EVOLUTION & SPECIATION Page 2 VOCABULARY REVIEW NEW VOCABULARY EVOLUTION CHANGE OVER TIME NATURAL SELECTION - INDIVIDUALS BETTER ADAPTED TO THE ENVIRONMENT ARE ABLE TO SURVIVE & REPRODUCE. A.K.A. SURVIVAL OF THE FITTEST POPULATION GROUP OF INDIVIDUALS OF SAME SPECIES THAT INTERBREED GENE POOL COMMON GROUP OF ALL GENES PRESENT IN A POPULATION Page 3 Page 4 Gene Pool Combined genetic info. of all members Allele frequency is # of times alleles occur Variation in Populations 2 processes can lead to this: Mutations - change in DNA sequence Gene Shuffling from sexual reproduction Page 5 Page 6 1
Genetic Drift changes populations. Random change in allele frequency causes an allele to become common Founder Effect: a cause of genetic drift attributable to colonization by a limited number of individuals from a parent population Page 7 Page 8 Gene Flow: genetic exchange due to the migration of fertile individuals or gametes between populations (reduces differences between populations) Nonrandom mating: inbreeding and assortive mating (both shift frequencies of different genotypes) Page 9 Page 10 Sexual selection Natural Selection: differential success in reproduction; only form of microevolution that adapts a population to its environment Sexual dimorphism: secondary sex characteristic distinction Sexual selection: selection towards secondary sex characteristics that leads to sexual dimorphism Page 11 Page 12 2
Evolution of Populations How natural selection works Occurs when there is a change in relative frequency of alleles Resistance to antibacterial soap Generation 1: 1.00 not resistant 0.00 resistant Page 13 Page 14 How natural selection works Resistance to antibacterial soap Generation 1: 1.00 not resistant 0.00 resistant How natural selection works Resistance to antibacterial soap Generation 1: 1.00 not resistant 0.00 resistant Generation 2: 0.96 not resistant 0.04 resistant mutation! Page 15 Page 16 How natural selection works Resistance to antibacterial soap Generation 1: 1.00 not resistant 0.00 resistant Generation 2: 0.96 not resistant 0.04 resistant Generation 3: 0.76 not resistant 0.24 resistant How natural selection works Resistance to antibacterial soap Generation 1: 1.00 not resistant 0.00 resistant Generation 2: 0.96 not resistant 0.04 resistant Generation 3: 0.76 not resistant 0.24 resistant Generation 4: 0.12 not resistant 0.88 resistant Page 17 Page 18 3
Phenotype Expression Single-Gene vs. Polygenic Traits Depends on how many genes control that trait Single-Gene: 2 Distinct Phenotypes Polygenic: Many Phenotypes (EG: tongue rolling) Page 19 Page 20 Allele Frequencies Natural Selection on Polygenic Traits Natural Selection Genetic Drift Shifts to middle range Single Gene Traits Polygenic Traits Shifts to 2 extremes Directional Selection Shifts to 1 extreme Stabilizing Selection Page 21 Disruptive Selection Page 22 Conditions needed for Genetic Equilibrium Page 23 Page 24 4
SPECIATION THE FORMATION OF NEW SPECIES AS NEW SPECIES EVOVLVE, POPULATIONS BECOME REPRODUCTIVELY ISOLATED REPRODUCTIVE ISOLATION MEMEBERS OF 2 POPULATIONS CANNOT INTERBREED & PRODUCE FERTILE OFFSPRING. 3 ISOLATING MECHANISMS.. BEHAVIORAL ISOLATION- CAPABLE OF BREEDING BUT HAVE DIFFERENCES IN COURTSHIP RITUALS (EX. MEADOWLARKS) GEOGRAPHICAL ISOLATION SEPARATED BY GEOGRAPHIC BARRIERS LIKE RIVERS, MOUNTAINS, OR BODIES OF WATER (EX. SQUIRREL) TEMPORAL ISOLATION 2 OR MORE SPECIES REPRODUCE AT DIFFERENT TIMES. Page 25 Page 26 Table 23.1a Page 27 Tigon Result of male tiger and female lion mating incaptivity. Page 28 Offspring are infertile. Separated both geographically and ecologically. Liger Page 29 Result of male lion and female tiger mating in captivity. Offspring are infertile. Page 30 5
Page 31 Page 32 Table 23.1b Page 33 Page 34 Fig. 23.6 Four species of leopard frogs: differ in their mating calls. Hybrids are inviable. Page 35 Page 36 These squirrels live on opposite sides of the Grand Canyon. This is an example of allopatric speciation. 6
Hawaiian Honeycreepers An example of adaptive radiation these species all diverged from a common ancestor (founder species) SPECIATION IN DARWIN S FINCHES SPECIAITON IN THE GALAPAGOS FINCHES OCCURRED BY: - FOUNDING OF A NEW POPULATION, - GEOGRAPHIC ISOLATION which led to -- REPRODUCTIVE ISOLATION and CHANGES IN THE NEW POPULATION S GENE POOL due to COMPETITION. Page 37 FOUNDER SPECIES Page 38 Page 39 Page 40 Evidence of Evolution 1. Fossil Record 2. Geographic Distribution of Living Species 3. Homologous Body structures 4. Similarities in Embryology Page 41 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 Page 42 over time 7
Page 43 Page 44 Sugar Glider Marsupial Mammals Flying Squirrel Convergent Evolution Placental mammals Page 45 Page 46 and Analogous Structures Mammalia Rat like common ancestor Big Question!!! How did life arise on the big blue planet?? Scientists attempt to answer this question scientifically. Page 47 Page 48 8
Relative Dating Relative Dating versus Absolute Dating Can determine a fossil s relative age Performed by estimating fossil age compared with that of other fossils Drawbacks provides no info about age in years Page 49 Page 50 Absolute dating Can determine the absolute age in numbers Is performed by radioactive dating based on the amount of remaining radioactive isotopes remain Drawbacks - part of the fossil is destroyed during the test Carbon-14 Dating Page 51 Page 52 Page 53 Fossil Formation A cosmic explosion that hurled matter and in all directions created the universe 10-20 billion years ago Evidence it explains why distant galaxies are traveling away from us at great speeds 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. Page 54 Big Bang Theory 9
What was early earth like? Page 55 Earth was Hot!! Little or no oxygen Gasses in atmosphere: Hydrogen cyanide (poison to you!) Hydrogen sulfide Carbon dioxide Carbon monoxide Nitrogen water So how did the earth get oxygen? Some of that oxygen was generated by photosynthetic cyanobacteria Some came from the chemical separation of water molecules into oxygen and hydrogen. Page 56 Oxygen drove some life forms to extinction Others evolved ways of using oxygen for respiration How did life begin? Miller and Urey s Experiment Passed sparks through a mixture of hydrogen methane ammonia and water This produced amino acids the building blocks of life Page 57 Page 58 Miller s experiment suggests that lightning could have produced amino acids Page 59 How can simple amino acids result in life? There are 3 theories 1. Formation of microspheres Page 60 Large organic molecules can sometimes form tiny proteinoid microspheres Store and release energy, selectively permeable membranes, may have acquired more characteristics of living cells 10
2 nd Hypothesis for Life Evolution of RNA to DNA RNA was assembled from simple organic molecules in a primordial soup RNA was able to replicate itself and eventually form DNA Not scientifically Page 61 proven to be possible 3 rd Theory of Life Endosymbiotic theory eukaryotic cells arose from living communities formed by prokaryotic organisms Ancient prokaryotes entered primitive eukaryotic cells and remained there as Page 62 organelles 11