Genetic Evidence of a Population Bottleneck and Inbreeding in the Endangered New Zealand Sea Lion, Phocarctos hookeri

Amy J Osborne; Sandra S Negro; B Louise Chilvers; Bruce C Robertson; Martin A Kennedy; Neil J Gemmell

doi:10.1093/jhered/esw015

Genetic Evidence of a Population Bottleneck and Inbreeding in the Endangered New Zealand Sea Lion, Phocarctos hookeri

J Hered. 2016 Sep;107(5):392-402. doi: 10.1093/jhered/esw015. Epub 2016 Mar 19.

Authors

Amy J Osborne¹, Sandra S Negro², B Louise Chilvers², Bruce C Robertson², Martin A Kennedy², Neil J Gemmell²

Affiliations

¹ From the Department of Anatomy, University of Otago, 270 Great King Street, Dunedin 9016, New Zealand (Osborne and Gemmell); Department of Pathology, University of Otago, Christchurch, New Zealand (Osborne and Kennedy); Computational Biology Group, Swiss Institute of Bioinformatics, Department of Medical Genetics, University of Lausanne, Lausanne, Switzerland (Negro); Marine Species and Threats Team, Department of Conservation, Wellington, New Zealand (Chilvers); Department of Zoology, University of Otago, Dunedin, New Zealand (Robertson); and Allan Wilson Centre for Molecular Ecology and Evolution, University of Otago, Dunedin, New Zealand (Gemmell). B. Louise Chilvers is now at Wildbase, Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North 4442, New Zealand. [email protected].
² From the Department of Anatomy, University of Otago, 270 Great King Street, Dunedin 9016, New Zealand (Osborne and Gemmell); Department of Pathology, University of Otago, Christchurch, New Zealand (Osborne and Kennedy); Computational Biology Group, Swiss Institute of Bioinformatics, Department of Medical Genetics, University of Lausanne, Lausanne, Switzerland (Negro); Marine Species and Threats Team, Department of Conservation, Wellington, New Zealand (Chilvers); Department of Zoology, University of Otago, Dunedin, New Zealand (Robertson); and Allan Wilson Centre for Molecular Ecology and Evolution, University of Otago, Dunedin, New Zealand (Gemmell). B. Louise Chilvers is now at Wildbase, Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North 4442, New Zealand.

PMID: 26995741
DOI: 10.1093/jhered/esw015

Abstract

The New Zealand sea lion (NZSL) is of high conservation concern due to its limited distribution and its declining population size. Historically, it occupied most of coastal New Zealand, but is now restricted to a few coastal sites in southern mainland New Zealand and the sub-Antarctic Islands. NZSLs have experienced a recent reduction in population size due to sealing in the 1900s, which is expected to have resulted in increased inbreeding and a loss of genetic variation, potentially reducing the evolutionary capacity of the species and negatively impacting on its long-term prospects for survival. We used 17 microsatellite loci, previously shown to have cross-species applications in pinnipeds, to determine locus- and population-specific statistics for 1205 NZSLs from 7 consecutive breeding seasons. We show that the NZSL population has a moderate level of genetic diversity in comparison to other pinnipeds. We provide genetic evidence for a population reduction, likely caused by historical sealing, and a measure of allele sharing/parental relatedness (internal relatedness) that is suggestive of increased inbreeding in pups that died during recent epizootic episodes. We hypothesize that population bottlenecks and nonrandom mating have impacted on the population genetic architecture of NZSLs, affecting its population recovery.

Keywords: bottleneck; diversity; microsatellites; structure.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Bayes Theorem
Endangered Species*
Evolution, Molecular
Genetic Variation
Genetics, Population*
Genotype
Inbreeding*
Microsatellite Repeats
New Zealand
Sea Lions / genetics*