Question

Claytonia virginica is a plant with flowers that vary from white, to pale pink, to bright pink. Slugs prefer to eat pink-flowering over white-flowering plants (due to chemical differences between the two), and plants experiencing severe herbivory are more likely to die. The bees that pollinate this plant also prefer pink over white flowers, so that Claytonia with pink flowers produce more seeds than Claytonia with white flowers. A researcher observes that the percentage of different flower colors remains stable in the study population from year to year. Given no other information, if the researcher removes all slugs from the study population, what do you predict will most likely happen to the percentage of flower colors in the population over time

Answer 1

Answer:

The frequency of pink flowers will increase to near one over time, while the frequency of white flowers will decrease to near zero.

Explanation:

There are two forces acting as selective pressures.

• Slugs prefer to eat pink-flowering over white-flowering plants → selective pressure against the pink genotype → plants with pink flowers suffer from severe herbivory and are more likely to die.
• Bees prefer to pollinate pink over white flowers → selective pressure favoring the pink genotypes → Plants with pink flowers produce more seeds than plants with white flowers.

When the researcher removes all slugs from the study population, he/she eliminates the selective pressure against the pink genotype, leaving only the force acting in favor of the genotypes. So plants with pink flowers will produce more seeds that will originate more plants with pink flowers. As there is no predator over these plants, they will keep reproducing and growing pink flowers. Over time, the frequency of the pink genotype will increase, while the frequency of the white genotype will decrease.