In most cases, an individual with the rarest phenotype is likely to have the greatest fitness, and over time that phenotype will increase in frequency, which then allows for a new rarer phenotype to be at an advantage. An example of frequency dependent selection in male-male competition is in species where males have two different mating strategies, to be either a Dominant male or a Sneaker male. If dominant males are very common in the population, then it may pay off for males to adopt a sneaker strategy, thereby avoiding the necessity of fighting with other dominants for access to females. What are the three conditions necessary for a Fisherian Runaway of exaggerated male traits due to sexual selection. There is variation in the male trait and it is heritable.
Female preference exists and is heritable.
There is a large enough frequency of females in the pop. What force can move an individual off of an adaptive peak and what force then can move it up to the top of another adaptive peak. Natural Selection is the process required to move individuals to the top of another adaptive peak. Initially inbreeding will not change allele frequencies but will lead to a decrease in genotype frequencies. This results if the inbreeding is a result of positive assortative mating, where individuals are mating with other individuals of the same genotype.