I. Fossil Record Theory of Evolution Slow Change over time C. E.g. Evolution of the modern horse A. The fossil record of Earth shows evidence that species of living things have undergone perpetual changes, changes, caused by changes in gene frequency. frequency. B. Changes in gene frequencies ☞ new species E.g. Evolution of the modern horse From Eohippus (5 toes, > 1 foot, size of a cat) To Equus (1 toe, 5 feet or more at the withers) D. Charles Darwin 2. Voyages of the HMS Beagle 1. Circa 1840, Charles Darwin sailed around the world for 5 years on the HMS Beagle. 1 b. Finches 3. He observed great biodiversity. Penguin a. E.g. Birds Blue-footed booby Albatross Frigate bird Galapagos dove c. Reptiles d. Plants Capparidaceae Galapagos tortoise Button mangrove Achupalla plant. Beach morning glory Marine iguana 4. Darwin’ Darwin’s observations lead to… a. Ideas to try explain what he had seen. b. Publishing of “The Origin of the Species” Species” Passion flower Aristolochia Lava cactus 5. Ideas contributing to the theory of evolution a.Evolution a.Evolution = slow change over time, sometimes causing new species to emerge b. Species = a group of organisms that : look very much alike share a common ancestry are capable of breeding and producing viable offspring that are capable of reproducing 2 b. Species E.g. c. Natural selection all dogs, same species However, horse + donkey = mule i. Species’ Species’ members survive if they have the genes that are best suited for the current environmental conditions. ii. Species unable to adapt to the current conditions become extinct. extinct. c. Natural selection iii. Nature selects “for” for” advantageous traits (genes) and ”against” against” traits that do not improve a species’ species’ chances of survival. survival. iv. Individuals with advantageous traits survive to breed and pass those traits to the next generation. vii. The Peppered Moth (an example of natural selection) c. Natural selection v. Gene frequency changes are caused by natural selection. selection. vi. Natural selection may lead to evolutionary change. vii. The Peppered Moth Facts: PrePre-Industrial revolution (late 18th & early 19th Centuries), ratio of light peppered moths to melanic (dark) was 50:50 Light Form of peppered moth Light and melanic (dark) forms 3 vii. The Peppered Moth Industrial Revolution, coal burning by factories caused tree trunks to become darkdark- colored. Bird predators ate more light moths, more melanic moths survived. # light moths < # Melanic moths 4. Adaptation anatomical structure, physiological process, or behavioral trait that improves an animal’ animal’s fitness for survival g. The Peppered Moth By the 1950’ 1950’s, coal burning stopped. Ratio of light to melanic returned to 50:50. Moths did NOT change color. Both colors always existed in the gene pool. Gene frequencies changed. changed. 5. Common descent = an 6. Homology = all life forms come from some original life form; closely related species have a common ancestor c. Homologous structures a. = similarity of organisms due to common embryonic or evolutionary origin b. E.g. a vertebrate forelimb could be an arm, a wing, or a flipper made of same bones may have different f(x)s 4 humerus radius & ulna 7. Adaptive Radiation metacarpals carpals bat = production of ecologically diverse species from a common ancestral stock mole human whale bird horse (see text figure 1.17) 8.Extinctions AT LEAST five major extinctions in geological time ¿ 65 million years ago during the Cretaceous era, what animal group become extinct? ¿Why? 8. Extinctions Dinosaurs. Unable to adapt to the changing environmental conditions (did not have the gene combinations to permit their survival E. Rapid evolution? 1. Antibiotic use creating “super germs” germs” 2. Use of pesticides creating “super bugs” bugs” 5