RESUMO
Goats have played a key role as source of nourishment for humans in their expansion all over the world in long land and sea trips. This has guaranteed a place for this species in the important and rapid episode of livestock expansion triggered by Columbus' arrival in the Americas in the late 1400s. The aims of this study are to provide a comprehensive perspective on genetic diversity in American goat populations and to assess their origins and evolutionary trajectories. This was achieved by combining data from autosomal neutral genetic markers obtained in more than two thousand samples that encompass a wide range of Iberian, African and Creole goat breeds. In general, even though Creole populations differ clearly from each other, they lack a strong geographical pattern of differentiation, such that populations of different admixed ancestry share relatively close locations throughout the large geographical range included in this study. Important Iberian signatures were detected in most Creole populations studied, and many of them, particularly the Cuban Creole, also revealed an important contribution of African breeds. On the other hand, the Brazilian breeds showed a particular genetic structure and were clearly separated from the other Creole populations, with some influence from Cape Verde goats. These results provide a comprehensive characterisation of the present structure of goat genetic diversity, and a dissection of the Iberian and African influences that gave origin to different Creole caprine breeds, disentangling an important part of their evolutionary history. Creole breeds constitute an important reservoir of genetic diversity that justifies the development of appropriate management systems aimed at improving performance without loss of genomic diversity.
Assuntos
Cruzamento , Variação Genética , Cabras , Animais , Brasil , Marcadores Genéticos , Cabras/genética , FilogeniaRESUMO
In this study, we genetically characterized the Uruguayan pig breed Pampa Rocha. Genetic variability was assessed by analyzing a panel of 25 microsatellite markers from a sample of 39 individuals. Pampa Rocha pigs showed high genetic variability with observed and expected heterozygosities of 0.583 and 0.603, respectively. The mean number of alleles was 5.72. Twenty-four markers were polymorphic, with 95.8% of them in Hardy Weinberg equilibrium. The level of endogamy was low (FIS = 0.0475). A factorial analysis of correspondence was used to assess the genetic differences between Pampa Rocha and other pig breeds; genetic distances were calculated, and a tree was designed to reflect the distance matrix. Individuals were also allocated into clusters. This analysis showed that the Pampa Rocha breed was separated from the other breeds along the first and second axes. The neighbour-joining tree generated by the genetic distances DA showed clustering of Pampa Rocha with the Meishan breed. The allocation of individuals to clusters showed a clear separation of Pampa Rocha pigs. These results provide insights into the genetic variability of Pampa Rocha pigs and indicate that this breed is a well-defined genetic entity.
RESUMO
The Uruguayan Creole cattle population (N = 600) is located in a native habitat in south-east Uruguay. We analyzed its genetic diversity and compared it to other populations of American Creole cattle. A random sample of 64 animals was genotyped for a set of 17 microsatellite loci, and the D-loop hyper-variable region of mtDNA was sequenced for 28 calves of the same generation. We identified an average of 5.59 alleles per locus, with expected heterozygosities between 0.466 and 0.850 and an expected mean heterozygosity of 0.664. The polymorphic information content ranged from 0.360 to 0.820, and the global FIS index was 0.037. The D-loop analysis revealed three haplotypes (UY1, UY2 and UY3), belonging to the European matriline group, with a haplotype diversity of 0.532. The history of the population, changes in the effective population size, bottlenecks, and genetic drift are possible causes of the genetic variability patterns that we detected.
Assuntos
DNA Mitocondrial/genética , Variação Genética , Repetições de Microssatélites/genética , Alelos , Animais , Cruzamento , Bovinos , Evolução Molecular , Frequência do Gene , Genética Populacional , Haplótipos , FilogeniaRESUMO
Brazilian goat breeds are believed to derive mainly from animals brought by Portuguese settlers since the 16th century. We used microsatellite markers in a sample of 436 animals to study genetic variability and differentiation of the six Portuguese (PT) and six Brazilian (BR) goat breeds currently recognized in the two countries. These breeds were also compared with an outgroup represented by a sample of Alpine (ALP) goats. The effective number of alleles and allelic richness were slightly higher in PT than in BR breeds. The global F(ST) was nearly 0.11 when PT and BR breeds were considered, with a mean pairwise F(ST) of about 0.03 among PT breeds, 0.07 among BR breeds and 0.15 between PT and BR breeds. The dendrogram illustrating relationships between populations and the correspondence analysis indicate the existence of two very distinct clusters, corresponding to the countries of origin of the breeds studied, which are nearly equidistant from the Alpine outgroup. The analysis with structure confirmed the separation between PT and BR breeds but suggests that some BR breeds, especially Graúna and Canindé, may share a common ancestry with PT breeds. The divergence observed between PT and BR breeds may result from founder effects and genetic drift but could also reflect the introduction in Brazil of goats originating from other regions, e.g., West Africa.
Assuntos
Deriva Genética , Cabras/genética , Animais , Oceano Atlântico , Brasil , Frequência do Gene , Loci Gênicos/genética , Variação Genética , Heterozigoto , Repetições de Microssatélites/genética , PortugalRESUMO
The African antelope Addax nasomaculatus is a rare mammal at high risk of extinction, with no more than 300 individuals in the wild and 1,700 captive animals distributed in zoos around the world. In this work, we combine genetic data and genealogical information to assess the structure and genetic diversity of a captive population located at Parque Lecocq Zoo (N=27), originated from only two founders. We amplified 39 microsatellites previously described in other Artiodactyls but new to this species. Seventeen markers were polymorphic, with 2-4 alleles per locus (mean=2.71). Mean expected heterozygosity (He) per locus was between 0.050 (marker ETH3) and 0.650 (marker D5S2), with a global He of 0.43. The mean inbreeding coefficient of the population computed from pedigree records of all registered individuals (N=53) was 0.222. The mean coancestry of the population was 0.298 and F(IS) index was -0.108. These results reflect the importance of an adequate breeding management on a severely bottlenecked captive population, which would benefit by the incorporation of unrelated individuals. Thanks to the successful amplification of a large number of microsatellites commonly used in domestic bovids, this study will provide useful information for the management of this population and serve as future reference for similar studies in other captive populations of this species.
Assuntos
Animais de Zoológico , Antílopes/genética , Criação de Animais Domésticos , Animais , Conservação dos Recursos Naturais , Feminino , Variação Genética , Masculino , Repetições de Microssatélites , Linhagem , UruguaiRESUMO
The population structure of the Murciano-Granadina breed was determined using 25 microsatellites from 266 goats of seven populations. The results of the genetic differentiation analysis showed that it is possible to differentiate the Murciana and Granadina populations even though a low F ST value (0.0432) had been obtained. Individuals could be assigned to their populations with a success rate of more than 80 percent. Bayesian-based clustering analysis of allele frequencies and multivariate analysis revealed that Murciana and Granadina populations were grouped in different clusters since K=3. The results demonstrate that Murciana and Granadina are still two different genetic groups included into Murciano-Granadina denomination. There is the opportunity to the genetically manage these populations, under a single herd-book but adding the necessary modifications to respect the conservation of the genetic diversity based on the use of multibreed models of genetic evaluation.
Determinou-se a estrutura da raça Murciano-Granadina, usando-se 25 microssatélites e 266 animais de sete populações. Os resultados da diferenciação genética mostram que é possível diferenciar populações de Murciana e Granadina, apesar dos baixos valores de F ST obtidos - 0.0432. Os indivíduos foram designados às suas populações com taxa de sucesso superior a 80 por cento. A análise bayesiana de agrupamento das frequências alélicas e a análise multivariada revelaram que as populações Murciana e Granadina foram agrupadas em diferentes clusters, uma vez que o melhor K obtido foi três. Os resultados demonstraram que Murciana e Granadina ainda são dois grupos genéticos distintos incluídos na denominação Murciano-Granadina. É possível manejar geneticamente essas populações dentro de um único livro de registro, porém adotando-se as modificações necessárias em relação à conservação e à diversidade genética, com base no uso de modelos de avaliação multirracial.
Assuntos
Animais , Cabras/genética , Variação Genética , Repetições de MicrossatélitesRESUMO
The population structure of the Murciano-Granadina breed was determined using 25 microsatellites from 266 goats of seven populations. The results of the genetic differentiation analysis showed that it is possible to differentiate the Murciana and Granadina populations even though a low F ST value (0.0432) had been obtained. Individuals could be assigned to their populations with a success rate of more than 80 percent. Bayesian-based clustering analysis of allele frequencies and multivariate analysis revealed that Murciana and Granadina populations were grouped in different clusters since K=3. The results demonstrate that Murciana and Granadina are still two different genetic groups included into Murciano-Granadina denomination. There is the opportunity to the genetically manage these populations, under a single herd-book but adding the necessary modifications to respect the conservation of the genetic diversity based on the use of multibreed models of genetic evaluation.(AU)
Determinou-se a estrutura da raça Murciano-Granadina, usando-se 25 microssatélites e 266 animais de sete populações. Os resultados da diferenciação genética mostram que é possível diferenciar populações de Murciana e Granadina, apesar dos baixos valores de F ST obtidos - 0.0432. Os indivíduos foram designados às suas populações com taxa de sucesso superior a 80 por cento. A análise bayesiana de agrupamento das frequências alélicas e a análise multivariada revelaram que as populações Murciana e Granadina foram agrupadas em diferentes clusters, uma vez que o melhor K obtido foi três. Os resultados demonstraram que Murciana e Granadina ainda são dois grupos genéticos distintos incluídos na denominação Murciano-Granadina. É possível manejar geneticamente essas populações dentro de um único livro de registro, porém adotando-se as modificações necessárias em relação à conservação e à diversidade genética, com base no uso de modelos de avaliação multirracial.(AU)