What must be true for natural selection to happen? A. There can be no competition for resources
B. There must be genetic variation in the population.
C. All organisms must reproduce the same amount.
O D. The population must be below carrying capacity.

1. in what ways have non-native species been beneficial? 2. what are some of the hypotheses for the collapse of honeybee colonies? 3. distinguish between regional and functional extinction. 4. why is it difficult to measure background extinction rates? 5. what three factors are most important in causing extinction rates to climb?