Answer to Question #119688 in Evolution for sam

Question

A population of moths consists of individuals that are white with black spots. Some are mostly white with just one tiny black spot, while others have lots of black spots with very little white but the majority are in the middle and are whitish with several black spots. These moths survive by hiding from predators on the sides of white birch bark trees. Suppose a coal factory starts to spew black pollution onto the white birch bark trees in the forest turning them black. Explain what is most likely to happen to the population of moths using the theory of evolution and the 4 principles of natural selection.

Answer 1

 According to the principles of natural selection, the moths possess variations (number and density of white and black dots) that are inherited and are passed to offspring. As the white birch bark trees turn black, white moths with few black spots will become more visible for predators. The efficiency of hiding from predators will be very low. As a result, the change in the environmental conditions will lead to increased mortality of white moths due to predators. The number of individuals with less dense black spot will decrease while the number of moths with dense black spots will increase as they are less visible for predators and significantly contribute to the growth of population. This trait (black colour) will be successfully passed to the offspring. As a result, as black moths are well suited for the protection against predators, they will produce more offspring to the next generation associated with differential survival and reproduction.