if a cow....?

Question

if a cow develops a preference for eating white four o`clock flowers and ignoring pink and red four o`clock flowers, what type of selection is being demonstrated? would the cow eventually eliminate all white four o`clock flowers from the population on which it feeds?

Answer 1

Four o"clocks are incompletely dominant for flower color. RR is red, Rr is pink, and rr is white flowered. If your cow ate only white flowers she would be selecting for the homozygous recessive genotypes. The r allele would remain in the population as pink flowers Rr. Each generation the numbers of white and pink flowers would be less than the generation before. But the r allele could never be completely eliminated from population. If this type of selection continued for several generations a white flower would pop up only occasionally.
If this were a real situation, I would venture a guess that the cow would soon become less choosy and start eating a few red and pink flowers as well and mess up the selection progress altogether.

Answer 2

1. This is an example of directional selection because it selects against one extreme.

2. There will still be white four o'clocks because the pinks are heterozygous with one allele for white and one allele for red. As long as there are pinks, there will be more whites.