Môn Sinh học - Chapter 22: Descent with modification: A darwinian view of life - Part B: Evidence for evolution

Ch. 22 Warm-UpCompare and contrast natural selection vs. artificial selection.What are the key ideas of natural selection?Define and give an example for the following:Homologous structureVestigial structureAnalogous structureChapter 22Descent with Modification:A Darwinian View of LifePart B: Evidence for EvolutionWhat you must know:Several examples of evidence for evolution.The difference between structures that are homologous and those that are analogous, and how this relates to evolution.Recap main ideas of natural selection:Evolution is change in species over time.There is overproduction of offspring, which leads to competition for resources.Heritable variations exist within a population.These variations can result in differential reproductive success.Over generations, this can result in changes in the genetic composition of the population.Remember:Individuals do NOT evolve! Populations evolve.Evidence for Evolution:Direct ObservationsFossil RecordHomologyBiogeographyEvidence for Evolution1. Direct Observations2. Fossil Record3. Homology4. BiogeographyEvidence for Evolution:1. Direct ObservationsExamples:Insect populations become resistant to pesticides (DDT)Antibiotic-resistant bacteria (MRSA)Peppered moth (pollution in city vs. country)The Rise of MRSA(methicillin-resistant Staphylococcus aureus)Evidence for Evolution:2. Fossil RecordFossils = remains or traces of organisms from pastFound in sedimentary rockPaleontology: study of fossilsShow evolutionary changes that occur over time and origin of major new groups of organismsAnkle bonesProkaryotes (oldest fossils)  eukaryotes (fish – amphibians – reptiles – birds – mammals)Transitional forms = links to modern speciesEvidence for Evolution:3. HomologyHomology: characteristics in related species can have underlying similarity even though functions may differExamples:Homologous structures: similar anatomy from common ancestors (eg. forelimbs of human/cat/whale/bat)Embryonic homologies: similar early development (eg. vertebrate embryos with tail & pharyngeal pouches)Vestigial organs: structures w/little or no use (eg. flightless bird wings)Molecular homologies: similar DNA and amino acid sequencesHomologous StructuresEmbryonic DevelopmentVestigial StructuresMolecular HomologiesCompare DNA and amino acid sequencesEvolutionary TreeConvergent EvolutionDistantly related species can resemble one anotherSimilar problem, similar solutions!Analogous structures: similar structures, function in similar environmentsEg. Torpedo shape of shark, penguin, & dolphinEvidence for Evolution:4. BiogeographyBiogeography = geographic distribution of a speciesSpecies in nearby geographic areas resemble each otherContinental drift and Pangaea explains similarities on different continentsEndemic species: found at a certain geographic location and nowhere elseEg. Marine iguanas in the GalapagosIsland BiogeographyGalapagos TortoisesTree of LifeHHMI Short Film:Natural Selection & AdaptationRock Pocket MiceRunning Time: 10:25 min