Natural selection

5. A series of actions or steps taken to achieve an end.
8. Change in a kind of organism over time; process by which modern organisms have descended from ancient organisms.
11. the surroundings or conditions in which a person, animal, or plant lives or operates.
12. selection Selection by humans for breeding of desirable traits from the natural variation among different organisms
14. to stay alive.
15. selection A natural process resulting in the evolution of organisms best adapted to the environment.
16. Ability of an organism to survive and reproduce in its environment.
17. differences in physical traits of an individual from the group to which it belongs.
18. A characteristic that improves an individual's ability to survive and reproduce in a particular environment.

1. Being of use; helpful; favorable.
2. bird's mouth.
3. being the only one of its kind.
4. a person that someone is descended from.
6. Product of reproduction, a new organism produced by one or more parents.
7. group of individuals of the same species that live in the same area.
9. A group of organisms that are closely related and can mate to produce fertile offspring.
10. a person considered as descended from some ancestor or race.
13. A characteristic that an organism can pass on to its offspring through its genes.
16. advantageous.