Systematics

Although historically maintained in genus Morus, and treated that way currently (Am. Ornithol. Union 1998), gannets sometimes merged with genus Sula (boobies; e.g., Cramp and Simmons 1977; Nelson 1978a, 1978b; Am. Ornithol. Union 1983). Name Sula bassana therefore used for Northern Gannet at times. Merging sulids into single genus based on morphological, ecological, and ethological characters. Alternatively, based on signal patterns, external morphological features, skeletal morphology, and most recently differences in mitochondrial DNA (mtDNA), Sula (boobies) and Morus (gannets) maintained in separate genera (van Tets 1965, Palmer 1976, Olson 1985, Olson and Warheit 1988, van Tets et al. 1988, Friesen and Anderson 1997).

Northern Gannet first described as Pelecanus Bassanus by Linnaeus in 1758 (type locality “in Scotia, America” designated as Bass Rock, Scotland).

None known; monotypic.

All 3 species of gannets—Northern, Cape, and Australasian—thought closely related and regarded as constituting a superspecies by Dorst and Mougin (1979). Specific status of gannets unresolved. Cape and Australasian gannets sometimes considered subspecies of Northern Gannet (e.g., Palmer 1976, among others) or combined together as single species under M. oruscapensis, this in part supported by occasional hybridization between Australasian and Cape gannets and observation that these 2 taxa share more characters between themselves than either does with Northern Gannet (Marchant and Higgins 1990). Based on sequences of mtDNA (cyto-chrome b), Cape and Australasian gannets more closely related to each other than either is to Northern Gannet (Friesen and Anderson 1997). Although estimate for dates of divergence among gannets unreliable, data from mtDNA analysis suggests all 3 recently diverged (<3 million yr; Friesen and Anderson 1997). Peripatric speciation (speciation in small, peripherally isolated populations; e.g., Slatkin 1996) suggested as most likely model of speciation for gannets (Friesen and Anderson 1997).

Distinction of boobies and gannets supported by analysis of skeletal features (van Tets et al. 1988). Analysis of mtDNA sequences suggests gannets and boobies form separate, monophyletic lineages that diverged about 23 million yr ago (mya; range 17–29 mya; Friesen and Anderson 1997), a date corresponding to Oligocene-Miocene boundary, from when fossils could first be referred clearly to either Morus or Sula (Olson 1985, Warheit 1990).

Hybridization

Unknown for Northern Gannet.