Genetic structure of seven European cattle breeds assessed using 20 microsatellite markers

Abstract

Genotype data from 20 microsatellites typed in 253 animals is used here to assess the genetic structure of seven European pedigree cattle breeds. Estimation of genetic subdivision using classical drift-based measures shows that the average proportion of genetic variation among breeds varies between 10 and 11% of the total, depending on the estimator used. We demonstrate that a simple allele-sharing genetic distance parameter can be used to construct a dendrogram of relationships among animals. This phylogenetic tree displays a remarkable degree of breed clustering and reflects an extensive underlying kinship structure, particularly for the Swiss Simmental breed and four breeds originating from the British Isles. Condensation of allele frequencies and individual genotypic compositions using principal component analysis is also used to investigate genetic structure among breeds and individual animals. In addition, the underlying genetic demarcation of European cattle breeds is emphasized in simulations of breeds assignment using allele frequency distributions from samples of microsatellite loci. Correct breed designation can be inferred with accuracies approaching 100% using data from a panel of 10 microsatellite loci.

Measuring genetic distances between breeds: use of some distances in various short term evolution models

“…Twenty genetically independent loci were considered, a number frequently found in diversity studies [33,37,40].…”

“…Therefore, a high level of polymorphism can be maintained within relatively small samples. The within breed average heterozygosity is generally higher than 0.5 [37,40,54] with extreme values above 0.8 observed for several loci [33]. For a large proportion of microsatellites, the number of alleles observed across mammalian populations can vary between less than 10 to 20 and can be even higher across natural populations of fish [56].…”

“…In order to measure the genetic distances between closely related populations like breeds, it is desirable to use highly polymorphic markers such as microsatellites [3,4,9,15,18,24,37,40,53,59,60,70].…”

Diversidade genética e eficiência de DNA microssatélites para o controle genealógico da raça Nelore

“…Coeficientes de endocruzamento para a raça também são elevados, entre 2 e 5%, e podem levar a valores ainda menores de tamanho efetivo (Machugh et al, 1998). Efeitos indesejáveis do endocruzamento incluem redução na produção de leite e na contagem de células somáticas (Notter, 1999), e recentemente foi documentada redução na eficiência reprodutiva, observando-se em gado leiteiro, a cada 1% de aumento de endocruzamento, a elevação na idade do primeiro parto em 0,4 dia, o aumento no intervalo de parto em 0,3 dia e o decréscimo de período de vida em 13 dias (Lucy, 2001;Weigel et al, 2001).…”

“…Os marcadores nucleares microssatélites são importantes ferramentas para o estudo de genética de populações e de relações de paternidade e parentesco genético, pela codominância, abundância nos genomas e alto nível de polimorfismo (Glowatzki-Mullis et al, 1995;Machugh et al, 1998).…”