No description available.

No description available.

An understanding of the level of both genetic and morphological diversity within a taxon and how that diversity is structured within and across habitats is important when determining the conservation value of that taxon and for successful habitat management programs to be developed. Atlin Lake is a large lake in northern British Columbia and is one of the largest lakes that contain relatively unperturbed populations of lake trout (Salvelinus namaycush). As the top aquatic predator, lake trout in Atlin Lake are a key component of the lake’s fish community and are important for local fisheries. I assayed lake trout from Atlin Lake and other western lake trout populations at eight microsatellite DNA loci and for body morphology to determine: (i) the level of genetic variation present, (ii) the level of substructure that occurs in Atlin Lake, and (iii) whether there was a relationship between the genetic and morphological variation present. STRUCTURE analysis identified five subpopulations within Atlin Lake. Morphological analysis was used to differentiate between the samples collected throughout Atlin Lake. Cluster analysis of size corrected data separated the fish into two groups making Atlin Lake the smallest lake identified to date to possess more than one morphotype. Genetic and morphological groupings were found not to be correlated with each other. Finally, I was interested in whether each of the genetic subpopulations contributed equally to the local fisheries catches. A mixed stock analysis of samples collected from the commercial fishery and recreational anglers indicated that all of the genetic subpopulations contribute to the fishery along with lake trout subpopulations in the interconnecting Tagish Lake; suggesting that no one subpopulation is being depleted by the fisheries. Continued genetic monitoring, however, is necessary to see if the trends in fishery contribution are temporally stable. Future studies should focus on understanding the source of the morphological variation and maintenance of genetic substructure.

An understanding of the level of both genetic and morphological diversity within a taxon and how that diversity is structured within and across habitats is important when determining the conservation value of that taxon and for successful habitat management programs to be developed. Atlin Lake is a large lake in northern British Columbia and is one of the largest lakes that contain relatively unperturbed populations of lake trout (Salvelinus namaycush). As the top aquatic predator, lake trout in Atlin Lake are a key component of the lake’s fish community and are important for local fisheries. I assayed lake trout from Atlin Lake and other western lake trout populations at eight microsatellite DNA loci and for body morphology to determine: (i) the level of genetic variation present, (ii) the level of substructure that occurs in Atlin Lake, and (iii) whether there was a relationship between the genetic and morphological variation present. STRUCTURE analysis identified five subpopulations within Atlin Lake. Morphological analysis was used to differentiate between the samples collected throughout Atlin Lake. Cluster analysis of size corrected data separated the fish into two groups making Atlin Lake the smallest lake identified to date to possess more than one morphotype. Genetic and morphological groupings were found not to be correlated with each other. Finally, I was interested in whether each of the genetic subpopulations contributed equally to the local fisheries catches. A mixed stock analysis of samples collected from the commercial fishery and recreational anglers indicated that all of the genetic subpopulations contribute to the fishery along with lake trout subpopulations in the interconnecting Tagish Lake; suggesting that no one subpopulation is being depleted by the fisheries. Continued genetic monitoring, however, is necessary to see if the trends in fishery contribution are temporally stable. Future studies should focus on understanding the source of the morphological variation and maintenance of genetic substructure.

An understanding of the level of both genetic and morphological diversity within a taxon and how that diversity is structured within and across habitats is important when determining the conservation value of that taxon and for successful habitat management programs to be developed. Atlin Lake is a large lake in northern British Columbia and is one of the largest lakes that contain relatively unperturbed populations of lake trout (Salvelinus namaycush). As the top aquatic predator, lake trout in Atlin Lake are a key component of the lake’s fish community and are important for local fisheries. I assayed lake trout from Atlin Lake and other western lake trout populations at eight microsatellite DNA loci and for body morphology to determine: (i) the level of genetic variation present, (ii) the level of substructure that occurs in Atlin Lake, and (iii) whether there was a relationship between the genetic and morphological variation present. STRUCTURE analysis identified five subpopulations within Atlin Lake. Morphological analysis was used to differentiate between the samples collected throughout Atlin Lake. Cluster analysis of size corrected data separated the fish into two groups making Atlin Lake the smallest lake identified to date to possess more than one morphotype. Genetic and morphological groupings were found not to be correlated with each other. Finally, I was interested in whether each of the genetic subpopulations contributed equally to the local fisheries catches. A mixed stock analysis of samples collected from the commercial fishery and recreational anglers indicated that all of the genetic subpopulations contribute to the fishery along with lake trout subpopulations in the interconnecting Tagish Lake; suggesting that no one subpopulation is being depleted by the fisheries. Continued genetic monitoring, however, is necessary to see if the trends in fishery contribution are temporally stable. Future studies should focus on understanding the source of the morphological variation and maintenance of genetic substructure. / Science, Faculty of / Zoology, Department of / Graduate

No description available.

No description available.

No description available.

An epidemic increase in severity and incidence of asochyta blight, caused by Ascochyta rabiei (Pass) Labrousse (teleomorph: <i>Didymella rabiei</i> (Kovachevski) v. Arx. Syn. <i>Mycosphaerella rabiei </i>Kovachevski), has occurred on chickpea (<i>Cicer arietinum</i> L.) crops in Saskatchewan over the past 5 growing seasons. In order to explore the nature of the outbreak, studies assessing population differences in pathogenicity and genetic variability were employed. Isolates of <i>A. rabiei</i> collected in 1998, 2001 and 2002 were inoculated onto 7 differential chickpea genotypes for pathogenicity testing. <p> Significant isolate by differential interaction occurred, but accounted for a low proportion of the total variability suggesting no genotype specific relationship exists between <i>A. rabiei</i> and <i>C. arietinum</i>. Furthermore, it was found that when averaged over all differentials, the isolates from 2001 and 2002 caused significantly greater disease than isolates from 1998, suggesting that the disease epidemic is in part due to a shift in the population to overall greater aggressiveness. The largest increase in disease severity was observed on the cultivar Sanford, which was widely grown in commercial chickpea fields before 1999. To evaluate the genetic diversity of different <i>A. rabiei</i> populations, 30 isolates from 1998 and 30 isolates from 2002 were compared with random amplified polymorphic DNA fingerprinting. Several clusters of isolates collected from either 1998 or 2002 were approximately 60% genetic similar suggesting divergence of these populations of <i>A. rabiei</i>. However, analysis of molecular variance showed that over 90% of the variation occurred within populations. Pairwise differences and gene diversity over loci showed that genetic diversity of the 2 populations had the same amount of genetic variability. Analysis of mating type distributions revealed that the populations from 1998, 2001 and 2002 did not significantly depart from a 1:1 ratio suggesting random mating of each population. Further supporting the hypothesis of a randomly mating population, linkage disequilibrium for both 1998 and 2002 populations was very low.

An epidemic increase in severity and incidence of asochyta blight, caused by Ascochyta rabiei (Pass) Labrousse (teleomorph: <i>Didymella rabiei</i> (Kovachevski) v. Arx. Syn. <i>Mycosphaerella rabiei </i>Kovachevski), has occurred on chickpea (<i>Cicer arietinum</i> L.) crops in Saskatchewan over the past 5 growing seasons. In order to explore the nature of the outbreak, studies assessing population differences in pathogenicity and genetic variability were employed. Isolates of <i>A. rabiei</i> collected in 1998, 2001 and 2002 were inoculated onto 7 differential chickpea genotypes for pathogenicity testing. <p> Significant isolate by differential interaction occurred, but accounted for a low proportion of the total variability suggesting no genotype specific relationship exists between <i>A. rabiei</i> and <i>C. arietinum</i>. Furthermore, it was found that when averaged over all differentials, the isolates from 2001 and 2002 caused significantly greater disease than isolates from 1998, suggesting that the disease epidemic is in part due to a shift in the population to overall greater aggressiveness. The largest increase in disease severity was observed on the cultivar Sanford, which was widely grown in commercial chickpea fields before 1999. To evaluate the genetic diversity of different <i>A. rabiei</i> populations, 30 isolates from 1998 and 30 isolates from 2002 were compared with random amplified polymorphic DNA fingerprinting. Several clusters of isolates collected from either 1998 or 2002 were approximately 60% genetic similar suggesting divergence of these populations of <i>A. rabiei</i>. However, analysis of molecular variance showed that over 90% of the variation occurred within populations. Pairwise differences and gene diversity over loci showed that genetic diversity of the 2 populations had the same amount of genetic variability. Analysis of mating type distributions revealed that the populations from 1998, 2001 and 2002 did not significantly depart from a 1:1 ratio suggesting random mating of each population. Further supporting the hypothesis of a randomly mating population, linkage disequilibrium for both 1998 and 2002 populations was very low.