Final answer:
The dairy farmer is using artificial selection by mating a male bull with female heifers that produce the most milk, aiming to pass the high milk production trait to the next generation of calves. This practice intensifies desired traits in livestock, but it must be managed to avoid reducing genetic diversity and potential health issues.
Step-by-step explanation:
Artificial Selection in Dairy Farming
When a dairy farmer chooses to mate a male bull only with the female heifers that produce the greatest amount of milk, he is employing the process of artificial selection. This process is a form of selective breeding where humans actively choose which animals to breed based on certain desirable traits. In the context of a dairy farm, the trait of interest is high milk production. By selectively breeding only those cows that yield more milk, the farmer aims to ensure that the next generation of calves carries the genes for high milk production, leading to an overall increase in the farm's milk productivity.
One famous example of artificial selection comes from the experiments of Gregor Mendel, who selectively bred pea plants to examine how traits were inherited. Similarly, the artificial selection applied by dairy farmers follows a comparable principle, seeking to amplify favorable traits like milk yield within their livestock populations.
However, it's important to note that artificial selection is not without its criticisms. Some concerns include reduced genetic diversity and the potential for the amplification of undesirable genetic traits along with the desired ones, resulting in unexpected health issues. Therefore, farmers must manage their breeding programs with care to maintain the health and well-being of their herds.