Analysis of genetic distance between Peruvian Alpaca (Vicugna Pacos) showing two distinct fleece phenotypes, Suri and Huacaya, by means of microsatellite markers

Two coat phenotypes exist in Alpaca, Huacaya and Suri. The two coats show different fleece structure, textile characteristics and prices on the market. Although present scientific knowledge suggests a simple genetic model of inheritance, there is a tendency to manage and consider the two phenotypes as two different breeds. A 13 microsatellite panel was used in this study to assess genetic distance between Suri and Huacaya alpacas in a sample of non-related animals from two phenotypically pure flocks at the Illpa-Puno experimental station in Quimsachata, Peru. The animals are part of a germplasm established approximately 20 years ago and have been bred separately according to their coat type since then. Genetic variability parameters were also calculated. The data were statistically analyzed using the software Genalex 6.3, Phylip 3.69 and Fstat 2.9.3.2. The sample was tested for Hardy-Weinberg equilibrium (HWE) and after strict Bonferroni correction only one locus (LCA37) showed deviation from equilibrium (P<0.05). Linkage disequilibrium (LD) was also tested and 9 loci associations showed significant disequilibrium. Observed heterozygosis (Ho= 0.766; SE=0.044), expected heterozygosis (He=0.769; SE=0.033), number of alleles (Na=9.667, SE=0.772) and Fixation index (F=0.004; SE=0.036) are comparable to data from previous studies. Measures of genetic distance were 0.06 for Nei’s and 0.03 for Cavalli-Sforza’s. The analysis of molecular variance reported no existing variance between populations. Considering the origin of the animals, their post domestication evolution and the reproductive practices in place, the results do not show genetic differentiation between the two populations for the studied loci

Fleece variation in alpaca (Vicugna pacos): a two-locus model for the Suri/Huacaya phenotype

Background: Genetic improvement of fibre-producing animal species has often induced transition from double coated to single coated fleece, accompanied by dramatic changes in skin follicles and hair composition, likely implying variation at multiple loci. Huacaya, the more common fleece phenotype in alpaca (Vicugna pacos), is characterized by a thick dense coat growing perpendicularly from the body, whereas the alternative rare and more prized single-coated Suri phenotype is distinguished by long silky fibre that grows parallel to the body and hangs in separate, distinctive pencil locks. A single-locus genetic model has been proposed for the Suri-Huacaya phenotype, where Huacaya is recessive. Results: Two reciprocal experimental test-crosses (Suri x Huacaya) were carried out, involving a total of 17 unrelated males and 149 unrelated females. An additional dataset of 587 offspring of Suri x Suri crosses was analyzed. Segregation ratios, population genotype frequencies, and/or recombination fraction under different genetic models were estimated by maximum likelihood. The single locus model for the Suri/Huacaya phenotype was rejected. In addition, we present two unexpected observations: 1) a large proportion (about 3/4) of the Suri animals are segregating (with at least one Huacaya offspring), even in breeding conditions where the Huacaya trait would have been almost eliminated; 2) a model with two different values of the segregation ratio fit the data significantly better than a model with a single parameter. Conclusions: The data support a genetic model in which two linked loci must simultaneously be homozygous for recessive alleles in order to produce the Huacaya phenotype. The estimated recombination rate between these loci was 0.099 (95% C. L. = 0.029-0.204). Our genetic analysis may be useful for other species whose breeding system produces mainly half-sib families

ÍNDICES REPRODUCTIVOS DE ALPACAS HUACAYA DEL INIA QUIMSACHATA 1997 – 2012 – PUNO - PERÚ

El objetivo fue determinar los índices reproductivos de alpacas Huacaya (edad al primer empadre, edad al primer parto, número de empadres por parto, descanso post parto, intervalo parto preñez, intervalo entre partos y tiempo de cópula), El estudio se realizó en el Centro de Investigación y Producción Quimsachata del Instituto Nacional de Innovación Agraria INIA – Puno; para lo cual se han utilizado registros individuales de empadre controlado y de parición de alpacas del periodo 1997-2012. Los datos fueron sistematizados en el programa Microsoft Excel. Los datos se han analizado en un diseño completamente al azar y prueba “Z”. Se ha utilizado el programa estadístico SAS para su procesamiento. Los resultados muestran que la edad al primer empadre es de 704.33 días, edad al primer parto 1077.45 días, número de servicios por parto 1.31, descanso post parto 24.47 días, intervalo parto preñez 30.20 días, intervalo entre partos 375.65 días y tiempo de cópula 21.16 minutos. Se concluye que el factor estado fisiológico de la hembra influye significativamente sobre el número de servicios por parto, descanso post parto, intervalo parto preñez, intervalo entre partos y tiempo de cópula (p<0.01)

A microsatellite study on the genetic distance between suri and huacaya phenotypes in peruvian alpaca (Vicugna pacos)

Two coat phenotypes exist in alpaca: the Huacaya and the Suri. The two coats have different textile characteristics and different prices on the market. Although present scientific knowledge suggests a simple genetic model of inheritance, there is a tendency to manage and consider the two phenotypes as two different breeds. A 14-microsatellite panel was used in this study to assess genetic distance between Suri and Huacaya alpacas in a sample of non-related animals from two phenotypically pure flocks at the Illpa-Puno experimental station in Quimsachata. Peru. The animals are part of a germplasm established approximately 20 years ago and have been bred separately according to their coat type since then. Genetic variability parameters were also calculated. The codominant data was statistically analysed using the software Genalex 6.3, Phylip 3.69 and Fstat 2.9.3.2. The sample was tested for Hardy-Weinberg equilibrium (HWE) and after strict Bonferroni correction only one locus (LCA37) showed deviation from equilibrium (P<0.05). Linkage disequilibrium (LD) was also tested and 9 loci associations showed significant disequilibrium. Observed heterozygosis (Ho= 0.766; SE=0.044), expected heterozygosis (He=0.769; SE=0.033), number of alleles (Na=9.667, SE=0.772) and Fixation index (F=0.004; SE=0.036) are comparable to data from previous studies. Measures of genetic distance were 0.06 forNei’s and 0.03 for Cavalli-Sforza’s. The analysis of molecular variance reported no existing variance between populations. Considering the origin of the animals, their post domestication evolution and the reproductive practices in place, the results suggest that there is no genetic differentiation between the two populations for the studied loci