Abstract
Uniquely selected breeds bred over thousands of years of domestication in a wide range of environments have been declared extinct over the last century. Still more breeds are at risk of becoming extinct and the rate continues to accelerate. Assessing the current status and possible future dynamics of livestock breeds is therefore a critical step in the management of Animal Genetic Resources (AnGR). This study applies a qualitative approach to comprehensively analyze cattle genetic resources in selected countries in order to better understand the risk status of cattle breeds and those that need to be considered extinct and/or quasi-extant. The status of each breed, i.e., not at risk, critical, endangered and extinct, was verified using information available at the Domestic Animal Diversity Information System (DAD-IS) web site, as well as cattle statistics (where available) and a breed survey. In most examples, breeds listed as extinct have played important roles in the development of new breeds, and should not be classified as extinct, unless proven otherwise, given that even breeds existing in vivo are developing. Therefore, a new risk status quasi-extant for this category of cattle breeds is suggested. In addition, based on the findings of this study, the concept of breed needs to be questioned as relates to it being a good measure of genetic diversity. Further investigations of the situation of cattle breeds (and other livestock species) in more countries/continents using similar categories are deemed necessary.
Highlights
Evolution is the change in the genetic material of a population of organisms from one generation to the
This study addressed the following key issues: (a) the status of breeds in the four countries; (b) whether indiscriminate cross breeding leads to the extinction of breeds; and (c) whether breeds really become extinct or play a part in the formation of new breeds
Experts in animal genetic resources (AnGR) from Sweden, Uganda, Brazil and Bangladesh assisted in suggesting the new risk status of the cattle breeds listed in the DAD-IS web site from their respective countries
Summary
Evolution is the change in the genetic material of a population of organisms from one generation to the next. Evolution itself is the product of processes that constantly introduce variation (i.e., mutation, migration and genetic recombination) and that make variants either to become more common or rare (i.e., natural/human selection and genetic drift). Through natural selection useful variations increase in frequency and those that are less useful are eliminated over generations [1]. Human and novel environmental pressures during domestication of animal species have been responsible for the generation of inter-breed genetic variation and formation of unique breeds [2]. Human pressures (i.e., selection of animals, or herd/breed management in general) create the potential for much loss of this between-breed component of diversity.
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