Final answer:
The Good Genes hypothesis suggests that certain male traits are honest signals of genetic fitness, while the Arbitrary Choice model (Fisherian runaway) suggests a feedback loop can exaggerate male traits based on female preferences. Both models agree with natural selection but differ in the direct benefits and the mechanism of trait amplification.
Step-by-step explanation:
The Good Genes hypothesis and the Arbitrary Choice models of sexual selection are two explanations for why traits such as vibrant plumage or elaborate displays evolve in certain species. In the Good Genes hypothesis, such traits are seen as honest signals of a male's genetic fitness which includes efficient metabolism or the ability to fight disease. Females then choose these males, leading to offspring with superior genetic qualities. The Arbitrary Choice model, or Fisherian runaway model, proposes that once a preference for a certain trait evolves in females, there will be an increase in both the male trait and the female preference, leading to a feedback loop which can drive the evolution of extremely exaggerated male traits.
Both models address the notion of sexual selection and are compatible with the broader patterns of natural selection. They incorporate the effects of gene flow, genetic drift, and mutation. However, while the Good Genes hypothesis is based on the direct benefits to female reproductive success through selection of high-quality mates, the arbitrary choice model attributes the evolution to a self-reinforcing process, sometimes independent of actual male quality.
It is crucial to understand that there's no such thing as a perfect organism. Natural selection works with existing genetic variance within a population and does not give organisms everything they 'need.' Even traits considered to be honest indicators of fitness in the context of either hypothesis are subject to the limitations of the underlying genetic variance.