Evolutionary!

3. A preserved trace of an organism from the past.
6. A difference in a physical trait.
7. A feature that an organism develops to better survive in its environment.
8. The ability for a trait to be passed down.
10. Selection When certain traits increase mating success.
11. Structure or organ that are similar structure, but different in purpose.
12. The complete elimination of an entire species .
13. The physical movement of particular alleles from one population, to another.
15. A natural mechanism by which a species, or member of that species inherits a beneficial adaptation that allows it to produce more offspring than others.
17. A form of evolution between similarly related species, into more different species, due to differing environmental conditions.
18. The theory that natural disasters shaped the earth's landforms and caused extinction.
20. The measure of survival ability and ability to produce for offspring.
21. An observable change in the allele frequencies in a population.

1. The idea that geologic processes that shape the earth remain constant over time.
2. A form of evolution between unrelated species, that result in similar characteristics, due to similar environmental conditions.
4. The process in which multiple species evolve in response to the changes in each other.
5. The process by which humans select traits through breeding.
9. Study of embryos, used to find similarities between species during development.
14. Producing more offspring than will likely survive.
16. The gradual biological process of change by which descendants begin to greatly differ from their ancestors.
19. The total number of genes of every individual in a population