Presentation is loading. Please wait.

Presentation is loading. Please wait.

February 13 B Day Test: Chapters 18, 19, 20 Coming up…………… Parade of Kingdoms due 2/23 - Dont wait until the last minute, study each chapter – there will.

Similar presentations


Presentation on theme: "February 13 B Day Test: Chapters 18, 19, 20 Coming up…………… Parade of Kingdoms due 2/23 - Dont wait until the last minute, study each chapter – there will."— Presentation transcript:

1 February 13 B Day Test: Chapters 18, 19, 20 Coming up…………… Parade of Kingdoms due 2/23 - Dont 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.

2 EVOLUTION & SPECIATION

3 Population: a localized group of individuals belonging to the same species 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 offspring Species: a group of populations whose individuals have the potential to interbreed and produce fertile offspring Gene pool: the total aggregate of genes in a population at any one time Gene pool: the total aggregate of genes in a population at any one time Population genetics: the study of genetic changes in populations Population genetics: the study of genetic changes in populations Modern synthesis/neo- Darwinism Modern 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 can lead to this: Mutations - change in DNA sequence Gene Shuffling – from sexual reproduction

6 Genetic Drift changes populations……. Random change in allele frequency causes an allele to become common Random change in allele frequency causes an allele to become common

7 Microevolution The 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 The 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 Microevolution Founder Effect: a cause of genetic drift attributable to colonization by a limited number of individuals from a parent population

9 Microevolution Gene Flow: genetic exchange due to the migration of fertile individuals or gametes between populations (reduces differences between populations Gene Flow: genetic exchange due to the migration of fertile individuals or gametes between populations (reduces differences between populations

10 Microevolution Nonrandom mating: inbreeding and assortive mating (both shift frequencies of different genotypes) Nonrandom mating: inbreeding and assortive mating (both shift frequencies of different genotypes)

11 Microevolution Natural Selection: differential success in reproduction; only form of microevolution that adapts a population to its environment Natural Selection: differential success in reproduction; only form of microevolution that adapts a population to its environment

12 SPECIATION - formation new species 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 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 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 Punctuated equilibrium

15 Population variation Polymorphism: coexistence of 2 or more distinct forms of individuals (morphs) within the same population Polymorphism: coexistence of 2 or more distinct forms of individuals (morphs) within the same population Geographical variation: differences in genetic structure between populations (cline) Geographical variation: differences in genetic structure between populations (cline)

16 Variation Preservation Prevention of natural selections reduction of variation Prevention of natural selections reduction of variation Diploidy 2nd set of chromosomes hides variation in the heterozygote Diploidy 2nd set of chromosomes hides variation in the heterozygote Balanced polymorphism 1- heterozygote advantage (hybrid vigor; i.e., malaria/sickle-cell anemia); 2- frequency dependent selection (survival & reproduction of any 1 morph declines if it becomes too common; i.e., parasite/host) Balanced polymorphism 1- heterozygote advantage (hybrid vigor; i.e., malaria/sickle-cell anemia); 2- frequency dependent selection (survival & reproduction of any 1 morph declines if it becomes too common; i.e., parasite/host)

17 Sexual selection Sexual dimorphism: secondary sex characteristic distinction Sexual dimorphism: secondary sex characteristic distinction Sexual selection: selection towards secondary sex characteristics that leads to sexual dimorphism Sexual selection: selection towards secondary sex characteristics that leads to sexual dimorphism

18 Natural Selection Shifts to Shifts to middle range Shifts to Shifts to 2 extremes Shifts to Shifts to 1 extreme

19 Fitness: contribution an individual makes to the gene pool of the next generation

20 Conditions needed for Genetic Equilibrium

21 Hardy-Weinberg Equation p=frequency of one allele (A); q=frequency of the other allele (a); p+q=1.0 (p=1-q & q=1-p) p=frequency of one allele (A); q=frequency of the other allele (a); p+q=1.0 (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 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.

23 Table 23.1a

24 Table 23.1b

25 Tigon Result of male tiger and female lion mating incaptivity. Offspring are infertile. Separated both geographically and ecologically.

26 Liger Result of male lion and female tiger mating in captivity. Offspring are infertile.

27

28

29

30

31 Fig Four species of leopard frogs: differ in their mating calls. Hybrids are inviable.

32 These squirrels living on opposite sides of the Grand Canyon demonstrate allopatric speciation.

33 Sympatric: reproductively isolated subpopulation in the midst of its parent population (change in genome); polyploidy in plants; cichlid fishesSympatric: reproductively isolated subpopulation in the midst of its parent population (change in genome); polyploidy in plants; cichlid fishes

34

35 Evidence of Evolution 1. Fossil Record 2. Geographic Distribution of Living Species 3. Homologous Body structures 4. Similarities in Embryology

36 Evidence of Evolution Fossil Record provides evidence that living things have evolved Fossils show the history of life on earth and how different groups of organisms have changed over time

37

38

39

40 Rat like common ancestor Mammalia Placental mammals Marsupial Mammals Sugar Glider Flying Squirrel Convergent Evolution and Analogous Structures

41 Big Question!!! How did life arise on the big blue planet?? How did life arise on the big blue planet?? Scientists attempt to answer this question scientifically. Scientists attempt to answer this question scientifically.

42 Relative Dating versus Absolute Dating

43 Relative Dating Can determine a fossils relative age Can determine a fossils relative age Performed by estimating fossil age compared with that of other fossils Performed by estimating fossil age compared with that of other fossils Drawbacks – provides no info about age in years Drawbacks – provides no info about age in years

44 Absolute dating Can determine the absolute age in numbers Can determine the absolute age in numbers Is performed by radioactive dating – based on the amount of remaining radioactive isotopes remain Is performed by radioactive dating – based on the amount of remaining radioactive isotopes remain Drawbacks - part of the fossil is destroyed during the test Drawbacks - part of the fossil is destroyed during the test

45 Carbon-14 Dating

46 Fossil Formation

47 A cosmic explosion that hurled matter and in all directions created the universe billion years ago A cosmic explosion that hurled matter and in all directions created the universe billion years ago Evidence Evidence it explains why distant galaxies are traveling away from us at great speeds it explains why distant galaxies are traveling away from us at great speeds Cosmic radiation from the explosion can be observed Cosmic radiation from the explosion can be observed The Big Bang theory probably will never be proven; consequentially, leaving a number of tough, unanswered questions. The Big Bang theory probably will never be proven; consequentially, leaving a number of tough, unanswered questions. Big Bang Theory

48 What was early earth like? Earth was Hot!! Earth was Hot!! Little or no oxygen Little or no oxygen Gasses in atmosphere: Gasses in atmosphere: Hydrogen cyanide (poison to you!) Hydrogen cyanide (poison to you!) Hydrogen sulfide Hydrogen sulfide Carbon dioxide Carbon dioxide Carbon monoxide Carbon monoxide Nitrogen Nitrogen water water

49 So how did the earth get oxygen? Some of that oxygen was generated by photosynthetic cyanobacteria Some of that oxygen was generated by photosynthetic cyanobacteria Some came from the chemical separation of water molecules into oxygen and hydrogen. Some came from the chemical separation of water molecules into oxygen and hydrogen.

50 Oxygen drove some life forms to extinction Oxygen drove some life forms to extinction Others evolved ways of using oxygen for respiration Others evolved ways of using oxygen for respiration

51 How did life begin? Miller and Ureys Experiment Passed sparks through a mixture of hydrogen methane ammonia and water Passed sparks through a mixture of hydrogen methane ammonia and water This produced amino acids – the building blocks of life This produced amino acids – the building blocks of life

52 Millers 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 microspheres Large organic molecules can sometimes form tiny proteinoid microspheres Large organic molecules can sometimes form tiny proteinoid microspheres Store and release energy, selectively permeable membranes, may have acquired more characteristics of living cells Store and release energy, selectively permeable membranes, may have acquired more characteristics of living cells

54 2 nd Hypothesis for Life Evolution of RNA to DNA RNA was assembled from simple organic molecules in a primordial soup RNA was assembled from simple organic molecules in a primordial soup RNA was able to replicate itself and eventually form DNA RNA was able to replicate itself and eventually form DNA Not scientifically proven to be possible Not scientifically proven to be possible

55 3 rd Theory of Life Endosymbiotic theory eukaryotic cells arose from living communities formed by prokaryotic organisms eukaryotic cells arose from living communities formed by prokaryotic organisms Ancient prokaryotes entered primitive eukaryotic cells and remained there as organelles Ancient prokaryotes entered primitive eukaryotic cells and remained there as organelles


Download ppt "February 13 B Day Test: Chapters 18, 19, 20 Coming up…………… Parade of Kingdoms due 2/23 - Dont wait until the last minute, study each chapter – there will."

Similar presentations


Ads by Google