Thesis--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references (p. 34-45).

The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on October 6, 2009). Thesis advisor: Dr. Douglas B. Noltie. Includes bibliographical references.

The modern species concept (Mayr, 1963) stresses the interbreeding within, and the reproductive isolation between, species. However, "interbreeding" is not strictly an intraspecific characteristic since numerous interspecific hybrids have been reported, especially among the temperate freshwater fishes. In this investigation, hybridizing (interbreeding) populations of the peamouth chub, Mylocheilus caurinum (Richardson), and the redside shiner, Richardsonius balteatus (Richardson) from Stave Lake, British Columbia, were studied to determine: (1) if interbreeding between them was resulting in the swamping (lack of reproductive isolation) of their gene pools, and (2) if swamping was absent, what isolating mechanisms were operative? To detect the presence or absence of swamping, two approaches were used. The first measured shifts in means of certain morphological characters for the two species within and outside the area of hybridization. The second determined the frequency of various hybrid generations. If swamping is not occurring, the frequency of hybrid backcross individuals should decrease as backcrossing continues. Both approaches indicated that swamping is absent between Mylocheilus and Richardsonius. In the absence of swamping, isolating mechanisms between the two species were examined. Seasonal, temporal (diel), spatial, and ethological premating isolating mechanisms do not appear to be effective since Mylocheilus, Richardsonius, and their hybrids spawn at the same time and place within Devils Creek, a major spawning area in Stave Lake. Egg and fry survival of crosses involving hybrid individuals were measured under experimental conditions to determine if they serve as post-mating isolating mechanisms. F₁ hybrid males are partially sterile as demonstrated by the poor egg survival of crosses involving them. However, egg survival of hybrid females when backcrossed with Mylocheilus and Richardsonius males was comparable to the parental species' crosses. Thus, fertility is not considered an effective isolating mechanism. The experiments testing the fry survival of the parental species, reciprocal F₁ hybrids, and hybrid backcrosses to Mylocheilus(= B CM) yield a clue to what isolating mechanism prevents swamping. The fry survival of reciprocal F₁ hybrid fry do not differ significantly from Mylocheilus fry. In contrast, the survival of hybrid backcross to Mylocheilus fry is approximately 20 % less than either reciprocal F₁ hybrids or Mylocheilus fry after only 48 days rearing. Additionally, 11. 5% of the surviving BCM fry possess gross abnormalities. Thus, hybrid inferiority is demonstrated experimentally. Circumstantial evidence was also gathered from Stave Lake in 1967 which suggests the inferiority of BCM fry. Relative to Mylocheilus, BCMs were five times more abundant as fingerlings than as adults. Little information was gathered on hybrid backcrosses to Richardsonius. They, appeared scarce as fingerlings as well as adults. / Science, Faculty of / Zoology, Department of / Graduate

The Blackmouth Shiner (Notropis melanostomus) is a small North American cyprinid that is listed as a Species of Concern due its relatively small range, occurring at only a few sites in Mississippi, Alabama, and Florida. Due to limited data and the small number of actual samples of N. melanostomus, the true characteristics of viable habitat and distribution remain unknown. The objective of my research was to utilize remote sensing data to gain a better understanding of the habitat characteristics where the N. melanostomus has been collected and use this information to identify other areas were populations are likely to occur during future sampling efforts. In particular, Landsat data were used to map the spatial and temporal extent of water inundation over a 20-year time-series within floodplain water bodies surrounding the Pascagoula River to determine the effects on the presence or absence of Blackmouth Shiners at historic collection sites. These characteristics could be used to inform future site selections within the Pascagoula River drainage as well as identify other river systems that have similar inundation patterns and morphology within and proximal to the known range.

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.

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.

Thesis (M.S.)--Wildlife and Fisheries Sciences Dept., South Dakota State University, 2008. / Includes bibliographical references. Also available via the World Wide Web.

Electrophoretic variation at twenty gene loci, patterns of behavioral thermoregulation, and genotype-specific malate dehydrogenase kinetics were investigated among populations of the red shiner, Notropis lutrensis, and the blacktail shiner, N. venustus, collected from thermally altered and thermally unaltered portions of their ranges. Genic variation was found to be high among red shiners and low among blacktail shiners. The behavioral response of the blacktail shiner to temperature was fixed among the populations sampled, whereas the response of the red shiner was mutable. Finally, blacktail shiners have incorporated into their genome an Mdh-B allele which functions well at low temperatures; red shiners, displaying high levels of Mdh-B polymorphism, maintain a more complex set of allozymes which function well over a wide range of environmental temperatures. These data are consistent with reported ecotypic distributions of the species in Texas waters; i.e., blacktail shiners occur in cool, thermally static habitats, and red shiners are tolerant of wide temperature ranges.

Thesis (M.S.)--North Carolina State University, 2003. / Title from PDF t.p. (viewed on Dec. 8, 2005). Vita. Includes bibliographical references (p. 97-103).

Twenty-two natural populations of the red shiner minnow, Notropis lutrensis were examined for morphological and genetic variation. This research was aimed at testing the hypothesis that morphological and genetic variation was primarily influenced by the degree of gene flow between populations. Ten linear measurements were taken from each of 1320 specimens. Morphological characters were adjusted for differential growth by least squares linear regression techniques. Genetic variability was estimated for each individual red shiner through the methods of starch gel electrophoresis. Twenty presumtive gene loci were resolved.