Theory of Evolution

1. Theory of Evolution Chapter 15

2. Idea of Evolution • Charles Darwin (1809-1882) • English naturalist • Took a trip around the world on a ship called H.M.S. Beagle • Mostly fascinated with the Galapagos Islands • Best known for his theory of evolution by natural selection

3. Idea of Evolution • Galapagos Islands • Groups of animals vary from island to island • Ex: tortoises on each island resemble each other but differ in the shape and function of their shells • Ex: finches on each island resembled each other but differ in the shape and function of their beaks • Darwin believed these unique animals all came from a common ancestor and they changed/adapted to their environment

4. Idea of Evolution • Evolution • Development of new types of organisms over time • Heritable change in the characteristics within a population from one generation to the next

5. Ideas of Darwin’s Time • Scientists thought all species were permanent and unchanging • The Earth was believed to only be a few thousand (not billions) of years old • Charles Lyell was a English geologist that believed the Earth’s surface continues to change • Influenced Darwin

6. Ideas of Darwin’s Time • Jean-Baptiste Lamarck • French biologist that supported the idea that populations of organisms change over time • Also believed in biogenesis of simple organisms • Proposed that individuals acquire traits during lifetime from behavior and pass them onto offspring • Called Theory of Acquired Traits

7. Darwin’s Ideas • Around the same time Darwin and Wallace formed theory to explain evolution • Published book On the Origin of Species in 1858 • Book explained how evolution occurs by means of natural selection

8. Descent with Modification • Idea that every species must have descended by reproduction from pre-existing species that arrange over time • Ex: finch beaks at Galapagos

9. Natural Selection • Mechanism from descent with modification • 1. Overproduction • More offspring are produced than survive to maturity • 2. Genetic variation • Traits vary within a species • Ex: deer fur thickness

10. Natural Selection (cont’d) • 3. Struggle to survive • Organisms need to compete with each other known as “struggle for existence” • When an organism is successful in a new environment its called an adaptation • 4. Differential Reproduction • Organisms best adapted for an environment will survive best and reproduce • Survival of the fittest • The ability for an organism to reproduce and pass on adaptations

11. The Fossil Record • Fossils • Remains of an organism that died long ago • Superposition • Idea that strata form in layers where the layers closest to the top are the younger than below

12. The Fossil Record • Relative Age • Age compared to other fossils in order of old to young • Absolute Age • Using radioactive dating to get actual number age

13. Transitional Species • Organisms with features that are between hypothesized ancestors

14. Biogeography • Study of locations of organisms around the world • Darwin used this method when exploring islands and observed animals variation based on environment

15. Anatomy and Embryology • Anatomy: study of the body • Embryology: study of development • Homologous structures • Anatomical structures that originated by heredity from a structure in most common ancestor • Ex: bones in arms of humans, penguins, alligator and bat • Related structure but function may differ

16. Anatomy and Embryology • Analogous Structures • When structures have similar function, but did not develop the same way • Ex: wings of bat vs. bird • Vestigial Structures • Organs that no longer serve a function in an organism • Ex: human tail bone, appendix

17. Phylogeny • Relationships among groups of organisms • Can make a “tree” of animals evolved • Trunk of the tree would represent species that are closely related • Branches represent a separate population or lineage

18. Caribbean Anole Lizard • Found in the Caribbean islands of Cuba, Hispaniola, Jamaica, and Puerto Rico • Each lizard species body type differs by their habitat • Ex: stocky body and long legged lizards are best adapted for tree truck environments, slender bodies and long tails are best adapted for grassy environments • Hypothesis #1: An ancestral anole species specialized for living on twigs originally lived on one island and later migrated to other islands OR • Hypothesis #2: Each twig-dwelling species evolved independently on each island from distant ancestor anole species

19. Evolution in Action • Biologists tested the hypothesis by comparing DNA from the various species • DNA evidence supported hypothesis 2 that each lizard evolved independently on each island • Convergent Evolution • Process by which different species evolve similar traits • Ex: twig-dwelling species came from different ancestors but evolved similar adaptations to their environment

20. Divergence & Radiation • Divergence evolution • Process by which the descendants of a single ancestor diversify into species that each fit different parts of the environment • Ex: lizards with genes for large toe pads and short legs ran slowly on the tree trunks and fell easily to predators, lizards with long legs and small toe pads were able to slip away and reproduce

21. Divergence & Radiation • Adaptive Radiation • Pattern of divergence when a new population in a new environment undergoes divergent evolution

22. Artificial Selection • Process the occurs when human breeders choose individuals that will parent the next generation • Ex: faster greyhounds, smaller tea cup dogs, high milk yield cows, high yielding grain per stalk • Darwin hypothesized domesticated dogs diverged from wolves • DNA evidence indicated similarities with wolves in East Asia, supporting Darwin’s hypothesis and humans selected domestic dogs from wolf population 15,000 years ago

23. Coevolution • Evolution is on-going and many species may evolve together • Coevolution • When two or more species have evolved adaptations to each other’s influence • Predator/Prey Interactions • Introduction of new species • Creating antibiotics