Across
- 3. study of embryos and their development
- 8. ability to survive and reproduce
- 13. characteristic that increases survival
- 14. similar function structurally different
- 16. reproduce at different times
- 19. actual age based on radioactive elements
- 20. physical barriers keep from reproducing
Down
- 1. similar structures in related species
- 2. difference in physical traits
- 4. concealing identity of something
- 5. evolution occurs slow and steady
- 6. a structure with no purpose
- 7. group of same species that reproduce
- 9. formation of new species
- 10. al genes including different alleles
- 11. animal looking like another animal
- 12. large population declines in number
- 15. breeding with specific traits
- 17. determine age by placement in rock layers
- 18. variety