The relative role of cospeciation and host switching in the phylogenetic history of ascomycete foliar symbionts is addressed in the orders Leotiales and Rhytismatales, fungi associated predominantly with Pinaceae (Coniferales). Emphasis is placed on comparing the evolution of the sister genera Pseudotsuga and Larix (Pinaceae) with that of the pathogenic and endophytic fungi in the genus Rhabdocline. Pinaceae evolved during the Mesozoic and divergence of all extant genera and several infrageneric lineages (esp. in Pinus) occurred prior to the Tertiary, with subsequent species radiations following climatic changes of the Eocene. The youngest generic pair to evolve from Pinaceae, Larix and Pseudotsuga, diverged near the Cretaceous-Tertiary boundary in East Asia or western North America. Rhabdocline is comprised of seven species and subspecies, six known from two species of Pseudotsuga and one, the asexual species Meria laricis, from three species of Larix. Evidence from host distributions and from nuclear ribosomal DNA suggests that Rhabdocline speciated in western North America and has been involved in several host switches. The ancestor of Meria laricis appears to have switched from P. menziesii to its current western North American hosts, L. occidentalis, L. lyallii, and very recently may have extended its host range to the European species, L. decidua. The occurrence of two lineages of R. weirii ssp. weirii on both North American species of Pseudotsuga is also probably the result of a recent host switch. Evidence of hostmediated divergence is seen in R. parkeri, which has different internal transcribed spacer types in the geographically isolated coastal and interior forms of P. menziesii. The wide host ranges of fungal genera closely related to Rhabdocline indicates that host switching is a prevalent pattern in the evolution of foliar symbionts in Leotiales and Rhytismatales. The prevalence of host switching in this group relative to other endosymbiotic organisms can probably be attributed to differences in dispersal mechanisms. Spores of foliar fungi are dispersed horizontally by wind and rain, rather than vertically from parent to offspring. Over evolutionary time, this provides more opportunities to shift to new hosts, particularly when the hosts are closely related and have overlapping distributions. / Graduation date: 1998

Results of an inter-laboratory round-robin study of the application of time-resolved emission spectroscopy (TRES) to the speciation of uranium(VI) in aqueous media are presented. The round-robin study involved 13 independent laboratories, using various instrumentation and data analysis methods. Samples were prepared based on appropriate speciation diagrams and, in general, were found to be chemically stable for at least six months. Four different types of aqueous uranyl solutions were studied: (1) acidic medium where UO22+aq is the single emitting species, (2) uranyl in the presence of fluoride ions, (3) uranyl in the presence of sulfate ions, and (4) uranyl in aqueous solutions at different pH, promoting the formation of hydrolyzed species. Results between the laboratories are compared in terms of the number of decay components, luminescence lifetimes, and spectral band positions. The successes and limitations of TRES in uranyl analysis and speciation in aqueous solutions are discussed.

The main objective of this study was to investigate small-bodied fish caging as an approach to evaluate selenium (Se) bioaccumulation and speciation in native fish species inhabiting lakes influenced by uranium (U) milling effluent in northern Saskatchewan, Canada. In contaminated environments freshwater fish show a high propensity to accumulate Se beyond levels needed for normal physiological function. Maternal transfer of elevated Se concentrations to offspring can cause deformities and reduced survival in fry, and in certain cases negatively impact the sustainability of native fish populations. This research included a caging validation study using wild, naïve (i.e., collected from a reference lake) lake chub (Couesius plumbeus) and spottail shiner (Notropis hudsonius), and three field based 21-day caging studies to investigate the dominance of the feeding pathway with respect to Se uptake and speciation in wild populations of northern small-bodied fish exposed to a gradient of Se. Three feeding regimes were used: an in situ benthic diet, a basal Se diet of Chironomus dilutus (1.5 µg Se/g dry weight) and a Se-spiked diet of C. dilutus (5.5 µg Se/g dry weight). Lake chub were identified as more suitable candidates for caging due to higher survival and condition factor at the completion of the in situ 21-day trial. The resulting Se bioaccumulation was compared among treatments as well as to wild small-bodied fish populations from the study area. Results from the caging experiments showed that caged lake chub exposed to natural and controlled diets with elevated Se had significantly greater whole-body Se concentrations after 21 days compared to fish caged in the reference lake. The results also showed that whole-body Se concentrations exceeded conservative Se thresholds, and approached the currently proposed USEPA regulatory threshold (7.91 µg/g dry weight) designed to protect fish species in only three weeks. The use of stable carbon (C), nitrogen (N), and sulphur (S) isotope ratios indicated that alternate benthic food sources native to the exposure lake were consumed in conjunction with the controlled diets. Stable isotope analysis of both wild and caged lake chub indicated that the N and S isotopic signatures decreased with increasing Se exposure, representing differences in isotopic signatures of the food sources. Speciation results from caged lake chub indicated that Se substituted for S in methionine (i.e. selenomethionine) was the dominant Se species found in caged lake chub exposed to dietary sources of elevated Se. Overall, this research demonstrates that using caged native lake chub represents a useful biomonitoring approach to investigate patterns of Se bioaccumulation and speciation in fish.

My Ph.D. research has examined the evolution of mating preferences and their role in speciation. I have addressed these topics empirically, using sympatric species pairs of limnetic and benthic threespine sticklebacks, and theoretically, with multilocus population genetics. Sticklebacks are small fish that occur in lakes, streams and estuaries throughout British Columbia. Most lakes contain one type of stickleback, however, several lakes support two differentially adapted sympatric species: a large benthic form (benthic), and a smaller zooplanktivorous form (limnetic). Chapter 2 examines the role of species interactions in shaping male mating preferences. I determined that the mate preferences of the small species have shifted from preferring large females (the ancestral state) to preferring small females due either to selection against hybrids (reinforcement), or to egg predation by the larger benthic species. Chapter 3 explores the idea that sexual imprinting may facilitate assortative mating between benthic and limnetic sticklebacks. Sexual imprinting occurs when individuals imprint on the phenotype of their parents, and subsequently prefer mates that resemble their parents. The results suggested that sexual imprinting does not contribute to assortative mating between the sympatric species pairs, implying that genetics are more important than early learning for the formation of mate preferences. Chapter 4 focuses on differences in male breeding colour between benthics and limnetics. The results reveal that limnetic males have more intense red and blue coloration than benthic and solitary males. These differences in colour could be due to reinforcement, to differences in visual sensitivity of females, or to territorial interactions between males. Chapter 5 examines the evolution of female mating preferences under different scenarios of sex-linkage, when the male display trait is sexually antagonistic. Theoretical analysis suggests that sexually antagonistic traits on the X chromosome (males XY, females XX), females will evolve to prefer mates carrying alleles beneficial to their daughters. In contrast, with a Z-linked trait (males ZZ, females ZW), females more often evolve preferences for mates carrying alleles beneficial to their sons (e.g., flashy displays). This provides an explanation for why males in ZW species have more elaborate sexual displays than males in XY species.

My Ph.D. research has examined the evolution of mating preferences and their role in speciation. I have addressed these topics empirically, using sympatric species pairs of limnetic and benthic threespine sticklebacks, and theoretically, with multilocus population genetics. Sticklebacks are small fish that occur in lakes, streams and estuaries throughout British Columbia. Most lakes contain one type of stickleback, however, several lakes support two differentially adapted sympatric species: a large benthic form (benthic), and a smaller zooplanktivorous form (limnetic). Chapter 2 examines the role of species interactions in shaping male mating preferences. I determined that the mate preferences of the small species have shifted from preferring large females (the ancestral state) to preferring small females due either to selection against hybrids (reinforcement), or to egg predation by the larger benthic species. Chapter 3 explores the idea that sexual imprinting may facilitate assortative mating between benthic and limnetic sticklebacks. Sexual imprinting occurs when individuals imprint on the phenotype of their parents, and subsequently prefer mates that resemble their parents. The results suggested that sexual imprinting does not contribute to assortative mating between the sympatric species pairs, implying that genetics are more important than early learning for the formation of mate preferences. Chapter 4 focuses on differences in male breeding colour between benthics and limnetics. The results reveal that limnetic males have more intense red and blue coloration than benthic and solitary males. These differences in colour could be due to reinforcement, to differences in visual sensitivity of females, or to territorial interactions between males. Chapter 5 examines the evolution of female mating preferences under different scenarios of sex-linkage, when the male display trait is sexually antagonistic. Theoretical analysis suggests that sexually antagonistic traits on the X chromosome (males XY, females XX), females will evolve to prefer mates carrying alleles beneficial to their daughters. In contrast, with a Z-linked trait (males ZZ, females ZW), females more often evolve preferences for mates carrying alleles beneficial to their sons (e.g., flashy displays). This provides an explanation for why males in ZW species have more elaborate sexual displays than males in XY species.

Speciation lies at the heart of evolution and the study of reproductive barriers allows a better understanding of the different steps leading to the complete isolation of two species. Pre-mating (behavior tactics, habitat or food divergence, phenotypic divergence and assortative mating) and post-mating, post-zygotic isolation barriers (selection against unfit hybrids) are well studied in numerous species, but little is known about what is happening between insemination and fertilization (post-mating, pre-zygotic isolation barriers). In this study, we chose the well-studied population of pied and collared flycatchers (Ficedula hypoleuca and F. albicollis) of the hybrid zone of Öland, Sweden, to investigate possible patterns of gamete divergence between these two closely related species. We compared sperm morphology between the two species and their hybrids, analyzing traits that are thought to play an important role in the fertilization success of the males. We did not detect any divergence in sperm morphology between the two species, but we report an extreme reduction of sperm production in hybrid males, as well as spermatogenesis dysfunctions and particularly high rates of extra-pair young in the nests of hybrid males.

The main objective of this study was to investigate small-bodied fish caging as an approach to evaluate selenium (Se) bioaccumulation and speciation in native fish species inhabiting lakes influenced by uranium (U) milling effluent in northern Saskatchewan, Canada. In contaminated environments freshwater fish show a high propensity to accumulate Se beyond levels needed for normal physiological function. Maternal transfer of elevated Se concentrations to offspring can cause deformities and reduced survival in fry, and in certain cases negatively impact the sustainability of native fish populations. This research included a caging validation study using wild, naïve (i.e., collected from a reference lake) lake chub (Couesius plumbeus) and spottail shiner (Notropis hudsonius), and three field based 21-day caging studies to investigate the dominance of the feeding pathway with respect to Se uptake and speciation in wild populations of northern small-bodied fish exposed to a gradient of Se. Three feeding regimes were used: an in situ benthic diet, a basal Se diet of Chironomus dilutus (1.5 µg Se/g dry weight) and a Se-spiked diet of C. dilutus (5.5 µg Se/g dry weight). Lake chub were identified as more suitable candidates for caging due to higher survival and condition factor at the completion of the in situ 21-day trial. The resulting Se bioaccumulation was compared among treatments as well as to wild small-bodied fish populations from the study area. Results from the caging experiments showed that caged lake chub exposed to natural and controlled diets with elevated Se had significantly greater whole-body Se concentrations after 21 days compared to fish caged in the reference lake. The results also showed that whole-body Se concentrations exceeded conservative Se thresholds, and approached the currently proposed USEPA regulatory threshold (7.91 µg/g dry weight) designed to protect fish species in only three weeks. The use of stable carbon (C), nitrogen (N), and sulphur (S) isotope ratios indicated that alternate benthic food sources native to the exposure lake were consumed in conjunction with the controlled diets. Stable isotope analysis of both wild and caged lake chub indicated that the N and S isotopic signatures decreased with increasing Se exposure, representing differences in isotopic signatures of the food sources. Speciation results from caged lake chub indicated that Se substituted for S in methionine (i.e. selenomethionine) was the dominant Se species found in caged lake chub exposed to dietary sources of elevated Se. Overall, this research demonstrates that using caged native lake chub represents a useful biomonitoring approach to investigate patterns of Se bioaccumulation and speciation in fish.

One objective of the present investigation was to compare Salmonella and Campylobacter recovery incidence from commercially processed turkeys immediately prior to and following pre-chill and immersion chiller intervention strategies being used in three distinct turkey processing facilities. In each plant, on a single day of processing, 100 carcass rinse samples prior to and following each post-evisceration, pre-chill intervention and following immersion chilling were obtained for Salmonella and Campylobacter recovery. Two of three plants demonstrated a trend of decreased Salmonella on carcasses following the Inside Outside Bird Wash (IOBW), with reductions of 13%, and 11% being observed for Plants 1 and 2, respectively. Results for reductions of Campylobacter contamination were not as straightforward, with only Plant 3 showing decreased levels (11% reduction) following the IOBW. Plant 2 used an additional pre-chill intervention, a low pressure, acetic acid final wash, which was not shown to be effective in causing an additional reduction in either Salmonella or Campylobacter on carcasses. In all three plants, properly managed immersion chilling systems were the most effective microbial intervention for achieving Salmonella andCampylobacter reduction on processed turkey carcasses. While not as effective, the IOBW present in each plant likely contributed to the effectiveness of immersion chiller interventions. If managed properly these intervention points have demonstrated themselves as a viable means to effectively reduce Salmonella and Campylobacter on processed turkeys. Another objective was to modify the scalder environment to an alkaline pH and determine the effects of thermal killing of Salmonella and Campylobacter. In each plant, on a single day of processing, 50 carcass rinse samples prior to and following scald tank immersion and following feather removal were obtained for Salmonella and Campylobacter recovery. Modification of the scald water to alkaline conditions (pH 9- 10) did not result in increased thermal killing of Salmonella or Campylobacter on turkey carcasses, as hypothesized before the investigation. Alkaline conditions are known to facilitate a more efficacious pluck and aid in the detachment of bacteria. Due to this, the bacteria that were recovered at these points on the processing line could have had an impact on the observed data.

Thesis (Ph. D.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains xvi, 193 p. : ill. Vita. Includes abstract. Includes bibliographical references.

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