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Download EVOLUTION Evolution = change over time. Evidence for evolution 1.Fossil evidence—molds, casts, amber, ice, or become petrified. (Fossil record is incomplete---soft

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  • EVOLUTIONEvolution = change over time.Evidence for evolution 1.Fossil evidencemolds, casts, amber, ice, or become petrified. (Fossil record is incomplete---soft tissues not preserved)2. Comparative anatomy the study of the structures of different organisms. -different kinds of organisms share similar structuresex: bird, horse, human forelimbs. -homologous partsmodified structures among different groups of descendants. (bird wing and insect wing are NOT) - the greater number of homologous parts two organisms share, the more closely related the organisms.

  • -vestigial structuresstructures which have no function in one organism but are homologous to functional structures in another organism. ex: whales have a nonfunctioning pelvis and leg bone. ex: humans: appendix3. Comparative embryologycompare the embryos of different organisms. (The more alike, the closer they are related)4. Comparative biochemistry----compare the biochemical components of organisms. Ex: DNA, compare amino acid sequences of proteins (hemoglobin in humans and chimpanzeesvery similar amino acid sequences.)

  • Genetic evidence--- -genes and chromosomes can mutate and give rise to new alleles or genes, and therefore new proteins.-meiosis and fertilization also reshuffle the genes= genetic recombination.leads to genetic variations.-In any given population there is constant change.--population=all organisms within a breeding group.

  • Selective breedinghumans choose those organisms with the traits they desire and mate them. (Artificial selection)

    DNA---the DNA of humans and chimpanzees are 99% identical.Humans and other mammals---80% identical

    Direct observationrapid evolution of bacteriaresistance to antibiotics. The few bacteria that are resistant to Penicillin will survive and reproduceproducing more bacteria that are also resistant to the Penicillin. Also a good reason to take your antibiotic prescription FULLY.

  • The organisms that continue to live and reproduce are adapted to the new environment.Also occurs in weeds and insectsevolve to have a resistance to pesticides.Darwins explanation----(1809-1882) Theory of Natural Selection.HMS Beagleships naturalistBecame aware that organisms adapted to their environment must change to remain adapted.The Galapagos Islands---evolution=descent with modificationGiant tortoises, swimming iguanasnot found anywhere elsePlants and animals on the islands were similar to the ones on the mainland.Galapagos finches: adaptive radiation

  • The Theory of Natural Selection 1. In nature there is a tendency of overproduction. 2. Not all offspring survive. 3. Variations (differences) exist in any population. 4. Variations are inherited. 5. Individuals with variations that make them more suited to their environment will live and produce more offspring that will have suitable traits like their parents. 6. The population as a whole changes as it becomes better adapted to its environment.

  • Adaptationsany structure,chemical or behavior that allows an organism to survive better.

    Structuralstructureshell, finch beaks, fur, blubber Physiological---Chemicaloctopus ink, snake venom, pheromones, chameleon skin colorBehavioral---something the organism doeshoneybee dance, insect acting like a leaf blowing in the wind.

    Gene poolcollection of all the genes present in a population.

  • Biological speciesSpecies- group of naturally interbreeding organisms that produce fertile offspring.(female horse x male donkey=mule=sterile) (lion x tiger =tiglon {in captivity only} )

    Evolution of a new species=speciation.

  • Tiglon vs. Liger

  • Monarch vs. ViceroyBad-tasting Monarch is mimicked by the good-tasting Viceroy butterfly.

  • Speciation-formation of new species over time. Can occur by:Geographic Isolation separation of a population by a river, canyon, mountain, etc. The population becomes separated, evolves different adaptations, and become genetically different. Too different to interbreed.Reproductive Isolation---no interbreeding, and gene exchange is prevented. (sperm unable to fertilize egg)Genetic Drift--- a small number of individuals become isolated, a rapid change in numbers and kinds of genes. ( G.I. Followed by R.I.)

  • Speciation continuedPolyploidyindividuals containing some multiple of the normal number of chromosomes. (Some plants are tetraploids4noften larger and produce larger flowers and fruits.) Ex. Wheat, cotton, daylilies.Adaptive Radiation ---Galapagos finches.

  • Divergent evolutionwhen one species evolves into two or more species with different characteristics.Convergent evolution---species that are not closely related evolve similar traits. It usually occurs in unrelated species that have similar roles and live in similar environments. Ex: butterfly and a bird Ex: Mimicry ( Viceroy and the Monarch Butterflies), Fish looks like coral, insect looks like a leaf. Ex: Coevolutionmutual adaptations evolve between a plant and its pollinator.

  • Tempo for Speciation

    Gradualism---slow, steady changes in a species.

    Punctuated equilibriumslow evolution interrupted by short events of rapid evolution.

  • *Industrial Melanism and Microevolution

  • *Causes of MicroevolutionGenetic MutationsThe raw material for evolutionary changeProvides new combinations of allelesSome might be more adaptive than others

  • *Causes of MicroevolutionGene FlowMovement of alleles between populations when:Gametes or seeds (in plants) are carried into another populationBreeding individuals migrate into or out of populationContinual gene flow reduces genetic divergence between populations

  • *Causes of MicroevolutionGenetic DriftOccurs by disproportionate random sampling from populationCan cause the gene pools of two isolated populations to become dissimilarSome alleles are lost and others become fixed (unopposed)Likely to occur:After a bottleneck When severe inbreeding occurs, orWhen founders start a new populationStronger effect in small populations

  • *Genetic Drift

  • *Bottleneck Effect: A random event prevents a majority of individuals from entering the next generation. Next generation composed of alleles that just happened to make it. Can be followed by Genetic Drift.Founder Effect: When a new population is started from just a few individuals. The alleles carried by population founders are dictated by chance and Formerly rare alleles will either:Occur at a higher frequency in the new population, or Be absent in new population

  • *Founder Effect

  • *Natural SelectionResults in:A change in allele frequencies the gene poolImproved fitness of the populationMajor cause of microevolution

  • *

    Directional Selection

  • *Stabilizing Selection

  • *Disruptive Selection

  • *Sickle-cell Disease

  • *Biological Species Definition

  • *Reproductive Isolating MechanismsReproductive isolating mechanisms inhibit gene flow between speciesTwo general types:(1) Prezygotic Mechanisms - Discourage attempts to mate Habitat IsolationTemporal IsolationBehavioral IsolationMechanical IsolationGamete Isolation

  • *Temporal Isolation

  • *Reproductive Isolating MechanismsTwo general types:(2) Postzygotic Mechanisms - Prevent hybrid offspring from developing or breedingZygote MortalityHybrid SterilityReduced F2 Fitness

  • ORIGIN OF LIFEEarth is about4.6 billion years old.Primitive atmosphereAlexander Oparin 1936 proposed -methane, ammonia, hydrogen and water vapor.Earths crust cooled, runoff from torrential rains created the oceans, UV radiation and lightning-The energy sources broke the bonds in the gas molecules releasing atoms to form simple organic compounds.1953Miller and Ureys experiments---presence of amino acids

  • First organismsocean= primordial soup anaerobic, prokaryotic, heterotrophic.--then the evolution of autotrophschemosynthetic, then photosynthetic---then oxygen in the atmosphere, then aerobic respiration, eukaryotes, ozone production=ozone layer (blocks harmful UV radiation), then life on Earths surface.-Endosymbiosis: A theorized process in which early eukaryotic cells were formed from simpler prokaryotes.

    Biology, 9th ed,Sylvia MaderProcesses of EvolutionSlide #*Chapter 18

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