The concept of species in bacteria is a matter of contention. The current definition is based on DNA-DNA hybridisation and does not account for evolutionary forces that are important in demarcating species. In this thesis we investigate two evolutionary forces that are important in speciation in bacteria, propose novel statistical models for them and infer parameters of interest. We present the first attempt at inferring the bias in the recombination process from whole bacterial genomes. Despite empirical evidence that recombination is biased and theoretical results that this bias is important in speciation, it is usually ignored. We propose a coalescent based model that accounts for the bias in the recombination process. We use approximate Bayesian computation for inference and describe an efficient method for simulating from the model. We show that our method performs well on simulated datasets and is robust to slight misspecification of the history of the samples. Application of our method to a Bacillus cereus dataset shows that it contain evidence that the recombination process depends on the evolutionary distance between donors and recipients. We demonstrate that the rate of bias in the recombination process for this dataset is far lower than what theoretical studies require for the spontaneous generation of populations that can be called species under neutral model. Next we propose a model for occurrence of adaptive events on a phylogenetic tree. We use the model to infer the boundaries of clusters on a phylogenetic tree that correspond to ecologically distinct lineages. we characterise our method using simulated datasets and show that it is conservative in estimating the number of adaptive events. Finally we apply our method to two bacterial datasets of Salmonella enterica and Vibrionaceae. We show that there is decisive evidence that isolates in these datasets partition into numerous ecologically distinct lineages and use our method to delineate the boundaries of these lineages.

Amidst the decisive events of the 20th century - the Holocaust and the rebirth of the Jewish homeland - which impacted heavily on Jewish attitudes, emerged a broadening of religious doctrines creating diversity within Judaism. Previous insularist tendencies were replaced by revised outlooks on proselytisation, blending with the unique characteristics of South African Jewry. Clearly, local Jewish society and the Rabbinate have placed these updated perceptions high on its agenda. The inevitable mixed reactions have been reviewed in this work, which looks at the long road travelled by the convert from the viewpoint of current motivations, acceptance by the community and post conversion levels of observance. My own theory is a model encompassing the respective components of local proselytism looking at categories of converts, their motives, demands to be met and obstacles. To comprehend the contemporary position, a historical survey delved into the issue from its Biblical origins via the influences of centuries, reaching the South African scene. This inquiry investigated the development of conversion policies drawn from an evolvement of energetic Halakhic debate. These attitudes manifest themselves in archival sources from 1924, of which my analysis is the first of its kind. From these records, together with those of my own community and data available from the Cape Beth Din, the interpretative statistics thus compiled identified characteristics and motivations of applicants and procedural mechanics. This work proceeded a step further. Focus on the Durban model provided an ideal observation point for the post conversion stages. Personal knowledge of the candidates gained from my service to Durban Jewry enabled me to assess their respective adherences and absorption into the community. Furthermore, responses to a questionnaire sent to the local Jewry and interviews revealed attitudes both of Jews by birth and the converts themselves whilst added perceptions were obtained from a questionnaire sent to the Rabbis of South Africa. In the final chapter I submitted proposals and recommendations, some of which are radical. Covering the entire process of conversion this model attempts to address the future of conversions in South Africa as this is expected to remain a pivotal issue of immense momentum. / Religious Studies & Arabic / D. Litt. et Phil. (Religious Studies)

Amidst the decisive events of the 20th century - the Holocaust and the rebirth of the Jewish homeland - which impacted heavily on Jewish attitudes, emerged a broadening of religious doctrines creating diversity within Judaism. Previous insularist tendencies were replaced by revised outlooks on proselytisation, blending with the unique characteristics of South African Jewry. Clearly, local Jewish society and the Rabbinate have placed these updated perceptions high on its agenda. The inevitable mixed reactions have been reviewed in this work, which looks at the long road travelled by the convert from the viewpoint of current motivations, acceptance by the community and post conversion levels of observance. My own theory is a model encompassing the respective components of local proselytism looking at categories of converts, their motives, demands to be met and obstacles. To comprehend the contemporary position, a historical survey delved into the issue from its Biblical origins via the influences of centuries, reaching the South African scene. This inquiry investigated the development of conversion policies drawn from an evolvement of energetic Halakhic debate. These attitudes manifest themselves in archival sources from 1924, of which my analysis is the first of its kind. From these records, together with those of my own community and data available from the Cape Beth Din, the interpretative statistics thus compiled identified characteristics and motivations of applicants and procedural mechanics. This work proceeded a step further. Focus on the Durban model provided an ideal observation point for the post conversion stages. Personal knowledge of the candidates gained from my service to Durban Jewry enabled me to assess their respective adherences and absorption into the community. Furthermore, responses to a questionnaire sent to the local Jewry and interviews revealed attitudes both of Jews by birth and the converts themselves whilst added perceptions were obtained from a questionnaire sent to the Rabbis of South Africa. In the final chapter I submitted proposals and recommendations, some of which are radical. Covering the entire process of conversion this model attempts to address the future of conversions in South Africa as this is expected to remain a pivotal issue of immense momentum. / Religious Studies and Arabic / D. Litt. et Phil. (Religious Studies)