Unit 6

2. A natural process resulting in the evolution of organisms best adapted to the environment.
5. mutations
6. A characteristic that improves an individual's ability to survive and reproduce in a particular environment.
8. Method of determining the age of a fossil by comparing its placement with that of fossils in other layers of rock
10. A scientist who studies fossils
13. Ability of an organism to survive and reproduce in its environment
14. that eukaryotic cells formed from a symbiosis among several different prokaryotic organisms
15. competition among members of a species for food, living space, and the other necessities of life
17. principle that all living things have a common ancestor
19. Theory
20. Pattern of evolution in which long stable periods are interrupted by brief periods of more rapid change
21. Change over time

1. English natural scientist who formulated a theory of evolution by natural selection (1809-1882)
3. evolutionary pattern in which many species evolve from a single ancestral species
4. Process by which unrelated organisms independently evolve similarities when adapting to similar environments
7. A time scale established by geologists that reflects a consistent sequence of historical periods, grouped into four eras: Precambrian, Paleozoic, Mesozoic, and Cenozoic.
9. Structures in different species that are similar because of common ancestry.
11. A term that typically describes a species that no longer has any known living individuals.
12. A trace of an ancient organism that has been preserved in rock.
16. A type of rock that forms when particles from other rocks or the remains of plants and animals are pressed and cemented together
18. Process by which two species evolve in response to changes in each other