Presentation on theme: "February 13 B Day Test: Chapters 18, 19, 20 Coming up……………"— Presentation transcript:
1 February 13 B Day Test: Chapters 18, 19, 20 Coming up…………… Parade of Kingdoms due 2/23- Don’t wait until the last minute, study each chapter – there will be multiple quizzes and a test at the end.Be ready for the Drosophila lab and the Transformation lab so we can start as soon as the live materials are in - highlight important points.
3 Population: a localized group of individuals belonging to the same species Species: a group of populations whose individuals have the potential to interbreed and produce fertile offspringGene pool: the total aggregate of genes in a population at any one timePopulation genetics: the study of genetic changes in populationsModern synthesis/neo-Darwinism“Individuals are selected, but populations evolve.”
4 Gene Pool Combined genetic info. of all members Allele frequency is # of times alleles occur
5 Variation in Populations 2 processes canlead to this:Mutations -change in DNAsequenceGene Shuffling –from sexualreproduction
6 Genetic Drift changes populations……. Random change in allele frequency causes an allele to become common
7 MicroevolutionThe Bottleneck Effect: type of genetic drift resulting from a reduction in population (natural disaster) such that the surviving population is no longer genetically representative of the original population
8 MicroevolutionFounder Effect: a cause of genetic drift attributable to colonization by a limited number of individuals from a parent population
9 MicroevolutionGene Flow: genetic exchange due to the migration of fertile individuals or gametes between populations (reduces differences between populations
10 MicroevolutionNonrandom mating: inbreeding and assortive mating (both shift frequencies of different genotypes)
11 MicroevolutionNatural Selection: differential success in reproduction; only form of microevolution that adapts a population to its environment
12 SPECIATION - formation new species - Anagenesis (phyletic evolution): accumulation of heritable changes- Cladogenesis (branching evolution): budding of new species from a parent species that continues to exist (basis of biological diversity))
13 Evolution of Populations Occurs when there is a change in relative frequency of alleles
14 Punctuated equilibrium Tempo of speciation: gradual vs. divergence in rapid bursts; Niles Eldredge and Stephen Jay Gould (1972); helped explain the non-gradual appearance of species in the fossil record
15 Population variationPolymorphism: coexistence of 2 or more distinct forms of individuals (morphs) within the same populationGeographical variation: differences in genetic structure between populations (cline)
16 Variation Preservation Prevention of natural selection’s reduction of variationDiploidy 2nd set of chromosomes hides variation in the heterozygoteBalanced polymorphism heterozygote advantage (hybrid vigor; i.e., malaria/sickle-cell anemia); frequency dependent selection (survival & reproduction of any 1 morph declines if it becomes too common; i.e., parasite/host)
17 Sexual selectionSexual dimorphism: secondary sex characteristic distinctionSexual selection: selection towards secondary sex characteristics that leads to sexual dimorphism
21 Hardy-Weinberg Equation p=frequency of one allele (A); q=frequency of the other allele (a); p+q= (p=1-q & q=1-p)P2=frequency of AA genotype; 2pq=frequency of Aa plus aA genotype; q2=frequency of aa genotype; p2 + 2pq + q2 = 1.0
22 AS NEW SPECIES EVOLVE, POPULATIONS BECOME REPRODUCTIVELY ISOLATED (gene pools are isolated) REPRODUCTIVE ISOLATION – MEMEBERS OF 2 POPULATIONS CANNOT INTERBREED & PRODUCE FERTILE OFFSPRING.
43 Relative Dating Can determine a fossil’s relative age Performed by estimating fossil age compared with that of other fossilsDrawbacks – provides no info about age in years
44 Absolute dating Can determine the absolute age in numbers Is performed by radioactive dating – based on the amount of remaining radioactive isotopes remainDrawbacks - part of the fossil is destroyed during the test
47 Big Bang TheoryA cosmic explosion that hurled matter and in all directions created the universe billion years agoEvidenceit explains why distant galaxies are traveling away from us at great speedsCosmic radiation from the explosion can be observedThe Big Bang theory probably will never be proven; consequentially, leaving a number of tough, unanswered questions.
48 What was early earth like? Earth was Hot!!Little or no oxygenGasses in atmosphere:Hydrogen cyanide (poison to you!)Hydrogen sulfideCarbon dioxideCarbon monoxideNitrogenwater
49 So how did the earth get oxygen? Some of that oxygen was generated by photosynthetic cyanobacteriaSome came from the chemical separation of water molecules into oxygen and hydrogen.
50 Others evolved ways of using oxygen for respiration Oxygen drove some life forms to extinctionOthers evolved ways of using oxygen for respiration
51 How did life begin? Miller and Urey’s Experiment Passed sparks through a mixture of hydrogen methane ammonia and waterThis produced amino acids – the building blocks of life
52 Miller’s experiment suggests that lightning could have produced amino acids
53 How can simple amino acids result in life? There are 3 theories 1. Formation of microspheresLarge organic molecules can sometimes form tiny proteinoid microspheresStore and release energy, selectively permeable membranes, may have acquired more characteristics of living cells
54 2nd Hypothesis for Life Evolution of RNA to DNA RNA was assembled from simple organic molecules in a primordial soupRNA was able to replicate itself and eventually form DNANot scientifically proven to be possible
55 3rd Theory of Life Endosymbiotic theory eukaryotic cells arose from living communities formed by prokaryotic organismsAncient prokaryotes entered primitive eukaryotic cells and remained there as organelles
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