Graduate Theses & Dissertations

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Investigating the regional variation in frequencies of the invasive hybrid cattail, Typha × glauca
Interspecific hybridization rates can vary depending on genomic compatibilities between progenitors, while subsequent hybrid spread can vary depending on hybrid performance and habitat availability for hybrid establishment and persistence. As a result, hybridization rates and hybrid frequencies can vary across regions of parental sympatry. In areas around the Laurentian Great Lakes, Typha × glauca is an invasive plant hybrid of native Typha latifolia and introduced Typha angustifolia. In areas of parental sympatry in Atlantic Canada and outside of North America, T. × glauca has been reported as either rare or non-existent. I investigated whether the low frequencies of hybrids documented in Nova Scotia, Atlantic Canada, are influenced by reproductive barriers that prevent hybrid formation or environmental factors (salinity) that reduce hybrid performance. I identified an abundance of hybrids in the Annapolis Valley (inland) and a scarcity of hybrids in coastal wetlands through preliminary site surveys throughout Nova Scotia. In Annapolis Valley populations, flowering times of progenitor species overlapped, indicating that asynchronous flowering times do not limit hybrid formation in this region. Viable progeny were created from interspecific crosses of T. latifolia and T. angustifolia from Nova Scotia, indicating that there are no genomic barriers to fertilization and germination of hybrid seeds. Typha × glauca germination in high salinity was significantly lower than that of T. latifolia, but there was no difference at lower salinities. Therefore, while germination of hybrid seeds may be impeded in the coastal wetlands where salinity is high, inland sites have lower salinity and thus an environment conducive to hybrid germination. However, I found that once established as seedlings, hybrids appear to have greater performance over T. latifolia across all salinities through higher ramet production. Moreover, I found that T. latifolia sourced from Ontario had reduced germination and lower survivorship in high salinities compared to T. latifolia sourced from Nova Scotia, which could indicate local adaptation by T. latifolia to increased salinity. These findings underline that interactions between environment and local progenitor lineages can influence the viability and the consequent distribution and abundance of hybrids. This, in turn, can help explain why hybrids demonstrate invasiveness in some areas of parental sympatry but remain largely absent from other areas. Author Keywords: flowering phenology, Hybridization, invasive species, physiology, pollen compatibility, salinity tolerance
Patterns of Vegetation Succession on Nickel-Copper Mine Tailings near Sudbury, Ontario
Natural establishment of vegetation on mine tailings is generally limited. Understanding the processes leading to vegetation germination and the survival mechanisms that vegetation species employ in these harsh environments is critical to future remediation efforts. As metalliferous mine tailings are generally nutrient-poor, high in harmful metals, and acidic, vegetation species require distinct mechanisms to germinate and survive in such harsh environments. In this study, edaphic and biotic factors linked to vegetation establishment and diversity were studied at two nickel-copper (Ni-Cu) tailings sites near Sudbury, Ontario. One site had experienced minimal treatment, and the second site was split into partial (hand-distribution of lime) and full (lime, fertilizer, seeding) treatment areas. Tailings were generally acidic, low in organic matter and “available” nutrients, and high in metals such as Al, Cu, Fe, and Ni, but these physical and chemical properties were extremely spatially variable. At both sites, vegetation was distributed in sparse patches, with the greatest diversity in treated areas. There was no clear link between metals and vegetation establishment/diversity at the sites. The primary limiting nutrients on the tailings were phosphorous (P) and potassium (K), and while there were areas of increased soil fertility at the sites, they were not clearly associated with increased vegetation diversity. Both traditional ecological succession and nucleation succession patterns were observed on the site, and the chief species associated with nucleation were primary colonizing trees such as B. papyrifera and P. tremuloides. The relationship between B. papyrifera nutrient retranslocation and tailings restoration was assessed and while B. papyrifera at the sites were deficient in P and K, the trees efficiently retranslocated both P and K during senescence. This research can provide insight into possibilities for future revegetation of similar tailings, enabling industry to make educated decisions when choosing where and how to revegetate, mimicking natural succession patterns. Author Keywords: Acid-mine drainage, Betula papyrifera, ecosystem health, metals, Sudbury, tailings
Shorebird Habitat Use and Foraging Ecology on Bulls Island, South Carolina During the Non-Breeding Season
Recent declines in North American shorebird populations could be linked to habitat loss on the non-breeding grounds. Sea-level rise and increased frequency of coastal storms are causing significant erosion of barrier islands, thereby threatening shorebirds who rely on shoreline habitats for foraging. I conducted shorebird surveys on Bulls Island, South Carolina in the winters of 2018 and 2019 and examined habitat selection and foraging behaviour in Dunlin (Calidris alpina), Sanderling (Calidris alba), Semipalmated Plovers (Charadrius semipalmatus), and Piping Plovers (Charadrius melodus). Area, tidal stage, and invertebrate prey availability were important determinants of shorebird abundance, behaviour, and distribution. My study highlights the importance of Bulls Island’s habitat heterogeneity to supporting a diverse community of non-breeding shorebirds. Considering both the high rate of erosion and the increased frequency of disturbance along the shoreline of the island, intertidal habitats should be monitored to predict negative effects of changes in habitat composition and area on non-breeding shorebirds. Author Keywords: foraging behaviour, habitat loss, habitat selection, invertebrate prey, non-breeding, shorebirds
Discriminating grey wolf (Canis lupus) predation events in a multi-prey system in central Saskatchewan
I investigated if spatio-temporal behaviour of grey wolves (Canis lupus) determined via GPS collar locations could be used to discriminate predation events generally, and among prey species, in Prince Albert National Park during winter, 2013-2017. I used characteristics of spatio-temporal GPS clusters to develop a predictive mixed-effect logistic regression model of which spatial clusters of locations were wolf kill sites. The model suffered a 60 % omission error when tested with reserved data due to the prevalence of deer kills with correspondingly low handling time. Next, I found a multivariate difference in the percentage of habitat classes used by wolves in the 2 hours preceding predation events of different prey species, suggesting that wolf habitat use reflects prey selection at a fine-scale. My results highlight the difficulty and future potential for remoting discriminating wolf predation events via GPS collar locations in multi-prey ecosystems. Author Keywords: Canis lupus, GPS clusters, GPS collars, grey wolf, habitat use, predation
multi-faceted approach to evaluating the detection probability of an elusive snake (Sistrurus catenatus)
Many rare and elusive species have low detection probabilities, thereby imposing unique challenges to monitoring and conservation. Here, we assess the detection probability of the Eastern Massasauga (Sistrurus catenatus) in contrast to a more common and conspicuous species, the Eastern Gartersnake (Thamnophis sirtalis). We found that patterns of detection probability differed between species, wherein S. catenatus was detected less often and under a more specific set of sampling conditions. Correspondingly, detection trials with S. catenatus found a high non-detection rate, while detection trials with artificial models suggest that regional differences in detection probability are driven by variation in population density and habitat use. Our results suggest that current monitoring efforts are not sufficient, and that S. catenatus is frequently undetected. Accordingly, we highlight the importance of species-specific monitoring protocols when monitoring rare and elusive species, and recommend a multi-faceted approach that estimates detection probability and identifies species-specific challenges to monitoring. Author Keywords: detection probability, elusive species, monitoring programs, non-detection, S. catenatus, snakes
Indirect Effects of Hyperabundant Geese on Sympatric-Nesting Shorebirds
Rising populations of Lesser Snow and Ross’ geese (hereafter collectively referred to as light geese) breeding in the North American Arctic have caused significant environmental change that may be affecting some populations of nesting shorebirds, which in contrast to geese, have declined dramatically. In this thesis I examine the indirect effects of light geese on sympatric-nesting shorebirds. I first conduct a literature review of the effects of light geese on northern wildlife and outline multiple mechanisms in which geese may affect shorebirds in particular. Using bird survey data collected in plots situated across the Canadian Arctic from 1999 to 2016, I then identify spatial effects of light goose colonies on shorebird, passerine, and generalist predator densities. The densities of cover- nesting shorebirds and passerines were depressed near goose colonies while the densities of open-nesting shorebirds were less so. Next, using habitat data collected at random sites and shorebird nest sites situated at increasing distances from a goose colony on Southampton Island, Nunavut, I outline the effects of geese on shorebird nest site selection. I found that the availability of sedge meadow and amount of lateral concealment increased as a function of distance from goose colony; cover-nesting shorebirds selecting nest sites with less concealment and sedge meadow near the colony. Then, to characterize spatial effects of light geese on predators and risk of predation I used time-lapse cameras and artificial shorebird nests placed at increasing distances from the goose colony. Activity indices of gulls, jaegers, and foxes were all negatively correlated with distance from the goose colony while the reverse was true for artificial nest survival probability. Finally, I relate changes in ground cover to goose use and link these changes to variation in invertebrate communities. I then use DNA metabarcoding to characterize the diet of six shorebird species across study sites and identify inter-site variation in the biomass of dominant shorebird prey items. Prey item biomass was elevated at the two study sites near the goose colony potentially indicating an enhancing effect of goose fecal deposition. Overall, I show that light geese interact with shorebirds in multiple ways and negatively affect their habitat availability, nest site selection, and risk of predation, effects that likely outweigh the positive effects of enhanced prey availability. Author Keywords:
Detectability and its role in understanding upland sandpiper (Bartramia longicauda) occurence in the fragmented landscape of southern Ontario
Upland Sandpipers (Bartramia longicauda), like many grassland birds, are undergoing population decline in parts of their range. Habitat fragmentation and change have been hypothesized as potential causes of decline. I used citizen-science occurrence data from Wildlife Preservation Canada’s Adopt-A-Shrike Loggerhead Shrike (Lanius ludovicianus) program in conjunction with validation surveys, using similar point-count methods, to examine detectability and determine if landscape level habitat features could predict occupancy of Upland Sandpipers in Southern Ontario. In a single season detectability study, I used Wildlife Preservation Canada’s survey protocol to determine detectability in sites that were known to be occupied. Detectability was low, with six surveys necessary to ensure detection using a duration of at least 18 minutes early in the breeding season. The proportion of open habitat did not affect detection on the landscape. Using a larger spatial and temporal scale, with five years of citizen-science data, I showed that Annual Crop Inventory data could not effectively predict Upland Sandpiper occupancy. Model uncertainty could be attributed to survey protocol and life history traits of the Upland Sandpiper, suggesting that appropriate survey methods be derived a priori for maximizing the potential of citizen-science data for robust analyses. Author Keywords: Bartramia longicauda, citizen-science, detection, landscape, occupancy, Ontario
Genomic architecture of artificially and sexually selected traits in white-tailed deer (Odocoileus virginianus)
Understanding the complex genomic architecture underlying quantitative traits can provide valuable insight for the conservation and management of wildlife. Despite improvements in sequencing technologies, few empirical studies have identified quantitative trait loci (QTL) via whole genome sequencing in free-ranging mammal populations outside a few well-studied systems. This thesis uses high-depth whole genome pooled re-sequencing to characterize the molecular basis of the natural variation observed in two sexually selected, heritable traits in white-tailed deer (Odocoileus virginianus, WTD). Specifically, sampled individuals representing the phenotypic extremes from an island population of WTD for antler and body size traits. Our results showed a largely homogenous genome between extreme phenotypes for each trait, with many highly differentiated regions throughout the genome, indicative of a quantitative model for polygenic traits. We identified and validated several potential QTL of putatively small-to-moderate effect for each trait, and discuss the potential for real-world application to conservation and management. Author Keywords: evolution, extreme phenotypes, genetics, genomics, quantitative traits, sexual selection
Fish and invertebrate use of invasive Phragmites in a Great Lakes freshwater delta
Invasive Phragmites australis ssp. australis (herein “Phragmites”) has established and rapidly spread throughout many coastal areas of the Great Lakes. Known to displace native vegetation communities as it forms large, monotypic stands, Phragmites has a bad reputation when it comes to losses of biodiversity and habitat provision for wildlife. However, the extent to which Phragmites provides habitat for fish and invertebrates in coastal freshwater wetlands remains relatively unquantified. Thus, this study assessed whether fish assemblages and invertebrate communities in stands of Phragmites differ from those in stands of two native emergent vegetation communities, Typha spp. and Schoenoplectus spp. The findings showed significant differences in habitat variables among the vegetation communities in terms of water depth, macrophyte species richness, stem density and water quality. While abundance of the functional feeding group filterer-collectors was found to be significantly less in stands of Phragmites when compared to Schoenoplectus, no difference was observed in invertebrate taxa richness among vegetation communities. Lastly, no difference in fish assemblage or invertebrate community was detected when using multivariate analyses, implying that invasive Phragmites provides habitat that appears to be as valuable for fish and invertebrates as other emergent vegetation types in the St. Clair River Delta. The findings of this study will ultimately benefit the literature on invasive Phragmites and its role as fish habitat in freshwater wetlands, and aid management agencies in decisions regarding control of the invasive species. Author Keywords: aquatic invasive species, aquatic macroinvertebrates, freshwater fish, freshwater wetlands, nMDS, Phragmites
Habitat selection by sympatric Canada lynx (Lynx canadensis) and bobcat (Lynx rufus)
Range expansion by the bobcat (Lynx rufus) may be contributing to range contraction by the Canada lynx (Lynx canadensis), but interactions between them are not well understood. To investigate the potential for competition, I conducted a literature review of hierarchical habitat selection by these two species. I determined that the lynx and the bobcat select different resources at the first and second orders, and that the fourth order is under-studied compared to higher orders. I therefore conducted a snow-tracking study of fine-scale habitat selection by lynx and bobcat in an area of sympatry in northern Ontario. I found that the two species selected similar resources at the fourth order, but appeared to be allopatric at the level of the home range. These results suggest that competition is unlikely to occur between lynx and bobcat, and other factors should be considered as more probable causes of the lynx range contraction. Author Keywords: Bobcat, Canada lynx, Competition, Habitat selection, Scale, Snow tracking
Temporo-spatial patterns of occupation and density by an invasive fish in streams
Since its introduction to North America in the 1990s, the Round Goby has spread throughout the Great Lakes, inland through rivers and is now moving into small tributary streams, a new environment for this species in both its native and invaded ranges. I explored density and temporal occupation of Round Gobies in four small streams in two systems in south-central Ontario, Canada in order to determine what habitat variables are the best predictors of goby density. Two streams are tributaries of Lake Ontario and two are tributaries of the Otonabee River, and all of these streams have barriers preventing upstream migration. I found that occupation and density differed between the systems. In the Otonabee River system, Round Gobies occupy the streams year round and the most important factor determining adult density is distance from a barrier to upstream movement, with the entire stream occupied but density highest next to the barriers. In the Lake Ontario system, density is highest at mid-stream and Round Gobies appear to occupy these streams mainly from spring to fall. Adult density in Lake Ontario tributaries is highest in sites with a high percentage of cobble/boulder and low percentage of gravel substrate, while substrate is less important in Otonabee River tributaries. Occupation and density patterns may differ due to contrasting environmental conditions in the source environments and distance to the first barrier preventing upstream movement. This study shows diversity in invasion strategies, and provides insight into the occurrence and movement patterns of this species in small, tributary streams. Author Keywords: biological invasion, Generalised Additive Mixed Model, habitat, Neogobius melanostomus, Round Goby, stream
Do birds of a feather flock together
Populations have long been delineated by physical barriers that appear to limit reproduction, yet increasingly genetic analysis reveal these delineations to be inaccurate. The eastern and mid-continent populations of sandhill cranes are expanding ranges which is leading to convergence and warrants investigation of the genetic structure between the two populations. Obtaining blood or tissue samples for population genetics analysis can be costly, logistically challenging, and may require permits as well as potential risk to the study species. Non-invasively collected genetic samples overcome these challenges, but present challenges in terms of obtaining high quality DNA for analysis. Therefore, methods that optimize the quality of non-invasive samples are necessary. In the following thesis, I examined factors affecting DNA quality and quantity obtained from shed feathers and examined population differentiation between eastern and mid-continent sandhill cranes. I found shed feathers are robust to environmental factors, but feather size should be prioritized to increase DNA quantity and quality. Further, I found little differentiation between eastern and mid-continent populations with evidence of high migration and isolation-by-distance. Thus, the two populations are not genetically discrete. I recommend future population models incorporate migration between populations to enhance our ability to successfully manage and reach conservation objectives. Author Keywords: feathers, genetic differentiation, non-invasive DNA, population genetics, population management, sandhill crane (Antigone canadensis)

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