<p>Adaptation is central to our understanding of the origin of biological diversity. Yet whether adaptive divergence promotes the formation of new lineages remains poorly understood. My dissertation addresses the role of adaptive divergence in diversification and speciation. I also investigate an alternative mechanism: dispersal, which can promote diversification and speciation through its effects on gene flow and allopatry. To address the role of divergent adaptation and dispersal in the process of diversification, I take an integrated approach, combining both comparative methods with quantitative genetics to characterize patterns of diversification and speciation in the tribe Brassiceae and genus Cakile. I start with a comparative study of the role of dispersal and adaptation in diversification, and then focus on the role of climatic and latitudinal divergence in the processes of adaptive divergence and speciation. In general, I find limited evidence for the role of divergent adaptation in the evolution of intrinsic reproductive isolation. Diversification in the tribe Brassiceae appears to be mediated by dispersal ability, while in the genus Cakile, the evolution of intrinsic reproductive isolation is largely independent of ecological divergence. Thus, while divergent adaptation to novel habitats and climate are likely occurring in Brassiceae, mediated in part by the evolution of long-distance dispersal, the evolution of intrinsic genic reproductive barriers appears to not be influenced by adaptation.</p> / Dissertation

Understanding how environmental variation affects fitness and population dynamics is a central goal in modern population biology. Using a multilevel path model, I simultaneously examined the effects of food and temperature on multiple stages of the breeding cycle, and their relative contribution to annual variation in reproductive success in two tree swallow (Tachycineta bicolor) populations over the same 35 year period. In one population where food abundance peaked during the laying and incubation portion of the breeding season, the primary driver of annual reproductive success was laying period food abundance, which directly influenced clutch size and the proportion of eggs hatched. In the second population, food was relatively low during the first half of the breeding season, and the primary driver of annual reproductive success was temperature during the nestling period, which directly influenced nestling survival. My results show that understanding the factors that influence reproductive performance requires linking environmental variables to reproductive events throughout the entire breeding period and clearly demonstrate how climate change can have opposite effects on two populations less than 35 km apart

As a contraceptive technology, women’s sterilization is a medical event that is uniquely situated in relation to the dominant discursive link between women and reproduction. Intended as a contraceptive option that permanently ends a woman’s potential ability to sexually reproduce, women’s sterilization presents a significant point for exploring the discursive formation of femininity, and how the concepts thereof relate to broader questions of access, control, and regulation of sterilization and the female sterilization patient. This study uses a Foucauldian feminist theory of discourse to explore such questions in a qualitative discourse analysis of women’s sterilization, from both a historical perspective and from within contemporary medical texts. Sterilization has had a particularly tumultuous history in the provision of reproductive healthcare for women; situated within public health and welfare discourse that differentiates the “unfit” from the “fit” reproducers, women have been forcibly sterilized under classist and racist eugenic programs, while subtle yet coercive forms of sterilization abuse continue to occur as inequality of reproductive healthcare access is an ongoing issue for immigrant women, poor women, and women of colour. In light of this historical analysis, as well as the impact of feminist and bioethics discourse upon contemporary medical practice, an analysis of medical texts further explores the association of women with reproduction in the discursive form of the sterilization patient. This study argues that the sterilization patient is situated within a discourse of ideal femininity, associated with normalized forms of mothering, sexuality, and family structure. Given the historical link between the discursive “fit” reproducer, these concepts have continued implications for women’s experience of accessing sterilization as a contraceptive option. / Thesis (Master, Sociology) -- Queen's University, 2007-07-17 17:09:15.595

According to traditional theory, superior competitive ability in plants generally requires a relatively large plant body size. Yet, within natural, crowded vegetation, most resident species are small, and species size distributions are right-skewed at virtually all scales. I aim to provide a potential explanation for this paradox: small species are able to coexist with and outcompete larger species because smaller species have greater ‘reproductive economy’—the ability for some seed production despite severe size suppression when under intense competition. Tracey and Aarssen (2011) found an isometric relationship between minimum reproductive threshold size (MRTS) and maximum resident plant size (MAX); however, a more accurate measure of maximum potential body size (MPBS) was needed (without competition), as typically the effects of competition are size-dependent. An isometric relationship, similar to Tracey and Aarssen (2011) was seen. Tracey and Aarssen (2011) also found that, contrary to the predictions of traditional theory, larger species were not more abundant (based on plot occupancy) in an old-field community. A more accurate measure of abundance was obtained by locating random 1 x 1 m plots and counting the number of ramets for each species in the plot. A significant negative relationship was seen between abundance and MRTS. This suggests that the most abundant plants in communities are not those that are bigger, or smaller, they are those with the smallest MRTSs. To test whether this relationship exists in other habitats, plots were located in different old-field, shrub-land and wood-land communities. Ramets for each species within the plots were counted, and the largest plant of each species was measured. Significant negative relationships between abundance and MAX plant body size were seen in the shrub-land and woodland sites; however, no relationship was detected in this old-field site. The data support the idea that smaller species have greater reproductive economy, but the mechanism remains unknown. These results suggest that a smaller plant body size results in more effective gene transmission into future generations in all habitat types and stages of succession and indicates a suggested paradigm shift in the predicted selection effects of competition on the evolution of plant body size. / Thesis (Master, Biology) -- Queen's University, 2012-07-30 11:56:23.999

No description available.

Abscisic acid (ABA) is a key plant hormone regulating agronomically important processes including seed maturation and dormancy, stomatal opening and closure, along with the transcriptional and physiological response of plants to abiotic and biotic stresses. The current study sought to functionally characterize members of an ABA-responsive gene family encoding GRAM (Glucosyltransferases, Rab-like GTPase activators and Myotubularins) domain proteins in Arabidopsis thaliana. Utilizing reverse genetics loss- and gain-of-function lines associated with GEM-RELATED 5 (GER5) were obtained, which displayed several defects in reproductive development. Gene expression profiling, RNA in situ hybridization and immunohistochemical techniques were utilized to evaluate GER5 and two closely related GRAM genes, GEM-RELATED 1 (GER1) and GLABRA2 EXPRESSION MODULATOR (GEM) in reproductive structures. Microarray profiling of seeds from ger5-2 mutants and wild-type plants revealed transcriptional changes in carbohydrate metabolism, hormone signaling and catabolic processes accompanied seed development defects of ger5-2 mutants. Seed germination assays further revealed ger5-2 mutants exhibited reduced sensitivity to ABA. In assessing GER5, GER1 and GEM as putative ABA-response genes, a second study evaluated the expression of GRAM, AuTophaGy-related (ATG), and ABA-response genes in source and sink organs exposed to abiotic stress or within mutant backgrounds deficient in sugar signaling. Monodansylcadaverine (MDC) staining was also utilized to localize autophagosomes or autophagic bodies within vegetative or reproductive organs during plant development, or in response to carbon starvation or abiotic stress. In a third study transcriptional differences in ABA metabolism, transport and homeostasis were examined within reproductive organs (cauline leaves, inflorescence meristem, developing siliques) exposed to cold and heat stress. This study revealed reproductive organs are characterized by unique patterns of ABA metabolism which differ from tissues typically associated with classical ABA responses. Together, these studies indicate GER5, an uncharacterized ABA-responsive GRAM domain gene, plays a novel role in the reproductive development of plants and that ABA metabolism and signaling are uniquely regulated in reproductive organs.

Despite habitat perturbations and seasonal fluctuations in reproduction, many studies report no significant inter-annual variation in Great Egret reproductive performance. I examined the reproductive performance of Great Egrets (Ardea alba) for two breeding seasons (2009 and 2010) immediately following Hurricane Ike at High Island, Texas. Breeding success, productivity, and mean brood size did not differ between years (U-test, P > 0.05). Fledging success at 21 days showed no significant difference between years, however fledging success at 28, 35, and 42 days decreased significantly between years (~15% reduction at 42 days; U-test, P = 0.027). The number of deaths per nest also differed significantly between 2009 and 2010 (0.36 and 0.95, respectively) (U-test, P = 0.013). Brood-size dependent mortality was also a significant between-year parameter (H test, P = 0.003). Successful nests in 2009 had a brood size range of 2 to 3, and of these nests, 6% and 50% experienced partial brood reduction, respectively; whereas 2010 brood size range for successful nests was 2 to 4, and 0%, 57%, and 100% of these nests, respectively, experienced partial brood reduction. Other parameters examined were water level, temperature, precipitation, prey availability, and human disturbance. I rejected my hypothesis that habitat conditions would be less conducive to high reproductive success in 2009 than 2010, due to the impacts of Hurricane Ike. My results suggest that Great Egrets have bimodal occurrences of nestling death that are expressed as a function of brood size, hatching spread, and nestling age. Reproductive performance studies should continue through at least fledging age (42 days post-hatching for Great Egrets) to better document the reproductive performance, especially by incorporating the apparent behavioral plasticity of nestlings.

While many norms sustain or destabilize certain religions, one domain is particularly relevant to the survival of some religions over others: norms about fertility and reproduction. Thus far, several ethnographic and correlational studies have found a positive association between religiosity and fertility rate, but there is a dearth of laboratory investigation utilizing experimental methods to isolate causation. In Study 1, I found that experimentally activating religious concepts led to an increased desire to have children (N = 462). In Study 2, the focal study, I attempted to replicate and extend the previous study by examining implicit behavior (N = 120). I predicted that individuals primed with religion would be more likely to show an implicit approach motivation towards images of children. Failing to support my hypothesis, participants with religion activated were no more likely to approach images of babies than controls. This null finding was not affected by taking into account several relevant covariates. Additionally, an exploratory investigation of the effect that religious community norms may have on reproductive behavior was conducted. I found that participants that come from religious communities in which sexual deviance is emphasized were more likely to approach baby images. Future directions are discussed.

Capelin (Mallotus villosus) is the key forage fish in the north Atlantic. A short-term anomalous event in Newfoundland waters in the early 1990’s caused many changes to their biology, including excursions into alternate (subtidal) spawning habitats. Subtidal spawning sites have drastically different environmental conditions than the beach sites that they have been using since at least the 1940’s. This thesis examines various aspects of the reproductive biology of capelin to understand the mechanisms underlying the use of two environmentally divergent spawning habitats. Local adaptation in early life history stages was examined by raising artificially fertilized capelin eggs across three temperatures that capelin are likely to encounter at both spawning habitats. At cool to medium temperatures, larvae experienced higher hatching success, were larger at hatching and had more nutritional reserves relative to warm temperature conditions. There was no evidence of local adaptation, providing the first support for a facultative spawning strategy. The influence of global warming temperatures may be buffered through the utilization of either spawning habitat provided it is within this thermal optimum. A comparative analysis of adult body shape and condition between the two habitats provided further evidence that spawning habitat use in a given year is facultative. Patterns in fecundity drastically changed for capelin since it was last examined prior to the 1990’s. In addition to lower average population fecundity, a wide range of fecundities was also observed across all length-classes. I show that the strong relationship between length and fecundity in capelin has broken down in recent years, making easily collected size measurements an inappropriate proxy for the reproductive potential of this fish. Within-female variation in offspring size and developmental duration was higher when compared to among-female variation. This supports diversified bet-hedging in capelin, a strategy that would allow capelin to spawn in thermally available habitats without experiencing reproductive failure in exceedingly warm or cold years. It is likely that high variation in traits allow capelin to utilize alternate spawning habitats, ensuring that at least some larvae survive.

Capelin (Mallotus villosus) is the key forage fish in the north Atlantic. A short-term anomalous event in Newfoundland waters in the early 1990’s caused many changes to their biology, including excursions into alternate (subtidal) spawning habitats. Subtidal spawning sites have drastically different environmental conditions than the beach sites that they have been using since at least the 1940’s. This thesis examines various aspects of the reproductive biology of capelin to understand the mechanisms underlying the use of two environmentally divergent spawning habitats. Local adaptation in early life history stages was examined by raising artificially fertilized capelin eggs across three temperatures that capelin are likely to encounter at both spawning habitats. At cool to medium temperatures, larvae experienced higher hatching success, were larger at hatching and had more nutritional reserves relative to warm temperature conditions. There was no evidence of local adaptation, providing the first support for a facultative spawning strategy. The influence of global warming temperatures may be buffered through the utilization of either spawning habitat provided it is within this thermal optimum. A comparative analysis of adult body shape and condition between the two habitats provided further evidence that spawning habitat use in a given year is facultative. Patterns in fecundity drastically changed for capelin since it was last examined prior to the 1990’s. In addition to lower average population fecundity, a wide range of fecundities was also observed across all length-classes. I show that the strong relationship between length and fecundity in capelin has broken down in recent years, making easily collected size measurements an inappropriate proxy for the reproductive potential of this fish. Within-female variation in offspring size and developmental duration was higher when compared to among-female variation. This supports diversified bet-hedging in capelin, a strategy that would allow capelin to spawn in thermally available habitats without experiencing reproductive failure in exceedingly warm or cold years. It is likely that high variation in traits allow capelin to utilize alternate spawning habitats, ensuring that at least some larvae survive.