A whale's tale of mtDNA diversity and differentiation : the Antarctic blue whale
Twentieth century commercial whaling drastically reduced the abundance of great whale populations in the Southern Ocean. Exploitation began on the south Atlantic island of South Georgia, where catch records account for over 175,000 whales killed. Modern whaling within the Southern Ocean depleted pop...
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| Other Authors: | , , , , |
| Format: | Master Thesis |
| Language: | English unknown |
| Published: |
Oregon State University
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| Subjects: | |
| Online Access: | https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/zw12z750m |
| Summary: | Twentieth century commercial whaling drastically reduced the abundance of great whale populations in the Southern Ocean. Exploitation began on the south Atlantic island of South Georgia, where catch records account for over 175,000 whales killed. Modern whaling within the Southern Ocean depleted populations rapidly, and by 1966, hunting blue whales south of 40°S was prohibited by the International Whaling Commission (IWC). After 40 years of protection, this species has shown little recovery. A current abundance estimate of 2,280 (CV=0.036) individuals from sighting data (1991/92-2003/04) represents less than 1% the original abundance. With such an intensive demographic 'bottleneck,' it is likely that genetic diversity has been lost from some or all components of the Southern Ocean population. Here I describe historical and contemporary Antarctic blue whale mtDNA diversity and report the first circumpolar analyses of contemporary population structure. In Chapter 2, historical mtDNA diversity is described from whale bones collected from the first Southern Hemisphere whaling stations established in 1904 on the island of South Georgia. A total of 281 whale bones were representative of three prominent species hunted in South Georgian waters. Using ancient DNA methods and sequencing of the mtDNA control region, bone samples were first identified to species, identifying 153 humpback, 49 fin, 18 blue, 2 sei, 1 southern right whale and 1 elephant seal. Within each of the three prominent historic species populations, mtDNA haplotypes were described resulting in 64 humpback, 34 fin, and 16 blue whale haplotypes. Haplotype and nucleotide diversity within each of the three historic species populations ranged from 0.980-0.987 and 1.87-3.16%, respectively. In chapter 3, I update the previous estimate of contemporary Antarctic blue whale mtDNA diversity with biopsy samples of living whales collected during research cruises conducted with IWC oversight from 1990-2009 (n=218) for comparison to historical blue whale mtDNA ... |
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