GG Epistasis Part 3

This lecture, part of a series on epistasis, provides concrete examples of epistatic phenotypes to illustrate the concepts discussed in previous parts. The instructor begins by revisiting single recessive epistasis using the classic example of coat color in Labrador retrievers, where the E locus (an expressor) interacts with the B locus to produce black, chocolate, or yellow labs. He then delves into the molecular basis of coat color, explaining the roles of the MC1R receptor, agouti signaling protein, and beta-defensin in melanin production, and how mutations in these genes lead to different color phenotypes. The lecture also covers examples from other species, such as jaguars and jaguarundis, and discusses the genetics of red hair in humans, including associated traits like pain sensitivity and vitamin D production. Finally, the instructor mentions epistatic lethality in carp, where certain allele combinations are lethal. The video aims to bridge theory and real-world examples, preparing students for problem-solving in subsequent parts.