Facial attractiveness plays a crucial role in human mate choice, with individuals from both sexes using facial attractiveness cues to some degree when choosing a partner. Although some of the general facial attractiveness preferences have been studied in cross-cultural populations, most of the research focused specifically on Western populations. Most previous studies also approached facial attractiveness solely from a psychological point of view. One notable exception was a recent study by Roberts et al. (2005) in which the authors linked the Human Leococyte Antigen (HLA) system to cues for health and facial attractiveness in males. This study provides fascinating evidence that genes involved in the immune response also signal attractiveness and health. But is this true cross-culturally and across genders? Roberts et al. (2005) used a British population, who compared to other populations worldwide, have relatively few pathogens that routinely challenge their immune response. The first objective of our study was to test the role of the HLA system in an African female population with a high pathogen load. We found that common HLA alleles, that seemingly provide resistance against common pathogens, play a more important role in health measures than heterozygosity per se. However, our results showed these individuals were not necessarily rated more attractive. So which facial cues do individuals from our study population find attractive in the opposite sex? According to this study individuals from both sexes prefer neotenous features in the opposite sex. Interestingly, we found no preference for facial symmetry and only a slight preference for femininity in females. Our findings support the hypothesis by Boothroyd et al. (2005) that preference for femininity is a by-product of preference for neotenous cues. To test if ethnic preference could not play a confounding role in facial attractiveness ratings of the ethnically mixed South African population, we tested ethnic recognition in two abundant South African ethnic groups. Our results showed that individuals from both sexes could not reliably assign ethnicity to facial images of the two groups. Ethnic preference could therefore not play a role in our study. But mate choice does not only depend on cues displayed by the person being observed. Conditional dependent factors, inherent to the observer, influence how choosy they are of potential partners and therefore how attractive they rate members of the opposite sex. We tested the role of three condition dependent factors, age self-perceived attractiveness and relationship status in both sexes. We observed no significant difference in choosiness between males and females. Male choice therefore plays a more important role in human mate choice than previously expected. Furthermore, our study showed that condition dependent factors affect choosiness differently in males and females. Females are generally more sensitive to condition dependent factors, especially self-perceived attractiveness, while males showed no correlation between any of the condition-dependent factors and choosiness. Since HIV is so prevalent in the South African population, we also tested the role of self esteem in predicting sexual risky behaviour. Our results showed that high self-esteem males were more likely to be sexually active after the age of 18, but that males with low self-esteem were more likely to start sexual activity prematurely. We observed no significant correlation for females. These results indicate that HIV prevention campaigns should focus more on behavioural outcomes other than abstinence, instead of challenging the cultural norms, as indicated by the behavior of high self-esteem individuals. In conclusion, this dissertation is based on the first comprehensive study of genetic and conditional cues associated with facial attractiveness and health in an African population. This African population, with its high pathogen load, high diversity and novel cultural background provided many novel findings, which would hopefully contribute to a more universal view of human mate choice. / Dissertation (MSc (Genetics))--University of Pretoria, 2006. / Genetics / unrestricted

Native fowl populations in South Africa were characterized genetically and phenotypically. Four South African native populations, two dual-purpose breeds, and two populations from Mozambique and Botswana were included for genetic analysis. For phenotypic characterization, two commercial lines were also included as a benchmark. Twenty-three micro satellite markers were selected and tested to obtain genetic data for estimation of genetic variability and distance. Growth (weight gain) and egg production were included for phenotypic characterization. A relatively high (53% ¬64%) genetic variation was found among the populations, which suggests conservation as a genetic resource for future use. The lowest genetic variation (53%) was found for the Koekoek and Australorp populations, which are the two populations that were subjected to formal selection, while the highest variation was observed in the Naked Neck population (64%). The New Hampshire has often been included in upgrading programs and this is evident from the close relationship with both the Lebowa- Venda and Naked Neck fowls. Phenotypic trials indicated significant differences among the populations included for growth, carcass and egg production traits. The Koekoek and New Hampshire populations had the best performance for egg production and growth (weight gain) in the study. Genetic and phenotypic differences indicate that the populations can be distinguished as different breeds or groups of fowl. The results of this study may contribute to selection for improved performance for household food production, as well as conservation of the populations as a genetic resource. / Thesis (PhD)--University of Pretoria, 2001. / Animal and Wildlife Sciences / unrestricted

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 106-116).

O presente estudo teve como objetivo estimar parâmetros genéticos e fenotípicos de número diâmetro e área de fibras musculares, bem como de características de desempenho, carcaça e qualidade de carne em uma linhagem de frangos pertencentes a um programa de seleção do tipo sib test, onde foram coletadas informações de carcaça dos irmãos completos dos indivíduos a serem selecionados, oriundos de um rebanho de pedigree, fornecidos pela Agroceres Ross Melhoramento de Aves S.A. Também foram fornecidos pela empresa 73.142 e 34.949 dados de peso à seleção juvenil e medidas de ultra-sonografia do músculo peitoral, respectivamente. As características analisadas foram: peso à seleção (PS), medidas de ultra-sonografia (US), peso de peito (PPEI), medida de pH inicial (pHi), medida de pH final (Phf), teor de luminosidade (L*), teor de vermelho (a*), teor de amarelo (b*), perdas de água por exsudação (EXSU), perdas de água por descongelamento (CONG), perdas de água por cozimento (COZ), força de cisalhamento (FC), número de fibras musculares (NCel), diâmetro de fibras musculares (DIAM) e área de fibras musculares (AREA). Os componentes de (co) variância foram estimados através do método de máxima verossimilhança restrita, utilizando-se o programa MTDFREML. A matriz de parentesco foi composta por 77.474 animais. As estimativas dos coeficientes de herdabilidade foram moderadas a altas para as características número de fibras musculares, peso à seleção juvenil, medida de ultra-sonografia, peso de peito, perda de água por exsudação, teor de luminosidade e teor de vermelho. As estimativas de correlações genéticas do número e diâmetro de fibras musculares com as características de perda de água da carne e força de cisalhamento indicaram a existência de uma importante associação genética entre as características, capazes de apresentar satisfatório potencial de resposta à seleção. / This research was conducted to estimate genetic and phenotypic parameters of muscle fibers of number, diameter and area, as well as of performace, carcass and meat quality traits in a male broiler line belonging to a program of selection of the type sib test, in which data from complete brothers of the individuals were selected, bred in a pedigree flock provided by Agroceres Ross Melhoramento de Aves S. A. Also were provided by the company 73,142 and 34,949 data concerning body weight at juvenile selection and ultrasound records of pectoral muscle, respectively. The traits analyzed were: body weight at juvenile selection (PS), ultrasound records of pectoral muscle (US), meat breast weight (PPEI), initial pH measure (pHi), final pH measure (pHf), lightness (L*), redness (a*), yellowness (b*), weep losses (EXSU), drip losses (CONG), shrik losses (COZ), shear force (FC), muscle fibers of number (NCel), muscle fibers of diameter and muscle fibers area (AREA). (Co) variance components were estimated by restricted maximum likelihood method, using the software MTDFREML. The numerator relationship matrix was composed by 77,474 individuals. Heritability coefficients estimates were from moderate to high for muscle fibers number, ultrasound records, meat breast weight, weep losses, lightness and redness traits. Genetic correlation estimates of muscle fibers number and diameter with the measures of meat water losses and shear force traits indicated the existence of an important genetic association between the traits, capable to present potential satisfactory respond to the selection.

Com o intuito de estudar o banco de dados da raça Pardo Suíço Corte no Brasil, foram estimados parâmetros genéticos para características de desenvolvimento ponderal e ganhos de peso pré e pós-desmama, perímetro escrotal e características de carcaça de animais dessa raça e seus cruzamentos, utilizando ultra-sonografia. As características de peso analisadas foram peso ao nascimento (PN), aos 120 dias (P120), aos 205 dias (P205), aos 365 dias (P365), aos 450 dias (P450) e peso aos 550 dias (P550), os ganho de peso analisados foram ganho de peso do nascimento aos 205 dias (GPN205), do nascimento aos 120 dias (GPN120), dos 120 aos 205 dias (GP120205), dos 205 aos 365 dias (GP205365), dos 205 aos 450 dias (GP205450), dos 205 aos 550 dias (GP205550), dos 365 aos 550 dias (GP365550), dos 365 aos 450 dias (GP365450) e ganho de peso dos 450 aos 550 dias (GP450550). Os perímetros escrotais foram analisados aos 205 dias (PE205), aos 365 dias (PE365), e aos 550 dias (PE550). Os componentes de co(variância) foram estimados utilizando-se metodologia de modelo animal completo, com o uso do programa MTDFREML. A matriz de parentesco continha 35.188 animais, sendo 18.688 com registros de produção. Para os pesos pré-desmama os coeficientes de herdabilidade aditiva direta e materna aumentaram sua magnitude do nascimento até a desmama. Nos pesos pós-desmama foi observada grande influência materna até os 550 dias de idade. Pode ser esperada boa resposta à seleção para perímetro escrotal tanto aos 205 como aos 365 dias de idade, havendo alta correlação genética entre estas características. O ganho de peso pré-desmama demonstrou grande influência materna até os 120 dias, e ambiental após esta data. Para o ganho pós-desmama foi observado importante efeito ambiental. A correlação genética entre os pesos foi maior quanto mais próximas foram as pesagens e não foi observada relação importante entre pesos e perímetro escrotal, indicando independência entre estas características. As correlações genéticas entre pesos e ganhos de peso foram maiores entre o ganho e o peso do limite superior do relativo ganho de peso. Devido ao pequeno volume de dados obtidos, estudos complementares são necessários para as características de carcaça. Este estudo possibilitará que seja melhor delineado o programa de melhoramento genético da raça Pardo Suíço Corte no Brasil. / The aim of this study was to investigate a database of the Braunvieh cattle in Brazil, to estimate genetic parameters for growth traits, preweaning and postweaning weight gains and scrotal circumference, as well as carcass traits in purebreed and crossbreed Braunvieh cattle. The growth traits analyzed were birth weight (PN), weight at 120 days (P120), 205 days (P205), 365 days (P365), 450 days (P450) and weight at 550 days (P550), Weight gains traits analyzed were, weight gain between birth and 205 days (GPN205), birth and 120 days (GPN120), 120 and 205 days (GP120205), 205 and 365 days (GP205365), 205 and 450 days (GP205450), 205 and 550 days (GP205550), 365 and 550 days (GP365550), 365 and 450 days (GP365450), 450 and 550 days (GP450550). The scrotal circumference was analyzed at 205 days (PE205), at 365 days (PE365), and at 550 days of age (PE550). The (co)variance components were estimated by full animal model, using MTDFREML program. The relationship matrix contained 35.188 animals, and 18.688 with production records. For the preweaning weights the coefficients of direct and maternal additive heritability increased your magnitude from the birth to weaning. In the postweaning weights were observed great maternal influence until the 550 days of age. Interesting response to selection can be expected to the selection for scrotal circumference realized at 205 and 365 days of age, due to high genetic correlation between these traits. The preweaning gain demonstrated great maternal influence until the 120 days, and environmental effect after this age. For postweaning gain great environmental effect was observed. Genetic correlation between the weights was larger for weights taken in shorter interval. Important relationship was not observed between weights and scrotal circumference, indicating independence between these characteristics. The genetic correlations between weights and weight gains were larger between the gain and the weight of the superior limit of the relative weight gain. Due to small amount of records for carcass traits, further studies are necessary to evaluate them. This study can contribute for the better delineated programs for genetic improvement of Braunvieh cattle in Brazil.

In long term, to discover the genes responsible for wood production, genetic control of wood specific gravity (WSG) in Pinus brutia Ten. (Turkish red pine) open pollinated Ceyhan progeny trial, which was established with the seeds collected from 168 clones originated from six clonal Turkish red pine seed orchards was studied. Wood samples were taken by destructive sampling during the rouging of this trial at the age of seven. Specifically / (1) to examine the magnitude of family differences and its components for wood specific gravity (WSG) and growth traits (height, diameter and stem volume) / (2) to determine WSG inheritance and its genetic correlation with growth traits / and (3) to estimate breeding values of 168 families for the WSG and to predict genetic gain if selection is based on phenotypic, rouged and genotypic seed orchard by reselecting the best parents with respect to WSG. Differences among the 168 families for mean WSG was large (ranged from 0.35 to 0.44), as indicated by high individual (0.42+0.07) and family mean (0.55+0.03) heritabilities. Family differences and high heritabilities were also observed for all growth traits. Genetic correlations between WSG and growth traits were statistically insignificant (near zero), while low and insignificant negative phenotypic correlations among the same traits were observed. Realized genetic gain for single trait selection at age seven was insignificant (0.37 %) for WSG and 8.4 % for stem volume in phenotypic seed orchards. Average genetic gain in breeding zone after roguing, by leaving the best 20 clones in each seed orchard, reached 1.7 % for WSG and 16.1 % for stem volume. Genetic gain (relative to controls) at the age of seven obtained from the first generation genotypic seed orchards consisting the best 30 clones was estimated 5.2 % for WSG and 35 % for stem volume. Multi-trait selection was also proposed in this study for the same traits. Selection of best 10 families for the highest WSG and stem volume breeding values produce 5.6 % genetic gain for WSG and 27.7 % genetic gain for stem volume. For the future, the 168 families with known phenotypic and genotypic values regarding to WSG will be screened for the genes responsible for wood production.

Com o intuito de estudar o banco de dados da raça Pardo Suíço Corte no Brasil, foram estimados parâmetros genéticos para características de desenvolvimento ponderal e ganhos de peso pré e pós-desmama, perímetro escrotal e características de carcaça de animais dessa raça e seus cruzamentos, utilizando ultra-sonografia. As características de peso analisadas foram peso ao nascimento (PN), aos 120 dias (P120), aos 205 dias (P205), aos 365 dias (P365), aos 450 dias (P450) e peso aos 550 dias (P550), os ganho de peso analisados foram ganho de peso do nascimento aos 205 dias (GPN205), do nascimento aos 120 dias (GPN120), dos 120 aos 205 dias (GP120205), dos 205 aos 365 dias (GP205365), dos 205 aos 450 dias (GP205450), dos 205 aos 550 dias (GP205550), dos 365 aos 550 dias (GP365550), dos 365 aos 450 dias (GP365450) e ganho de peso dos 450 aos 550 dias (GP450550). Os perímetros escrotais foram analisados aos 205 dias (PE205), aos 365 dias (PE365), e aos 550 dias (PE550). Os componentes de co(variância) foram estimados utilizando-se metodologia de modelo animal completo, com o uso do programa MTDFREML. A matriz de parentesco continha 35.188 animais, sendo 18.688 com registros de produção. Para os pesos pré-desmama os coeficientes de herdabilidade aditiva direta e materna aumentaram sua magnitude do nascimento até a desmama. Nos pesos pós-desmama foi observada grande influência materna até os 550 dias de idade. Pode ser esperada boa resposta à seleção para perímetro escrotal tanto aos 205 como aos 365 dias de idade, havendo alta correlação genética entre estas características. O ganho de peso pré-desmama demonstrou grande influência materna até os 120 dias, e ambiental após esta data. Para o ganho pós-desmama foi observado importante efeito ambiental. A correlação genética entre os pesos foi maior quanto mais próximas foram as pesagens e não foi observada relação importante entre pesos e perímetro escrotal, indicando independência entre estas características. As correlações genéticas entre pesos e ganhos de peso foram maiores entre o ganho e o peso do limite superior do relativo ganho de peso. Devido ao pequeno volume de dados obtidos, estudos complementares são necessários para as características de carcaça. Este estudo possibilitará que seja melhor delineado o programa de melhoramento genético da raça Pardo Suíço Corte no Brasil. / The aim of this study was to investigate a database of the Braunvieh cattle in Brazil, to estimate genetic parameters for growth traits, preweaning and postweaning weight gains and scrotal circumference, as well as carcass traits in purebreed and crossbreed Braunvieh cattle. The growth traits analyzed were birth weight (PN), weight at 120 days (P120), 205 days (P205), 365 days (P365), 450 days (P450) and weight at 550 days (P550), Weight gains traits analyzed were, weight gain between birth and 205 days (GPN205), birth and 120 days (GPN120), 120 and 205 days (GP120205), 205 and 365 days (GP205365), 205 and 450 days (GP205450), 205 and 550 days (GP205550), 365 and 550 days (GP365550), 365 and 450 days (GP365450), 450 and 550 days (GP450550). The scrotal circumference was analyzed at 205 days (PE205), at 365 days (PE365), and at 550 days of age (PE550). The (co)variance components were estimated by full animal model, using MTDFREML program. The relationship matrix contained 35.188 animals, and 18.688 with production records. For the preweaning weights the coefficients of direct and maternal additive heritability increased your magnitude from the birth to weaning. In the postweaning weights were observed great maternal influence until the 550 days of age. Interesting response to selection can be expected to the selection for scrotal circumference realized at 205 and 365 days of age, due to high genetic correlation between these traits. The preweaning gain demonstrated great maternal influence until the 120 days, and environmental effect after this age. For postweaning gain great environmental effect was observed. Genetic correlation between the weights was larger for weights taken in shorter interval. Important relationship was not observed between weights and scrotal circumference, indicating independence between these characteristics. The genetic correlations between weights and weight gains were larger between the gain and the weight of the superior limit of the relative weight gain. Due to small amount of records for carcass traits, further studies are necessary to evaluate them. This study can contribute for the better delineated programs for genetic improvement of Braunvieh cattle in Brazil.

O presente estudo teve como objetivo estimar parâmetros genéticos e fenotípicos de número diâmetro e área de fibras musculares, bem como de características de desempenho, carcaça e qualidade de carne em uma linhagem de frangos pertencentes a um programa de seleção do tipo sib test, onde foram coletadas informações de carcaça dos irmãos completos dos indivíduos a serem selecionados, oriundos de um rebanho de pedigree, fornecidos pela Agroceres Ross Melhoramento de Aves S.A. Também foram fornecidos pela empresa 73.142 e 34.949 dados de peso à seleção juvenil e medidas de ultra-sonografia do músculo peitoral, respectivamente. As características analisadas foram: peso à seleção (PS), medidas de ultra-sonografia (US), peso de peito (PPEI), medida de pH inicial (pHi), medida de pH final (Phf), teor de luminosidade (L*), teor de vermelho (a*), teor de amarelo (b*), perdas de água por exsudação (EXSU), perdas de água por descongelamento (CONG), perdas de água por cozimento (COZ), força de cisalhamento (FC), número de fibras musculares (NCel), diâmetro de fibras musculares (DIAM) e área de fibras musculares (AREA). Os componentes de (co) variância foram estimados através do método de máxima verossimilhança restrita, utilizando-se o programa MTDFREML. A matriz de parentesco foi composta por 77.474 animais. As estimativas dos coeficientes de herdabilidade foram moderadas a altas para as características número de fibras musculares, peso à seleção juvenil, medida de ultra-sonografia, peso de peito, perda de água por exsudação, teor de luminosidade e teor de vermelho. As estimativas de correlações genéticas do número e diâmetro de fibras musculares com as características de perda de água da carne e força de cisalhamento indicaram a existência de uma importante associação genética entre as características, capazes de apresentar satisfatório potencial de resposta à seleção. / This research was conducted to estimate genetic and phenotypic parameters of muscle fibers of number, diameter and area, as well as of performace, carcass and meat quality traits in a male broiler line belonging to a program of selection of the type sib test, in which data from complete brothers of the individuals were selected, bred in a pedigree flock provided by Agroceres Ross Melhoramento de Aves S. A. Also were provided by the company 73,142 and 34,949 data concerning body weight at juvenile selection and ultrasound records of pectoral muscle, respectively. The traits analyzed were: body weight at juvenile selection (PS), ultrasound records of pectoral muscle (US), meat breast weight (PPEI), initial pH measure (pHi), final pH measure (pHf), lightness (L*), redness (a*), yellowness (b*), weep losses (EXSU), drip losses (CONG), shrik losses (COZ), shear force (FC), muscle fibers of number (NCel), muscle fibers of diameter and muscle fibers area (AREA). (Co) variance components were estimated by restricted maximum likelihood method, using the software MTDFREML. The numerator relationship matrix was composed by 77,474 individuals. Heritability coefficients estimates were from moderate to high for muscle fibers number, ultrasound records, meat breast weight, weep losses, lightness and redness traits. Genetic correlation estimates of muscle fibers number and diameter with the measures of meat water losses and shear force traits indicated the existence of an important genetic association between the traits, capable to present potential satisfactory respond to the selection.

Made available in DSpace on 2015-03-26T13:42:23Z (GMT). No. of bitstreams: 1 texto completo.pdf: 2141668 bytes, checksum: b7f9269723d229ff78c781b127e1558b (MD5) Previous issue date: 2011-07-25 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Data from the herd of goat industry, Federal University of Viçosa were used to evaluate the factors that influence milk production on the control (PLDC) and content of the Milk constituents (percentages of protein, fat, lactose and total solids in days of collection) in dairy goats fitness, define the best model of random regression using Legendre polynomials orthogonal to the first lactation in Alpine goats and check the effect of different control intervals (7, 14, 21 and 28 days) on genetic evaluation of Alpine goats. The editing of the data was performed using the SAS program, recoding and correction of the pedigree was made using the program RENPED. The program WOMBAT was used in all genetic evaluations. The program RENPED was used to calculate the area under the curve of breeding values for ranges from 7 to 210 and 7 to 290 days of production, resulting accumulated genetic values, A210 and A290 respectively. The Pearson and Spearman correlations were obtained using the SAS program. It was concluded that there is variation in the factors that significantly influenced each trait studied and each race. In genetic evaluation using random regression models, it is recommended to use only the covariate age of dam at kidding, avoiding the use of fixed effect of birth order. The random regression model using orthogonal Legendre polynomials more suitable for genetic evaluation of Alpine goat breed used was fixed regression of order 4, the regression of additive genetic effects of order 2, the regression of permanent environmental effects of order 7 and at least Five classes of residual variance. The prior study of the best model for genetic evaluation of a herd is very important to increase the precision and accuracy of the analysis. Range of controls to evaluate the milk production of Alpine goat breed using random regression models, must be seven days for breeding and improvement programs with high technical level. / Dados do rebanho do setor de caprinocultura da Universidade Federal de Viçosa foram utilizados para avaliar os fatores que influenciam a produção de leite no dia do controle (PLDC) e teor dos constituintes do leite (porcentagens de proteína, gordura, lactose e extrato seco total no dia da coleta) em caprinos de aptidão leiteira, definir o melhor modelo de regressão aleatória, utilizando polinômios ortogonais de Legendre, para primeira lactação de cabras Alpinas e verificar o efeito de diferentes intervalos de controle (7, 14, 21 e 28 dias) sobre a avaliação genética de cabras Alpinas. A edição dos dados foi feita utilizando o programa SAS, a recodificação e correção de erros do pedigree foi feita utilizando o programa RENPED. O programa WOMBAT foi utilizado em todas as avaliações genéticas. O programa RENPED foi utilizado para calcular a área abaixo da curva de valores genéticos dos animais para intervalos de 7 a 210 e 7 a 290 dias de produção, gerando os valores genéticos acumulados, a210 e a290 respectivamente. As correlações de Pearson e Spearman foram obtidas utilizando o programa SAS. Concluiu-se que existe variação quanto aos fatores que influenciaram significativamente cada característica estudada e cada raça. Em avaliações genéticas, utilizando modelos de regressão aleatória, recomenda-se a utilização apenas da covariável idade da cabra ao parto, evitando o uso do efeito fixo de ordem de parto. O modelo de regressão aleatória utilizando polinômios ortogonais de Legendre mais indicado para avaliação genética dos caprinos da raça Alpina utilizados, foi regressão fixa de ordem 4, a regressão de efeitos genéticos aditivos de ordem 2, a regressão de efeitos de ambiente permanente de ordem 7 e ao menos 5 classes de variância residual. O estudo do melhor modelo de análise previamente à avaliação genética de um rebanho é imprescindível para aumentar a precisão e acurácia das análises. Intervalos de controles para avaliar a produção de leite de caprinos da raça alpina utilizando modelos de regressão aleatória, devem ser de sete dias para programas de melhoramento e criatórios com alto nível de tecnificação.

The canine transmissible venereal tumour (CTVT) is a contagious cancer that is naturally transmitted between dogs by the allogeneic transfer of living cancer cells during coitus. CTVT first arose several thousand years ago and has been reported in dog populations worldwide. The goals of this Thesis were (1) to gain further understanding of CTVT distribution patterns and prevalence around the world, (2) to use genetics to trace the historical spread of CTVT and (3) to map the genetic as well as phenotypic diversity of CTVT tumours around the world. To understand the distribution patterns of CTVT, I obtained information from 645 veterinarians and animal health workers in 109 countries, and generated a snapshot of the locations in which this disease is found. Additionally, as preparation for further genetic analysis, I collected samples from over one thousand CTVT cases from more than 50 countries, optimised methods for high-throughput DNA extraction and quantification and optimised a qPCR-based assay for CTVT diagnosis and host contamination detection. With the goal of tracing the historical spread of CTVT and learning about the genetic diversity of this disease, I sequenced complete mitochondrial genomes of 449 CTVT tumours and their matched hosts. The analysis of the CTVT mitochondrial diversity revealed that CTVT has captured mitochondrial DNA (mtDNA) through horizontal transfer events at least five times during the history of the lineage, delineating five tumour clades. CTVT appears to have spread rapidly around the world within the last 2,000 years, perhaps transported by dogs travelling along historic maritime trade routes. This work indicated that negative selection has operated to prevent accumulation of deleterious mutations in captured mtDNA, and that recombination has caused occasional mtDNA re-assortment. A histology-based screen of CTVT clades did not show any significant phenotypic differences between groups. In order to determine how the five mtDNA clades relate to each other, I analysed data from 539 CTVT exomes. This revealed that a single canine mtDNA haplogroup has recurrently and recently undergone multiple horizontal transfer events. Analysis of this haplotype highlighted a number of candidate genetic variants which may be conferring a selective advantage to this haplotype in CTVT, possibly by influencing mtDNA transcription or replication. Overall, genetic and phenotypic analysis of CTVT tumours from across the globe has broadened our understanding of CTVT diversity, and provided important insights into the biology of a unique transmissible cancer.