USA Biology Olympiad (USABO) Practice Exam

In the context of artificial selection, how do breeders maintain "purity" in dog breeds when females are in heat?

1. By isolating dogs based on size

2. By ecological isolation

3. By tracking lineage carefully

4. By monitoring health conditions

The correct answer is: By ecological isolation

In the context of artificial selection, breeders maintain the "purity" of dog breeds primarily by tracking lineage carefully. This practice is crucial for preserving specific traits and characteristics that define different breeds. When breeders are aware of the genetic background and lineage of their dogs, they can ensure that breeding occurs between individuals that share desirable traits, while avoiding potential genetic problems associated with inbreeding. Tracking lineage allows breeders to know exactly which dogs have been bred together and helps them identify any potential genetic issues in future offspring. This meticulous record-keeping ensures that the unique qualities of a breed are maintained over generations. For instance, if a particular dog exhibits desirable traits, breeders can track its ancestry to select compatible mates that will enhance those traits while maintaining genetic diversity and health. While isolation based on size, ecological isolation, and monitoring health conditions may play roles in the overall breeding strategy, they do not directly address the specific goal of maintaining breed purity as effectively as careful lineage tracking does. Breeders’ focus on lineage provides a clear and systematic approach to achieving the goals of artificial selection in dog breeding.