Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 221/12/13 Chapter 2Biology: from natural philosophy to Darwin1/12/13 Darwin’s insights form the foundation of evolutionary theory •Explains how patterns of diversity came to be•Combined his ideas with work of many others1/12/13 Early naturalists classified life’s diversity Carl Linnaeus (1707-78): Father of modern taxonomy1/12/13 Some recognized record of historical changeNicolas Steno (1638-86): Father of geology and stratigraphy1/12/13 Early ideas about evolution•Earth formed according to laws of physics and chemistry–Older than previously thought•Life emerged as distinct types–Transformed when environment changed Georges Buffon(1707-88)1/12/13 Paleontology provided evidence that life changed•Georges Cuvier (1769-1832)–Fossils resemble but are not exactly the same as modern species–Many past species are extinct1/12/13 Geologists recognized that change was gradual•James Hutton–Observable processes produce small changes that accumulate over time–The earth must be old•William Smith–Different rock layers contain distinct fossilsWilliam Smith (1769-1839)1/12/13 Smith created first geological map1/12/13 Geologists named rock formations from different periods1/12/13 Evolution as striving•Life driven from simple to complex–Complex species descended from microbes–Microbes continually generated spontaneously•Adaptation occurs through inheritance of acquired changesJean-Baptiste Lamarck(1744-1829)1/12/13 Key Concepts•Georges-Louis Buffon–Species arise as distinct entities–Diverse environments give rise to new varieties•Georges Cuvier–Extinction•James Hutton–Earth transformed gradually1/12/13 Key Concepts•William Smith–First geological map•Jean Baptiste-Larmarck–Species evolve through natural processes–Life constantly generated–Adaptation through inheritance of acquired changes1/12/13 Charles Darwin (1809-1882)•Medical school in Edinburgh–Preferred to study nature•Trained to become clergyman at Cambridge•Invited to serve as unofficial naturalist for HMS Beagle in 18311/12/13 Voyage of the Beagle•Collected many fossils and living organisms•Studied geology while reading Principles of Geology by Lyell•Uniformitarianism: observable natural processes responsible for events in the past1/12/13 Observations convinced Darwin that life evolved1/12/13 Prompted to go public•Letter from Alfred Russel Wallace proposed similar evolutionary ideas–Common ancestry–Natural selection•Letters from Darwin and Wallace presented at Linnean Society in 18581/12/13 Darwin’s book published in 1859•On the Origin of Species by Means of Natural Selection, or the Preservation of Favored Races in the Struggle for Life•Descent with modification–All species share common ancestry–Changes occur through natural selection1/12/13 Common descent makes sense of puzzling patterns in natureHomologous trait: similar because of inheritance from a common ancestor1/12/13 Common descent makes sense of puzzling patterns in nature1/12/13 Natural selection: Darwin’s mechanism of changeAdaptations: traits that have evolved by natural selection1/12/13 Key Concepts•Charles Lyell–Popularized idea that earth changes gradually•Alfred Russel Wallace–Independently formulated idea of natural selection1/12/13 Darwin’s theory has been expanded •Sexual selection–Selection for traits that provide a mating advantage•Genetic drift–Change in frequency of traits due to chance