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Analysis of the Mitochondrial genome of Cephalorynchus

Colm Carraher

School of Biological Sciences
University of Auckland, Auckland, New Zealand
Email: c.carraher@auckland.ac.nz

Assoc Prof C.Scott Baker
Dr Franz Pichler


My MSc is based on sequencing and analysing the entire mitochondrial genome (mtDNA) of the genus Cephalorhynchus. This is a group of dolphins found in temperate inshore waters of the southern Hemisphere, and include Hector's dolphin (Cephalorhynchus hectori), Heavisides dolphin (C. heavisidii), Chilean dolphin (C. eutropia), and Commersons dolphin (C. commersonii). The phylogeny for the genus has recently been substantiated based on a 485bp portion of the D-loop or control region of the mtDNA. However due to the recent radiation of this genus there are only a limited number of base pair substitutions along the control region from which to construct a phylogeny. The first objective of my research is to construct a phylogeny for the group based on the sequences from the 13 protein coding genes in the mtDNA. This will allow a more robust phylogeny to be constructed from neutrally evolving synonymous substitutions.

The second objective of my research is an analysis of the protein coding genes in the mtDNA to evaluate the effect of point mutations on sperm motility. A recent studied has identified base pair substitutions within the mtDNA that have been associated with some deleterious effect on human sperm motility. As mitochondria are maternally inherited, mutations in the genome that do not adversely affect females will not be subject to selection. This could result in such deleterious haplotypes reaching relatively high frequencies, particularly in small populations. The Cephalorhynchus species are characterised be small, isolated populations(all species have fewer than 10000 individuals), therefore this phenomenon may be having a significant detrimental effect on the long-term persistence of such populations. The North Island Hector's dolphin is listed under the International Union for the Conservation of Nature as critically endangered, and there are believed to be fewer than 100 individuals left. This is a perfect population with which to study this problem.