Tag: "genetic"

  • The origins of South America's domestic alpaca and llama remain controversial due to hybridization, near extirpation during the Spanish conquest and difficulties in archaeological interpretation. Traditionally, the ancestry of both forms is attributed to the guanaco, while the vicuña is assumed never to have been domesticated. Recent research has, however, linked the alpaca to the vicuña, dating domestication to 6000–7000 years before present in the Peruvian Andes. Here, we examine in detail the genetic relationships between the South American camelids in order to determine the origins of the domestic forms, using mitochondrial (mt) and microsatellite DNA. MtDNA analysis places 80% of llama and alpaca sequences in the guanaco lineage, with those possessing vicuña mtDNA being nearly all alpaca or alpaca–vicuña hybrids. We also examined four microsatellites in wild known–provenance vicuña and guanaco, including two loci with non–overlapping allele size ranges in the wild species. In contrast to the mtDNA, these markers show high genetic similarity between alpaca and vicuña, and between llama and guanaco, although bidirectional hybridization is also revealed. Finally, combined marker analysis on a subset of samples confirms the microsatellite interpretation and suggests that the alpaca is descended from the vicuña, and should be reclassified as Vicugna pacos. This result has major implications for the future management of wild and domestic camelids in South America. more »
  • The purpose of the meeting was to bring together genomic scientists from the National Institutes of Health, academic geneticists, clinical veterinarians, veterinary pathologists, and organizational administrators to share thoughts and opinions on camelid genetics. The workshop was truly international in scope with attendees from Australia, Canada, Peru, and the United States. Among the disciplines represented were geneticists, molecular biologists, genomic researchers, clinical veterinarians, pathologists, academicians, and fiber specialists. more »
  • Yearling fibre diameter profiles from the OFDA2000 instrument were used to derive records on mean and coefficient of variation (CV) of fibre diameter at multiple points in the post-weaning age window, from 20 to 90% of staple profile length. Genetic correlations were calculated between these traits and their yearling equivalents. Results showed that from 50% of the staple profile and higher, post-weaning fibre diameter is genetically the same trait as yearling fibre diameter. Although the derivation of CV of fibre diameter was less accurate, genetic correlations with the yearling expression were greater than 0.9 for all except one percentile point. The expected correlation between post-weaning and yearling fleece weight was also derived, and under simple assumptions it is not unreasonable to expect estimates of genetic correlations greater than 0.9. more »
  • Genome research has progressed rapidly in recent years and DNA-based selection tools are now available in a number of domesticated species. To date, advanced genomics technologies have not been developed in alpacas (Vicugna pacos). Therefore, breeders select for traits of economic importance (fleece phenotypes) using traditional techniques such as line breeding. Alpacas have experienced a history of population bottlenecks including the mass destruction of alpacas and llamas during the 16th Century, therefore traditional breeding may exacerbate an already depleted gene pool. Alpaca veterinarians report a prevalence of congenital defects much higher than any other livestock species. This study investigated levels of genetic diversity at genome-wide markers in Australian alpacas. Samples have been collected from unrelated individuals with normal and defective phenotypes including choanal atresia, polydactyly, cyclopia, syndactyly, vulval atresia and anal atresia. Multi-locus heterozygosity and inbreeding coefficients were estimated using microsatellite data from 53 or 22 loci. In addition, pedigrees were examined in order to detect pedigree inbreeding. Inbreeding coefficients estimated from genomic data reveal that individuals with congenital defects do not have significantly higher molecular inbreeding levels than healthy individuals. These results suggest that high levels of inbreeding cannot explain the high prevalence of congenital abnormalities in alpacas. This study is the first to report on the genetic variability of Australian alpacas and represents an important first step in the use of genomics to inform alpaca breeding practices. more »
  • The aim of this research was to estimate for the first time the heritability and genetic relationship between medullation and fiber diameter in each fiber by itself. A total of 21,600 fibers from 36 samples from white fleeces, 600 fibers each sample, from males between 0.4 and 10.4 years old from Pacomarca experimental farm (Inca Group, Puno, Peru) were tested using projection microscope (PM). The individual fiber diameter (FD) and the category of medullation (CM) was recorded in each fiber. CM of each fiber was assigned to one of the five categories established in the literature. The percentage of medullated fiber ranged from 12.33% to 91.67% per sample. The correlation between OFDA 100 ® medullation percentage and PM measurements was 0.79. The statistical model used for estimation of genetic parameters for CM and FD included the age as a linear and quadratic covariate as systematic effect, and the additive genetic and the permanent environmental as random effects. The pedigree that served to predict genetic values was very robust and strong, allowing obtaining reliable and significant parameters. Univariate and bivariate models were used to estimate heritability for CM and DF, as well as its genetic correlation. Different models considering CM as continuous or categorical trait were tested. The highest heritability estimate for CM was 0.36 ± 0.13 obtained using a bivariate continuous model. Using the same model, the heritability estimate for FD was 0.35 ± 0.15 and the genetic correlation between CM and FD was 0.93 ± 0.12. These results implied that selection against medullated fiber is feasible while at the same time reducing the FD in alpacas. Since measurement of CM per fiber sample was time-consuming, PM measured by OFDA 100 ® would be useful as an indicator to reduce the number of medullated fiber in alpaca fleeces. more »

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