Monitoring role for the national managers

216 Utilisation and conservation of farm animal genetic resources Glossary Bayesian is an approach to statistical inference that assumes parameter values are random variables, with prior distributions describing our strength of belief in possible values before the collection of data. In contrast, a frequentist approach assumes parameters are unknown constants. hese diferent starting points result in diferent philosophies of inference ater the collection of data, with Bayesian inference based upon the posterior distributions for parameters, and frequentist inference based upon conidence intervals and hypothesis testing calibrated by hypothetical repetition of the data collection. BLUP is an acronym for Best Linear Unbiased Prediction. It is a standard statistical method for estimating breeding values in populations in an optimal way. BLUP accounts for genetic relationships and adjusts for systematic ixed efects simultaneously. Bootstrapping is an analysis in which multiple datasets are formed by random sampling with replacement from an actual data set, in order to estimate a degree of conidence in an estimated parameter. his process is used widely in QTL mapping and in phylogeny reconstruction. Bottleneck is a period when the number of parents used to reproduce the breed was particularly small. In such a period the genetic drit is high due to a marked reduction in the efective size of the population. Breed is an interbreeding group of animals within a species with some identiiable common appearance, performance, ancestry or selection history; see box 3.1 for more details. Breeding organisation is a term to represent all organisations involved in livestock improvement: breeding companies, breed societies and breeders collaborating in group-breeding schemes. Breeding objectives or goals represent the direction of change desired within the population. Very oten these objectives are limited by what records are available for evaluation, and an organisation will deine its objectives by what it can do rather than what it would do if records existed, although this is not best practice. New opportunities will expand the achievement of objectives in practice. Utilisation and conservation of farm animal genetic resources 217 Glossary Breeding programme or a breeding scheme is a programme aiming at deined breeding objectives for the production of a next generation of animals. It is the combination of recording selected traits, the estimation of breeding values, the selection of potential parents and a mating programme for the selected parents including appropriate artiicial reproduction methods. Breeding value is the mean genetic value of an individual as a parent, for one trait or a combination of traits. It is estimated as twice the average superiority of the individual’s progeny relative to all other progeny under conditions of random mating. An individual’s breeding value deines its additive genetic value. Candidate gene is a gene chosen among genes known to afect a studied trait or among genes in a QTL region found as an important source of variation in a genome screen. See ‘Positional candidate’. Centi-Morgan is a linkage map distance of 0.01 Morgans, corresponding roughly to 1 per cent recombination; abbreviated cM. See ‘Morgan’. Chromosome is a discrete block of DNA and is one of the basic structures of the genome. All nuclear DNA is organised into chromosomes with the number varying between animal species. Genes on a chromosome are linked and tend to be inherited together. Clone animal is an individual that is genetically identical to another or a group of individuals that are genetically identical to each other. Co-ancestry is the relationship by a common ancestor of both one’s father and one’s mother; synonym for kinship coeicient. Co-dominance is a situation in which a heterozygote shows the phenotypic efects of both alleles equally. See ‘Additivity’. Comparative genomics is a joint analysis of the genome between two or more species, making use of known similarities between the structures of their genomes. Conservation potential is the marginal diversity multiplied by the extinction probability. It relects the beneit in terms of conserved diversity of making a breed completely safe.