2 Evolution: the change over time of the genetic composition of populations Natural Selection: populations of organisms can change over the generations if individuals having certain heritable traits leave more offspring than others (differential reproductive success)Evolutionary Adapations: a prevalence of inherited characteristics that enhance organisms’ survival and reproduction
6 DARWIN’S INFLUENCES Taxonomy matured during mid-eighteenth century Linnaeus believed in:He developed the binomial system of nomenclatureSystem of classification for living thingsCount Buffon:Wrote 44-volume catalog of all known plants and animalsSuggested descent with modification6
7 DARWIN’S INFLUENCES Lamarck = First biologist to: Propose evolutionLink diversity with environmental adaptationConcluded more complex organisms are descended from less complex organisms: SIMPLE TO COMPLEXProposed inheritance of acquired characteristics – Lamarckianism
11 HMS BEAGLE VOYAGE Invited to travel around the world (22 years old!)makes many observations of naturemain mission of the Beagle was to chart South American coastline
12 While on the voyage of the HMS Beagle in the 1830s, Charles Darwin observed similarities between living and fossil organismsthe diversity of life on the Galápagos Islands, such as blue-footed boobies and giant tortoisesFigure 13.1A
14 MALTHUS Overpopulation and species control DARWIN’S INFLUENCESMALTHUS Overpopulation and species controlLYELLEarth is subject to slow but continuous cycles of erosionProposed uniformitarianism, rates and processes of change are constant
15 Darwin became convinced that the Earth was old and continually changing He concluded that living things also change, or evolve over generationsHe also stated that living species descended from earlier life-forms: descent with modification (originally Buffon and Erasmus Darwin)All organisms are related through decent from an ancestor that lived in the remote past.
16 DARWIN’S 5 MAJOR CONCLUSIONS 1. Population has Variation2. Variations may be favorable3. More offspring are produced than survive4. Survivors have favorable traits5. Populations change over time
17 ON THE ORIGIN OF SPECIES ......ALL THIS LEADS TO HIS THEORY OF NATURAL SELECTION and SURVIVAL OF THE FITTEST1859 PublicationWallace influence
18 WITNESSING NATURAL SELECTION Early 19th centuryIndustrialRevolution
21 The fossil record shows that organisms have appeared in a historical sequence Many fossils link early extinct species with species living todayThese fossilized hind leg bones link living whales with their land- dwelling ancestorsFigure 13.2G, H
22 2006 Fossil Discovery of Early Tetrapod Tiktaalik“missing link” from sea to land animals
23 Evolution evidence: Homologous Structures Similar structureSimilar developmentDifferent functionsEvidence of close evolutionary relationshiprecent common ancestor
25 Evolution evidence: Analogous Structures Separate evolution of structuressimilar functionssimilar external formdifferent internal structure & developmentdifferent originno evolutionary relationshipDon’t be fooled by their looks!
27 Evolution evidence: Vestigial Structures Modern animals may have structures that serve little or no functionremnants of structures that were functional in ancestral speciesdeleterious mutations accumulate in genes for non- critical structures without reducing fitnesssnakes & whales — remains of pelvis & leg bones of walking ancestorseyes on blind cave fishhuman tail bone
28 Evolution evidence: Molecular Biology Similarities in DNA, proteins, genes, and gene productsCommon genetic codeClosely related species have sequences that are more similar than distantly related speciesDNA & proteins are a molecular record of evolutionary relationships
29 Evolution evidence: Biogeography FigDarwin’s observations of biogeography, the geographic distribution of species, formed an important part of his theory of evolutionIslands have many endemic species that are often closely related to species on the mainlandFigure Convergent evolution
30 NATURAL SELECTION IN ACTION Insecticide & drug resistanceinsecticide didn’t kill all individualsresistant survivors reproduceresistance is inheritedinsecticide becomes less & less effectiveThe evolution of resistance to insecticides in hundreds of insect species is a classic example of natural selection in action.The results of application of new insecticide are typically encouraging, killing 99% of the insects.However, the effectiveness of the insecticide becomes less effective in subsequent applications. The few survivors from the early applications of the insecticide are those insects with genes that enable them to resist the chemical attack. Only these resistant individuals reproduce, passing on their resistance to their offspring. In each generation the % of insecticide-resistant individuals increases.
31 ARTIFICIAL SELECTIONArtificial breeding can use variations in populations to create vastly different “breeds” & “varieties”“descendants” of wild mustard“descendants” of the wolf