3Theory of Life cont. Endosymbiotic theory eukaryotic cells arose from living communities formed by prokaryotic organismsAncient prokaryotes entered primitive eukaryotic cells and remained there as organelles
5Lamark Theory of acquired characteristics Lamark said organisms acquired traits by using their bodies in new waysThese new characteristics were passed to offspringLamark was totally wrong!
6Geologists: Hutton and Lyell Fundamentalists said that the earth was around 6000 years oldHutton and Lyell argued that the earth is many millions of years old b/clayers of rock take time to formprocesses such as volcanoes and earthquakes shaped the earth and still occur today
7MalthusReasoned that if the human population continued to grow unchecked, sooner or later there would be insufficient living space and food for everyone
9Charles Darwin (1809-1882) Sailed around the world 1831-1836
102. What did Darwin’s Travels reveal The diversity of living species was far greater than anyone had previously known!!These observations led him to develop the theory of evolution!!
113.How did tortoises and birds differ among the islands of the Galapagos? Warbler finchWoodpecker finchSmall insectivoroustree finchLargeinsectivorousVegetarianCactus finchSharp-beaked finchSmall groundfinchMediumground finchLarge groundInsect eatersBud eaterSeed eatersCactuseaterWarblerTree finchesGround finches
13Evolution is when organisms change over time Evolution is when organisms change over time. So, modern organisms descended from ancient ones
14Evolution is a Theory – Just like Gravity! Evolution is a well supported explanation of phenomena that have occurred in the natural worldA theory in science must be supported by facts, it can’t be based on supposition.
15Darwin finally published his ideas in 1859 Only when other naturalists were developing the same theory that he had did Darwin finally publish his findings.
16Artificial Selectionnature provides variation, humans select variations that are useful.Example - a farmer breeds only his best livestock
17Natural SelectionThe traits that help an organism survive in a particular environment are “selected” in natural selection
19What’s happening to the color genes in the beetle gene pool?Why is this happening?
20Explain why we say green beetles have been selected against while brown beetles havebeen selected for?
21Natural Selection and Species Fitness Overtime, natural selection results in changes in the inherited characteristics of a population.These changes increase a species fitness (survival rate)Bottom line:Those that are best adapted to their environment survive to reproduce.
22Evidence of Evolution Fossil Record Geographic Distribution of Living SpeciesHomologous Body structuresSimilarities in EmbryologyVestigial organs
23Evidence of EvolutionFossil Record provides evidence that living things have evolvedFossils show the history of life on earth and how different groups of organisms have changed over time
24Primate FossilsAustralopithecus Homo erectus Homo sapien
26Evidence of Evolution Geographic Distribution of Living Species Similar animals in different locations were the product of different lines of descent
27Evidence of Evolution Analogous Structures are the result of Geographic Distribution of Living SpeciesAnalogous Structuresare the result ofconvergent evolutionSimilar animals in different locations exhibit analogous structures due to similar environmental pressures.Eg. North American flying squirrel and the Australian sugar glider
29Convergent evolution Fish: aquatic vertebrates Dolphins: aquatic mammalssimilar adaptations to life in the seanot closely relatedThose fins & tails& sleek bodies are analogous structures!
30Evidence of Evolution Adaptive radiation leads to Homologous Body Structures thru divergent evolutionStructures that have different mature forms but develop from the same embryonic tissuese.g. Wing of bat, leg of turtle & human arm, are similar by de- scent not function.TurtleAlligatorBird
31Convergent evolution Fish: aquatic vertebrates Dolphins: aquatic mammalssimilar adaptations to life in the seanot closely relatedThose fins & tails& sleek bodies are analogous structures!
32Homologous Body Structures………… …………are the result of divergent evolution
3313. Evidence of Evolution Similarities in Embryology In their early stages of development, chickens, turtles and rats look similar, providing evidence that they shared a common ancestry.
35Vestigial organsModern animals may have structures that serve little or no functionremnants of structures that were functional in ancestral speciesevidence of change over timesome snakes & whales show remains of the pelvis & leg bones of walking ancestorseyes on blind cave fishhuman tail boneThis is not LaMarck’s loss from “disuse”!
38Molecular record Comparing DNA & protein structure universal genetic code!DNA & RNAcompare common genescytochrome C (respiration)hemoglobin (gas exchange)Why compare these genes?255075100125Millions of years agoHorse/donkeySheep/goatGoat/cowLlama/cowPig/Rabbit/rodentHorse/cowHuman/rodentDog/Human/Human/kangarooNucleotide substitutionsClosely related species have sequences that are more similar than distantly related speciesDNA & proteins are a molecular record of evolutionary relationships
39Comparative hemoglobin structure HumanMacaqueDogBirdFrogLampreyWhy does comparing amino acid sequence measure evolutionary relationships?8324567125102030405060708090100110120Number of amino acid differences betweenhemoglobin (146 aa) of vertebrate species and that of humans
40Descent with Modification Each living species has descended with changes from other species over time
42Summary of Darwin’s Theory 1. Organisms differ; variation is inherited2. Organisms produce more offspring than survive3. Organisms compete for resources4. Organisms with advantages survive to pass those advantages to their children5. Species alive today are descended with modifications from common ancestors
43Variation in Populations 2 processes canlead to this:Mutations -change in DNAsequenceGene Shuffling –from sexualreproduction
44Gene Pool Combined genetic info. of all members Allele frequency is # of times alleles occur
45Genetic Drift changes populations… Random change in allele frequency causes an allele to become common
46Founder Effect: a cause of genetic drift attributable to colonization by a limited number of individuals from a parent population
47Evolution of Populations Occurs when there is a change in relative frequency of alleles……….in other words – a change in the contents of the gene pool
48Gene Flow: genetic exchange due to the migration of fertile individuals or gametes between populations (reduces differences between populations)
49Nonrandom mating aka artificial selection: inbreeding and assortive mating (both shift frequencies of different genotypes)
50Natural Selection: differential success in reproduction; only form of microevolution that adapts a population to its environment
51Single-Gene vs. Polygenic Traits 2 Distinct PhenotypesPolygenic:Many Phenotypes(EG: tongue rolling)
52Natural Selection on Polygenic Traits Shifts tomiddle range2 extremes1 extreme
53Are you more closely related to a turtle or a frog?
54Natural 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.