I. I.History of Evolutionary Thought A. A.Before Darwin Concept of evolution predates Darwin by >2000 years (not widely accepted) Fossils known long before Darwin and recognized as remains of organisms 1. 1.Aristotle ( B.C.) Organisms could be arranged on a natural scale of increasing complexity (scala naturae) Species fixed and unchanging 2. 2.Carolus Linnaeus ( ) Swedish physician who founded taxonomy Believed in natural theology (study nature to understand the Creator) Developed binomial nomenclature and modern classification hierarchy Did not intend system to reflect evolutionary relationships

I. I.History of Evolutionary Thought A. A.Before Darwin 3. 3.James Hutton ( ) Gradualism 4. 4.Jean Baptiste de Lamarck ( ) Old earth, adaptation (natural change w/o divine guidance), evolution 5. 5.Thomas Malthus ( ) Population increase  Competition for survival 6. 6.Georges Cuvier ( ) Paleontology, extinction, catastrophism 7. 7.Charles Lyell ( ) Uniformitarianism

Fig. 22.2

I. I.History of Evolutionary Thought B. B.Charles Darwin ( ) Went to University of Edinburgh at 16 to study medicine Transferred to Cambridge University; changed major to theology Became protégé of botanist Initial observations for theory of evolution made on 5-year cruise to prepare navigation charts for British Navy; naturalist aboard HMS Beagle

Fig. 22.5

I. I.History of Evolutionary Thought B. B.Charles Darwin ( ) 1. 1.Crucial information for development of theory a. a.Similarities & differences among species in Galapagos Islands vs. South America Suggested divergence from common ancestor b. b.Principles of Geology (1830) by Lyell Contradicted idea of static, young earth c. c.Artificial selection Selective breeding in dogs, cattle, wild mustard

Fig. 22.9

I. I.History of Evolutionary Thought B. B.Charles Darwin ( ) 1. 1.Crucial information for development of theory a. a.Similarities & differences among species in Galapagos Islands vs. South America Suggested divergence from common ancestor b. b.Principles of Geology (1830) by Lyell Gradualism contradicted idea of static, young earth c. c.Artificial selection Selective breeding in dogs, cattle, wild mustard d. d.Writings of Malthus on population growth Suggested that not all offspring can survive when resources are limited

I. I.History of Evolutionary Thought B. B.Charles Darwin ( ) 2. 2.Major components of evolutionary theory a. a.Descent with Modification Recognized that groups in Linnaeus’ classification hierarchy could reflect patterns of descent from common ancestors b. b.Natural Selection Mechanism by which populations adapted to local conditions Developed from five major observations and three inferences (according to Ernst Mayr)

I. I.History of Evolutionary Thought B. B.Charles Darwin ( ) 3. 3.Observations a. a.Overproduction – Not all offspring survive to reproduce b. b.Stability – Populations tend to remain stable in size c. c.Limited Resources d. d.Within-Species Variation – Not all individuals identical e. e.Heritability – Traits passed from parent to offspring 4. 4.Inferences a. a.Competition – Leads to limited survivorship b. b.Differential Fitness – Best adapted individuals most likely to survive c. c.Gradual Change – Favorable traits accumulate over generations

II. II.Evidence for Evolutionary Theory A. A.Natural Selection Has been tested experimentally

Fig

II. II.Evidence for Evolutionary Theory A. A.Natural Selection Has been tested experimentally Soapberry bugs Drug resistance

II. II.Evidence for Evolutionary Theory B. B.Homologies 1. 1.Anatomical Homologous features derived from same structure in ancestor Homoplastic features arose from same functional need (convergent evolution) Some important clues to ancestry come from vestigial structures Ex: Hindlimb bones in whales and some large snakes

Fig

II. II.Evidence for Evolutionary Theory 2. 2.Embryological Features in early development often conserved throughout a taxon Ex: Gill pouches and tail in mammals, just like fishes, amphibians, reptiles, birds 3. 3.Molecular Divergent traits based on divergent genes and proteins Some proteins and parts of proteins diverge more than others (some regions conserved)

Fig