Question

a population of beetles lives on light - colored sand.
trait color % of population (gen 1) % of population (gen 10)
light 55% 80%
dark 45% 20%
which darwin observation best explains the change?
○ genetic variation
○ overproduction
○ survival of the fittest

Explanation:

The problem is about beetle population change over generations on light - colored sand. Darwin's "Survival of the fittest" (natural selection) states that organisms with traits better suited to the environment are more likely to survive and reproduce. Light - colored beetles are better camouflaged on light - colored sand, so their proportion increases (from 55% to 80%) and dark - colored beetles' proportion decreases (from 45% to 20%) over generations. Genetic variation is about differences in genes within a population, overproduction is about producing more offspring than can survive, and genetic variation alone doesn't explain the change in proportions. The change is due to differential survival and reproduction based on fitness (camouflage), which is survival of the fittest. Wait, no, wait. Wait, the correct concept here is natural selection, which is related to survival of the fittest. Wait, but let's re - evaluate. The beetles live on light - colored sand. Light - colored beetles are more likely to survive (not be eaten by predators) because they blend in. So over generations, the proportion of light - colored beetles increases. This is survival of the fittest: individuals with traits (light color) that help them survive in their environment (light sand) are more likely to survive and pass on their genes, leading to a change in the population's trait distribution. Genetic variation is the presence of different traits (light and dark) initially, but the change in proportion is due to survival of the fittest. Overproduction is about producing many offspring, which is not directly related to the change in trait proportion here. So the correct answer should be Survival of the fittest? Wait, no, wait the options: Genetic Variation, Overproduction, Survival of the fittest. Wait, maybe I made a mistake. Wait, Darwin's observations: survival of the fittest (natural selection) is the process where organisms with favorable traits survive and reproduce more. In this case, light - colored beetles have a favorable trait (camouflage on light sand) so they survive better, leading to their higher proportion in Gen 10. So the answer is Survival of the fittest? Wait, but let's check the options again. The options are Genetic Variation, Overproduction, Survival of the fittest. Wait, maybe the correct answer is Survival of the fittest. Wait, no, wait: Genetic variation is the existence of different traits (light and dark) in the population. Overproduction is producing more offspring than can survive. Survival of the fittest is that those with better traits survive. So the change in the population (more light, less dark) is because light - colored beetles survived better (survival of the fittest), so their proportion increased. So the correct option is Survival of the fittest. Wait, but let's confirm. The population of beetles on light - colored sand: light - colored beetles are more fit (better camouflaged) so they survive and reproduce more, leading to an increase in their percentage. So the Darwin observation that best explains this is Survival of the fittest.

Answer:

Survival of the fittest