Genetic variation in the kakerori (Pomarea dimidiata), an endangered endemic bird successfully recovering in the Cook Islands
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The Cook Islands endemic kakerori (Pomarea dimidiata) underwent a severe population decline following the introduction of ship rats (Rattus rattus) in the late 1800s. By 1989, the sole population on Rarotonga consisted of 29 known birds. Subsequent intensive management efforts enabled this population to recover to around 250–300 birds in recent years. This study, using microsatellite and mitochondrial DNA markers, assesses the level of genetic diversity and the genetic structure of the contemporary kakerori population on Rarotonga. No mitochondrial control region and cytochrome b haplotype diversity was found in the 11 samples examined at each locus. In 81 samples genotyped at 7 polymorphic microsatellite loci, an average of 4 alleles per locus were found, with an average observed heterozygosity of 0.65. No subpopulation division was found in this population. There was no evidence of inbreeding, but genetic bottleneck tests showed that the population had indeed experienced a significant genetic bottleneck. Recovery of the kakerori was successful in the past two decades despite low genetic diversity in terms of allelic diversity. Our data suggested that low allelic diversity did not hamper population expansion and the continued survival of this species, however, longer-term effects are still possible.
KeywordsPomarea dimidiata Genetic diversity Microsatellites Cytochrome b Mitochondrial control region Bottleneck
This work is supported by the University Research Fund 26151/1469 of Victoria University of Wellington, the Takitumu Conservation Area Project, and the New Zealand Department of Conservation. The kakerori recovery programme and Takitumu Conservation Area Project has been supported over the years by the Avifauna Conservation Programme of the South Pacific Regional Environment Programme, New Zealand Agency for International Development (NZAID), the Pacific Conservation and Development Trust, the South Pacific Biodiversity Conservation Programme, the Pacific Initiatives for the Environment (NZAID), the Disney Wildlife Conservation Foundation, the Swedish Club of 300, and the Global Environment Facility. We would like to thank Ian Karika and many conservation volunteers for field support, and two anonymous reviewers for their comments and suggestions in improving this manuscript.
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