Final answer:
The breed of rabbit known for good commercial traits and laboratory use is the New Zealand rabbit. White fur in rabbits serves as camouflage in snowy environments, a trait favored by natural selection. The Himalayan phenotype of rabbits exemplifies how genetics and environment interact to produce distinctive fur coloration.
Step-by-step explanation:
The breed of rabbit described as having excellent growth characteristics, a meaty carcass, used as a show animal, and having a popular white variety for laboratory use is likely the New Zealand rabbit. This breed fits the commercial and laboratory use criteria due to their size, rapid growth rate, and docile nature, which makes them ideal for handling and research purposes.
In cold environments like the Arctic, the white fur of some rabbits is advantageous for survival, which is evident through natural selection. Over time, rabbits with white fur become more numerous in such environments as they are better camouflaged against predators like foxes. This survival trait gets passed on to future generations. This principle of adaptation and selection is crucial in understanding the development of beneficial traits in various species.
Interestingly, the Himalayan phenotype of rabbits is a result of an allele that produces a pigment in the cooler extremities of the rabbit's body, similar to the fur color found in Siamese cats. This characteristic arises from a temperature-sensitive gene product that only produces pigment at lower temperatures, leading to their unique coloration.