Question

1. describe how having dark skin may have provided an advantage in survival and reproduction to people thousands of years ago in some places in the world but not in others.
2. biologists sometimes say that

atural selection depends on the specific environment where a species lives.\ what does this statement mean?
a. if populations of a species are in different environments, traits that individuals need to meet their needs in each environment will appear.
b. traits can be helpful or harmful. if populations of a species are in different environments, some traits that are helpful in one environment might be harmful in another environment.
c. traits are always either helpful or harmful, and the environment of a population doesnt matter. if populations of a species are in different environments, the same traits will always be helpful.
d. species were formed to perfectly match their environment. the traits of individuals in a species depend on the specific environment in which they were created.

1. describe how uv light is harmful to people but can also be necessary.
2. the graph in figure 2 summarizes the age at which people are diagnosed with melanoma, the most serious form of skin cancer. use the graph to explain why protection from skin cancer may not explain the strong selective pressure for dark skin in high - uv areas.

Explanation:

The statement means that the adaptive value of a trait depends on the environment. A trait helpful in one environment may be harmful in another because natural selection favors traits that improve survival/reproduction in a specific setting.

Answer:

b. Traits can be helpful or harmful. If populations of a species are in different environments, some traits that are helpful in one environment might be harmful in another environment.