approximation, with dominant beneficials deviating most in their dynamics when common, and recessives when rare (Table 1).
In a phenomenon known as Haldane's Sieve, recessive beneficial mutations have a higher probability of fixation in selfing than in outbreeding populations, because of the increase in homozygosity in selfers which results in greater exposure of recessive alleles to selection (Charlesworth 1992).
All mutations are identical in their effect on fitness, nearly recessive (dominance coefficient [h.
In other words, tallness was dominant and dwarfness recessive
, so that tallness overwhelmed dwarfness--but only temporarily.
Indeed, an increase in the number of loci segregating for recessives will simply decrease the variation of replicate founder populations about the expected additive variance (Robertson 1952).
Clearly, increases in heritability following a bottleneck are expected in this case when genetic variation is caused by rare recessives or partial recessives.