Final answer:
The breed of rabbit with distinctive markings suitable for shows and as a lab animal is the Himalayan rabbit. This breed exhibits a unique phenotype that produces pigment only on the cooler parts of their body, aiding in camouflage and adaptive advantages in specific environments.
Step-by-step explanation:
The breed of rabbit noted for its distinctive markings, popular for shows, and its small size useful as a lab animal, is likely the Himalayan rabbit. The Himalayan phenotype in rabbits is the result of an allele that produces a temperature-sensitive gene product, leading to pigment only in the cooler extremities of the rabbit's body, which is similar to the pattern seen in Siamese cats. The small size of the Himalayan rabbit not only makes it desirable for display in shows but also useful for laboratory purposes, primarily because they require less space and resources compared to larger breeds.
In the wild, the coloration of rabbits can provide camouflage, helping them to blend into their environment and avoid predators. For example, the white fur of rabbits in the Arctic helps them to hide in snowy conditions, thus improving their chances of survival and reproduction. This natural selection process favors traits such as fur color that are beneficial in particular environments. In contrast, rabbits in rocky environments might benefit from gray or Himalayan coloration, providing better camouflage and thus a selective advantage over other phenotypes.