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Review organic evolution
- 1. A Quick ReviewofEvolution
- 2. EvolutionEvolution is thecentral theme of biologyNothing in biology makes sense except in the light of evolutionTheodosius Dobzhansky
- 3. EvolutionEvolution: change overtime; can be applied to many things, so we use a more specific definition in biologyOrganic evolution = change in allele frequencies over timeAllele = alternate form of a gene; if one variation of a gene confers some sort of advantage in a particular environment, it is more likely to be passed on.
- 4. EvolutionThe term evolutiondoes not imply a mechanismmany mechanisms have been hypothesizedNatural Selection is accepted as the primary mechanism of adaptive evolutionOther mechanisms include sexual selection, genetic drift, and genetic bottlenecks.How does evolution occur?
- 5. SpeciationSpeciation: the formationof a new speciescan proceed by many mechanismsresults in the bifurcation(separation of 1 into 2) of a lineage(group of related organisms)
- 6. SpeciationAllopatric Speciation: believedthe most common method of speciation (and the method of human speciation). Results primarily from genetic drift and Natural selection
- 7. Genetic DriftGenetic Drift:random change in allele frequencies over timemost common in genes not subject to natural selectionDifferences accumulate when two populations become separated from each other.
- 8. History of EvolutionEvolutionis an old theoryDarwin didn’t come up with evolutionHe did provide evidence for it and therefore popularized it and made possible the scientific discipline called evolutionary biology.He also didn’t come up with the phrase “survival of the fittest” that you should probably forget you ever heard.
- 9. DarwinCharles Darwin usedand preferred the phrasedescent with modificationDarwin developed the theory of Natural SelectionIt is a mechanism of evolution, not an equivalent term to evolutionWho came up with the idea of natural selection independent of Darwin?Alfred RusselWallaceKnown as the father of biogeography
- 10. InfluencesCharles LyellPopularized uniformitarianism,a concept developed by James Hutton.Thomas MalthusWrote an essay on population that highlighted a struggle for limited resources in a large population.
- 11. Inspiration - GeologyUniformitarianism:theprocesses which shape the earth today are the sameandoccur at the same ratesas the processes that have shaped the earth in the pastFor example, canyons formed over a very long time through the same process of erosion as occurs right now; sand on the beach formed through millenia of waves hitting the shore just like they do now.
- 12. Natural Selection -Logical Argument1Reproduction results in more offspring than the size of the current population2 There is variationin all traits (phenotype)3 Much of the variation is heritable4There is variation in fitness as a result of having or not having certain variations of traits.
- 13. FitnessFitness: average numberof offspring left by an individual relative to the number of offspring left by an average member of the populationYou could say Fitness = Relative ReproductionWhat can influence fitness?
- 14. Natural SelectionIf naturalselection occurs:the distribution of genotypes (phenotypes) of the next generation will reflect the distribution of the more fit members of the previous generationNot all traits are under the influence of natural selection
- 15. What happens dependson the nature of the selective force: It is not progressive, it depends on the environmentWhy do some find this idea so disturbing?
- 16. Forms of SelectionStabilizingselectionDirectional selectionDisruptive selection
- 17. DefinitionsMutation: any changeoccurring in the message that a gene carries Provides variation upon which natural selection can actUsually the result of copy errors during DNA replication in mitosis or meiosis
- 18. DefinitionsAdaptation: the conditionof organisms beingwell fit for life in their environmentsas resulting from natural selectionNon-adaptive change?Acclimation
- 19. DefinitionsExaptation: a biologicaltrait (adaptation) where the current biological function is different from the function of the original adaptationOr, you could sayThe selection pressures are now exerted on a different function than those that initially controlled the trait
- 21. DefinitionsPhenotypic plasticity: sometimesthe same genotype is expressed as a different phenotype in different environmentsThe organism has not adaptedAcclimation
- 22. Units of Evolutionand Natural SelectionUnit of evolution=Speciescan change over time based on the differential representation of genes in each generation caused by natural selection It is often more proper to view the population as the unit of evolutionWhen are a species and population not equivalent?
- 23. Units of Evolutionand Natural SelectionUnit of selection=An individualthe unit that survives or does not, breeds or does not, passes on genes to the next generation or does notIndividuals do not evolve
- 24. How does EvolutionIllustrate the History of Life?Phylogeny: branching diagram indicating the evolutionary history of an organismWhat does the history of life look like?A phylogeny is a data based hypothesis about evolutionary relationshipsHow is it a hypothesis?
- 25. PhylogenyWhat kind ofinformation is used to make a phylogeny?Derived HomologiesWhat are homologies?What does derived mean?
- 26. PhylogenyAnalogous: shared by2 or more species, but not present in their common ancestorLikely developed by convergent evolutionHomologous: shared by 2 or more species, also present in their common ancestor
- 28. PhylogenyAncestral homologies: presentin common ancestor and more distant relativesOpposable thumb in apesDerived homologies: evolved in common ancestor, not present in more distant ancestorsOpposable thumb in primates
- 29. What types ofdata support evolution?Stephen J. Gould discusses three arguments for evolution in his essay “Evolution as Fact and Theory”
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- 31. Imperfections of natureWhy?Conflictsbetween selection pressures and limitations of descentHumans:increased brain sizerequires large pelvic outletbipedal locomotionrequires narrow pelvic outlet
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