Science 10 with CSS teacher

In sexual reproduction, offspring have unique combinations of genes (half from each parent). This creates variation in a population, because every individual is a little different from all the others.

Variation is very important to the survival of a species. The greater the diversity, the more likely it is that a species can adapt to change. Perhaps not all individuals will survive whatever change may occur, but at least some will! Why do some members of a species survive, but not others? In a way, the survivors have won a “genetic lottery.” Their genes happened to give them a lucky advantage that matched the conditions of change that occurred. Because they're still around to reproduce, their traits will be passed on to their offspring.

However, if a population gets too small, genetic diversity can be permanently lost. Read the Case Study on Cheetah, on the next page, for an example of this situation.