Chapter 15 Evolution

Chapter 15 Evolution I

Evolution: process where organisms change over time. A) Changes among organisms of the same kind are called variations. B) Fossils: remains of organisms long ago.

II 2 main theories of Evolution A) 1809 Jean Baptiste Lamarck – his theory is based on 2 hypotheses. 1) Organisms develop traits or characteristics by their use or disuse of body parts. (a)PLAUSIBLE 2) Inheritance of acquired characteristics – traits an organism develops during their lifetime are passed from parents to offspring. (a)NOT PLAUSIBLE B) 1822 Charles Darwin – 5 year study on the ship HMS Beagle as a naturalist studying nature on the Galapagos Islands. 1) Darwins four theories of evolution 2) Overproduction: each species produces more offspring than can survive. 3) Competition: beacause of overproduction of offspring, competition for food and H2O is limited. 4) Variations: differences occur among members of the same species. 5) Survival of the fittest: those who have traits to make them better adapt to the environment will survive and reproduce = natural selection (a)These traits help them survive and pass them on.

6) Environment deter mines which variations will be selected III Evidence from Living Organisms A) Comparitive Anatomy: likenesses in anatomy among different kinds of organisms 1) Homologous structures: structures embryologically similar (skeletal) but have a different function. 2) Analogous structures: structures serve similar functions but differ in structure. B) Vestigial organs: remnants of functions less parts in animals. 1) Humans: tail bone, appendix 2) Boa constrictors: hind legs 3) Whale: hind legs C) Biochemistry: organisms have similarities in chemical processes. IV Causes that change evolution are: A) Natural selection: those that are well adapted survive and reproduce less fit – die B) Mutation: a change in the gene or chromosome can cause a change in the organism. C) Migration: movement of members of a species in or out of an area. D) Geographic isolation: when a group of organisms become separated or isolated from the rest. V Rate of Evolution A) Gradualism: show change over long periods of time. B) Punctuated equilibrium: species remain unchanged for a long period then many die and others appear. VI Patterns of evolution

A) Adaptive radiation: many related species evolved from a single ancestral species. B) Divergent evolution: where two or more related species become more dissimilar. C) Convergent evolution: unrelated species become more and more similar in appearance due to the same environment.