Darwinian Evolution

Darwinian EvolutionChapter 17The cornerstone of biologyEvolution:Inherited changes within a population over timeNot changes in an individuals lifetimeMicroevolution:Minor changes over a few generationsMacroevolution:Major changes over a long period of timePre-Darwin ideasAristotlemovement toward perfectionda VinciInterpretation of fossils of extinct creaturesLamarkInheritance of acquired characteristicsLamarks giraffe

Darwins Big 4VariationOverproductionLimits on population growthDifferential reproductive successDarwins finches

Whats the difference?Lamark:Traits that are acquired over an organisms lifetime are passed onDarwin:Traits are inherited from the organisms parents and are selected for by the environmentLamark if your father loses the use of his hand in an accident before you are born, you will not have strong hands see the problem with this??Darwins workable explanationNatural selectionsurvival of the fittestIndividuals with the best adaptations survive to reproduce and pass on (?) those adaptations to their offspringArtificial selectionDomesticated plants and animals have been selected for reproduction by humans for centuriesEvidence: The Fossil RecordMostly sedimentary rock but includes bogs, tar, amber, and iceOldest layer at the bottom; youngest at the topTends to favor aquatic organisms and those with hard body partsSome fossils show gradual transitions but others do not

Evidence: Comparative AnatomyHomologous features derived from the same structure in a common ancestorHuman arm, cat foreleg, whale flipper, bat wingAnalogous features are not from a common ancestor but look similar because they have a similar functionBird wing and insect wingVestigial structures organs which are no longer functionalHuman coccyx, wisdom teeth

Evidence: BiogeographyThe geographic distribution of organisms makes sense closely related organisms are found nearbyRelated to Earths geologic history and continental drift

Evidence: Developmental BiologySimilar patterns of embryological development indicate common ancestryontology recapitulates phylogeny

Evidence: The Genetic CodeThe universality of the genetic code points to common ancestry in organismsRandom non-selective mutations in the DNA happen at a known rate and can be use to develop a molecular clock for that geneThese can be used to validate information from the fossil record

Evidence: TestingReznick and Endler work with guppiesBacterial antibiotic resistanceInsecticide resistance in various pest species