Genetic Characterization of a Sheep Population in Oaxaca, Mexico: The Chocholteca Creole.

Creole sheep in México have undergone crossbreeding, provoking the loss of genetic variability. The objective of the present study is to determine the intra-racial genetic diversity, the genetic relationship with other genotypes, and the populational substructure of the Oaxacan Creole sheep. Twenty-nine blood samples were obtained of Creole sheep of the Oaxaca Mixteca region in México. A genetic analysis was made with 41 microsatellites recommended for studies of genetic diversity in sheep. An analysis was made of genetic diversity, populational structure, and genetic distance with 27 other sheep populations. The study found 205 alleles with a range of 2 to 9 by locus and an effective number of 3.33. The intra-racial analysis showed a moderate genetic diversity with values of expected heterozygosity of 0.686 and observed of 0.756, a mean polymorphic information content of 0.609, and a mean coefficient of consanguinity of -0.002. In interracial genetic diversity for the coefficients of consanguinity, the values were FIS = 0.0774, FIT = 0.16993, and FST = 0.10028, showing an elevated genetic distance with other creole breeds, but close to Argentine Creole, to another Creole of México and the Spanish Merino. Its genetic structure showed that it does not have any populational subdivision nor mixes with the others analyzed. It is concluded that it is a distinct and isolated population and is proposed as the creole breed "Chocholteca" for its conservation.

Molecular inference in the colonization of cattle in Ecuador.

The aim of the present paper was to evaluate genetic diversity within and among Ecuadorian bovine breeds using microsatellite markers. The genetic identity and the exotic influences from taurine or zebuine cosmopolitan breeds on Macabea, Loja, Santa Elena, Manabí and Isla de Puná breeds were evaluated. Twenty-eight microsatellite markers were tested across 254 individuals belonging to the five Ecuadorian populations to investigate intra and inter population genetic diversity levels. Nineteen markers in common with a set of 1595 samples of 35 previously typed breeds were used to determine the potential origin of Ecuadorian bovine breeds and to identify and quantify their genetic relationships. The findings of FIS > FST (0.0814 > 0.0499), even in the context of low but significant FST values, may be indicative of the intrapopulation origin of the variability of allelic frequencies across populations. Conclusively, the study of genetic distances and population structure suggested the origin of Ecuadorian populations may likely stem from Southern Spanish breeds, with no significant recent influence from cosmopolitan Taurine or Zebuine breeds. These findings may provide a solid basis for the demonstration of an Ecuadorian breeds identity in the framework of the genetic conservation of the American creole populations.

Genetic Characterization of the "Chusca Lojana", a Creole Goat Reared in Ecuador, and Its Relationship with Other Goat Breeds.

The largest population of goats (62%) in Ecuador is in the dry forest region in the south of the country. A Creole goat, named "Chusca Lojana", has adapted to the dry forest region where environmental conditions are warm-dry, with sparse vegetation. Knowledge of the genetic information of the Creole goat is important to determine intra-racial diversity, the degree of genetic distance among other breeds of goats, and the possible substructure of the population, which is valuable for the conservation of such a species' genetic resources. A total of 145 samples of the Creole goat was taken from the four biotypes previously identified. Genetic analyses were performed using 38 microsatellites recommended for studies of goat genetic diversity (FAO-ISAG). The results of within-breed genetic diversity showed a mean number of alleles per locus (MNA) of 8, an effective number of alleles (Ae) of 4.3, an expected heterozygosity (He) of 0.71, an observed heterozygosity (Ho) of 0.63, polymorphic information content (PIC) of 0.67, and an FIS value of 0.11. Between-breed genetic diversity among 43 goat populations (native of Spain, American Creole, Europeans, and Africans) showed the following values: FIS = 0.087, FIT = 0.176, and FST = 0.098. Regarding the analysis of the population structure, the results showed that the Creole Chusca Lojana goat population is homogeneous and no genetic separation was observed between the different biotypes (FST = 0.0073). In conclusion, the Chusca Lojana goat has a high genetic diversity, without exhibiting a genetic substructure. Therefore, it should be considered as a distinct population because crossbreeding with other breeds was not detected.