Why might miniature terriers exhibit lower genetic diversity compared to bull terriers?

The correct choice focuses on the effect of selective breeding practices on genetic diversity. Miniature terriers typically have been bred for specific traits, leading to a more homogeneous gene pool. In contrast, bull terriers may have a broader genetic variance because they have been bred with more emphasis on physical and behavioral traits rather than strict adherence to maintaining a specific size or appearance.

Selective breeding usually focuses on a limited number of individuals, especially if there are specific desired traits, which can lead to reduced genetic diversity over generations. In miniature terriers, if there is a strong emphasis on size and specific characteristics, this can lead to inbreeding, where closely related individuals are bred to maintain these traits. This practice can exacerbate the effects of reduced genetic diversity, as it limits the gene pool.

The other options do not connect as directly to the reduction in genetic diversity observed in miniature terriers compared to bull terriers. For instance, inbreeding practices might actually be more common in miniature terriers, not less, which would contribute to lower genetic diversity. Genetic mutation rates are not inherently higher in bull terriers, and dietary variety does not directly influence genetic diversity in the same way selective breeding practices can.