There is a growing recognition that conservation programs using hatchery-reared fish should strive to produce individuals that represent phenotypes present in natural environments. Size variability within cohorts, mediated through inter-individual differences in growth rates, provides one avenue by which phenotype can be studied. High growth rates are generally equated with greater fitness. However, there is evidence that fish with slower relative growth and smaller sizes continue to persist within populations. This thesis aimed to better understand the causes and potential implications of variable sizes and growth rates on the potential recruitment of hatchery-reared Lake Sturgeon, Acipenser fulvescens. Studies were developed to 1) determine the mechanisms behind these observed variations and 2) assess the behavioural and physiological consequences of being either a fast- or slow-grower (i.e., large or small). Laboratory studies concluded that external factors, most notably the presence of conspecifics during feeding events, influenced size variability more than inherent predispositions towards faster or slower growth. Examination of size-dependent versus size-independent feeding interactions further confirmed that variability does not appear to be the result of underlying fixed behaviours. The consequence of slower growth rates and smaller sizes did not lead to higher mortality or reduced body condition during a low temperature challenge. Recapture rates and downstream movements following stocking events of both young-of-the-year (YOY) and yearling Lake Sturgeon in the Winnipeg River, Manitoba could not be correlated to inter-individual differences in size. Although initial study on the cause of growth and size divergence may lead one to conclude that slow-growing (i.e., small) Lake Sturgeon represent a substandard phenotype, subsequent studies could not point to inferior performance of these individuals when compared to faster-growing (i.e., large) individuals of the same age. As such, the practice of size-selection for relatively faster-growing and larger individuals in future Lake Sturgeon enhancement programs is discouraged, at least until there are more conclusive findings to suggest otherwise. Future studies should continue to look at recruitment in relation to growth rate and size among naturally produced Lake Sturgeon juveniles in order to put the results of this research into context.

No description available.

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

This study seeks to investigate whether the biodiversity conservation of the Sinharaja rainforest in Sri Lanka can be economically justified solely in terms of its non-timber forest products (NTFPs) extraction potential as claimed by some recent research. A variety of methods and techniques were deployed including a botanical inventory survey, a crosssectional ethnobotanical survey, an ethnobotanical log-book survey and an ethnozoological survey. Several aspects relating to the NTFPs use: a) valuing the total inventory stock, the total extractable stock limit, the potential flow and actual flow; b) estimating the wild meat flow; c) seasonality of harvesting; d) sustainability issues; e) influence of phytosociological characteristics; f) influence of socio-economic characteristics; and g) forest accessibility; and h) market accessibility were investigated. Biophysical and socio-economic factors influencing the NTFPs value were investigated using a regression analysis. The impact of the NTFPs extraction on the regeneration of the natural population was investigated using three forest sites, a proximal site, a distant site, and a logged forest. The local peoples' perception about the sustainability of NTFPs harvesting was analysed using logit regression analysis. A geographic information system was used to investigatet he influenceo f accessibilityt o the forest and to the marketplace from the villages on the forest products flow. Finally, the NTFPs value was compared with alternative land-clearance use and timber use values. The results indicate that the NTFPs extraction value is insufficient on its own to economically justify the rainforest biodiversity conservation in Sri Lanka, and perhaps elsewhere. There is also some doubt about the long term sustainability of forest products extraction. The study concludes that the rainforest conservation will have to be justified by a full total economic value (use and non-use values) appraisal, together with other scientific and ethical reasoning and cannot be promoted solely on the basis of non-timber extraction value.

<p> Habitat use by federally threatened California Red-Legged Frogs (CRLF; <i>Rana draytonii</i>) is incompletely understood. I captured, PIT-tagged, and radio-tracked CRLFs (n = 20) at Waddell Creek, Santa Cruz County, from July&ndash;December 2012. Limited tracking for movements was also conducted in 2013. Frogs were clumped in deep, complex habitats along the stream within 2 km of breeding ponds near the stream mouth, but most adults were concentrated in the lagoon. Marked and tracked frogs had very small summer home ranges, and most returned to the same home range after breeding. Frogs tended to use good aquatic (e.g., wood, undercut banks, dense willows) and bank cover (e.g., ground vegetation, wood) at all times but used open habitats more at night than during the day. Visual night surveys were biased against cryptic frogs compared to radio-tracking results. Early fall rains increased upland habitat use, but later heavy winter rains were needed to trigger migration to breeding sites and subsequent breeding. Site-specific studies using radio-tracking are needed to design protections for breeding, migration, and nonbreeding habitats.</p>

<p> Individual variation and fitness are the cornerstones of evolution by natural selection. The trophic niche represents an important source of phenotypic variation on which natural selection can act. Although individual variation is fundamental to species-level ecological and evolutionary change, individual variation is often ignored in population-level approaches to wildlife ecology, conservation and management. Failing to link individual resource use to fitness or to biological outcomes related to fitness limits us to managing for the average resource needs of a population, which may be insufficient for protecting the diversity of resource use within populations and the underlying eco-evolutionary processes that generate that diversity. My goals were to provide insights into the mechanisms that generate and constrain intrapopulation trophic niche variation, evaluate whether linkages exist between individual biological outcomes and variation in food habits across the range of resources consumed within generalist consumer populations and examine how that variation manifests in population-level responses. </p><p> I investigated the causes and physiological consequences of intrapopulation trophic niche variation in two generalist consumers, the American black bear (<i>Ursus americanus</i>) and brown bear (<i>U. arctos</i>) across three sites in British Columbia, CAN and at one site in Alaska, USA. My primary tools included stable isotope analysis to estimate diet, enzyme-linked immunoassay of hair to quantify the hormone cortisol for indexing physiological stress, and genetic analyses to identify individuals, species, and sex and to estimate ancestry. I found that individual differences in resource use can result in similar biological outcomes and that similar resource use can result in different biological outcomes. Intra- and interspecific competition, sex-based differences in nutritional and social constraints and annual variation in food availability all influenced trophic niche variation and the resultant biological outcomes. I also found evidence of a link between intrapopulation trophic niche variation and population genetic structure. My results highlight the diverse ecological drivers and diverse consequences of trophic niche variation, which further illuminates why the trophic niche is a nexus for eco-evolutionary dynamics.</p>

Population genetic methods can be employed to inform the conservation of a species in a number of ways. For instance, they can be used to determine if a species has gone through a genetic bottleneck (i.e. a drastic reduction in population size that results in reduced genetic variation), and also if a species exhibits local genetic structure, (i.e., whether there is population genetic structure among neighbouring populations of an otherwise widely distributed species). The objectives of this thesis were to investigate the population genetic structure and long-term effective population size of the recently rediscovered subspecies of the masked booby, the Tasman booby, Sula dactylatra tasmani, which unlike masked boobies ,which have a pantropical distribution and are widespread, are range restricted to three island groups in the North Tasman Sea. To achieve this, I apply population genetic methods to mitochondrial control region sequence data, and microsatellite genotype, along with morphometric data. I first examined the cross utility of 43 microsatellite loci developed for the blue-footed (S. nebouxii), red-footed (S. sula) and Peruvian (S. variegata) booby for a population genetic study in my focal subspecies, the Tasman booby. All of these loci amplified in the Tasman booby, and from these 13 independent polymorphic loci were found and used as nuclear data, along with mitochondrial sequence data, to estimate population genetic structure. I also used these two types of data to determine the effective population size of this subspecies, both recently and historically. I found strong population genetic structure from the mitochondrial sequence data, while the microsatellite genotype data revealed weak but significant population genetic structure. I suggest the differences in these two types of marker are most likely due to stochasticity in the mitochondrial genome and/or male-mediated gene flow. Combined, the mitochondrial and microsatellite data revealed the Tasman booby has existed at a relatively stable population size for the last 25,000 years, but estimates of the current effective population size of this subspecies were unreliable. From these combined data I recommend that the Tasman booby should be treated as a single management unit, and conservation efforts from Australia and New Zealand could benefit from communication regarding their management plans. Future work including both autosomal and sex-linked introns could help in resolving the presence or absence of male-mediated gene flow, and/or help estimate an accurate effective population size in this subspecies.

No description available.

No description available.

No description available.