Future policies for animal genetic resources

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. 218 Utilisation and conservation of farm animal genetic resources Glossary Core set is the smallest set of breeds or lines of a species that still encompasses the genetic diversity in that species. Crossbreeding means matings between animals of diferent breeds or lines. Cryoconservation or cryopreservation is the maintenance of germplasm in the form of tissues, semen, oocytes, or embryos in long-term storage at ultra-low temperatures, typically between -150 and -196 Celsius in liquid nitrogen, for the purpose of subsequent use to produce viable live animals. Cytoplasmatic inheritance is the transmission of hereditary traits through self-replicating factors in the cytoplasm, for example: mitochondria and chloroplasts. Diploids carry two sets of chromosomes. With the exception of sex chromosomes, diploids carry 2 copies of each locus and 2 copies of like-structured chromosomes. DNA is Deoxyribonucleic Acid, which is a macromolecule in the form of a double- stranded helix that carries the genetic information in all cells in higher organisms. Domestication is the process in which animal populations adapt to mankind and its environment. It may be also considered as a form of mutualism involving a parallel evolution in culture and genome. Animals such as dogs, pigs, cows, and sheep were domesticated from their wild relatives by humans thousands of years ago. Dominance is when the alleles of a locus are non-additive. When a locus shows dominance, the genotypic value of the heterozygote on a trait is not the average of the two homozygotes. Overdominance occurs when the heterozygote has a genotypic value more extreme than either parent. See ‘Recessive allele’. EBV is an acronym for Estimated Breeding Value. Ecosystem is the complex of a living community of species and its environment, functioning as an ecological unit in nature. Utilisation and conservation of farm animal genetic resources 219 Glossary Efective population size Ne for a population is the number of diploid, single-sex individuals that when randomly selected and randomly mated including seling that would be expected to have the same rate of inbreeding as the population itself. See chapter 3.6. Epistasis is when loci are non-additive. he genotypic value of a locus on a trait depends upon the genotypes at other loci or a situation in which the diferential phenotypic expression of a genotype depends on the genotype at another locus. Evolutionary tree is a diagram of the inferred ancestry and descent among a group of species or populations. Within species, a tree assumes that sub-populations, once diverged, never mix. Ex situ cryoconservation see ‘Cryoconservation’. Ex situ in vivo conservation or ex situ live conservation is deined as conservation by maintaining a live population either under abnormal farm conditions, or outside of the area in which it evolved or is now normally found, or both: e.g. when a few animals of a breed kept in zoos or farm parks for cultural or historic reasons. he costs of this type of conservation are low, but further adaptation of the population to the native environment is impossible. Extinction probability is the probability that a breed will go extinct within a deined time horizon e.g. within the next 25 years. Factorial mating is a mating scheme where each male is mated to more than one female, and each female is mated to more than one male. Such mating schemes can either be partial or complete; the latter being when each parent is mated to all parents of the opposite sex. In some species, this is made more tractable by means of in vitro embryo production. Such a mating scheme substantially reduces the rate of inbreeding in genetic improvement. Fitness is an important genetic concept and is the trait deined by the relative number of ofspring let by an individual compared to its competitors. Whilst artiicial selection in improvement schemes inluences this process, itness is viewed as a composite of all traits involving health and well-being inluencing the ability of an individual to survive and to produce viable ofspring.