Question

which scenario describes an example of genetic drift?
some of the rare, red - winged finches from a small island fly to a nearby island to feed. they mate with the native
brown - winged finches, which results in an increase in the red - wing allele frequency on the new island.
a mistake during dna replication causes the offspring of a yellow flowering plant to have blue flowers. the
blue - flower trait is passed on to successive generations.
some individuals in a population of bears have very thick coats that help them conserve heat and energy during cold
winters. after several generations, the proportion of bears with thick coats increases.
a drought killed many of the orchids living on a small island. by chance, only the pink and purple varieties survive,
whereas the white - flower variety is lost completely.

Explanation:

Genetic drift refers to random changes in allele frequencies in a population due to chance events, not natural selection. Option D describes a random event (drought) causing a loss of an allele (white-flower) by chance, which is genetic drift. Option A is gene flow, Option B is mutation, Option C is natural selection.

Answer:

D. A drought killed many of the orchids living on a small island. By chance, only the pink and purple varieties survive, whereas the white-flower variety is lost completely.