Upper Klamath Lake in southern Oregon has two species of lacustrine suckers, Lost River sucker Deltistes luxatus and shortnose sucker Chasmistes brevirostris that were historically abundant. Results of surveys performed in the mid-1980's indicated that populations of both species were declining and ageing with apparent recruitment failure in most years since 1970. In 1988 both species were listed as endangered species and high priority has been placed on investigating recruitment of Upper Klamath Lake suckers. Lapilli are the preferred otolith for ageing suckers. Lapilli form predictably on the day of hatch, have the most conservative morphology of the three otoliths, and deposit easily discernable increments that begin on the day of hatch and proceed daily, and grow in a predictable relationship with somatic growth. Ages estimated by otolith analysis and resulting hatch dates of young-of-the-year Lost River sucker and shortnose sucker were consistent annually and consistent with reported spawning period for suckers from Upper Klamath Lake. Otolith increment analysis is necessarily lethal, whereas scale circuli analysis is not lethal. My findings suggest that scale circuli count is an inefficient estimator of daily Daily age estimates for age in young-of-the-year Lost River sucker and shortnose sucker. any given circuli count varied by approximately 51 days in Lost River sucker and 30 days Additionally, my results do not accurately predict the size or age at in shortnose sucker. which scales are formed, thereby invalidating an assumption of age and growth models. Consequently, scale circuli analysis cannot be used to produce accurate estimates of age or growth for young-of-the-year Lost River sucker and shortnose sucker. Lost River sucker and shortnose sucker achieve a relatively large size by the autumn of their first year, consistent with other members of Catostomidae. Interspecific difference in growth rates was evident in each year with Lost River sucker exhibiting faster growth than shortnose sucker in each year. Abundance of young-of-the-year suckers does not appear to be strongly correlated to somatic growth rate, though hatch date and environmental parameters are highly correlated with abundance. In both Lost River sucker and shortnose sucker, in years with the highest abundance (1991 and 1993), the mean hatch dates of surviving fish were later than in years with the lowest abundance. Also, young-of-the-year Lost River sucker and shortnose sucker experienced wide environmental fluctuations in Upper Klamath Lake as seasonal limnological and climatic variation create a dynamic habitat for young suckers. Water temperature, precipitation, air temperature, and minimum lake elevation are all strongly correlated to abundance of young-of-the-year suckers. / Graduation date: 1999

Understanding how biodiversity evolves is a major goal in evolutionary developmental biology because changes in developmental processes are tightly linked with evolutionary diversification. Heterochrony--alteration to the rate or timing of development--can significantly alter the appearance of descendant species. Heterochronic shifts in gene expression and associated morphological change may explain the morphological divergence between the threatened June sucker (Chasmistes liorus) and the sympatric Utah sucker (Catostomus ardens) in Utah Lake, UT, USA. June sucker are endemic to Utah Lake and have subterminal mouths adapted for pelagic feeding, while Utah sucker (Catostomus ardens) have ventral mouths adapted for benthic feeding. As larvae, both June sucker and Utah sucker have terminal mouths. However, within the first 14 weeks of development, the Utah sucker's mouth shifts to a ventral position, whereas the June sucker's mouth only shifts to a subterminal position. Using geometric morphometrics and RNA-seq time courses, we document a difference in the timing of shape development and a corresponding change in the timing of gene expression between June sucker and two Utah sucker lineages. Our results suggest that the distinctive mouth morphology in June sucker may be the result of paedomorphosis in which adult June sucker exhibit an intermediate mouth morphology between that of the larval (terminal) and ancestral (ventral) states. On a broader scale, additional Chasmistes / Catostomus pairs exist in the Intermountain West that are also morphologically divergent, but genetically similar. These pairs could be the result of repeated convergent evolution driven by differential expression of genes in response to environmental cues.

The purpose of this study is to add to our knowledge of the embryology and osteology of the Weberian apparatus as found in the sucker, Catostamus ardens J. & G. ot Utah Lake. Observations were made on the embryological development for twenty one days. This information has been discussed and pictures showing the development included. The literature on the osteology ot the Weberian apparatus was reviewed and it is believed that this study presents the first descriptions of the bones of this species. The ossicles were found to be comparatively stable within species indicating some taxonomic value. More study is needed, however, before any definite statement can be made.

Several hypotheses from community ecology were tested using habitat and diet patterns for six catostomid fishes of the Assiniboine River, Manitoba. Specifically, I examined expected assemblage patterns based on the equilibrium-nonequilibrium continuum that are based on competition as a structuring mechanism. The catostomid assemblage showed characteristics of both equilibrium and nonequilibrium assemblages. Habitat utilization was not proportional to habitat availability for depth, velocity, and substrate indicating habitat selection occurs. These patterns are influenced by the distributions of soft Lake Agassiz deposits and harder glacial till-plain habitats and therefore localized. Species co-occurred in relation to abundance indicating negative associations assumed in competition-based theory were not apparent. In addition, species from the same subfamily co-occurred more often than expected by chance, indicating positive within-group comparisons, except for silver redhorse, which did not co-occur differently than random. Species from the same feeding group co-occur most frequently with conspecifics, indicating species have specific habitat patterns. Benthic invertebrate distributions and fish distributions were positively correlated with fish diet. Within-feeding-group comparisons indicated species that co-occurred frequently consumed the same food items, but showed subtle differences in abundance of diet items. The most common diet items varied among white sucker, silver redhorse, golden redhorse, and shorthead redhorse, indicating that, although these species co-occur, subtle differences in feeding behavior may account for differences in relative abundance and frequency of diet items. Quillback and bigmouth buffalo shared a few core food items, but co-occurred infrequently. Inter-specific interactions showed silver redhorse diets were a subset of white sucker diets, white sucker diets were a subset of golden redhorse diets, shorthead redhorse diets were a subset of silver redhorse and golden redhorse diets, while bigmouth buffalo diets were a subset of quillback diets. Lower richness and prevalence of organisms in quillback and bigmouth buffalo diets were due to highly aggregated prey items. Benthic invertebrate distributions were aggregated and dependent on the predictable patterns of substrates, based on hydraulic sorting in the meandering along the river. Large-scale redundancy of species-habitat associations was correlated with historical (phylogenetic) or adaptive (morphological) constraints on habitat selection. Stream habitats are constrained by regional factors of slope and sediments, but also determined by stable, repetitive and predictable local processes of erosion, transport, and deposition (meandering). The fish-habitat associations of catostomids in the Assiniboine River provide an example of interaction between the abundance of the component species, the phylogenetic constraints on the niche, and the deterministic nature of the spatial distribution of habitats. Within-feeding-group pairs showed that local habitat overlap is positively correlated with geographic overlap, while local diet overlap is negatively correlated with geographic overlap. Two species pairs (silver redhorse and golden redhorse and bigmouth buffalo and quillback) were concluded to have symmetric overlaps at the geographic scale and stable interactions. Using the functional niche concept ecological theory provides a link between ecology and biogeography of sympatric species. The multi-analytical approaches in this study provide insights into the structuring of north temperate prairie river fish communities, through hypothesis testing and correlation that have application beyond Prairie Rivers. / October 2005

Several hypotheses from community ecology were tested using habitat and diet patterns for six catostomid fishes of the Assiniboine River, Manitoba. Specifically, I examined expected assemblage patterns based on the equilibrium-nonequilibrium continuum that are based on competition as a structuring mechanism. The catostomid assemblage showed characteristics of both equilibrium and nonequilibrium assemblages. Habitat utilization was not proportional to habitat availability for depth, velocity, and substrate indicating habitat selection occurs. These patterns are influenced by the distributions of soft Lake Agassiz deposits and harder glacial till-plain habitats and therefore localized. Species co-occurred in relation to abundance indicating negative associations assumed in competition-based theory were not apparent. In addition, species from the same subfamily co-occurred more often than expected by chance, indicating positive within-group comparisons, except for silver redhorse, which did not co-occur differently than random. Species from the same feeding group co-occur most frequently with conspecifics, indicating species have specific habitat patterns. Benthic invertebrate distributions and fish distributions were positively correlated with fish diet. Within-feeding-group comparisons indicated species that co-occurred frequently consumed the same food items, but showed subtle differences in abundance of diet items. The most common diet items varied among white sucker, silver redhorse, golden redhorse, and shorthead redhorse, indicating that, although these species co-occur, subtle differences in feeding behavior may account for differences in relative abundance and frequency of diet items. Quillback and bigmouth buffalo shared a few core food items, but co-occurred infrequently. Inter-specific interactions showed silver redhorse diets were a subset of white sucker diets, white sucker diets were a subset of golden redhorse diets, shorthead redhorse diets were a subset of silver redhorse and golden redhorse diets, while bigmouth buffalo diets were a subset of quillback diets. Lower richness and prevalence of organisms in quillback and bigmouth buffalo diets were due to highly aggregated prey items. Benthic invertebrate distributions were aggregated and dependent on the predictable patterns of substrates, based on hydraulic sorting in the meandering along the river. Large-scale redundancy of species-habitat associations was correlated with historical (phylogenetic) or adaptive (morphological) constraints on habitat selection. Stream habitats are constrained by regional factors of slope and sediments, but also determined by stable, repetitive and predictable local processes of erosion, transport, and deposition (meandering). The fish-habitat associations of catostomids in the Assiniboine River provide an example of interaction between the abundance of the component species, the phylogenetic constraints on the niche, and the deterministic nature of the spatial distribution of habitats. Within-feeding-group pairs showed that local habitat overlap is positively correlated with geographic overlap, while local diet overlap is negatively correlated with geographic overlap. Two species pairs (silver redhorse and golden redhorse and bigmouth buffalo and quillback) were concluded to have symmetric overlaps at the geographic scale and stable interactions. Using the functional niche concept ecological theory provides a link between ecology and biogeography of sympatric species. The multi-analytical approaches in this study provide insights into the structuring of north temperate prairie river fish communities, through hypothesis testing and correlation that have application beyond Prairie Rivers.

Several hypotheses from community ecology were tested using habitat and diet patterns for six catostomid fishes of the Assiniboine River, Manitoba. Specifically, I examined expected assemblage patterns based on the equilibrium-nonequilibrium continuum that are based on competition as a structuring mechanism. The catostomid assemblage showed characteristics of both equilibrium and nonequilibrium assemblages. Habitat utilization was not proportional to habitat availability for depth, velocity, and substrate indicating habitat selection occurs. These patterns are influenced by the distributions of soft Lake Agassiz deposits and harder glacial till-plain habitats and therefore localized. Species co-occurred in relation to abundance indicating negative associations assumed in competition-based theory were not apparent. In addition, species from the same subfamily co-occurred more often than expected by chance, indicating positive within-group comparisons, except for silver redhorse, which did not co-occur differently than random. Species from the same feeding group co-occur most frequently with conspecifics, indicating species have specific habitat patterns. Benthic invertebrate distributions and fish distributions were positively correlated with fish diet. Within-feeding-group comparisons indicated species that co-occurred frequently consumed the same food items, but showed subtle differences in abundance of diet items. The most common diet items varied among white sucker, silver redhorse, golden redhorse, and shorthead redhorse, indicating that, although these species co-occur, subtle differences in feeding behavior may account for differences in relative abundance and frequency of diet items. Quillback and bigmouth buffalo shared a few core food items, but co-occurred infrequently. Inter-specific interactions showed silver redhorse diets were a subset of white sucker diets, white sucker diets were a subset of golden redhorse diets, shorthead redhorse diets were a subset of silver redhorse and golden redhorse diets, while bigmouth buffalo diets were a subset of quillback diets. Lower richness and prevalence of organisms in quillback and bigmouth buffalo diets were due to highly aggregated prey items. Benthic invertebrate distributions were aggregated and dependent on the predictable patterns of substrates, based on hydraulic sorting in the meandering along the river. Large-scale redundancy of species-habitat associations was correlated with historical (phylogenetic) or adaptive (morphological) constraints on habitat selection. Stream habitats are constrained by regional factors of slope and sediments, but also determined by stable, repetitive and predictable local processes of erosion, transport, and deposition (meandering). The fish-habitat associations of catostomids in the Assiniboine River provide an example of interaction between the abundance of the component species, the phylogenetic constraints on the niche, and the deterministic nature of the spatial distribution of habitats. Within-feeding-group pairs showed that local habitat overlap is positively correlated with geographic overlap, while local diet overlap is negatively correlated with geographic overlap. Two species pairs (silver redhorse and golden redhorse and bigmouth buffalo and quillback) were concluded to have symmetric overlaps at the geographic scale and stable interactions. Using the functional niche concept ecological theory provides a link between ecology and biogeography of sympatric species. The multi-analytical approaches in this study provide insights into the structuring of north temperate prairie river fish communities, through hypothesis testing and correlation that have application beyond Prairie Rivers.

This project focused on the relationship between instream flows and smallmouth buffalo (Ictiobus bubalus) recruitment in the Gulf Coastal Plain of Texas. The flow regime is the dominant factor in lotic systems and, consequently, the relationship between instream flows, including impacts to natural flow regimes, and life-history is a subject of growing interest. Smallmouth buffalo is a good model to investigate the relationship between river flows and variable interannual recruitment success of periodic life-history strategist fish species. Smallmouth buffalo were collected from the Brazos, Colorado, and Guadalupe Rivers of Texas, U.S.A., and otoliths were extracted from individuals in the field and sectioned and photographed in the lab. Photographs of sectioned otoliths were used to estimate age and thus the year in which the individual was spawned by counting back from the time of capture. Population age structure (i.e. a ‘state' or condition at a point in time) was used to infer effects of flow variation on a rates-based process (i.e. recruitment). After controlling for mortality using recruitment index values, interannual variation in recruitment was modeled using multiple components of the flow regime quantified as indicators of hydrologic alteration (IHA) variables based on daily discharge data from USGS gaging stations in each river system. Model selection followed a two-tier approach, first fitting models using only flow attributes associated with the spawning season then adding additional informative parameters from the pre-spawn and post-spawn periods. The primary finding from model selection was that duration of high flow pulses during the spawning season is a critical component of the flow regime associated with successful Smallmouth Buffalo recruitment. These findings have implications for river management and conservation of ecological integrity, in particular populations of periodic life-history strategist species.

Low copy number anonymous nuclear loci were used to search for species markers in four species of Klamath Basin suckers. We sequenced 28 randomly chosen loci representing 10,421 bp; 21 loci were similar to sequences in GenBank. Eight fixed sequence differences were found among Klamath species. Locus 120 contained rare but diagnostic markers for Deltistes luxatus and for Catostomus rimiculus. Locus 4 also contained three rare but unique sites in Catostomus rimiculus. No sequence differences were found between Chasmistes brevirostris and Catostomus snyderi. Loci 4 and 120 exhibited allele frequency differences between Rogue River C. rimiculus and all Klamath Basin suckers. Genotype BB of locus 4 was a fixed diagnostic marker and genotype BB of locus 120 was a frequency dependent marker for Rogue C. rimiculus. Although Klamath suckers represent three genera, very limited variation was found among 10,431 base pairs. We examined phylogenetic patterns of five loci in eleven catostomid genera and 25 species to determine if the homogeneity in the Upper Klamath Basin was due to massive hybridization and introgression or to retention of ancestral sequences. Two loci with no similarity to GenBank sequences (non-coding loci) and three loci with substantial similarity to GenBank sequences (coding loci) gave similar results, providing support for various subfamilies and tribes, more support for eastern genera and little support for western genera. Each locus was a mosaic of species or population markers, sometimes providing discriminatory power for allopatric populations of a species, such as C. macrocheilus, while not discriminating other species. Upper Klamath Basin species were noteworthy in their lack of autapomorphies, but had similar numbers of derived informative sites as other catostomins. Upper Klamath Basin species consistently shared ancestral or equivocal informative sites either with moxostomatins or a variable group of western species and shared derived sites with other western species, especially C. occidentalis. The data suggest that Upper Klamath Basin species have retained a largely ancestral genome at these loci. Thus, the failure of this technique to uncover significant variation in Upper Klamath Basin species may be a reflection of their plesiomorphic genome at these loci and not necessarily hybridization. / Graduation date: 2004

The archaeology of the Northern Rio Grande region of New Mexico has recently received an increased amount scholarly attention. In particular, understanding past trends in demographics, agricultural productivity, violence, and social networks have been primary goals of archaeological research. Understanding patterns in animal exploitation has, however, received far less attention due to a small yet growing regional zooarchaeological database. Through the identification of animal remains from a site called Ponsipa (occupied ca. A.D. 1300 to 1600), this thesis adds one large dataset to this growing database. In addition, this thesis expands on the pre-impoundment distribution of an endangered native freshwater fish species in the state of New Mexico called the blue sucker (Cycleptus elongatus). The blue sucker is a unique fish that is currently experiencing range reduction across all of its known North American distribution due to anthropogenic habitat fragmentation and degradation. Skeletal remains that were identified from Ponsipa represent the farthest known northern record of its occurrence in the state of New Mexico and highlight the extent of range restriction of the species in the area. The data concerning the historical biogeography of the blue sucker from Ponsipa have implications for the effective conservation and restoration of blue sucker located in the Rio Grande Basin.