Question

in a population of lizards found on an island, 99% have straight tails and 1% have curly tails. a hurricane passes over the island and leaves only 10 survivors, two of which have a curly tail. many generations later, 10% of lizards possess a curly tail. what evolutionary mechanism best describes this scenario?
genetic drift
natural selection
mutation
gene flow
sexual selection

Explanation:

Genetic drift is a mechanism of evolution where allele frequencies in a population change due to random sampling of organisms. In this case, a hurricane (a random event) drastically reduced the lizard population (bottleneck effect, a type of genetic drift). The small number of survivors (10 lizards) had a different allele frequency (2 out of 10 with curly tails, which is 20% initially compared to the original 1% in the larger population). Over generations, this random change in allele frequency (from the random event of the hurricane reducing population size) led to 10% of the lizards having curly tails. Natural selection would involve traits conferring a survival/reproductive advantage (no indication of that here). Mutation is a new genetic variation (no mention of new mutations). Gene flow is transfer of genes between populations (no other populations mentioned). Sexual selection is about mating - related advantages (not described here).

Answer:

Genetic drift