Guo Bao Zhu. / Thesis (Ph.D.)--Chinese University of Hong Kong. / Includes bibliographical references. / Abstract --- p.1 / Introduction --- p.3 / Chapter Chapter 1. --- Semigroup for Age-Dependent Population Equations with Time Delay / Chapter 1.1 --- Introduction --- p.13 / Chapter 1.2 --- Problem Statement and Linear Theory --- p.14 / Chapter 1.3 --- Spectral Properties of the Infinitesimal Generator --- p.20 / Chapter 1.4 --- A Nonlinear Semigroup of the Logistic Age-Dependent Model with Delay --- p.26 / References --- p.34 / Chapter Chapter 2. --- Global Behaviour of Logistic Model of Age-Dependent Population Growth / Chapter 2.1 --- Introduction --- p.35 / Chapter 2.2 --- Global Behaviour of the Solutions --- p.37 / Chapter 2.3 --- Oscillatory Properties --- p.47 / References --- p.51 / Chapter Chapter 3. --- Semigroups for Age-Size Dependent Population Equations with Spatial Diffusion / Chapter 3. 1 --- Introduction --- p.52 / Chapter 3.2 --- Properties of the Infinitesimal Generator --- p.54 / Chapter 3.3 --- Properties of the Semigroup --- p.59 / Chapter 3.4 --- Dynamics with Age-Size Structures --- p.61 / Chapter 3.5 --- Logistic Model with Diffusion --- p.66 / References --- p.70 / Chapter Chapter 4. --- Semi-Discrete Population Equations with Time Delay / Chapter 4. 1 --- Introduction --- p.72 / Chapter 4.2 --- Linear Semi-Discrete Model with Time Delay --- p.74 / Chapter 4.3 --- Nonlinear Semi-Discrete Model with Time Delay --- p.88 / References --- p.98 / Chapter Chapter 5. --- A Finite Difference Scheme for the Equations of Population Dynamics / Chapter 5.1 --- Introduction --- p.99 / Chapter 5.2 --- The Discrete System --- p.102 / Chapter 5.3 --- The Main Results --- p.107 / Chapter 5.4 --- A Finite Difference Scheme for Logistic Population Model --- p.113 / Chapter 5.5 --- Numerical Simulation --- p.116 / References --- p.119 / Chapter Chapter 6. --- Optimal Birth Control Policies I / Chapter 6. 1 --- Introduction --- p.120 / Chapter 6.2 --- Fixed Horizon and Free Point Problem --- p.120 / Chapter 6.3 --- Time Optimal Control Problem --- p.129 / Chapter 6.4 --- Infinite Horizon Problem --- p.130 / Chapter 6.5 --- Results of the Nonlinear System with Logistic Term --- p.143 / Reference --- p.148 / Chapter Chapter 7. --- Optimal Birth Control Policies II / Chapter 7. 1 --- Free Final Time Problems --- p.149 / Chapter 7.2 --- Systems with Phase Constraints --- p.160 / Chapter 7.3 --- Mini-Max Problems --- p.166 / References --- p.168 / Chapter Chapter 8. --- Perato Optimal Birth Control Policies / Chapter 8.1 --- Introduction --- p.169 / Chapter 8.2 --- The Duboviskii-Mi1yutin Theorem --- p.171 / Chapter 8.3 --- Week Pareto Minimum Principle --- p.172 / Chapter 8.4 --- Problem with Nonsmooth Criteria --- p.175 / References --- p.181 / Chapter Chapter 9. --- Overtaking Optimal Control Problems with Infinite Horizon / Chapter 9. 1 --- Introduction --- p.182 / Chapter 9.2 --- Problem Statement --- p.183 / Chapter 9.3 --- The Turnpike Property --- p.190 / Chapter 9.4 --- Existence of Overtaking Optimal Solutions --- p.196 / References --- p.198 / Chapter Chapter 10. --- Viable Control in Logistic Populatiuon Model / Chapter 10. 1 --- Introduction --- p.199 / Chapter 10. 2 --- Viable Control --- p.200 / Chapter 10.3 --- Minimum Time Problem --- p.205 / References --- p.208 / Author's Publications During the Candidature --- p.209

Orientador: Adilson Fransozo / Banca: Rogério C. da Costa / Banca: Roberto Munehisa Shimizu / Banca: Valter José Cobo / Banca: Gustavo Monteiro Teixeira / Resumo: Não disponível / Abstract: Not available / Doutor

A study was undertaken to determine the abundance, distribution, perching heights, diets and territory sizes of Red-Tailed Hawks on Sauvie Island, Oregon. Sauvie Island supported a large wintering population of non-territorial Red-Tailed Hawks. The establishment of territories began around 10 January. Average perch height was found to be 14.2 m. Average perch height increased from fall to spring, corresponding-to the onset of the breeding season and to the onset of egg-laying and incubation. Voles (Microtus spp.) were the principal prey year-round, though waterfowl were more important in terms of biomass in the winter and early spring. Territory sizes on the Island ranged from .31 - 3.73 km squared The abundance of voles was assessed in different habitats within five Red-Tailed Hawk territories. Territory size was shown to be inversely correlated to the population density of voles. The implications of this finding for the type of territoriality exhibited by Red-Tailed Hawks is discussed, as are some proximate factors affecting habitat selection.

Foxtail pine (Pinus balfouriana) is a subalpine conifer endemic to California, notably separated into two disjunct subspecies. Previous studies have described the northern subspecies,Pinus balfouriana subsp. balfouriana,as having an uncommonly high level of genetic differentiation and no discernible spatial patterns in phenotypic variation. This study seeks to characterize the spatial genetic structure and patterns of selection of the northern subspecies (Pinus balfouriana subsp. balfouriana) using genome-wide data and to identify the influence of ecology and environment on the unique genetic patterns. I show that genetic differentiation among populations is much less than previously estimated (FST= 0.000644) and there is weak isolation-by-distance structure, but ongoing gene flow is unlikely. Within populations, stand density and competitor effects contribute to inbreeding. I also show that previously measured traits are predominantly determined by genetics. Analyzing by sliding window in the genome, I show that connectivity patterns vary widely throughout the genome and identify several areas that are important to the genetic architecture of the phenotypic traits and plasticity (GxE). Overall, there is high connectivity, genetic similarity, and genetically based trait variation among and within populations of the northern subspecies of foxtail pine due to historical processes, despite biotic interactions driving inbreeding. Persistent genetic isolation, however, may make adaptation to future climate a challenge for the subspecies.

Thesis (Ph. D.)--University of St Andrews, January 2007. / Includes bibliographical references. Available in PDF format via the World Wide Web.

This study examined population density and habitat use of a species of greater galago, genus Otolemur, around Mt. Kasigau, Kenya. Mt. Kasigau has a unique regional microclimate, a cloud forest, which provides many different flora and fauna a home. To examine population density, two different methods were used. The first method was using line transects and analyzing results using Distance 6.0. These surveys were conducted during both dry and wet season and results were compared after the study. The second method was to trap individuals and use mark-recapture to determine population density. When caught in a trap, individuals were also weighed and measurements were taken. Accurate weight was taken for 17 individuals; ear height, tail length, and hind foot length were recorded for 21 individuals. Mark-recapture data were analyzed using Krebs/WIN 3.0. Population density estimates using both methods were compared and provided similar results; Distance 6.0 estimated 0.62 individuals per hectare and Krebs/WIN 3.0 estimated 0.51 individuals per hectare. Morphological measurements were not consistent with published data of known species of Otolemur garnettii, which is the most common greater galago in East Africa. It is possible the Mt. Kasigau population is reproductively isolated and DNA analysis should be conducted in the future. Habitat usage of greater and lesser galagos and diurnal primates was examined to determine which tree species are commonly used by these individuals.

Coyotes fed upon agricultural carrion at feedlots operated by the Farmer's Investment Company (FICO) and Roisland Farms. Agricultural carrion was not available in the Whetstone area. The FICO feedlot stopped operating in May 1976, and carrion was not available there after that time. Coyotes were trapped and shot at the FICO feedlot from November 1975 through March 1976, from June through August 1976, and from May through August 1977. Coyotes were trapped at Roisland Farms in July and August 1976 and January and February 1977. A trapper collected coyotes in the Whetstone area from January through March 1976 and from November 1976 through February 1977. I operated a scent station line on the Santa Rita Experimental Range on a monthly basis from October 1975 through June 1976, from September 1976 through June 1977, and in December 1977. From data on the visitation of scent stations by coyotes, lagomorphs, and small mammals I calculated indices of monthly relative abundance for each animal group. There were no differences among the age distributions, weights, ovulation rates, and litter sizes of coyotes from the 3 study areas. The mean weights of all adult-sized male and female coyotes collected during this study were 11.1 and 9.3 kg, respectively. The overall mean ovulation rate and mean litter size were 4.1 and 3.4, respectively. At FICO and Roisland, 70 to 90% of yearling and adult females bred, but only 20% bred in the Whetstone area. There were more male than female coyotes at FICO, but sex ratios were not different from 1:1 at Roisland and Whetstone. The visitation rates of coyotes, lagomorphs, and small mammals fluctuated greatly during this study. Monthly visitation rates of coyotes differed significantly, but annual and daily rates did not. The visitation rates of both lagomorphs and small mammals were significantly different between years and among months, but not among days. Lagomorph and small mammal visitation increased significantly after the trapping of coyotes and the end of the FICO carrion supply in the summer of 1976. Coyote visitation appeared to decrease after the summer of 1976. Prior to the summer of 1976, the visitation rates of coyotes and lagomorphs were positively correlated, but the rates of coyotes and small mammals were not correlated. After the summer of 1976, coyote visitation was negatively correlated with both lagomorph and small mammal visitation. The distribution of coyote and lagomorph visits along the scent station line did not change after the summer of 1976. Small mammal visitation, however, increased in the distant section of the line after the summer of 1976. Coyotes visited stations located on the upwind side of the road more frequently than they stopped at stations on the downwind side. Lagomorphs showed no preference for either side of the road, but small mammals visited more stations on the downwind side of the road than on the upwind side. The breeding rate at FICO did not decrease after the carrion supply ended. It seems unlikely, therefore, that the high breeding rate at FICO was caused by feeding on carrion. The scent station technique has potential as a means of monitoring the monthly relative abundance of coyotes and certain prey groups. Unfortunately, visitation is a function of animal numbers and activity. Further research is required to quantify the relationship between visitation and abundance for each animal group.

No description available.

Despite being the world’s largest batoid fish, manta rays have been the focus of very little research in the last century. Almost nothing is currently known about their ecology or distribution throughout the world’s oceans. Manta rays are considered to be near-threatened to vulnerable by the World Conservation Union’s Redlist of endangered species, yet many populations still face threats from target fishing for their fin cartilage, branchial filaments and meat. The taxonomic history of the genus Manta has been questionable and convoluted,with Manta having one of the most extensive generic and species synonymies of any living genus of cartilaginous fish. Currently this genus is considered to be monotypicwith a single recognized species, Manta birostris. Behavioural and morphological data collected during this study showed that there are two distinct, sympatric species of manta ray in Mozambique. This discovery has led to an examination of manta ray distribution worldwide, with the two species hypothesis receiving further support from study sites in the Indian and Pacific Oceans. This thesis examined large populations of both putative species in Mozambique. Development and application of a photographic-identification methodology allowed identification of individuals based on their unique ventral surface markings (spots). The ability to recognise individuals enabled many aspects of both populations to be examined. A total of 449 individual rays were identified of Manta birostris variant A and 101 individual rays were identified of Manta birostris variant B. Both populations exhibited a highly significant female bias in observed sex ratios of 1:3.5 and 1:7.4 respectively. The photographic identification approach was used in studies of population size and structure and to examine the reproductive ecology of these two distinct populations. Population estimates incorporating four years of re-sighting data on Manta birostris variant A and five years of data on Manta birostris variant B were conducted using the program MARK resulting in super population estimates of 890 and 600 individuals respectively. The region encompassing the study site was identified as a mating ground for Manta birostris variant A based on observations of mating events and fresh pectoral fin tip scars on female rays produced when the male rays bite onto the fins during copulation. The distribution of scars was highly biased, with 99% on the left pectoral fin, indicative of a strong lateralised behavioural trait in this species. No other elasmobranch has been reported to display behavioural lateralisation. The study region also acts as a birthing ground, with individuals giving birth in the summer after a gestation period of approximately one year. Reproductive periodicity in M. birostris variant A was most commonly biennial, but a few individuals were seen to be pregnant in consecutive years, confirming an annual ovulatory cycle. The production of a single pup appears to be the normal situation, although observations in the wild as well as during opportunistic dissections of individuals killed in fisheries revealed that two pups are conceived on occasion. Morphometric analysis of late-term foetus (M. birostris variant A) was contrasted with measurements taken from adult rays. These are the only detailed measurements on M. birostris variant A from the western Indian Ocean. Predatory scarring and bite injuries on individuals of both variant A and B were consistent with attacks from sharks of various sizes. The frequency and effect of these predatory injuries on the two populations were examined over a three-year period. Acoustic tags were attached to fourteen rays and their presence/absence at sites around the major inshore reefs was explored to evaluate how the rays utilised their environment on a temporal scale. Cleaning activity of both putative species of manta rays by small fishes occurred on these reefs and was considered to be the main reason why the rays were present at these sites. Parasite removal and wound healing were implicated as the benefits received. Host cleaner fish species partition the manta ray body to avoid interspecific competition while the two putative species appear to partition cleaning habitats, with very little overlap apparent. This research on manta rays is the first of its kind in African waters. Many aspects of the study have contributed to the limited baseline data currently available for this genus. The study additionally provided sufficient empirical evidence to warrant the separation of these two putative species of Manta and a full revision of the genus with the systematic examination of specimens throughout Manta’s range. The results of this study may be useful in this endeavour as diagnostic characteristics have been isolated that may help to differentiate members of this genus. The results of this research study are directly applicable to management strategies for both putative species of manta rays off the East Coast of Africa as well as populations worldwide and have highlighted the potential need for different conservation strategies

Despite being the world’s largest batoid fish, manta rays have been the focus of very little research in the last century. Almost nothing is currently known about their ecology or distribution throughout the world’s oceans. Manta rays are considered to be near-threatened to vulnerable by the World Conservation Union’s Redlist of endangered species, yet many populations still face threats from target fishing for their fin cartilage, branchial filaments and meat. The taxonomic history of the genus Manta has been questionable and convoluted,with Manta having one of the most extensive generic and species synonymies of any living genus of cartilaginous fish. Currently this genus is considered to be monotypicwith a single recognized species, Manta birostris. Behavioural and morphological data collected during this study showed that there are two distinct, sympatric species of manta ray in Mozambique. This discovery has led to an examination of manta ray distribution worldwide, with the two species hypothesis receiving further support from study sites in the Indian and Pacific Oceans. This thesis examined large populations of both putative species in Mozambique. Development and application of a photographic-identification methodology allowed identification of individuals based on their unique ventral surface markings (spots). The ability to recognise individuals enabled many aspects of both populations to be examined. A total of 449 individual rays were identified of Manta birostris variant A and 101 individual rays were identified of Manta birostris variant B. Both populations exhibited a highly significant female bias in observed sex ratios of 1:3.5 and 1:7.4 respectively. The photographic identification approach was used in studies of population size and structure and to examine the reproductive ecology of these two distinct populations. Population estimates incorporating four years of re-sighting data on Manta birostris variant A and five years of data on Manta birostris variant B were conducted using the program MARK resulting in super population estimates of 890 and 600 individuals respectively. The region encompassing the study site was identified as a mating ground for Manta birostris variant A based on observations of mating events and fresh pectoral fin tip scars on female rays produced when the male rays bite onto the fins during copulation. The distribution of scars was highly biased, with 99% on the left pectoral fin, indicative of a strong lateralised behavioural trait in this species. No other elasmobranch has been reported to display behavioural lateralisation. The study region also acts as a birthing ground, with individuals giving birth in the summer after a gestation period of approximately one year. Reproductive periodicity in M. birostris variant A was most commonly biennial, but a few individuals were seen to be pregnant in consecutive years, confirming an annual ovulatory cycle. The production of a single pup appears to be the normal situation, although observations in the wild as well as during opportunistic dissections of individuals killed in fisheries revealed that two pups are conceived on occasion. Morphometric analysis of late-term foetus (M. birostris variant A) was contrasted with measurements taken from adult rays. These are the only detailed measurements on M. birostris variant A from the western Indian Ocean. Predatory scarring and bite injuries on individuals of both variant A and B were consistent with attacks from sharks of various sizes. The frequency and effect of these predatory injuries on the two populations were examined over a three-year period. Acoustic tags were attached to fourteen rays and their presence/absence at sites around the major inshore reefs was explored to evaluate how the rays utilised their environment on a temporal scale. Cleaning activity of both putative species of manta rays by small fishes occurred on these reefs and was considered to be the main reason why the rays were present at these sites. Parasite removal and wound healing were implicated as the benefits received. Host cleaner fish species partition the manta ray body to avoid interspecific competition while the two putative species appear to partition cleaning habitats, with very little overlap apparent. This research on manta rays is the first of its kind in African waters. Many aspects of the study have contributed to the limited baseline data currently available for this genus. The study additionally provided sufficient empirical evidence to warrant the separation of these two putative species of Manta and a full revision of the genus with the systematic examination of specimens throughout Manta’s range. The results of this study may be useful in this endeavour as diagnostic characteristics have been isolated that may help to differentiate members of this genus. The results of this research study are directly applicable to management strategies for both putative species of manta rays off the East Coast of Africa as well as populations worldwide and have highlighted the potential need for different conservation strategies