Bowman, Jeff

Globally, wildlife populations are experiencing increasing rates of range loss, population decline, and extinction. Caribou (Rangifer tarandus) have experienced dramatic declines in both range and population size across Canada over the past century. Boreal caribou (R. t. caribou), one of twelve Designatable Units, have lost approximately half of their historic range in the last 150 years, particularly along the southern edge of their distribution. Despite this northward contraction, some populations have persisted at the trailing range edge, over 150 km south of the boreal continuous range (BCR) in Ontario, along the coast and near-shore islands of Lake Superior. Better understanding the population structure and evolutionary history of caribou in the Lake Superior range (LSR) could help to inform conservation and management actions, such as the delineation of conservation or management units or translocations between populations. In this thesis, I use whole genome sequences from boreal, eastern migratory and barren-ground caribou sampled in Manitoba, Ontario, and Quebec to investigate evolutionary history and population structure. I discovered that the LSR caribou form a distinct group but also some evidence of gene flow with the BCR. Notably, caribou from the LSR demonstrated relatively high levels of inbreeding (measured as Runs of Homozygosity; ROH) and genetic drift, which may contribute to the differentiation observed between caribou occupying the two ranges. Despite inbreeding, the LSR caribou retained Heterozygosity Rich Regions (HRR). I found genomic structure among caribou populations from the LSR and BCR but found these two ranges had similar demographic histories. My analyses indicate that the LSR caribou display distinct genomic characteristics but share ancestry with the BCR, with historical gene flow between these two ranges. Collectively, this dissertation characterizes the population structure and evolutionary history of caribou from the southernmost range in Ontario, providing key insights for the conservation and management of these small and isolated populations.

Northern flying squirrels (NFS) are mycophagous specialists (fungi-dominated diet) thatmay be displaced with southern flying squirrel (SFS) range expansion, thereby limiting fungal dispersal in forest communities. To understand the implications of squirrel species turnover on mycophagy, we investigated the home ranges of both flying squirrel species who are living in stable sympatry. We found no significant difference in home range sizes and identified spatial overlap between the two species. Through habitat selection ratios we found SFS were strongly selecting for deciduous-dominated habitats more than NFS. Lastly, we conducted microscopy on flying squirrel scat and found NFS were eating more fungi than SFS. We conclude that the squirrels are sharing the same habitat landscape but are finding ways to partition the habitat accordingly to allow for sympatry. SFS may contribute to the spore-dispersal cycle similarly to their northern counterpart through moderate fungus consumption and large home range sizes.

Author Keywords: diet, flying squirrels, Glaucomys, home range, mycophagy, sympatry

Acoustic communication is vital for mediating interactions between individuals and their environment. From echolocating bats to isolated rodent pups, ultrasonic vocalizations are a useful mechanism for producing localized and cryptic acoustic signals. Flying squirrels have been demonstrated to produce almost exclusively ultrasonic calls which is rare in both squirrels and mammals, though the significance of this acoustic range is unknown. To investigate the context of ultrasonic calls in these gliding mammals, I created phylogenetic comparative analyses to compare ecological and morphological traits against call frequencies. I found that nocturnality, a trait entangled with gliding in squirrels, was related to higher-frequency calls. Furthermore, by comparing all gliding mammals and their non-gliding counterparts, I found that gliding mammals produce significantly higher frequencies than these relatives. This form of cryptic communication is likely used to avoid predation, which was further supported by behavioural experiments wherein flying squirrels used significantly higher frequencies when predation risk increased. While high frequency communication was used by most gliders, I found that ultraviolet-induced photoluminescence, another potential form of crypsis, was strongly associated with nocturnality, with half of the tested gliding mammals showing evidence of this unique colouration. While ultrasonic vocalizations are widespread in echolocating bats and echonavigating mammals, I did not find evidence to support echonavigation in flying squirrels. Instead, I found that ultrasonic vocalizations are used in a variety of social contexts and during solitary foraging and exploration. These combined results demonstrate the unique ecological and evolutionary pressures acting on small-bodied, nocturnal gliding taxa and the resulting cryptic behaviours and communication.

Author Keywords: communication, flying squirrels, gliding mammals, Sciuridae, ultrasound, ultraviolet-induced photoluminescence

Hybridization contributes to the genetic diversity and can impact speciation. This study investigates the genetic evidence of recent hybridization under climate change in sympatric populations of northern and southern flying squirrels in Ontario. Using low-coverage whole-genome sequences, my research examines the existing population structure and measures the genomic variation of the Glaucomys species. The global estimates of FST (0.308) and DXY (0.141) are indicative of substantial differentiation between the species. Measures of genetic diversity (π), differentiation (FST), and divergence (DXY) across the genome reveal insights into the divergent selection driving speciation. Results indicate an absence of contemporary hybridization or introgression at a site with longstanding sympatry. Across both species' genomes, signatures of selection align with four different scenarios for the formation of genomic landscapes of differentiation, shedding light on the complex speciation history of these flying squirrels. These findings enhance understanding of evolutionary dynamics, adaptation, speciation, and genetic differentiation.

Author Keywords: Genomic differentiation, Glaucomys, northern flying squirrel, southern flying squirrel, speciation

Muskrat populations are declining across North America. In recent decades, hybrid cattail Typha x glauca has been invading wetlands in North America. This invasion is degrading wetland habitat, leading to reduced interspersion of water and vegetation. Muskrats are wetland-obligates and their populations are positively linked to marsh interspersion. Therefore, muskrat populations may be declining due to the invasion of T. x glauca and subsequent reduction in interspersion. To test this hypothesis, I first sampled marshes across south-central Ontario, comparing muskrat densities with the relative frequency of T. x glauca and the degree of interspersion. Second, I measured intensity of use by muskrats in a large wetland along a gradient of interspersion. My findings suggest that reduced interspersion may be contributing to muskrat population declines, but it is unclear to what degree T. x glauca is responsible. Further research is needed to understand the effects of wetland invasions on muskrat populations.

Author Keywords: invasive species, Ondatra zibethicus, Southern Ontario, Typha x glauca, wetlands, wildlife conservation

Advanced generation/backcrossed (non-F1) hybrids can be challenging to identify when their traits are similar to those of parental taxa, F1 hybrids, or both. This is particularly evident in the North American hybrid zone involving Typha latifolia, T. angustifolia, F1 T. × glauca and non-F1 hybrids. Cattails are challenging to differentiate based on gross morphological characteristics. Microscopic characteristics in female inflorescences have not been previously studied to differentiate parental taxa from non-F1 hybrids. To investigate whether researchers can use microscopic floret and bracteole characteristics for taxonomic identification, I compared pistillate flower length, bracteole length and width, and bracteole colour among taxa. I found that floret and bracteole characteristics can be useful for identifying T. latifolia but cannot accurately differentiate T. angustifolia and F1 T. × glauca from non-F1 hybrids. Further, a flowering bias can lead to the underestimation of the frequency of T. latifolia when using floral characters to examine the relative abundance of cattail taxa.

Author Keywords: advanced-generation hybrids, backcrossed hybrids, invasive species, morphology, species identification, Typha spp.

Wetlands are highly susceptible to the invasion of invasive species. The invasive hybrid cattail (Typha × glauca) is prevalent in the southeastern Prairie Pothole Region (PPR) wetlands. However, concerns arise about its recent proliferation in the northwestern PPR without maternal T. angustifolia. To determine taxonomic distribution, I used species-specific PCR-RFLP and microsatellite markers for genotyping 245 samples from 50 northwest PPR sites. I found 75% T. latifolia, 7% T. angustifolia, 16% T. × glauca, and 2% backcrossed or advanced-generation hybrids. F1 T. × glauca has expanded in western PPR without its mother species, and the low occurrence of later-generation hybrids indicates their recent range expansion. Additionally, T. angustifolia offspring make fewer hybrids, which suggests that reproductive barriers may limit hybridization between parental species. This study highlights the vulnerability of prairies to cryptic invasions by Typha hybrids, and early detection of invasive species is a critical factor in wetland management success.

Increased plant size is expected to have negative consequences for mating by increasing pollen transfer among the same plant. However, recent theoretical studies have demonstrated that this may not be true for clonal plants. Instead, clonal expansion could enhance outcrossing opportunities without increasing selfing by reducing distances to potential mates. I investigated how the spatial structure of clones influences patterns of pollen dispersal, selfing rates and siring success in a natural population of Sagittaria latifolia. I found that pollen dispersal distances typically exceeded the spatial extent of clones and there was a positive association between clone size and the likelihood that clones were intermingled. Together, this resulted in a weak positive association between clone size and selfing rates, and a strong positive association between clone size and outcross siring success. This is the first empirical support for the theoretical expectation that any negative effects of selfing in large clones might be offset by increased siring success.

Author Keywords: clonal growth, fitness gain curve, geitonogamy, plant mating, plant reproductive ecology, sex allocation theory

AbstractDifferences and similarities in exploration and risk-taking behaviours of two Myotis bat species. Laura Michele Scott Behaviours that are repeatable across circumstances and time determine an individual's personality. Personality and behavioural variation are subject to selective pressures, including risks related to the use of different habitat types. I explored the ecological and evolutionary consequences of habitat selection by comparing the behaviour of two sympatric bat species, Myotis leibii and M. lucifugus. These species display overlap in roosting preferences, however, M. leibii tend to roost in crevices on the ground, while M. lucifugus tend to roost in crevices or cavities that are raised off the ground. I hypothesized that the habitat selection patterns of these two species create behavioural reaction norms at the species level. I predicted that ground roosting behaviour favours bolder personality and more exploratory and active traits when compared with bats that do not ground roost. I examined inter- and intra-specific variation in behaviour using a modified, three-dimensional open-field test and quantified the frequency and duration of behaviours such as flying, landing, and crawling. Bats were continuously video-recorded over 1-hour nocturnal and diurnal trials. I used a priori mixed models with combinations of individual characteristics and life-history traits to select the models that best describe each species. We found that M. leibii (n = 15) displayed more exploratory and bolder behaviours than M. lucifugus while on the ground (n = 21) and higher overall activity during the trial. I also found that M. leibii displayed crawling behaviours and movements consistent with foraging while on the ground which is a rare behaviour in bats and only observed in a few species (Desmodus rotundus and Mystacina tuberculate to my knowledge). Future research should explore biomechanical adaptations associated with ground-foraging in M. leibii.

Author Keywords: Bats, Behaviour, Exploration, Myotis leibii, Myotis lucifugus, Roosting

Roosts offer bats protection from predators, shelter from external environmental conditions, and a space where sociality, mating, and the rearing of young can occur. However, knowledge gaps still remain for many forest roosting species, such as the little brown bat (Myotis lucifugus) surrounding what roosts are selected, and what variables are influential at differing scales of selection. As a species-at-risk, identifying and predicting roost habitat selection may aid conservation and management. I identified forest roosts in a previously unexamined area of this species' range using radio-telemetry, and measured tree-scale characteristics of located roosts. I then used a logistic model selection process with stand-scale variables to predict roost presence across forest stands. Height of trees in a given stand was the best predictor of roost presence - which may be linked to solar exposure and other thermal benefits. I then examined roost-level variables effecting the abundance of roosting bats in an artificial roosting environment (bat boxes). I found that temperature and social effects were both significant predictors of bat abundance, with warmer minimum temperatures in the box having a positive effect. These results suggest maternal bats may select roosts with higher minimum temperatures, likely due to the energetic benefits that may be gained over the course of reproduction.

Author Keywords: forest roost, habitat selection, little brown bat, Myotic lucifugus, roost choice, stand selection