Theory predicts that sexual reproduction confers an advantage over asexual reproduction due to the generation and maintenance of genetic variation afforded by the processes of recombination and segregation. However, this prediction has rarely been empirically tested. Oenothera is a flowering plant genus whose evolutionary history is punctuated with numerous transitions from sexual reproduction to a form of functionally asexual reproduction known as Permanent Translocation Heterozygosity (PTH). In Ch. 2, a greenhouse experiment examined patterns of phenotypic and genetic variation within and between populations across eight Oenothera species, representing four independent transitions to PTH. I found some evidence for a decrease in heritability and an increase in population differentiation in phenotypic traits associated with the loss of sex. Ch. 3 explored the possibility that rare outcrossing events represent a mechanism for the maintenance of variation in a PTH species. Analysis of microsatellite markers showed evidence for extremely low rates of outcrossing in natural populations (< 1%) of O. biennis, a PTH species.

Theory predicts that sexual reproduction confers an advantage over asexual reproduction due to the generation and maintenance of genetic variation afforded by the processes of recombination and segregation. However, this prediction has rarely been empirically tested. Oenothera is a flowering plant genus whose evolutionary history is punctuated with numerous transitions from sexual reproduction to a form of functionally asexual reproduction known as Permanent Translocation Heterozygosity (PTH). In Ch. 2, a greenhouse experiment examined patterns of phenotypic and genetic variation within and between populations across eight Oenothera species, representing four independent transitions to PTH. I found some evidence for a decrease in heritability and an increase in population differentiation in phenotypic traits associated with the loss of sex. Ch. 3 explored the possibility that rare outcrossing events represent a mechanism for the maintenance of variation in a PTH species. Analysis of microsatellite markers showed evidence for extremely low rates of outcrossing in natural populations (< 1%) of O. biennis, a PTH species.

Terrestrial target tracking using low Earth orbit satellites provides essential daily services and vital scientific data. In this thesis, the Attitude and Orbit Control System of such a terrestrial tracking satellite, Nanosatellite for Earth Monitoring and Observation Aerosol Monitor, is presented in detail. The satellite is a new generation Earth observation mission with the objective of detecting global atmospheric aerosol content through sub-degree pointing. The design is presented from initial hardware selection and budget development to operation definition and mission operation. The efficacy of performing precise autonomous Earth-pointing on a small satellite platform is validated through high fidelity simulations involving satellite and environmental dynamics, test-characterized hardware models and flight software-in-the-loop. The results provide practical target tracking methodologies which in the past have been publicly inaccessible to the author's best knowledge and which can be now be applied to a broad range of precise Earth-pointing satellites.

Terrestrial target tracking using low Earth orbit satellites provides essential daily services and vital scientific data. In this thesis, the Attitude and Orbit Control System of such a terrestrial tracking satellite, Nanosatellite for Earth Monitoring and Observation Aerosol Monitor, is presented in detail. The satellite is a new generation Earth observation mission with the objective of detecting global atmospheric aerosol content through sub-degree pointing. The design is presented from initial hardware selection and budget development to operation definition and mission operation. The efficacy of performing precise autonomous Earth-pointing on a small satellite platform is validated through high fidelity simulations involving satellite and environmental dynamics, test-characterized hardware models and flight software-in-the-loop. The results provide practical target tracking methodologies which in the past have been publicly inaccessible to the author's best knowledge and which can be now be applied to a broad range of precise Earth-pointing satellites.

Brachyglottis (Asteraceae) is a genus of approximately 30 species in the Brachyglottidinae, a recently recognised sub-tribe of tribe Senecioneae. Within Brachyglottis is a clade of five species of rosette-forming herbs: B. bellidioides, B. haastii, B. lagopus, B. southlandica and B. traversii. A sixth species, B. saxifragoides, has recently been synonymised with B. lagopus. The rosette-Brachyglottis have historically been recognised as a taxonomically problematic group because species overlap in both morphology and geographical distribution. A recent molecular study of rosette-Brachyglottis using AFLP data indicated that genetic distances among populations of rosette-Brachyglottis in the South Island appear to be correlated with geographical distance between populations rather than taxonomic identification. This is problematic as the currently described rosette-Brachyglottis species have overlapping ranges which implicitly hypothesises reproductive barriers other than geographic distance. We conducted an investigation into the species delimitation of rosette-Brachyglottis with the aim of answering two related questions: Does the current delimitation of rosette-Brachyglottis accurately reflect patterns of genetic similarity? Do the patterns of genetic structure in rosette-Brachyglottis support the presence of multiple biological species? A total of 46 populations of rosette-Brachyglottis were represented in this study. Herbarium specimens collected from these populations were identified following the taxonomic treatment of Allan (1961). Twenty one discrete and numerical morphological characters were measured from herbarium specimens including those collected for this study and previously collected herbarium specimens. Morphological dissimilarity of 354 herbarium specimens was investigated by performing a PCoA on Gower’s pairwise morphological distances among individuals. The pattern of genetic similarity was explored using DNA fragment length variation in nine markers for 273 individuals and this resulted in a total 177 unique alleles. Bayesian clustering analysis was performed on this data set using STRUCTURE, in addition, pairwise genetic distances were calculated among individuals and populations using Jaccard and Nei’s dissimilarity coefficient’s respectively. Jaccard genetic distances among individuals were analysed using PCoA and Nei’s genetic distances among populations were analysed using a Neighbour-Net analysis. The relationship between pairwise genetic and geographic distances among populations was analysed using a combination of linear regression and a Mantel Test. The pattern of morphological similarities among specimens was generally congruent with the currently delimited species in rosette-Brachyglottis. However, many morphologically intermediate specimens confound the recognition of distinct morphological entities. Comparison of patterns of genetic similarity and the current morphologically-based species delimitation showed that the delimitation does not accurately reflect the genetic structure of rosette-Brachyglottis. Furthermore, patterns of genetic dissimilarity did not indicate discrete genetic groups at the individual or population levels. The finding of incongruence between patterns of genetic and morphological similarity and absence of morphologically or genetically discrete groups suggests that rosette-Brachyglottis are best considered a single, yet morphologically diverse, biological species. In addition genetic structure within this species appears to be primarily driven by geographical isolation.

MORPHOMETRIC AND GENETIC DIFFERENTIATION BETWEEN ANATOLIA AND CYPRUS BOMBUS (BOMBUS) TERRESTRIS (L. 1758) POPULATIONS BETON, Damla M. Sc., Department of Biology Supervisor: Prof. Dr. Aykut Kence September 2004, 86 pages Four microsatellite loci were used to investigate differentiation in Bombus terrestris, a bumblebee of interest for its high value crops pollination. Two bumblebee populations, one from Ankara (the capital of Turkey) and one from North Cyprus were analyzed. In these populations, the total number of alleles detected per polymorphic locus ranged from 7 to 12. FST genetic distance between Ankara and North Cyprus B. terrestris populations based on four microsatellite loci was calculated as 0,09351. This applies that there is significant (P&lt / 0,001) differentiation between Anatolian and Cypriot populations. Moreover, statistically significant differences between two populations were found in wing characters studied. According to the potential for local adaptation and individual fitness of bumblebees, microsatellite data calls for protection of Bombus terrestris populations against importation of bumblebees of foreign origin which are used as crop pollinator.

In this study the genetic diversity in Turkish native sheep breeds was investigated based on microsatellite DNA loci. In total, 423 samples from 11 native and crossbreed Turkish sheep breeds (Akkaraman, Morkaraman, Kivircik, ivesi, Dagli&ccedil / , Karayaka, HemSin, Norduz, Kangal, Konya Merinosu, T&uuml / rkgeldi) and one Iraqi breed (Hamdani) were analyzed by sampling from breeding farms and local breeders. After excluding close relatives by Kinship analysis, the genetic variation within breeds was estimated as gene diversities (HE), which ranged between 0.686 and 0.793. The mean number of observed alleles (MNA) ranged between 5.8 and 11.8. The allele frequency distribution across Turkey showed no gradient from east to west expected in accordance with the Neolithic Demic Diffusion model. The differentiation between different samples of Akkaraman, Dagli&ccedil / and Karayaka breeds was tested by FST index. Akkaraman1 sample from the breeding farm was significantly (P&lt / 0.001) different from the other two Akkaraman samples. Deviation from HW expectations observed for Akkaraman1, ivesi, Morkaraman and HemSin breeds. AMOVA analysis revealed that most of the total genetic variation (~90%) was partitioned within the individuals. In parallel to this observation, when factorial correspondence analysis and shared alleles distances were used to analyze the relationship between the individuals of the breeds, there was no clear discrimination between breeds. Moreover, NJ tree constructed based on DA genetic distance, and PC analyses were used to analyze among breed differentiation. Delaunay Network drew 4 genetic boundaries (two of them being parallel to geographic boundaries) between breeds. All the results indicated that Kivircik was the most differentiated breed. Finally, Mantel Test and Bottleneck analysis did not reveal a significant result. Kivircik breed, among all native Turkish breeds, was found to be the genetically closest to the European breeds based on the loci analyzed. The genetic variation in Turkish breeds was not much higher than that of European breeds, which might be a consequence of the recent sharp decrease in sheep number.

Drug resistance is a major obstacle to management and control of malaria and currently progressing at a rapid rate across Africa. This thesis has examined factors influencing evolution of resistant P. falciparum at two sites in Africa, including parasite migration, cross mating and fitness cost of resistance. In Asar village, eastern Sudan, the frequencies of drug sensitive and resistant parasites were monitored throughout the dry season in the absence of anti-malarial drug usage to examine whether persistence of resistant parasites is reduced in the absence of drug pressure. Two cohorts of P. falciparum infected patients were treated with chloroquine in the transmission season (Oct-Dec), and followed monthly in the dry season into the next transmission season. A large proportion of the cohort maintained sub-patent asymptomatic P. falciparum infections throughout the entire study period. Alleles of the chloroquine resistance transporter (Pfcrt) and multi-drug resistance protein (Pfmdr1) were examined. Mutant alleles of Pfcrt reached fixation following CQ treatment and remained high in the transmission season. However, at the start of the dry season, wild type alleles of both genes started to emerge and increased significantly in frequency as the season progressed. The mutant Pfcrt haplotype was invariably CVIET, indicating migration of CQ resistant parasites into an area; otherwise the CVMNK haplotype is normal. In addition, microsatellite haplotypes of dihydrofolate reductase (dhfr) gene and dihydropteroate synthase (dhps) genes, which control the parasite response to pyrimethamine and sulfadoxine respectively, were characterized. One major dhfr haplotype with double dhfr mutations and two major mutant dhps haplotypes were seen in eastern Sudan. These haplotypes are distinct from those prevailing in other African countries, suggesting the likely local origin of dhfr and dhps haplotypes conferring drug resistance. Transmission capacities of different P. falciparum clones within a single infection in The Gambia have a high ability to produce gametocytes and infect Anopheles mosquitoes even when they exist at levels not detectable by microscopy and PCR. These findings emphasize the crucial role of gametocyte complexity and infectivity in generating the remarkable diversity of P. falciparum genotypes seen in infected people. Parasites with different resistant dihydrofolate reductase (dhfr) haplotypes have the ability to infect Anopheles mosquitoes following drug treatment, and cross-mating between parasites with different dhfr haplotypes was detected. Our results showed that the major dhfr haplotype in the Gambia is similar to the common one seen in other African countries, suggesting that parasite migration plays a major role in spread of resistance. Indeed, the dominant resistant haplotype seen in infected patients was readily transmitted to infect mosquitoes.

No description available.

This thesis describes the results of an investigation into the population genetic structure of the blue swimmer crab, Portunus pelagicus, in Australian waters. P. pelagicus is an Indo-West Pacific species, with adults and juveniles that inhabit sheltered benthic coastal environments and a planktonic phase (of modest duration) in its life cycle. The investigation was done by examining the patterns of variation at six microsatellite loci and in a 342 bp portion of the cytochrome oxidase subunit I (COI) gene in the mitochondrial DNA in samples of Portunus pelagicus from a total of 16 different assemblages/waterbodies. Overall, the samples were collected from throughout the geographical range of this species in Australian waters, i.e. from the western seaboard, from the eastern seaboard, from Darwin on the north coast and from South Australia on the south coast. The samples sizes ranged from 4 to 57 individuals, depending on the sample and the genetic assay. The population genetic structure of P. pelagicus was analysed from both a traditional population structure perspective and from a phylogeographical and historical demography perspective. The traditional assessment of the population genetic structure of Portunus pelagicus indicates that this species exhibits a significant amount of genetic heterogeneity in Australian waters (e.g. FST for microsatellite data = 0.098; ¥èST for COI data = 0.375 and ¥ÕST for COI data = 0.492). This assessment also indicates that P. pelagicus exhibits varying degrees of genetic heterogeneity within and between geographical regions in Australian waters, as follows. (1) The genetic compositions of the samples from the different coastlines (i.e. north, south, east and west) invariably showed statistically significant differences for at least two microsatellite loci, although the differences between the samples from the eastern seaboard, Darwin and those from the western seaboard to the north of Port Denison were not as great as those within the western seaboard samples or within South Australian samples. (2) The genetic compositions of the samples from the assemblages on the eastern seaboard of Australia, which ranged from Mackay (21¨¬06¡ÇS) to Port Stephens (32¡Æ40¡ÇS), were essentially homogeneous. (3) The samples from the assemblages on the western seaboard of Australia, which ranged from Broome (17¡Æ58¡ÇS) to Geographe Bay (33¡Æ35¡ÇS), exhibited significant levels of genetic heterogeneity. Furthermore, those from south of Port Denison formed a highly distinctive (but not invariant) group compared to those from elsewhere. (4) The samples from South Australia were also highly genetically distinctive compared to those from elsewhere, although they also showed significant heterogeneity amongst themselves. The above findings were more or less suggested by both the microsatellite and COI markers, although the former generally provided a higher resolution picture of the population structure of P. pelagicus than did the latter. The main findings of the investigation into the phylogeography and recent demographic history of Portunus pelagicus in Australian waters were as follows. (1) A phylogeny constructed from COI sequence variation was shallow, with the lineages showing varied geographical distributions. (2) The results of a nested clade analysis of this variation indicate that range expansion has been a predominant influence on the historical demography of P. pelagicus in Australian waters. (3) The samples from the assemblages on the western seaboard to the south of Port Denison contained low levels of genetic diversity, a sub-set of the diversity present in the samples from lower latitude sites on the western seaboard, and microsatellite-based evidence of having coming from assemblages that have undergone a bottleneck (or founder effect) followed by an expansion in size. (4) The samples from the assemblages in South Australia contained low levels of genetic diversity, phylogenetic affinities with samples from the eastern seaboard, and microsatellite-based evidence of having coming from assemblages that have undergone a bottleneck (or founder effect) followed by an expansion in size. The two major interpretations to stem from the results of this investigation are as follows. (1) Overall, Portunus pelagicus has undergone a recent (in an evolutionary sense) range expansion, from a single source, within Australian waters. At a finer-scale, this species appears to have colonised south-western Australia from a lower latitude site(s) on the western seaboard and probably colonised South Australia from the southern margins of its range on the eastern seaboard. Regardless, there has been limited penetrance of genetic variation into temperate waters on the western seaboard and into South Australia, presumably due one or more of the barriers to gene flow listed below. (2) P. pelagicus experiences significant restrictions to gene flow within its present-day geographical range in Australian waters due to (i) geographic distance per se; (ii) discontinuities in the distribution of the sheltered coastal environments; (iii) hydrological barriers to dispersal and (iv) possibly low temperatures in the temperature margins of the range.