The lake sturgeon (Acipenser fulvescens), is a species with considerable ecological, social and economic value. Unfortunately, over-exploitation and habitat alteration have led to the collapse of lake sturgeon fisheries across North America. Based on conservation concerns, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) identified eight designatable units (DUs) among Canadian populations of lake sturgeon using the limited information available. These DUs are intended to represent taxonomically, genetically, geographically, or biogeographically distinct units below the species level. In this study, the genetic structuring among 20 lake sturgeon localities was examined using nine microsatellite loci. Lake sturgeon localities conformed to hierarchical partitioning of genetic diversity, with the greatest genetic divergence between localities in the Great Lakes and Hudson Bay drainages. Finally, minimal divergences among the current DUs warrant adjustment of lake sturgeon DU boundaries, to more appropriately reflect the distribution of genetic differentiation among lake sturgeon localities.

The lake sturgeon (Acipenser fulvescens), is a species with considerable ecological, social and economic value. Unfortunately, over-exploitation and habitat alteration have led to the collapse of lake sturgeon fisheries across North America. Based on conservation concerns, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) identified eight designatable units (DUs) among Canadian populations of lake sturgeon using the limited information available. These DUs are intended to represent taxonomically, genetically, geographically, or biogeographically distinct units below the species level. In this study, the genetic structuring among 20 lake sturgeon localities was examined using nine microsatellite loci. Lake sturgeon localities conformed to hierarchical partitioning of genetic diversity, with the greatest genetic divergence between localities in the Great Lakes and Hudson Bay drainages. Finally, minimal divergences among the current DUs warrant adjustment of lake sturgeon DU boundaries, to more appropriately reflect the distribution of genetic differentiation among lake sturgeon localities.

Friedreich ataxia (FRDA) is the most common inherited ataxia disorder, caused by a GAA repeat expansion mutation within the first intron of the FXN gene. The subsequent deficiency of frataxin protein leads to neurological disability, increased risk of diabetes mellitus, cardiomyopathy and premature death. The exact FRDA disease mechanism is not yet clear, despite some understanding of epigenetic, transcriptional and DNA repair system effects that lead to frataxin reduction. Previous studies have shown that mismatch repair (MMR) genes can affect other trinucleotide repeat disorders by destabilisation of the repeats. Furthermore, it has been proposed that frataxin deficiency might lead to cell malignancy by an as yet undefined mode of action. Therefore, the principle aim of this thesis was to use human and genetically altered mouse cells and tissues to understand the effects of MMR proteins on GAA repeat instability and FXN transcription, and also to identify potential changes in MMR transcription that might cause malignancy in FXN-defective human cells. Firstly, by using FXN and MMR genetically altered mice, MMR proteins were shown to be involved in both intergenerational and somatic GAA repeat instability, although their effects in the two systems were different. Thus, Msh2 or Msh3 were both found to protect against intergenerational transmission of GAA contractions, while loss of Msh2 or Msh3 reduced somatic GAA repeat expansions and increased levels of FXN transcription in brain and cerebellum tissues. Loss of Msh6 induced both intergenerational GAA repeat expansions and contractions, while the frequency of somatic GAA repeat expansions was reduced. Curiously, the level of FXN transcription was also reduced in Msh6-deficient brain and cerebellum tissues. On the other hand, Pms2 was found to protect against both intergenerational and somatic GAA repeat expansions, with loss of Pms2 causing increased GAA repeat expansions and decreased levels of FXN transcription in brain and cerebellum tissues. Finally, loss of Mlh1 led to a reduced frequency of both intergenerational and somatic GAA repeat expansions, but the level of FXN transcription was also reduced in brain and cerebellum tissues. Furthermore, upregulation of MMR mRNA expression was detected in human FRDA fibroblast cells, but downregulation was seen in FRDA cerebellum tissues, suggesting tissue-dependent control of FXN and MMR expression. In summary, these studies indicate that the MMR system can affect GAA repeat expansion instability and FXN transcription through different mechanisms of action. Furthermore, frataxin deficiency can also affect the levels of MMR mRNA expression in a tissue-dependent manner. These findings will assist future investigations aimed at identifying novel FRDA therapies.

As a prelude to strain selection for domestication and future marker assisted selection, genetic variation revealed by microsatellite DNA was evaluated in yellow perch, Perca flavescens, from four wild North American populations collected in 2003-2004 (Maine, ME; New York, NY; North Carolina, NC; and Pennsylvania, PA), and two captive populations (Michigan, MI; Ohio, OH). For the loci examined, levels of heterozygosity ranged from He = 0.04 to 0.88, genetic differentiation was highly significant among all population pairs, and effective migration ranged from low (Nem = 0.3) to high (Nem = 4.5). Deviation from Hardy-Weinberg 1equilibrium was regularly observed indicating significant departures from random mating. Instantaneous measures of inbreeding within these populations ranged from near zero to moderate (median F = 0.16) and overall inbreeding levels averaged FIS = 0.18. Estimates of genetic diversity, Φ ST and genetic distance were highest between Michigan and all other populations and lowest between New York and Ohio. Genetic differentiation among populations did not correlate with geographic distance. Overall, the patterns of variation exhibited by the captive (Michigan and Ohio) populations were similar to patterns exhibited by the other allegedly wild populations, indicating that the spawning and management practices to date have not significantly reduced levels of genetic variation.

0009014A Msc thesis Science Animal plant and environmental sciences / Anopheles arabiensis is considered an important vector of human malaria in the southern African region where the disease is the major cause of morbidity and mortality. Gene flow plays an important role in malaria control with the spread of insecticide resistance. The main objectives of this study were to (i) measure the genetic variability within and between five populations (Botswana, Namibia, South Africa, Swaziland and Zimbabwe) of wild An. arabiensis and (ii) estimate the level of gene flow between natural populations across the Southern-limits of An. arabiensis. A total of 1225 An. arabiensis specimens were identified out of 1300 mosquitoes collected from 2000-2003 with the sample sizes ranging from 180-292 per country. Variation at four microsatellite markers was investigated on non-denaturing polyacrylamide gels. The results showed fewer variations between populations (2.96%) than within populations (82.60%) suggesting considerable homogeneity. However, estimates of gene flow (Nm) calculated from mean FST and RST statistics were relatively low, 1.14 and 1.19 respectively, suggesting somewhat restricted gene flow between populations. The occurrence of gene flow within subpopulations of An. arabiensis in Zimbabwe but not in South Africa is interesting with regard to the spread of insecticide resistance in Zimbabwe. The results presented here are obviously subject to the limitations inherent in manual, silver staining method of analysing microsatellite DNA markers. It is possible that a different set of results would be obtained if an Automated Sequencing Analyzer were used. ii

The genetic status of the critically endangered Mississippi sandhill crane (Grus canadensis pulla) was analyzed using 2009 studbook data from the U.S. Fish and Wildlife Service managed captive breeding and release program. Microsatellite DNA data provided information on shared founder genotypes, allowing for refined analysis of genetic variation in the population, and informed breeding recommendations. The genetic variation observed in the Mississippi sandhill crane was contrasted with variation observed in the Florida sandhill crane (Grus canadensis pratensis). Results show far less variation in the Mississippi population. Results also suggest that while gene flow no longer occurs between the two populations, the introduction of cranes from the Florida population would help to increase the observed genetic diversity of the Mississippi sandhill crane population.

Melongena corona and closely related congeners are a conspicuous part of the marine intertidal benthic communities of Florida and southeastern Alabama. Significant genetic differentiation among adjacent populations has been conjectured based on variation in shell morphology, habitat discontinuity, low levels of adult motility, and the presence of an aplanic lecithotrophic larval stage. Furthermore, studies of the highly variable shell morphology often have resulted in confusing specific and subspecific definitions of these gastropods, which are often referred to as the "corona complex". Variation in shell morphology may indicate local adaptation or environmentally induced phenotypic plasticity. In this study I utilized mitochondrial DNA sequences in order to reconstruct the phylogenetic relationships of crown conchs, and nuclear microsatellite loci to investigate the patterns of relatedness within and among populations inhabiting the southeastern United States. Approximately 500 individuals from 20 populations throughout the known range of the Crown Conch were genotyped at eight microsatellite loci. Additionally, a 1200bp portion of the cytochrome oxidase subunit I gene was sequenced along with a 490bp fragment of the 16s ribosomal gene from individuals representing all known species and subspecies of the genus Melongena. Phylogenetic analyses completed with these data provide no support for current taxonomic designations within this group and these genetic data indicate that the corona complex is composed of a single polymorphic species. Furthermore, microsatellite data reveal population structure consistent with restricted gene flow between extant populations and phylogeography heavily influenced by historical sea-level fluctuations during the Late Pleistocene.

Title from PDF of title page. / Document formatted into pages; contains 201 pages. / Thesis (M.S.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: Melongena corona and closely related congeners are a conspicuous part of the marine intertidal benthic communities of Florida and southeastern Alabama. Significant genetic differentiation among adjacent populations has been conjectured based on variation in shell morphology, habitat discontinuity, low levels of adult motility, and the presence of an aplanic lecithotrophic larval stage. Furthermore, studies of the highly variable shell morphology often have resulted in confusing specific and subspecific definitions of these gastropods, which are often referred to as the "corona complex". Variation in shell morphology may indicate local adaptation or environmentally induced phenotypic plasticity. In this study I utilized mitochondrial DNA sequences in order to reconstruct the phylogenetic relationships of crown conchs, and nuclear microsatellite loci to investigate the patterns of relatedness within and among populations inhabiting the southeastern United States. / ABSTRACT: Approximately 500 individuals from 20 populations throughout the known range of the Crown Conch were genotyped at eight microsatellite loci. Additionally, a 1200bp portion of the cytochrome oxidase subunit I gene was sequenced along with a 490bp fragment of the 16s ribosomal gene from individuals representing all known species and subspecies of the genus Melongena. Phylogenetic analyses completed with these data provide no support for current taxonomic designations within this group and these genetic data indicate that the corona complex is composed of a single polymorphic species. Furthermore, microsatellite data reveal population structure consistent with restricted gene flow between extant populations and phylogeography heavily influenced by historical sea-level fluctuations during the Late Pleistocene. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

I combined long-term ecological data and population genetic data using microsatellite DNA markers to examine among- and within-population genetic structure and parentage in Tiger Rattlesnake (Crotalus tigris) populations from the Tucson Basin of southern Arizona located in the northern Sonoran Desert. Based on long-term data from radio telemetry, I determined that C. tigris show strong fidelity to both their home range and winter shelter sites, remaining in close proximity to rocky habitats within mountain ranges, which leads to apparent natural isolation of populations. Therefore, I predicted that C. tigris populations would show substantial genetic differentiation among mountain ranges. However, Bayesian clustering analyses revealed a surprising pattern of extensive admixture among mountain ranges, indicating the presence of gene flow among populations. This pattern of genetic admixture can likely be explained by historical changes in climate and physiognomy in the Sonoran Desert. Analyses of pack rat midden remains clearly show that mountain ranges were previously connected by mesic woodland habitats that may have led to panmixia in C. tigris populations as recently as 5,000-8,000 years ago. At present, C. tigris show a strong preference for xeroriparian washes, which allows individuals to occasionally move relatively long distances, likely resulting in contemporary gene flow. To maintain connections among mountain ranges, I recommend effective management, protection, and restoration (if needed) of wash habitats, which also act as corridors for a suite of other species. At the within population scale, genetic clustering analyses revealed the existence of fine-scale genetic structure in C. tigris subpopulations located in the Rincon Mountains. Further analyses based on location data of individuals indicated the existence of a potential barrier to gene flow, which corresponded to a watershed divide. Although the watershed divide would appear not to present a physical barrier to gene flow, it likely acts to segregate populations based on habitat and movement preferences associated with wash habitats. Data on spatial ecology and reproductive behavior, indicate that C. tigris distribute gametes across the landscape in the absence of actual displacement of individuals due to fidelity to home ranges and winter shelter sites. Analyses of parentage were constrained by the difficulty in obtaining offspring from gravid female C. tigris that give birth deep in rock outcrops. However, I did conduct analyses on over 30 offspring from known mothers and nearly 60 free-ranging offspring found while conducting ecological research. Surprisingly, not a single male C. tigris found courting or copulating with a female was identified as the father, indicating that reproductive behavior is a poor predictor of parentage, and therefore, fitness. Interestingly, males identified as fathers were found up to 2 km distance from their offspring, demonstrating that males from surrounding areas may move relatively long distances to mate. The mating system of C. tigris, which is characterized by promiscuity in both sexes, appears to drive dramatic differences in spatial ecology between males and females, and may lead to fine-scale genetic structure among females and not males who spend a great deal of time searching for receptive females.

Broad whitefish, Coregonus nasus, is an important subsistence fish species in Arctic North America, yet virtually nothing is known regarding the genetic population structure of Nearctic populations of this species. In this thesis, microsatellite DNA variation was assayed among 1213 broad whitefish from 47 localities throughout North America, with emphasis on the Mackenzie River system, Northwest Territories. Specifically, I examined geographic variation in allele frequencies to assess how historical factors (Pleistocene glaciations) have shaped the current structuring of genetic variability and population differentiation. Microsatellite data was also used to resolve the relative contributions of broad whitefish populations to subsistence fisheries in the Mackenzie River system. Overall, broad whitefish exhibit relatively high intrapopulation microsatellite variation (average 12.29 alleles/locus, average HE = 0.58) and there were declines in these measures of genetic diversity with distance from putative refugia suggesting historical factors, namely post-glacial dispersal, have influenced current microsatellite variation. Interpopulation divergence was low (overall FST = 0.07), but the main regions assayed in this study (Russia, Alaska, Mackenzie River and Travaillant Lake systems) are genetically differentiated. Strong isolation-by-distance among samples was resolved when including only those populations occupying former Beringia, but not when assaying those at the periphery of the range in the Mackenzie River system, suggesting that broad whitefish in the Mackenzie system have not occupied the region long enough since their invasion post-glacially to have approached equilibrium between gene flow and drift. Mixture analysis indicated that most fish from the lower Mackenzie River subsistence fishery originated from the Peel River, highlighting the importance of this tributary. Additionally the mixture analysis provides evidence for a putative riverine life history form in the Mackenzie River. My results indicate that glaciation and post-glacial colonization have been important in shaping the current genetic population structure of North American broad whitefish. They also illustrate the utility of microsatellite DNA to delineate population structure and patterns of genetic diversity in recently founded populations in addition to resolving contributions to fisheries. My data also support the hypothesis that there are several designatable units of conservation among broad whitefish populations and that management strategies should be implemented accordingly.