No description available.

No description available.

In this thesis I have investigated variation in the effective population size (Ne) between species, and the impact that this population genetics parameter has on molecular evolution. In Chapter 1 I review literature in order to outline our present understanding of variation in Ne, both between species and within a genome. In Chapter 2 I determine whether island species have lower effective population sizes than their mainland counterparts. I found that island species did not differ substantially from mainland species in terms of molecular evolution, despite their considerably smaller ranges. Chapter 3 examines the role of life history and demographic traits in shaping molecular evolution in mammals. Using mitochondrial DNA, I found significant correlations with species range for both genetic diversity (pS) and the efficiency of selection (pN/pS). Both latitude and body mass are also predictive of pS. However, these relationships are surprisingly weak. Additionally, no trait was predictive of nuclear molecular evolution. In Chapter 4 I determine whether there is adaptive evolution in animal mitochondrial DNA using McDonald-Kreitman style tests. While mitochondrial evolution is dominated by deleterious mutations, mitochondria also experience adaptive evolution, such that 26% of all nonsynonymous mutations are fixed by adaptive evolution. I also found evidence to suggest that the rate of adaptive evolution is correlated to Ne. In Chapter 5 I explore the relationship between pN/pS and pS, two variables that are expected to depend on Ne. I quantified the relationship between pS and pN/pS, after controlling for the statistical nonindependence between the two, to show that as πS doubles, πN/πS is reduced by 34%. I also investigated whether the slope of the regression between these variables is predicted by the shape parameter of the distribution of fitness effects. In Chapter 6 I give a general overview of my research, and bring together the key findings of this thesis.

A basic tenet of social structure is the assumption that the benefits of cooperative behavior must outweigh its costs if sociality is to evolve. The temperate spider, Anelosimus studiosus, exhibits a social behavioral polymorphism: individuals may defend asocial nests against intrusion by conspecifics or cooperate with them in multi-female nests. I initiated my investigation into this system by examining the extent to which social behavior phenotype is correlated with other behavioral traits and whether these correlations had adaptive consequences (Chapter 1). Using field surveys and laboratory experiments, I compared the success of asocial and social individuals in encounters over contested prey and prospective mates (Chapters 2, 3, 4). I then considered whether these trait correlations possess explanatory power for population-level divergence in behavior (Chapter 5). My results indicate social tendency is phenotypically correlated with several other types of behavior (e.g., activity-level, aggressiveness towards prey, exploratory behavior). The observed linkage between social tendency and other behavioral traits imposes a number of non-intuitive costs and benefits to possessing the social phenotype (e.g., social females are disadvantaged in agonistic interactions, but are more attractive to prospective mates). Finally, I examined the phenotypic correlations among behavioral traits for 18 different populations of An. Studiosus. I find that within- and between-population trait correlations resemble one another. Thus social tendency may not be “free” to evolve independently from other behavioral traits.

Thesis (M.Sc.)--York University, 2003. Graduate Programme in Mathematics. / Typescript. Includes bibliographical references (leaves 73-78). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL:http://gateway.proquest.com/openurl?url%5Fver=Z39.88-2004&res%5Fdat=xri:pqdiss&rft%5Fval%5Ffmt=info:ofi/fmt:kev:mtx:dissertation&rft%5Fdat=xri:pqdiss:MQ99406

Oyster drills are common on rocky shores and oyster (Crassostrea gigas) farming areas in Taiwan. Most studies on the oyster drill (Thais clavigera) were on its impact on the oyster industry. However, there are at least three Thais species in the west coast of Taiwan. And the basic biology of T. rufotincta and T. keluo was insufficient. Thus, the present study was undertaken to investigate population biology of the three congeneric drills(Thais spp.), including feeding rate, reproductive characters and population dynamics. T. clavigera was distributed from Tamsui to Tongkong along the west coast of Taiwan. But, it was rare at Tongkong. T. keluo was primarily found at Tamsui and Tongkong. The distribution of T. rufotincta was from Tongkong to Tamsui and mostly occurred between Tongkong and Taishi. Mean feeding rates (¡ÓSE) of T. clavigera, T. keluo and T. rufotincta were 0.054(¡Ó0.010), 0.038(¡Ó0.004) and 0.010(¡Ó0.003) oysters/snail¡Eday, respectively. The feeding rate of T. rufotincta was significantly lower than other species (P<0.05). It is suggested that the major damage on oyster culture is caused by T. clavigera and T. keluo. The spawning seasons of T. clavigera, T. keluo and T. rufotincta were from November to May, from February to September, and from April to October, respectively. The number of eggs per capsule was correlated with the length of the capsule (P<0.001) in T. clavigera, T. keluo and T. rufotincta and the number of eggs (¡Ó 95% C.I.) among them was 203(¡Ó14), 168(¡Ó15) and 43(¡Ó3) per capsule, respectively. The mean egg diameter (¡Ó 95% C.I.) of the three drills was 185(¡Ó3), 175(¡Ó4) and 240(¡Ó6) £gm, respectively. Positive curve relationships between size and weight were found among Thais spp. (P<0.001). Using the length-frequency data, analyzed by the ELEFAN (Electronic Length Frequency Analysis) program, the seasonalized von Bertalanffy growth parameters for Thais spp. were estimated. The growth performance index (&#x00F8;') and growth parameter (K) showed a similar trend, i.e. Chiku>Tamsui>Shiangsan for T. clavigera, Tamsui > Tongkong for T. keluo, and Chiku > Tongkong for T. rufotincta. It is suggested that water temperature and food abundance are important factors affecting drills¡¦ growth in the west coast of Taiwan. The recruitment of T. rufotincta at Chiku and Tongkong had two peaks. It was different from T. clavigera and T. keluo with only one peak. Futher studies are necessary to elucidate the relationship between recruitment with different peak periods among sites and environment variables such as primary production, salinity, current and so on.

No description available.

Since the advent of world travel and exploration, humans have been introducing animals to new countries and environments to which they were not native. Wild horses in North America are protected by the Wild Free-Roaming Horses & Burros Act, and their growing populations can damage native species and ecosystems. These feral horses organize themselves into harems consisting of several mares, a dominant stallion, and occasionally subordinate stallions. In the breeding season, a peak in stallion libido and mare ovulation elicit distinct reproductive behaviors. Population numbers of feral horses (Equus caballus) need to be humanely controlled without the disruption of these key behaviors. The Adopt-A-Horse program, a current program consisting of roundup and public adoption for a fee, is not effective on its own. The proposed study examines two minimally-invasive immunocontraceptive methods that may be effective in reducing population growth: Gonadotropin releasing hormone (GnRH) agonists, antibodies that prevent mares from entering estrous, and porcine zona pellucida (PZP), an antibody that changes the conformation of ova sperm receptors to prevent fertilization. This potential study proposes that 8 independent populations of feral horses will be tracked for 4 years to assess normal behavior. After 4 years, populations will undergo one of four treatments: control (n=1), roundup and adoption (n=1), mares treated with 2-year remotely administered PZP vaccine (n=3), and mares treated with 2-year remotely administered GnRH agonist (n=3). Urinalysis will be used to test for pregnancy, and behavior of mares will be monitored over the course of 4 years after administration. Combined observations of behavioral effects and growth rates will be used to determine the most efficient and humane method of population control. Both chemical methods of fertility control should greatly reduce the overall number of foals produced. Where PZP will potentially be the better choice for immunocontraception due to its minimal interference with the endocrine system of feral horses, GnRH agonists are likely to affect normal behavior and may not be suitable for implementation in wild rangelands. Efforts to control populations will be most effective when the current Adopt-A-Horse program is combined with administration of PZP every second year. Success of an immunocontraception program for feral horses in overpopulated rangelands may pave the way for more invasive populations to be controlled in this manner.

The aim of this thesis was to identify the factors determining reproductive success and breeding density in a rural population of blackbirds occupying contiguous woodland and farmland habitats. Once these factors were identified, an attempt was made to assess the quality of the two habitats in terms of reproductive success. Predation was the major factor affecting reproductive success. There were no significant effects of habitat on predation when habitat was defined as farmland, woodland and woodland edge. When defined in terms of nesting density, high density 'hot-spot' areas had significantly greater nesting cover and lower predation rates than territories in farmland or in the rest of the wood. Parents could adjust their provisioning rates according to chick demand. Consequently chicks in larger broods were not significantly different in weight to chicks in smaller broods. The seasonal change in clutch size is therefore well adapted to conditions for raising nestlings, although there was indirect evidence that female condition may limit clutch size early in the season. The nestlings were fed two main diet types, earthworms and caterpillars, the availability of the former being related to rainfall and temperature and the latter occurring in a seasonal peak. Nestlings fed on predominantly earthworm diets were significantly heavier, thus caterpillars are probably a lower quality prey. Starvation was a minor cause of nestling mortality. There was some evidence that farmland birds were more dependent on earthworms than woodland birds, and consequently only farmland broods showed a significant relationship between weight and rainfall. This conferred no disadvantage to farmland broods, although this may have implications for reproductive success in very dry years. Farmland breeders showed some characteristics of a population in a suboptimal habitat. Breeding density was low on farmland compared with woodland. This in part may have been due to lack of suitable nesting cover. An experiment with artificial nests indicated that predation would be proportionately higher on farmland if nesting density was increased. Year-to-year variations in density across the whole study site paralleled the relative harshness of the preceding winter. Food supplementation prior to the breeding season had no effect on subsequent breeding density or clutch size. It is concluded that farmland is potentially a sub-optimal habitat if subject to different conditions of weather or breeding density than those observed during the three years of this study.

Thesis (Ph.D.) in Marine Biology--University of Maine, 2008. / Includes vita. Includes bibliographical references (leaves 121-135).