Objectives, criteria and methods for using molecular genetic data in priority setting for conservation of animal genetic resources

Abstract

SummaryThe genetic diversity of the worldÕs livestock populations is decreasing, both within and across breeds. A wide variety of factors has contributed to the loss, replacement or genetic dilution of many local breeds. Genetic variability within the more common commercial breeds has been greatly decreased by selectively intense breeding programmes. Conservation of livestock genetic variability is thus important, especially when considering possible future changes in production environments. The world has more than 7500 livestock breeds and conservation of all of them is not feasible. Therefore, prioritization is needed. The objective of this article is to review the state of the art in approaches for prioritization of breeds for conservation, particularly those approaches that consider molecular genetic information, and to identify any shortcomings that may restrict their application. The Weitzman method was among the first and most well-known approaches for utilization of molecular genetic information in conservation prioritization. This approach balances diversity and extinction probability to yield an objective measure of conservation potential. However, this approach was designed for decision making across species and measures diversity as distinctiveness. For livestock, prioritization will most commonly be performed among breeds within species, so alternatives that measure diversity as co-ancestry (i.e. also within-breed variability) have been proposed. Although these methods are technically sound, their application has generally been limited to research studies; most existing conservation programmes have effectively primarily based decisions on extinction risk. The development of user-friendly software incorporating these approaches may increase their rate of utilization.

Relative breed contributions to neutral genetic diversity of a comprehensive representation of Iberian native cattle

“…Both methodological Table 5 Pairwise correlation coefficients between the contributions obtained with the different methods, in the same order as shown in Table 3 and Table 4 Core MEKs and field studies have been widely published in recent years (Bennewitz and Meuwissen, 2004;Fabuel et al, 2004;Mateus et al, 2004;Garcia et al, 2005;Bennewitz et al, 2006;European Cattle Genetic Diversity Consortium, 2006;Hayes et al, 2006;Tapio et al, 2006;Boettcher et al, 2010), and yet no consensus has been reached on how to appropriately account for the between-and within-population components of genetic variation (Meuwissen, 2009;Caballero et al, 2010). The choice between prioritising within-or between-breed diversity is not an easy task.…”

“…Under the assumption that the main genetic force acting is genetic drift, with the well-known consequences of increasing both within-population homozygosity and betweenpopulations genetic differences (Falconer and Mackay, 1996), neutral markers, such as microsatellites, are the most appropriate to evaluate the relative contribution of each breed to overall genetic diversity (Boettcher et al, 2010). The substantial genetic differentiation and relatively high genetic diversity found in Iberian cattle should allow for a relevant analysis of genetic contributions.…”

Assessing the genetic diversity in small farm animal populations

“…There are many scientific, political and social issues involved. Perhaps the most important ones are how to make local breeds more self-sustaining through conservation actions and how to set up priorities in conservation (Boettcher et al, 2010;Hiemstra et al, 2010). In both issues, the assessment and the management of genetic diversity are key aspects.…”

Genetic diversity and population structure of the endangered Namaqua Afrikaner sheep

“…Several genetic characterisation studies using DNA markers have been reported for indigenous sheep breeds; these include the South African Pedi, Nguni and Damara (Buduram, 2004) and Zulu sheep (Kunene et al, 2009), Kenyan Red Maasai sheep (Muigai et al, 2009 and Indian Ganjam sheep (Arora et al, 2010). Microsatellite markers have been proved to be a popular and suitable DNA marker, providing useful molecular information for the conservation of rare and endangered breeds (Toro et al, 2009;Boettcher et al, 2010).…”