Mechanisms of Evolution

1. Mechanisms of Evolution

5. EVOLUTION Change over time

6. Scientists who studied change Alfred Wallace Described early ideas related to natural selection. Co-discoverer of natural selection.

7. Scientists who studied change Jean Lamarck -over the lifetime of an organism, physical features increase in size because of use or disuse. New traits passed to offspring. INCORRECT!!!

8. Acquired Characteristics? Lamarck said that the animals were selecting themselves to survive Photo courtesy of ucumari, creative commons, flickr

9. Scientists who studied change Charles Darwin -studied all over the world but primarily in South America and the Galápagos Islands. 1859-book “On the Origin of Species by Means of Natural Selection” Populations- change over time.

10. Population- all the individuals of a species that live in a specific geographical area. Evolution- a change in the characteristics of a population from one generation to the next.

11. Marine Iguana, photo courtesy of mtchm, flickr creative commons Blue-footed booby, photo courtesy of stirwise, flickr creative commons

12. Finch, photo courtesy of stirwise, flickr, creative commons Giant tortoise, photo courtesy of Planetgordon, flickr creative commons

14. Darwin’s finches - evolution on a small scale Change in available food means finches with some beaks survive while others die out This is natural selection

15. Evolution of Species Species – a group of organisms that are closely related and naturally mate to produce offspring Speciation – occurs when members of a similar population no longer interbreed to produce fertile offspring.

16. KEY POINTS 1. Variation exists among individuals in a species 2. In particular environments, some individuals are better able to survive and have more offspring. Photo courtesy of digitalART2, flickr creative commons

17. KEY POINTS 3. Over time, the traits that make certain individuals able to survive tend to spread in the population-competition 4. Individuals that had advantageous variations are more likely to survive and reproduce Photo courtesy of digitalART2, flickr creative commons

18. KEY POINTS This process came to be known as: • NATURAL SELECTION- favors individuals that are best able to survive and reproduce The favored variations are:ADAPTATIONS • An adaptation is a trait that enables an organism to better survive in it’s environment.

19. Fossil Evidence All organisms living today share common ancestry with earlier simpler life forms Give some examples of fossil’s…page 285.

20. ANATOMY and DEVELOPMENT • Homologous Structures • Structures that share a common ancestry • Same structure; Different function

21. ANATOMY and DEVELOPMENT • Analogous Structure • Features that don’t derive from a common ancestor • Same Function: Different Structure

22. Analogous Structures Ex: insect and bird wing, same function, but don’t come from a common ancestor Ex: streamlined bodies of seals and penguins

23. ANATOMY and DEVELOPMENT • Vestigial Structure • Structures that are considered evidence of an species evolutionary past • Not used anymore • Ex. The hind limbs in whale

24. Embryological Development Embryos of different species develop in almost identical ways. Human fetus at 8 weeks

25. Natural Selection is Driven by 4 Factors 1. All populations have genetic variation 2. The environment presents challenges to successful reproduction

26. Natural Selection is Driven by 4 Factors 3. Individuals tend to produce more offspring than the environment can support 4. Individuals that are better able to cope with the challenges presented by their environment tend to leave more offspring than those less suited to the environment

27. REPRODUCTIVE ISOLATION • The condition in which two populations of the same species do not breed with one another because of: geographic separation difference in mating periods and other barriers Ex. The Grand Canyon Squirrels pg. 281