SEARCHING FOR ENVIROMENTAL ADAPTATION IN BEEF CATTLE
By Troy Rowan and Jared Decker, Ph.D., University of Missouri
The United States is home to diverse climates and geographies. Over the past 150 years, beef cattle have found their way into nearly every one of these unique environments. Some cattle thrive in particular environments, while others struggle. Animals well-suited to an environment performed well and are selected to stay in herds. Poorly-suited animals are culled. As a result, selection occurred on traits that improved cattle performance in different environments. Now, resulting from this selection, there may be a significant amount of region-specific genetic diversity, even within the same breed. In a USDA-funded research project, we are looking to find the DNA variants responsible for this environmental adaption. We will then use these variants to create geographic region-specific genomic predictions.
Jared Decker, Ph.D.
Animals that are poorly adapted to their local environment are less efficient and more expensive to maintain. Most previous local adaptation research has focused on heat tolerance in Bos indicus influenced cattle. Work has only begun on identifying the genetic components of issues like cold tolerance, hair shedding, altitude adaptability, tolerance to pathogens, and other region-specific stressors in Bos taurus cattle populations. The potential economic impact of this research to the beef cattle industry is substantial. A 1993 study predicted that
animals poorly adapted to toxic fescue cost the beef industry close to $1 billion per year. Toxic fescue tolerance is only one slice of the local adaptation pie. Other environmental stressors have similar economic impacts. If breeders can tap into genetic potential for tolerance to environmental stressors and animals are optimized for production in their specific geographic regions, the beef industry could save billions of dollars each year.
Detecting Region-Specific Selection Much like natural selection in wild populations, region-specific selection occurs on existing genetic variation that may be beneficial in one environment, but neutral or unfavorable in another. Over several generations, this beneficial variation becomes more common within a regional population. Put simply, animals that are well-adapted to their regional environments produce successful offspring that remain in the gene pool. Poorly-adapted animals in most cases produce poorly and are culled from their respective herds. These poorly-adapted animals have minimal contributions to future generations. Advancements in genomic tools have made it possible for this diversity to be categorized. We can compare differences between regional populations on the DNA base pair level.
Figure 1.â€‚ â€‚ Hypothetical example of local adaptation to different regions of the United States.
Published on Nov 7, 2017