Chap. 15 : Darwin’s Theory of Evolution I.Fossils - traces of dead organisms, collect in sediments (dust, mud, etc) to form sedimentary rock. - traces of dead organisms, collect in sediments (dust, mud, etc) to form sedimentary rock.

A. Types :  1. Mold – imprint (living parts maybe left behind) common in limestone rock.  2. Cast – when molds fill in with minerals  3. Amber – fossilized sap or petrified rocks B. Law of Superposition – states that layers of succession (called strata) build on top of each other.

youngest youngest oldest oldest ** all fossils found in same area are from the same time period. ** all fossils found in same area are from the same time period. ** relative age – comparison between fossils. ** relative age – comparison between fossils. ** absolute age - determined by radioisotopes. ** absolute age - determined by radioisotopes. (carbon dating) (carbon dating) A B C D

C. Succession layers – shows periods of boom of certain organisms then periods of mass extinctions. Caused by environmental changes.  D. Biogeography – the study of distribution of living (or once living) organisms. II. Evolution Theories A. Lamarck – 1 st to suggest that similar species arose from common ancestors. A. Lamarck – 1 st to suggest that similar species arose from common ancestors.

 Suggested the term acquired trait ( not passed by genes but changed by habitat or behavior and then passed to offspring). Ex. webbed feet – resulted from repeated stretching. B. Darwin – “Origin of Species” – book about the idea of natural selection (nature selects for the most fit organisms to survive) - fitness – how well an organism is adapted to its environment - fitness – how well an organism is adapted to its environment

III. Evidence of Evolution  A. Homologous/Analogous Structures - Homologous Structures – features that originated from a shared ancestor. Ex. Different beaks, forelimbs of penguins, alligators, bats, and humans. - Homologous Structures – features that originated from a shared ancestor. Ex. Different beaks, forelimbs of penguins, alligators, bats, and humans. ** indicates that different species shared a common ancestor ** indicates that different species shared a common ancestor - Analogous Structures – features that look somewhat alike and serve similar functions but do not share the same embryo development. Ex. Birds and moth’s wings. - Analogous Structures – features that look somewhat alike and serve similar functions but do not share the same embryo development. Ex. Birds and moth’s wings.

B. Vestigial Structures – structures that presently serve no function.  Ex. Appendix and tail bone in humans, 4- chambered stomach in whales, “legs” in boas and pythons. --- organisms with similar vestigial structures shared an ancestor C. Similar Embryo Development - in the early stages of development all vertebrates are the same. Ex. Fish,rabbits,birds, and humans - in the early stages of development all vertebrates are the same. Ex. Fish,rabbits,birds, and humans

D. Similar Macromolecules – homologous structures have similar amino acid sequences. The # of differences are related to how recent their ancestor was. IV. Patterns of Evolution 1. Coevolution – change of 2 or more species in close association with each other. Ex. Predator/prey, plants/animal pollinators 1. Coevolution – change of 2 or more species in close association with each other. Ex. Predator/prey, plants/animal pollinators -- bats and flowers – bats long tongue and slender nose, flower light in color and smells fruity -- bats and flowers – bats long tongue and slender nose, flower light in color and smells fruity

2. Convergent evolution – environment selects similar phenotypes even though the ancestors were quite different. Ex. Sharks and porpoises 3. Divergent Evolution – 2 or more related populations become more and more dissimilar. Caused by a change of habitat. --- usually results in new species --- usually results in new species a. Adaptive Radiation – related species evolve from single ancestor. Ex. Darwin finches. a. Adaptive Radiation – related species evolve from single ancestor. Ex. Darwin finches. b. Artificial selection – speeding up of divergence by artificial means. Ex. Domestic dogs, horses b. Artificial selection – speeding up of divergence by artificial means. Ex. Domestic dogs, horses -- doesn’t result in new species but rather varieties of species. -- doesn’t result in new species but rather varieties of species.

V. Events that lead to new species :  Barrier separating like organisms forms (flood, volcanic eruptions, earthquakes, forest fires, etc.)  Time passes (thousands of yrs), environment changes  Natural selection breeds changes  Enough change occur overtime to change DNA significantly so no longer recognized.

VI. Primates and Human Evolution 45 million years ago 45 million years ago New World Monkeys (tails that grasp, upward noses) Old World Monkeys (non- grasping tail, downward nose) Some evolved into apes and gorillas Evolved into humans monkeysbaboons