Darwin & Evolution by Natural Selection

1. Warbler finch Cactus eater Tree finches Ground finches Insect eaters Seed eaters Bud eater Darwin & Evolution by Natural Selection

2. Incorrect Theories of Evolution: Lamarck • Lamarck proposed an incorrectmechanism for how organisms evolve. • Believed organisms could pass on aquired traits to offspring • Simple life forms continually came into existence from dead matter • Continually become more complex • More "perfect" -- as they transformed into new species. • He correctly pointed out that change in species is linked to an organism’s environment.

3. Charles Darwin • Proposed a way how evolution works • How did creatures change over time? • by natural selection • Collected a lot of evidence to support his ideas • 1809-1882 • British naturalist • -Wrote the Origin of Species

4. Voyage of the HMS Beagle • Invited to travel around the world • 1831-1836 (22 years old!) • makes many observations of nature • main mission of the Beagle was to chart South American coastline Robert Fitzroy

5. Voyage of the HMS Beagle • Stopped in Galapagos Islands • 500 miles off coast of Ecuador

6. Galapagos Recently formed volcanic islands. Most of animals on the Galápagos live nowhere else in world, but they look like species living on South American mainland. 800 km west of Ecuador

7. Darwin’s Observations • Animals on the coast of S. America: • Resembled those on the nearby islands • Evolved differences Or • Descended w/ modification after separating from a common ancestor.

8. Darwin found…many unique species Many of Darwin’s observations made him wonder… Why? Darwin asked: Why were these creatures found only on the Galapagos Islands?

9. present day Armadillos ancient Armadillo Darwin found…clues in the fossils Darwin found: Evidence that creatures have changed over time Darwin asked: Why should extinct armadillos & modern armadillos be found on same continent?

10. present day Sloth (extinct) Giant ground sloth Darwin found… more fossils Darwin found: Evidence that creatures have changed over time Darwin asked: Why should extinct sloths & modern sloths be found on the same continent?

11. Darwin found: Different shells on tortoises on different islands Darwin asked: Is there a relationship between the environment & what an animal looks like?

12. Finch? Sparrow? Warbler? Woodpecker? But Darwin found… a lot of finches Darwin was amazed to find out: All 14 species of birds were finches… But there is only one species of finch on the mainland! Large ground finch Small ground finch Finch? Sparrow? Darwin asked: If the Galapagos finches came from the mainland, why are they so different now? Warbler finch Tree finch Warbler? Woodpecker?

13. Finch? Sparrow? Warbler? Woodpecker? The finches cinched it! • different beaks are inherited variations • serve as adaptationsthat help birds compete for food • these birds survive & reproduce • pass on the genes for those more fit beaks • over time nature selected for different species with different beaks Darwin said: Ahaaaa! A flock of South American finches were stranded on the Galapagos… Darwin found: The differences between species of finches were associated with the different food they ate. Large ground finch Big seed eater Small ground finch Small seed eater Warbler finch Insect eater Tree finch Leaf & bud eater

14. Relationship between species (beaks) & food

15. Darwin’s finches • Darwin’s conclusions • variations in beaks • differences in beaks in the original flock • adaptations to foods available on islands • natural selection for most fit • over many generations, the finches were selected for specific beaks & behaviors • offspring inherit successful traits • accumulation of winning traits:both beaks & behaviors • separate into different species

16. Warbler finch Cactus finch Woodpecker finch Sharp-beaked finch Small insectivorous tree finch Small ground finch Warbler finch Large insectivorous tree finch Cactus eater Medium ground finch Tree finches Ground finches Insect eaters Seed eaters Large ground finch Vegetarian tree finch Bud eater From 1 species to 14 species… natural selection for best survival & reproduction variation

17. Growth of Populations • Darwin was influenced by Thomas Malthus • He wrote: Populations grow as much as the environment allows.

18. Evolution by Natural Selection • The process of: “Survival of the Fittest” • Organisms that adapt to their environment survive while those that do not adapt disappear • N.S. leads to adaptations in a population.

19. ADAPTATIONS LEAD TO FITNESS Living things that are well adapted to their environment survive and reproduce. Those that are not well adapted don’t survive and reproduce. An adaptation is any characteristic that increases fitness, which is defined as the ability to survive and reproduce.  YOU CANNOT AQUIRE AN ADAPTATION, MUST BE AN INHERITED TRAIT.

20. Genetic Variation • a. • b. • Overproduction of Offspring a. • b. • Struggle for Existence a. • b. • Differential Survival & Reproduction a. • b. Label Paper: Natural Selection Video http://www.pbs.org/wgbh/evolution/library/11/2/e_s_4.html 6 min 39 sec

21. SUMMARY: Individuals best suited to their environment survive and reproduce most successfully. The characteristic that make them best suited to their environment are passed on to offspring. Individuals whose characteristics are not as well suited to their environment die or leave fewer offspring.

22. Species change over time. This is natural selection. Over long periods of time, natural selection causes changes in the characteristics of a species, such as in shape and form. New species arise, and other species disappear.

23. Species alive today have descended with modifications form species that lived in the past. African wild dog Jackal Fox Thousands tomillions of yearsof natural selection Fox Coyote Wolf Ancestral canine • These five canine species evolved from a common ancestor through natural selection

24. Darwin’s Ideas Updated 1) Change Within Populations • N.S. causes the frequency of certain alleles in a population to change over time. 2) Species Formation • Under certain conditions, change within a species due to reproductive isolation can lead to new species. 3) The Tempo of Evolution • Gradualism is a process of evolution in which speciation occurs gradually • Punctuated Equilibrium is a process in which speciation occurs rapidly between periods of little or no change.

26. Natural Selection at Work Examples of Evolution-- 1) Factors in Natural Selection • Organisms w/traits helping them survive—reproduce & pass genes. 2) Evolution of Antibiotic Resistance • Experiments show that evolution through N.S. has occurred within populations of antibiotic-resistant bacteria • Tuberculosis bacteria 3) Evolution in Darwin’s Finches • Experiments show that evolution through N.S. has occurred in beak size in Darwin’s Finches.

27. Formation of New Species 1)Speciation • Speciation begins as a population adapts to its environment. 2) Forming Subspecies • Populations of the same species that differ genetically b/c of adaptations to different living conditions are called: subspecies. • Newly formed subspecies are on the road towards speciation. 3) Maintaining New Species • Reproductive isolation through barriers keeps species from breeding with one another.

28. Speciation • Geographic isolation of populations • Can lead to • Reproductive isolation of population • Can lead to • New Species • (unable to breed when together)

29. Geographic Isolation • Members of a population may become isolated from one another by geographic boundaries like mountains, rivers or even oceans

30. Reproductive Isolation

31. Convergent Evolution

32. Divergent Evolution(Adaptive Radiation)

33. Dichotomous Keys • Tool used when new species is found • Used to categorize different species based on physical characteristics • Classification is a way of separating a large group of closely related organisms into smaller subgroups. • A Dichotomous Key is a listing of characteristics, such as structure and behavior, organized in such a way that an organism can be identified or classified.