of deep genetic divergence in DNA barcodes within species were further investigated with other molecular and phenotypic markers and were found to be cases of evolutionarily isolated lineages, some of which even deserved species status (Sanin et al 2009;Efe et al 2009;Kerr and Dove 2013;Lavinia et al 2015a;García et al 2016). Moreover, the large geographic coverage of bird DNA barcoding projects allowed researchers to compare the patterns of genetic divergence across different biogeographic regions to study the diversifying factors acting in each of them (Lohman et al 2010;Lijtmaer et al 2011;Tavares et al 2011;Milá et al 2012;Campagna et al 2012b;Nishiumi and Kim 2015).…”

Migratory Connectivity at High Latitudes: Sabine’s Gulls (Xema sabini) from a Colony in the Canadian High Arctic Migrate to Different Oceans

“…Because much of the North American Arctic has only relatively recently been exposed after the last glacial period, the colonization and migration patterns of birds breeding there are difficult to interpret; some species show distinct genetic structuring in populations (e.g. northern fulmars Fulmarus glacialis ; [45]) while others do not (e.g. ivory gulls Pagophila eburnea ; [46]).…”