Final answer:
Mongrels and pedigrees are both canines with the main difference being genetic purity, with pedigrees being purebred and mongrels having a mixed heritage. Selective breeding can lead to health issues in pedigreed animals whereas mongrels may benefit from greater genetic diversity and resilience.
Step-by-step explanation:
Mongrels and pedigrees share the commonality of being canines, but they differ in their genetic backgrounds. A pedigree dog is a purebred, meaning its ancestry contains only members of the same breed, leading to predictable physical traits and behaviors. On the other hand, a mongrel, also known as a mixed-breed dog, has a more diverse genetic heritage with ancestors from multiple breeds, resulting in a greater genetic diversity which can often translate to a lower risk of inherited health issues. Pedigrees have their ancestry carefully documented and are often selectively bred for specific traits, which can sometimes lead to inherited health problems due to a narrowed gene pool. In contrast, mongrels have no such documented lineage and are typically not the result of selective breeding.
When discussing genetics, a pedigree chart is employed to display family relationships and can tell us if individuals are heterozygous or homozygous for certain traits. Studies have shown that the selective breeding leading to purebred animals can cause various health issues. This breeding practice can sometimes prioritize appearances or specific traits over the well-being of the animal. In some cases, such as the English bulldog, the consequences of selective breeding have necessitated human intervention, such as cesarian sections for birthing, due to the anatomical changes that have occurred in the breed over time. Conversely, the mixed ancestry of mongrels can lead to a wider range of traits and often a broader genetic reservoir making them more resilient to certain inherited conditions.