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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Phylogeography and conservation genetics of the lesser white-fronted goose (<em>Anser erythropus</em>)

Ruokonen, M. (Minna) 28 March 2001 (has links)
Abstract Analyses of mitochondrial control region sequences were used to infer phylogeny of Anser species, phylogeography of the lesser white-fronted goose, and genetic background of a captive stock. The genetic distances among the Anser species ranged from 0.9 to 5.5% in the complete control region sequences and supported the view of close relatedness of these species. Among the four most closely related species, the bean, pink-footed, white-fronted and lesser white-fronted goose, the branching order is uncertain. The short internal branches and low support for the branching order suggest that the species have diverged recently within short time-intervals. The mtDNA tree obtained is incongruent with the traditional view of the species relationships, but the reasons for this remain to be clarified. Two diverged mitochondrial lineages were found in the lesser white-fronted goose and a refugial origin was proposed. Basal haplotypes are geographically widespread and indicate a recent common ancestry for populations. The derived haplotypes are confined to singular breeding populations and suggest restrictions to the present female gene flow. A shift in the frequency of the mtDNA lineages approximately coincides with a migratory divide in the Taimyr Peninsula. Low mtDNA diversity and significant difference in the haplotype frequencies observed in Fennoscandian subpopulation suggested that it should be considered as a management unit. The fossil record was examined to gain additional information about the colonisation history of the species, but was found to be of limited use. The captive lesser white-fronted goose stock used for reintroduction/restocking was shown to be incompatible with the Fennoscandian wild population. Some captive individuals carried the mtDNA of the white-fronted goose suggesting a hybrid origin. Hybridisation has probably occurred during captive propagation, but to clarify further the extent of introgression, nuclear markers should be applied. The structure and evolution of the control region were studied by comparing complete avian sequences. Saturation was found to occur at pairwise divergences of 10% as shown for third codon positions of the mitochondrial genes previously. In pairwise comparisons of the control region and cytochrome b sequences, the rate of divergence varied among the lineages. Two conserved sequence blocks showed considerable sequence conservation when compared to mammalian sequences.
2

Variation of mitochondrial control region sequences of Steller sea lions: the three-stock hypothesis

Baker, Alyson Renee 30 September 2004 (has links)
Sequence variation of a 238 bp segment of the mitochondrial control region was analyzed for 1,568 Steller sea lions (2.8% of the estimated species population) sampled from 50 rookeries representing nearly every locality at which Steller sea lions are known to breed in significant numbers. Haplotype diversity (H = 0.9164 ± 0.0035) was high and nucleotide diversity (π = 0.00967 ± 0.00586) was moderate. No evidence was observed for significant genetic bottleneck effects. Rookeries were grouped into regions and stocks to examine structure at different spatial scales. F- and Φ-statistics were computed for all pairwise comparisons of rookeries, regions and stocks. Significant (P<0.05) divergence of eastern stock (southeastern Alaska to California) animals from western stock animals was supported in analyses at all spatial scales. Likewise, rookeries and regions from Asia were found to be significantly different from all other western stock rookeries. This was most clearly demonstrated using Φ-statistics at the regional level. The Commander Islands clearly associate with Alaskan western stock rookeries, not with the Asian rookeries. Within each of the three stocks there is significant isolation by distance among rookeries. This relationship does not hold for inter-stock comparisons indicating that there are important barriers to gene flow among stocks. Mitochondrial DNA analysis supports the recognition of three stocks for appropriate conservation of the species. The currently recognized eastern stock is unaffected, but the western stock is now partitioned west of the Commander Islands yielding a western stock which ranges from Prince William Sound west to the Commander Islands, and an Asian stock including rookeries from the Kamchatka Peninsula, Kuril Islands, and Sea of Okhtosk.
3

Variation of mitochondrial control region sequences of Steller sea lions: the three-stock hypothesis

Baker, Alyson Renee 30 September 2004 (has links)
Sequence variation of a 238 bp segment of the mitochondrial control region was analyzed for 1,568 Steller sea lions (2.8% of the estimated species population) sampled from 50 rookeries representing nearly every locality at which Steller sea lions are known to breed in significant numbers. Haplotype diversity (H = 0.9164 ± 0.0035) was high and nucleotide diversity (π = 0.00967 ± 0.00586) was moderate. No evidence was observed for significant genetic bottleneck effects. Rookeries were grouped into regions and stocks to examine structure at different spatial scales. F- and Φ-statistics were computed for all pairwise comparisons of rookeries, regions and stocks. Significant (P<0.05) divergence of eastern stock (southeastern Alaska to California) animals from western stock animals was supported in analyses at all spatial scales. Likewise, rookeries and regions from Asia were found to be significantly different from all other western stock rookeries. This was most clearly demonstrated using Φ-statistics at the regional level. The Commander Islands clearly associate with Alaskan western stock rookeries, not with the Asian rookeries. Within each of the three stocks there is significant isolation by distance among rookeries. This relationship does not hold for inter-stock comparisons indicating that there are important barriers to gene flow among stocks. Mitochondrial DNA analysis supports the recognition of three stocks for appropriate conservation of the species. The currently recognized eastern stock is unaffected, but the western stock is now partitioned west of the Commander Islands yielding a western stock which ranges from Prince William Sound west to the Commander Islands, and an Asian stock including rookeries from the Kamchatka Peninsula, Kuril Islands, and Sea of Okhtosk.
4

Nutritional and genetic adaptation of galliform birds: implications for hand-rearing and restocking

Liukkonen-Anttila, T. (Tuija) 17 May 2001 (has links)
Abstract The impact of hand-rearing on the morphology and physiology of captive and wild grey partridges (Perdix perdix) and capercaillies (Tetrao urogallus) was studied in three feeding trials conducted under laboratory conditions, and two comparative studies between wild and captive birds. Finally, wild and hand-reared grey partridges from several localities in Europe were sampled and the control region 1 of mitochondrial DNA was sequenced to reveal genetic variation between populations, as well as to compare wild and captive stocks. Wild capercaillies had heavier pectoral muscles, hearts, livers and gizzards, longer small intestines than hand-reared ones, and a higher cytochrome-c oxidase activity in muscle and heart. Invertebrates were essential to the growth, primary and temperature regulation development in grey partridge chicks. Fish was not sufficient to replace invertebrates in the diet. A change in diet from commercial to natural decreased the assimilation efficiency in the grey partridge. It also increased the mass of gizzard reflecting the need for greater grinding ability. Of hepatic P450 enzymes used in this study 7-ethoxyresorufin-0-deethylase and 7-pentoxyresorufin-0-deethylase differed between wild and hand-reared birds. Coumarin-7-hydroxylase activity was higher in grey partridges than capercaillies. Diet differences may have caused these differences. Quebracho tannin added to the diet lowered nitrogen concentration in caecal feces, and elevated the level of excreted tannin. Otherwise its effects were slight. Mitochondrial control region revealed 14 variable sites between two main lineages detected. Nucleotide and haplotype diversities varied greatly between populations. The markedly deep divergence between the two lineages indicated most probably post-glacial recolonisations from geographically isolated refuges. In Finland, wild birds represented the eastern lineage, while the farmstock represented the western lineage. Surprisingly little trace, contrary to expectations, from the large-scale releasing of imported partridges could be seen in the European populations.
5

Molecular Ecology of Globally Distributed Sharks

Testerman, Christine B. 01 April 2014 (has links)
Many sharks have life history characteristics (e.g., slow growth, late age at maturity, low fecundity, and long gestation periods) that make their populations vulnerable to collapse due to overfishing. The porbeagle (Lamna nasus), bull shark (Carcharhinus leucas), great hammerhead (Sphyrna mokarran), and smooth hammerhead (S. zygaena), are all commercially exploited. The population genetic structure of these species was assessed based on globally distributed sample sets using mitochondrial control region (mtCR) sequences and/or nuclear markers. Complex patterns of evolutionary and demographic history were inferred using coalescent and statistical moment-based methods. All four species showed statistically significant genetic partitioning on large scales, i.e., between hemispheres (L. nasus mtCR φST = 0.8273) or oceanic basins (C. leucas nuclear FST = 0.1564; S. mokarran mtCR φST = 0.8745, nuclear FST = 0.1113; S. zygaena mtCR φST = 0.8159, nuclear FST = 0.0495). Furthermore, S. zygaena mtCR sequences indicated statistically significant matrilineal genetic structuring within oceanic basins, but no intrabasin structure was detected with nuclear microsatellites. S. mokarran showed statistically significant genetic structure between oceanic basins with both nuclear and mitochondrial data, albeit with some differences between the two marker types in fine scale patterns involving northern Indian Ocean samples. A microsatellite assessment of C. leucas demonstrated no population structuring within the Atlantic or Indo-Pacific, with the exception that samples from Fiji were differentiated from the remaining Indo- Pacific Ocean locations. In contrast, the L. nasus mitochondrial and nuclear ITS2 sequences revealed strong northern vs. southern hemispheric population differentiation, but no differentiation within these hemispheres. These geographic patterns of genetic structure were used to determine the source of fins obtained from the international fin trade and to develop forensic tools for conservation.
6

Global Genetic Connectivity and Diversity in a Shark of High Conservation Concern, the Oceanic Whitetip, Carcharhinus longimanus

Ruck, Cassandra L 20 April 2016 (has links)
The oceanic whitetip shark, Carcharhinus longimanus, is a circumtropical pelagic shark of high conservation concern (IUCN Red List: “Critically Endangered” in the Western North and Western Central Atlantic and “Vulnerable” globally). I present the first, population genetic assessment of the oceanic whitetip shark on a global scale, based on analysis of two mitochondrial genome regions (entire 1066-1067 bp control region and 784 bp partial ND4 gene), and nine nuclear microsatellite loci. No population structure was detected within the Western Atlantic. However, highly significant population structure was detected between Western Atlantic and Indo-Pacific Ocean sharks across all markers. Additionally, a nominally significant signal of matrilineal structure between the Indian and Pacific Ocean sharks was detected by AMOVA and pairwise tests of the ND4 gene only (pairwise ΦST = 0.051, P = 0.046; pairwise Jost’s D = 0.311, 95% CI = 0.020, 0.0614). Although significant inter-basin population structure was evident, it was associated with deep phylogeographic mixing of mitochondrial haplotypes and evidence of contemporary migration between the Western Atlantic and Indo-Pacific Oceans. I theorize that semi-permeable thermal barriers are responsible for the differentiation between the Western Atlantic and Indo-Pacific set in a framework of global phylogeographic mixing. Relatively low mtDNA genetic diversity (concatenated mtCR-ND4 nucleotide diversity π = 0.32% ± 0.17%) compared to other circumtropical elasmobranch species raises potential concern for the future genetic health of this species. Overall, significant population structure exists, at a minimum, between the Western Atlantic and Indo-Pacific Ocean, and effective management strategies must take this into consideration.
7

Development of a DNA barcode for species identification of tuna

Nordquist, Clara, Edwall, Jonathan, Eriksson, Leonora, Mäkinen, Nelly, Sayehban, Minna, Styfberg, Matilda January 2022 (has links)
Today, DNA-barcoding with the gene COI is regularly used in the identification of fish. However, this is not an adequate way of identifying species of tuna due to COI lacking sufficient interspecies divergence. This is problematic since fraud and mislabeling are a major concern within the fish and tuna industries. Thus, there is a need for a new genetic barcode region when identifying the 15 tuna species within the tribe Thunnini. This study has considered six mitochondrial genetic regions (16S, ATP8, COII, CR, CytB, and ND2) and their potential as barcodes in comparison to COI. To be of practical use, the barcode has to be able to differentiate between all 15 tuna species, as well as contain conserved primer binding sites and be approximately 400 bp, or shorter. Analyses of the regions were made through Multiple Sequence Alignments built using ClustalW in Mega 11.0. The candidates were first evaluated through neighbor-joining trees and plots of inter- and intraspecies variation, and then analyzed further in search of conserved regions for primer binding, flanking a segment of approximately 400 bp (or shorter). This resulted in two possible barcode candidates with corresponding primers from the CR and ND2 genes. As a final step, these two were analyzed for specificity using BLAST, to evaluate their actual utility in differentiating the tuna species. The results show that they both can identify the different tuna species, but that ND2 is superior with 100% identification accuracy. In addition to the theoretical analysis, the ability of the primers was measured through a real PCR amplification. Unfortunately, only the CR barcode could be evaluated, but the results show it to be practically useful. Even though the utility of ND2 in PCR could not be analyzed, it is highly recommended as a region for further investigations. Given the strong theoretical support, it definitely shows promise as a new barcode for species identification of tuna.

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