Biomedical subjects

G K Chambers

Publications and source records attributed to G K Chambers.

58 records · Page 4Linked to original sources

PubMedDate not supplied

New Zealand population data at five VNTR loci: validation as databases for forensic identity testing.

Databases were developed for three New Zealand ethnic groups (Caucasian, Maori and Polynesian), at five VNTR loci (D1S7, D2S44, D4S139, D5S110 and D12S11), and validated for interpretation of forensic identity tests. A +/-2.8% sliding window was used to define the alleles at each locus and allelic frequency distributions were obtained for each locus. The conservative nature of the sliding window approach for forensic casework was demonstrated. Tests for independence of alleles within and between loci showed good agreement with the expectation of independence. Although Polynesians are known to have reduced genetic diversity at some VNTR loci, this was found not to be a concern for the present methodology. Procedures for the analysis and reporting of DNA profile results used by New Zealand forensic scientists are therefore appropriate.

Alleles↗

PubMedDate not supplied

Genetic variation of southern hemisphere fur seals (Arctocephalus spp.): investigation of population structure and species identity.

We have examined phylogenetic and geographic patterns of variation in the mitochondrial cytochrome b gene of Southern Hemisphere fur seals (Arctocephalus spp.). Our survey of 106 individuals from four putative species reveals three distinct patterns of variation reflecting ancient, recent historic, and contemporary gene flow. For the combined samples of Subantarctic (Arctocephalus tropicalis) and Antarctic (Arctocephalus gazella) fur seals, we find low levels of sequence diversity and reciprocal paraphyly of hapiotypes (where representative haplotypes of a species are found to occur infrequently in another species and vice versa). For the Australian and Cape fur seal subspecies (Arctocephalus pusillus doriferus and A. p. pusillus, respectively), we find low levels of sequence diversity but significant differences in the regional distribution of haplotypes that are consistent with, but not conclusive of, the current subspecies definition based on nonmolecular data. For the New Zealand fur seal (Arctocephalus forsteri), we find high levels of average sequence diversity because of the survival of two divergent lineages of mitochondrial hapiotypes with differences approaching that found in interspecific comparisons of other mammals. The two divergent clades are distributed sympatrically in some regions, but the overall geographic structure of the variation is significant across the range of this species. These new molecular data are inconsistent with current taxonomic definitions of species within the Southern Hemisphere fur seals and argue for reevaluation of these "species" definitions. For management purposes, the definition of evolutionarily significant units (Ryder 1986) and genetic management units (Moritz 1994) in relation to these species may also be evaluated in light of this molecular genetic information.

Animals↗

PubMedDate not supplied

Population characteristics of DNA fingerprints in humpback whales (Megaptera novaeangliae).

Humpback whales exhibit a remarkable social organization that is characterized by seasonal long-distance migration (> 10,000 km/year) between summer feeding grounds in high latitudes and winter calving and breeding grounds in tropical or near-tropical waters. All populations are currently considered endangered as a result of intensive commercial exploitation during the last 200 years. Using three hypervariable minisatellite DNA probes (33.15, 3'HVR, and M13) originally developed for studies of human genetic variation, we examined genetic variation within and among three regional subpopulations of humpback whales from the North Pacific and one from the North Atlantic oceans. Analysis of DNA extracted from skin tissues collected by biopsy darting from free-ranging whales revealed considerable variation in each subpopulation. The extent of this variation argues against a recent history of inbreeding among humpback whales as a result of nineteenth- and twentieth-century hunting. A canonical variate analysis suggested a relationship between scaled genetic distance, based on similarities of DNA fingerprints, and geographic distance (i.e., longitude of regional subpopulation). Significant categorical differences were found between the two oceanic populations using a multivariate analysis of variance (MANOVA) with a modification of the Mantel nonparametric permutation test. The relationship between DNA fingerprint similarities and geographic distance suggests that nuclear gene flow between regional subpopulations within the North Pacific is restricted by relatively low rates of migratory interchange between breeding grounds or assortative mating on common wintering grounds.

Animals↗

PubMedDate not supplied

DNA fingerprinting: a versatile technology.

DNA fingerprinting originally developed as a genetic mapping strategy but has quickly found many other applications ranging from forensic casework to wildlife conservation. The versatility of various DNA fingerprinting methods is illustrated by a series of examples taken from the work of one laboratory in New Zealand.

Animals↗