Transcript Evolution
Evolution Objectives: 12.0 Describe protective adaptations of animals, including mimicry, camouflage, beak type, migration, and hibernation. 12.1 Identifying ways in which the theory of evolution explains the nature and diversity of organisms 12.2 Describing natural selection, survival of the fittest, geographic isolation, and fossil record Lamarck’s Theory of Evolution Proposed that selective use or disuse of organs caused organisms to acquire or lose certain traits during their lifetime.This would lead to those traits being passed on (or not) to their offspring. EX:You work out and have huge biceps, so your offspring will have huge biceps. WRONG!!!! (Why?) Adam and Eve – ribs? Thomas Malthus Reasoned that if human population continued to grow unchecked, sooner or later there would be insufficient living space and food for everyone. What are some “forces” that influence (decrease) human population? Answer: war, famine, disease Darwin realized this applied even more strongly with plants and animals! (Why?) Natural Selection (Darwin) We have already agreed that artificial selection happens, so why couldn’t natural selection occur on a slower scale? 1. Struggle for existence a. competition among members of a population for resources b. “hiding” from predators Natural Selection 2. Survival of the fittest a. Those who survive long enough to produce offspring and pass on their traits b. Adaptation – any inherited characteristic that increases an organism’s chance of survival 3. Descent with modification a. Over long periods of time, natural selection produces organisms that look different from their ancestors b. Carried to its fullest extreme: common descent says we all have one common ancestor. Evidence (Support) of Evolution 1. 2. Geographic distribution- species that are better adapted to their environment survive in higher numbers. Homologous body structures – similarities among body parts of animals with backbones (vertebrates): a. b. c. d. e. Arms Wings Flippers Forelegs Vestigial organs – have no apparent use now, but still show up in some form (i.e., human appendix) Evidence (Support) of Evolution 3. 4. Similarities in early development Fossil record a. Intermediate stages of organisms found as scientists work their way through sediment layers b. GAPS exist! Galapagos Tortoises Summarizing Darwin (p.386) Individual organism differ, and some of this variation is heritable. Organisms produce more offspring than can survive, and not all that survive reproduce. (Do you have an aunt, uncle, or family friend with no children?) Because more organisms are produced than can survive, they compete for limited resources. Summarizing Darwin (p.386) Each unique organism has different advantages and disadvantages in the struggle for existence. Individuals best suited to their environment survive and reproduce most successfully. (What is this called?) These individuals pass on their heritable traits to their offspring. _______ selection causes species to change over time. Species alive today are descended with modification from ancestral species.