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Geology topics

Matthew A. Cronin

Publications and source records attributed to Matthew A. Cronin.

9 recordsLinked to original sources
USGS2015

Biological response to climate change in the Arctic Ocean: The view from the past

The Arctic Ocean is undergoing rapid climatic changes including higher ocean temperatures, reduced sea ice, glacier and Greenland Ice Sheet melting, greater marine productivity, and altered carbon cycling. Until recently, the relationship between climate and Arctic biological systems was poorly known, but this has changed substantially as advances in paleoclimatology, micropaleontology, vertebrate paleontology, and molecular genetics show that Arctic ecosystem history reflects global and regional climatic changes over all timescales and climate states (10 3 –10 7 years). Arctic climatic extremes include 25°C hyperthermal periods during the Paleocene-Eocene (56–46 million years ago, Ma), Quaternary glacial periods when thick ice shelves and sea ice cover rendered the Arctic Ocean nearly uninhabitable, seasonally sea-ice-free interglacials and abrupt climate reversals. Climate-driven biological impacts included large changes in species diversity, primary productivity, species’ geographic range shifts into and out of the Arctic, community restructuring, and possible hybridization, but evidence is not sufficient to determine whether or when major episodes of extinction occurred.

arktos↗
USGS2009

Problems with the claim of ecotype and taxon status of the wolf in the Great Lakes region

Koblmuller et al. (2009) analysed molecular genetic data of the wolf in the Great Lakes (GL) region of the USA and concluded that the animal was a unique ecotype of grey wolf and that genetic data supported the population as a discrete wolf taxon. However, some of the literature that the researchers used to support their position actually did not, and additional confusion arises from indefinite use of terminology. Herein, we discuss the problems with designation of a wolf population as a taxon or ecotype without proper definition and assessment of criteria.

Great Lakes Region↗
USGS2004

The controversy about salmon hatcheries

The use of hatcheries has been a subject of lengthy debate in the management of salmon and trout resources in the Pacific Northwest. The problem has resulted in part from the wide distribution of hatchery fish in circumstances where natural populations were disadvantaged by management policy involving hatchery fish and the confusion of the effects of management with the effects of artificial propagation. Recently, the controversy has been epitomized by the recommendations to fisheries management agencies that excess hatchery fish should not be allowed to spawn in the wild, and hatchery fish should be excluded from salmon populations listed under the Endangered Species Act. The authors of the present article disagree with those recommendations and conclude that hatchery fish have an important role in recovery and supplementation of wild stocks. The present article is an attempt to help give balance to the discussion by providing a different perspective on hatchery fish and the literature pertaining to artificial propagation.

Fisheries Magazine↗
USGS1998

Caribou distribution during the post-calving period in relation to infrastructure in the Prudhoe Bay oil field, Alaska

There is concern that caribou ( Rangifer tarandus ) may avoid roads and facilities (i.e., infrastructure) in the Prudhoe Bay oil field (PBOF) in northern Alaska, and that this avoidance can have negative effects on the animals. We quantified the relationship between caribou distribution and PBOF infrastructure during the post-calving period (mid-June to mid-August) with aerial surveys from 1990 to 1995. We conducted four to eight surveys per year with complete coverage of the PBOF. We identified active oil field infrastructure and used a geographic information system (GIS) to construct ten 1 km wide concentric intervals surrounding the infrastructure. We tested whether caribou distribution is related to distance from infrastructure with a chi-squared habitat utilization-availability analysis and log-linear regression. We considered bulls, calves, and total caribou of all sex/age classes separately. The habitat utilization-availability analysis indicated there was no consistent trend of attraction to or avoidance of infrastructure. Caribou frequently were more abundant than expected in the intervals close to infrastructure, and this trend was more pronounced for bulls and for total caribou of all sex/age classes than for calves. Log-linear regression (with Poisson error structure) of numbers of caribou and distance from infrastructure were also done, with and without combining data into the 1 km distance intervals. The analysis without intervals revealed no relationship between caribou distribution and distance from oil field infrastructure, or between caribou distribution and Julian date, year, or distance from the Beaufort Sea coast. The log-linear regression with caribou combined into distance intervals showed the density of bulls and total caribou of all sex/age classes declined with distance from infrastructure. Our results indicate that during the post-calving period: 1) caribou distribution is largely unrelated to distance from infrastructure; 2) caribou regularly use habitats in the PBOF; 3) caribou often occur close to infrastructure; and 4) caribou do not appear to avoid oil field infrastructure.

Alaska↗
USGS1997

Population genetic studies of the sea otter ( Enhydra lutris ): A review and interpretation of available data

C urrent information about the utility of genetic markers for estimating population structuring in sea otters ( Enhydra lutris ) is reviewed. Analyses of spatial population structuring with biochemical and molecular genetic markers are discussed in the context of the species' ecology and history of exploitation. Studies that have used a diversity of genetic markers including allozymes, mitochondrial DNA (mtDNA), and multilocus minisatellites revealed that geographically spearated populations of sea otters are highly differentiated, though little evidence for phylogeographic structuring was suggested. Analyses of population relationships based on mtDNA haplotype frequency distribution suggested that populations can be separated into four major groups: (1) California; (2) Prince William Sound, Alaska; (3) Kodiak Island, Alaska, and islands of the Aleutian archipelago, including the Commander Islands; and (4) the Kuril Islands. Populations from locales separated by large geographic distances often shared haplotypes, suggesting recent common ancestry and some degree of historical gene flow. THe large differences among populations in nuclear and mtDNA gene frequency suggested strong constrains on contemporary gene flow and/or considerable drift in gene frequencies due to population bottlenecks. No evidence for microgeographic structuring was noted. Levels of genetic diversity within populations varied greatly across the species range but were not related to contemporary estimates of population size.

Conference Paper↗
USGS1991

Mitochondrial and nuclear genetic relationships of deer ( Odocoileus spp.) in western North America

Odocoileus hemionus (mule deer and black-tailed deer) and Odocoileus virginanus (white-tailed deer) are sympatric in western North America and are characterized by distinct morphology, behavior, and allozyme allele frequencies. However, there is discordance among nuclear and mitochondrial genetic relationships, as mule deer ( O . h . hemionus ) and white-tailed deer have similar mitochondrial DNA (mtDNA) which is very different from that of black-tailed deer ( O . h . columbianus , O . h . sitkensis ). I expanded previous studies to clarify the genetic relationships of these groups by determining mtDNA haplotype and allozyme genotypes for 667 deer from several locations in northwestern North America. Different mtDNA haplotypes in mule deer, black-tailed deer, and white-tailed deer indicate that mitochondrial gene flow is restricted. Allozyme allele frequencies indicate that there is also restriction of nuclear gene flow between O . virginianus and O . hemionus , and to a lesser extent between mule deer and black-tailed deer. There is a low level of introgressive hybridization of mtDNA from mule deer and black-tailed deer into white-tailed deer populations and considerable interbreeding of mule deer and black-tailed deer in a contact zone. The discordance of mitochondrial and nuclear genomes is apparent only if mtDNA sequence divergences, and not haplotype frequencies, are considered.

Canadian Journal of Zoology↗
USGS1991

Inter- and intraspecific mitochondrial DNA variation in North American bears (Ursus)

We assessed mitochondrial DNA variation in North American black bears (Ursus americanus), brown bears (Ursus arctos), and polar bears (Ursus maritimus). Divergent mitochondrial DNA haplotypes (0.05 base substitutions per nucleotide) were identified in populations of black bears from Montana and Oregon. In contrast, very similar haplotypes occur in black bears across North America. This discordance of haplotype phylogeny and geographic distribution indicates that there has been maintenance of polymorphism and considerable gene flow throughout the history of the species. Intraspecific mitochondrial DNA sequence divergence in brown bears and polar bears is lower than in black bears. The two morphological forms of U. arctos, grizzly and coastal brown bears, are not in distinct mtDNA lineages. Interspecific comparisons indicate that brown bears and polar bears share similar mitochondrial DNA (0.023 base substitutions per nucleotide) which is quite divergent (0.078 base substitutions per nucleotide) from that of black bears. High mitochondrial DNA divergence within black bears and paraphyletic relationships of brown and polar bear mitochondrial DNA indicate that intraspecific variation across species' ranges should be considered in phylogenetic analyses of mitochondrial DNA.

Canadian Journal of Zoology↗
USGS1991

Mitochondrial DNA in wildlife forensic science: Species identification of tissues

A common problem in wildlife law enforcement is identifying the species of origin of carcasses, meat, or blood when morphological characters such as hair or bones are not available. Immunological and protein electrophoretic (allozyme or general protein) procedures have been used in species identification with considerable success (Bunch et al. 1976, McClymont et al. 1982, Wolfe 1983, Mardini 1984, Pex and Wolfe 1985, Dratch 1986), However, immunological tests often are not sensitive enough to distinguish closely related species. Furthermore, electrophoretically detectable protein polymorphisms may be lacking in certain populations or species and may not be species-specific. Analysis of DNA in human and wildlife forensics has been shown to be a potentially powerful tool for identification of individuals (Jeffreys et al. 1985, Vassartet al. 1987, Thommasen et al. 1989). Differences in copy number and nucleotide sequence of repetitive sequences in the nuclear (chromosomal) DNA result in hypervariability and individual-specific patterns which have been termed DNA "fingerprints." However, these patterns may be too variable for species identification necessitating analyses of more conservative parts of the genome. Mitochondrial DNA (mtDNA) is haploid, maternally inherited, similar in nucleotide sequence among conspecifics from the same geographic region, and more suitable for species identification, in contrast to hypervariable DNA fingerprints. MtDNA has several characteristics which make it useful as a species-specific marker. In mammals, individuals have a single mtDNA genotype shared by all tissues. Because mtDNA is haploid and reflects only maternal ancestry, the mtDNA gene number in a population is 4 times less than the nuclear gene number (Birky et al. 1983). This can result in relatively rapid loss or fixation of mtDNA genotypes so that all individuals in a population may be descended from a single ancestral female in as few as 4N ( N = population size) generations (Avise et al., 1984). This suggests there is great potential for identification of species-specific or population-specific mtDNA genotypes, Within species, mtDNA genotypes are thought to be selectively neutral, i.e., there is little evidence that genotypes differ in fitness (Nigro and Prout 1990).

Wildlife Society Bulletin↗