Evidence for Evolution

1. Evidence for Evolution

2. The Fossil Record

3. Why is the giraffe's neck so long?

5. Adaptation The evolution of a structure, behavior, or internal process that enables an organism to respond to stimuli and better survive in an environment. A trait that gives an organism an advantage in the struggle for survival. Adaptation in species develop over many generations and can be physiologicalor structural.

6. Mimicry Lab Can a human tell the difference between three types of candies? Milk chocolate M&M – mmmmmmmm yummy good! Skittles – tasty but will make you sick every time Dark chocolate M&M – you DIE!!

7. Organisms have ___2___ of many traits and sometimes the environment can ___1___one ___2___over another. Other times a __1__can occur and a ___2___will appear that gives an organism ___3___in the environment. Those with the ___1__have a __1___and often live long and___2___. These organisms have a high level of ___2___ in the environment in which they live. As these organisms continue to______1____, passing on the __1___for the__2___, the frequency of those___3___ increases so that over time the species will__2___. This process is known as_____3____. A species ___3__ to its environment can take___1___. This is known as___1___. __3___evolve___2___ adapt. • 1 • Evolution • favored trait • genetic mutation • alleles • favor • reproduce • survival advantage • thousands or millions of years • 2 • natural variations • change • variation • favored trait • produce more offspring • new trait • organisms • 3 • Species • an advantage • natural selection • fitness • alleles • adapting

8. Types of Natural Selection

12. The Origin of Species

13. Speciation can occur… Gradualism Punctuated Equilibrium

14. NO Can They Reproduce? Western Meadowlark Eastern Meadowlark The biological species concept is based on inter-fertility, rather than physical similarity. YES

15. SPECIATION A species is defined as being reproductively isolated from other species. How are they isolated? TEMPORAL ISOLATION BEHAVIORAL ISOLATION HABITAT ISOLATION MECHANICAL ISOLATION GAMETIC ISOLATION

16. The Mechanics – attempts to reproduce may be made but because anatomy is incompatible reproduction can’t occur

17. SPECIATION Allopatric speciation, a species emerges due to geographic isolation Parapatric speciationadjacent populations become distinct species. Come in contact along a common border but prefer to mate with own kind – weak hybrids Sympatric speciationspecies form within the range of a parent species. Something other than geographic isolation

18. Geographic barriers can start the process of speciation

19. Allopatric Speciation Ammospermophilus leucurus Ammospermophilus harisi

20. Parapatric Speciation Two species of garter snakes live in the same area but because one lives mainly in water and the other is primarily terrestrial they rarely encounter each other.

21. Sympathetic Speciation Gamete Isolation – The gametes do not form a zygote Chromosomal changes due to mutations More common in plants

22. Temporal Isolation Western Spotted skunk & Eastern Spotted skunk Share a habitat but mate at different times of the year Western = summer Eastern = winter

23. Courtship What lights your fire? Many species have elaborate rituals for attracting a mate – what works for one species doesn’t necessarily work for others

24. Divergent Evolution Species that were once similar to an ancestral species become increasingly distinct adapting to different environmental conditions

25. Convergent Evolution Unrelated species occupy similar environments in different parts of the world. Develop similar characteristics due to similar environmental pressures.

26. MASS EXTINCTION It’s all over!!