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Conservation of livestock breed diversity

Published online by Cambridge University Press:  01 August 2011

J.S.F. Barker
Affiliation:
Department of Animal Science, University of New England, Armidale, NSW 2351, Australia
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Summary

Mankind uses some 40 species of animals as domestic livestock to meet our needs for food, clothing, power, etc. Within these species, there are in total some 4,500 breeds that are referred to as the global animal genetic resources. Each breed comprises a unique set of genes. More than 30% of breeds are estimated to be at risk of extinction, and many more, particularly in developing countries, are threatened by inefficient utilization. The Food and Agriculture Organization of the United Nations has been mandated by its member nations to manage the global animal genetic resources, and major progress has been made in the last few years. However, resources are limited, and priorities will have to be set for breed conservation, for breed development programmes and for evaluation studies. Breeds that are taxonomically distinct should be favoured for conservation, the objective being to maintain maximum genetic diversity of each livestock species. Genetic distances and phylogenetic diversity provide the best available objective criterion, and microsatellites are the current markers of choice for obtaining the genetic data. Microsatellite-based genetic distances will describe breed similarities due to common ancestry, but cannot account for consequences of artificial or natural selection. Phylogenetic trees for 11 water buffalo populations in southeast Asia, constructed using 25 polymorphic protein coding loci or 21 microsatellite loci, show differences in both topology and branch lengths, but the microsatellite tree is a better representation of the similarities due to common ancestry. Thus phylogenetic diversity, based on microsatellite loci, should be used as an initial guide in making conservation decisions for livestock breeds.

Resumen

El Hombre utiliza unas 40 especies animales como ganado doméstico para satisfacer sus necesidades de alimentación, ropa, tracción, etc. Dentro de estas especies, existe un total de 4 500 razas conocidas como recursos genéticos animales globales. Cada raza comprende un grupo único de genes. Se estima que más del 30% de las razas están en peligro de extinción y muchas más, sobre todo en los países en vías de desarrollo, están amenazadas por una utilización ineficaz. La Organización para la Alimentación y la Agricultura de las Naciones Unidas ha sido encomendada por sus naciones miembros de gestionar los recursos genéticos animales globales. Se han hecho grandes progresos en este sentido en los últimos años, sin embargo, los recursos son limitados, y será necesario establecer prioridades para la conservación de razas, para programas de desarrollo de razas y para estudios de evaluación. Las razas taxonómicamente diferentes deberían ser favorecidas para la conservación, ya que el objetivo es de mantener la máxima diversidad genética de cada especie ganadera. Las distancias genéticas y la diversidad filogenética proporcionan el mejor criterio objetivo disponible y los microsatélites son actualmente los marcadores elegidos para obtener los datos genéticos. Las distancias genéticas basadas en microsatélites describirán las similitudes entre razas debido a sus antecedentes comunes pero no podrán explicar las consecuencias de la selección artificial ni natural. Arboles filogenéticos para 11 poblaciones de búfalos de agua en el sudeste de Asia, elaborados utilizando 25 loci polimórficos codificadores de proteína o 21 loci de microsatélites, muestran diferencias tanto en topología como longitudes de ramas, pero el árbol de microsatélites es una mejor representación de las similitudes debidas a antecesores comunes. Por consiguiente, la diversidad filogenética, basada en loci de microsatélites, debería utilizarse como una guía inicial para tomar decisiones sobre la conservación de razas ganaderas.

Type
Research Articles
Copyright
Copyright © Food and Agriculture Organization of the United Nations 1999

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