2D.2.1 Define allele frequency, gene pool. % of certain allele (variation of a gene) in the population for a certain locus/geneGene poolAll genetic info of reproducing members of the populationVariation
3Mutation introduces new alleles Old alleles “die out” D.2.2 State that evolution involves a change in allele frequency in a population’s gene pool over a number of generations.Mutation introduces new allelesOld alleles “die out”Advantageous survivesChange in allele freq = evolutionSEVERAL generations!
4D.2.3 Discuss the definition of the term species. Xref- species- 5.1.1 Organisms have similar physiological and morphological characteristicsAbility to interbreed, produce fertile offspringGenetically distinct from other speciesCommon phylogenyNot exactly that simple, but good enough for now!
7SEPARATE POPULATIONS...MAY LEAD TO SPECIATION geographical isolation D.2.4 Describe three examples of barriers between gene pools. Examples includeSEPARATE POPULATIONS...MAY LEAD TO SPECIATIONgeographical isolationPhysical barriers (land, water formation) prevent males/females from meeting & interbreeding—populations are separatedhybrid infertility2nd generation unlikelyGenetic barrier between speciestemporal isolationIncompatible time frames for mating (flowers blooming/seasons; hibernations; migrations)behavioural isolationLifestyle, habits incompatible with other populationCourtship displays
8Cell division mistakes, chromosomes don’t separate completely D.2.5 Explain how polyploidy can contribute to speciation. Xref- Meiosis / 10.1Avoid examples involving hybridization as well as polyploidy, such as the evolution of wheat.3n, 4n, 5n, etc.Cell division mistakes, chromosomes don’t separate completelyCommon in plantsExtra chroms plant more vigorousReplication errors more common2 populations could evolve at different rates b/c of difference in ploidyCould lead to speciation
9D.2.6 Compare allopatric speciation, sympatric speciation. Speciation: the formation of a new species by splitting of an existing species.Sympatric: in the same geographical area—Temporal, behavioural isolationPheromones, mating calls, etc. may be changed slightly, allow for mates or notAllopatric: in different geographical areas—geographic isolation2 pops separated, evolve separatelyIf allowed to mingle in future, may not be able to interbreed...new speciesSnow geese (Chen caerulescens)SawFly (Tenthredo livida)FertilisationPin and thrumb primroses (Primula vulgaris)
10Genetic Hybrid inviability Hybrid offspring die Hybrid infertility Hybrids survive but are incapable of producing gametesZedonk
11D.2.7 Outline the process of adaptive radiation. “Rapid” evolution from 1 (or a few) species into moreSlightly diff niches, more successfulNatural selectionSpeciation event(s) (isolation)EX-finches, lemursLemurs once widespread b/c no competition (apes, monkeys)Lots phenotypic diversitySome better adapted to certain niches, led to adaptive radiationApes, monkeys...outcompete lemurs, so lemurs not found
13D.2.8 Compare convergent evolution, divergent evolution. Not a recent common ancestor2 species or characteristics look similarAustralia & N America: marsupials vs placentalsWings (bat, bird); bioluminescence (bacteria, fungi)DivergentRecent common ancestorLess similar over time
14Gradualism: small, continuous, slow change from one form to another D.2.9 Discuss ideas on the pace of evolution including gradualism and punctuated equilibrium.Gradualism: small, continuous, slow change from one form to anotherFossil recordPresent day examplesP. 429 diagramsPunctuated equilibrium: long periods without appreciable change and short periods of rapid evolutionResponse to change in environmentVolcanic eruptions and meteor impacts affecting evolution on Earth65mya...dinosaurs extinct; mammals survivedUntil a big environmental change, little/no change in fossil record
21Problems... Fossil evidence is the only evidence of either theory Not all characteristics of a species are present in fossil recordNot necessarily proof of phylogeny
22NATURAL SELECTION AT THE LEVEL OF THE ALLELE Sickle cell anemiaBiston betularia
23D.2.10 Describe one example of transient polymorphism. Polymorphisms = many “shapes” (phenotypes)Industrial melanism: peppered mothBiston betulariaPeppered (grey)Melanic (black)Pre-Industrial Revolution: advantageous to be grey, camouflaged on tree barkInd. Rev. soot on trees, black bark; black p’types survived (more fit)Natural selection!Clean Air Act…grey more fitTemporary change TRANSIENT polymorphism
24D.2.11 Describe sickle-cell anemia (SCA) as an example of balanced polymorphism. Xref- SCA-4.1.4; malaria2/more alleles of population are not transient and changing. They’re stabilized by natural selection.Sickle-cell anemiaBalanced polymorphismHeterozygotes have advantage in malarial regionsHbAHbSMore fit than either homozygoteAA = very susceptible to malariaSS = sickle cell, but resistant to malariaAS = some sickled cells, but usually not anemic; K-deficient sickled cells kills Plasmodium parasite“S” Selected for & selected against ... balanced