mass extinction. global warming. gene dominance. natural selection.
I gave my students this multiple choice question: Edith's checkerspot butterfly is a non-migratory species found in distinct populations from Canada to Mexico. Today, populations in southern regions are declining while new populations push the northern limit further north. This range shift provides evidence for the theory of

Only one answer is correct among these 4 choices:
- mass extinction.
- global warming.
- gene dominance.
- natural selection.

Could you tell me which one is correct?

global warming.