The effects of selective breeding against scrapie susceptibility on the genetic variability of the Latxa Black-Faced sheep breed

Alfonso, L.; Parada, Analia; Legarra, Andrés; Ugarte, E.; Arana, A.

doi:10.1186/1297-9686-38-5-495

Cited by 19 publications

(6 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the case of the breeds considered here, pedigree data and molecular markers assumed to be neutral (relative to the selection objectives) provided consistent views of neutral genetic variability, as observed by Alfonso et al [1] in the Latxa breed. However, some differences were found from one breed to another.…”

Section: Comparison Of Results From Pedigree Data and From Neutral Masupporting

confidence: 79%

See 1 more Smart Citation

Impact of strong selection for the PrP major gene on genetic variability of four French sheep breeds(Open Access publication)

Palhière

BRochard²,

Moazami‐Goudarzi

et al. 2008

Genet. Sel. Evol.

View full text Add to dashboard Cite

-Effective selection on the PrP gene has been implemented since October 2001 in all French sheep breeds. After four years, the ARR ''resistant'' allele frequency increased by about 35% in young males. The aim of this study was to evaluate the impact of this strong selection on genetic variability. It is focussed on four French sheep breeds and based on the comparison of two groups of 94 animals within each breed: the first group of animals was born before the selection began, and the second, 3-4 years later. Genetic variability was assessed using genealogical and molecular data (29 microsatellite markers). The expected loss of genetic variability on the PrP gene was confirmed. Moreover, among the five markers located in the PrP region, only the three closest ones were affected. The evolution of the number of alleles, heterozygote deficiency within population, expected heterozygosity and the Reynolds distances agreed with the criteria from pedigree and pointed out that neutral genetic variability was not much affected. This trend depended on breed, i.e. on their initial states (population size, PrP frequencies) and on the selection strategies for improving scrapie resistance while carrying out selection for production traits.genetic variability / scrapie resistance / molecular marker / pedigree / sheep *

show abstract

Section: Comparison Of Results From Pedigree Data and From Neutral Masupporting

confidence: 79%

“…II and IV). The alternative strategy using only ARR/ ARR rams from the beginning of the PrP selection would elicit a rapid increase in scrapie resistance, but would have strong consequences on genetic progress and genetic variability, as described by Alfonso et al [1].…”

Section: Genetic Variability Assessed Via Pedigree Datamentioning

confidence: 99%

Impact of strong selection for the PrP major gene on genetic variability of four French sheep breeds(Open Access publication)

Palhière

BRochard²,

Moazami‐Goudarzi

et al. 2008

Genet. Sel. Evol.

View full text Add to dashboard Cite

show abstract

“…The conflict between selection and maintenance of diversity is evident in studies such as that by Alfonso et al (2006). These authors show that in favouring resistant prion alleles in sheep, the selection of only ARR/ARR males would result in major losses in founder animals (87%) and in rare alleles (30%) in the ram population.…”

Section: Practical Applications Of Pedigree-based Managementmentioning

confidence: 99%

Management of genetic diversity in small farm animal populations

Fernández

Meuwissen

Toro

et al. 2011

Animal

View full text Add to dashboard Cite

Many local breeds of farm animals have small populations and, consequently, are highly endangered. The correct genetic management of such populations is crucial for their survival. Managing an animal population involves two steps: first, the individuals who will be permitted to leave descendants are to be chosen and the number offspring they will be permitted to produce has to be determined; second, the mating scheme has to be identified. Strategies dealing with the first step are directed towards the maximisation of effective population size and, therefore, act jointly on the reduction in the loss of genetic variation and in the increase of inbreeding. In this paper, the most relevant methods are summarised, including the so-called 'Optimum Contribution' methodology (contributions are proportional to the coancestry of each individual with the rest), which has been shown to be the best. Typically, this method is applied to pedigree information, but molecular marker data can be used to complete or replace the genealogy. When the population is subjected to explicit selection on any trait, the above methodology can be used by balancing the response to selection and the increase in coancestry/inbreeding. Different mating strategies also exist. Some of the mating schemes try to reduce the level of inbreeding in the short term by preventing mating between relatives. Others involve regular (circular) schemes that imply higher levels of inbreeding within populations in the short term, but demonstrate better performance in the long term. In addition, other tools such as cryopreservation and reproductive techniques aid in the management of small populations. In the future, genomic marker panels may replace the pedigree information in measuring the coancestry. The paper also includes the results of several experiments and field studies on the effectiveness and on the consequences of the use of the different strategies.

show abstract

“…The effectiveness of such breeding programmes for increasing the frequency of resistant alleles has been investigated in mainstream commercial e.g. [2,3,21,22] and numerically small breeds e.g. [11,15,28].…”

Section: Introductionmentioning

confidence: 99%

“…[11,15,28]. Four of the studies also assessed the impact of selection on PrP genotypes on inbreeding and genetic variability [2,11,21,28].…”

Section: Introductionmentioning

confidence: 99%

Predicting the consequences of selecting on PrP genotypes on PrP frequencies, performance and inbreeding in commercial meat sheep populations

et al. 2007

View full text Add to dashboard Cite

-Selection programmes based on prion protein (PrP) genotypes are being implemented for increasing resistance to scrapie. Commercial meat sheep populations participating in sire-referencing schemes were simulated to investigate the effect of selection on PrP genotypes on ARR and VRQ allele frequencies, inbreeding and genetic gain in a performance trait under selection. PrP selection strategies modelled included selection against the VRQ allele and in favour of the ARR allele. Assuming realistic initial PrP frequencies, selection against the VRQ allele had a minimal impact on performance and inbreeding. However, when selection was also in favour of the ARR allele and the frequency of this allele was relatively low, there was a loss of up to three to four years of genetic gain over the 15 years of selection. Most loss in gain occurred during the first five years. In general, the rate of inbreeding was reduced when applying PrP selection. Since animals were first selected on their PrP genotype before being selected on the performance trait, the intensity of selection on performance was weaker under PrP selection (compared with no PrP selection). Eradication of the VRQ allele or fixation of the ARR allele within 15 years of selection was possible only with PrP selection targeting all breeding animals. sire referencing / scrapie / prion / PrP selection / inbreeding

show abstract

The effects of selective breeding against scrapie susceptibility on the genetic variability of the Latxa Black-Faced sheep breed

Cited by 19 publications

References 24 publications

Impact of strong selection for the PrP major gene on genetic variability of four French sheep breeds(Open Access publication)

Impact of strong selection for the PrP major gene on genetic variability of four French sheep breeds(Open Access publication)

Management of genetic diversity in small farm animal populations

Predicting the consequences of selecting on PrP genotypes on PrP frequencies, performance and inbreeding in commercial meat sheep populations

Contact Info

Product

Resources

About