Phylogenetics and population genetics of the Australasian silver gull (Larus novaehollandiae).
Published: 2004
Language: eng
Number of pages: 222
Description: Phylogenetic and population genetic studies of gulls have proven difficult due to highly conserved morphology, low levels of sequence divergence and frequent hybridization among taxa. Consequently, while a number of species groups are well supported, species relationships within many of these groups are poorly understood. In this thesis, I investigated phylogenetic relationships in the masked gull species group using mtDNA sequence data. Additionally, using both control region sequences and microsatellite loci 1 elucidated population genetic differentiation in one species, the silver gull (Larus novaehollandiae ). Using approximately 3,600 bp of sequence from four mitochondrial genes I recovered a well supported phylogeny for the masked gulls, clarifying relationships within the group. Divergence time estimates indicate that much of the diversity evident in the group today is attributable to a recent radiation. The black-billed and red-billed gulls of New Zealand share mitochondrial DNA haplotypes, providing the first molecular evidence for hybridization between the two species. Silver gulls in Australasia appear to be subdivided into five populations on the basis of analysis of control region sequences and microsatellites, with isolation-by-distance an important factor in promoting differentiation among distant populations. The Tasman Sea is an effective barrier to gene flow between Australian and New Zealand silver gulls populations, thus indicating along with morphological differences that silver gulls in these two regions be elevated to full species status (L. scopulinus in New Zealand and L. novaehollandiae  in Australia and New Caledonia). This study has not only answered a number of longstanding questions regarding classification within the masked species group, but has also illustrated the effectiveness of molecular markers in resolving phylogenetic relationships and population structure in closely related groups of organisms.
Notes: Adviser: Allan J. Baker.

Thesis (Ph.D.)--University of Toronto, 2004.

Electronic version licensed for access by U. of T. users.

Source: Dissertation Abstracts International, Volume: 65-05, Section: B, page: 2292.