Question

natural selection: peppered moths

1. explain the expected changes to the moth population in the 19th century in terms of natural selection.
2. this graph shows the population size of dark - colored moths between 1960 and 2000. suggest what may have happened to cause this change in population size.

Explanation:

1. In the 19th - century, due to the Industrial Revolution, pollution darkened tree trunks. Light - colored moths became more visible to predators, while dark - colored moths had better camouflage. Natural selection favored dark - colored moths, increasing their survival and reproduction rates, thus their population increased while the light - colored moths' population decreased.
2. The decline in the population size of dark - colored moths between 1960 and 2000 may be due to improved air quality and reduced pollution. Lighter tree trunks made dark - colored moths more visible to predators, reducing their survival and reproduction rates. Natural selection now favored light - colored moths, causing the dark - colored moths' population to decline.

Answer:

1. Due to industrial pollution, dark - colored moths had a survival advantage and their population increased while light - colored moths' population decreased.
2. Improved air quality made dark - colored moths more visible to predators, causing their population decline.