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Unit 7: Natural Selection (AP BIO)

front 1 What do fossils provide evidence of?	back 1 changing life forms
front 2 strata	back 2 layers of rock where fossils are deposited the older strata are deposited first
front 3 Charles Lyell	back 3 geologic processes that have shaped planet = uniform over time -> Earth must be older than previously thought (a few thousand years)
front 4 Jean Baptiste de Lamarck	back 4 proposed a mechanism for evolution based on use and disuse & inheritance of acquired characteristics

front 5 Use and disuse	back 5 parts of the body use extensively become larger and stronger those not used deteriorate
front 6 Inheritance of acquired characteristics	back 6 characteristics acquired in lifetime -> passed onto next generation (flawed theory)
front 7 What was the significance of Lamarck's findings?	back 7 recognized that species evolve; organisms and environment match through this gradual evolutionary change inheritance of acquired characteristics - wrong
front 8 What was the significance of Lyell's findings?	back 8 an old Earth has time for evolution; a young Earth doesn't -> gave Darwin the "gift of time"

front 9 Example of inheritance of acquired characteristics	back 9 A weightlifter's child could be born with a more muscular anatomy
front 10 What was the impetus for the development of Darwin's evolution by natural selection?	back 10 Darwin's voyage on the HMS Beagle
front 11 Natural Selection	back 11 Darwin's mechanism for evolution explains how adaptations arise results in alleles being passed to the next generation in proportions different from their relative frequencies in the present generation
front 12 Adaptations	back 12 heritable characteristics enhance an organism's ability to survive and reproduce in specific environments

front 13 Example of an adaptation	back 13 Desert foxes have large ears, which radiate heat Arctic foxes have small ears, which conserve body heat
front 14 Darwin's theory of evolution: principle one	back 14 members of a population often vary in their inherited phenotypic traits
front 15 Darwin's theory of evolution: principle two	back 15 a species can produce far more offspring than environment can support competition is inevitable
front 16 Darwin's theory of evolution: principle three	back 16 individuals with inherited traits that are better suited to local environment = more likely to survive and reproduce "differential reproductive success"

front 17 Fitness	back 17 the reproductive success of an individual in a population
front 18 Darwin's theory of evolution: principle four	back 18 evolution -> unequal reproductive success of individuals -> accumulation of favorable traits in the population over generations
front 19 What does natural selection improve over time?	back 19 the match between organisms and their environment
front 20 If individuals move to a new environment, or their environment changes...	back 20 natural selection may result in adaptation to these new conditions

front 21 different genetic variations can be selected depending on...	back 21 the new environment
front 22 Individuals DO NOT EVOLVE...	back 22 populations evolve an individual cannot change its genetic makeup, but differential reproduce success overtime can change it.
front 23 Evolution	back 23 a change in the genetic makeup of a population over time change in allelic frequencies
front 24 Artificial selection	back 24 process by which species are modified by humans

front 25 Example of artificial selection	back 25 selective breeding for milk or meat production; development of dog breeds
front 26 Evidence for Evolution	back 26 direct observations homology the fossil record biogeography
front 27 Direct observations of evolutionary change	back 27 populations of organisms continue to evolve in real time
front 28 examples of direct observation of evolutionary change	back 28 insect populations can become rapidly resistant to pesticides such as DDT bacterial populations become resistant to antibiotics, and viruses become resistant to other drugs

front 29 Homology	back 29 similarity resulting from common ancestry characteristics in related species can have an underlying similarity even though they have very different functions
front 30 Homologous structures	back 30 anatomical signs of evolution
front 31 examples of homologous structures	back 31 forelimbs of mammals that are now used for a variety of purposes: flying in bats, swimming in whales present and used in a common ancestor
front 32 Embryonic homologies	back 32 comparison of early stages of animal development reveals many anatomical homologies in embryos, not visible in the adult organism

front 33 example of embryonic homologies	back 33 all vertebrate embryos have a post-anal tail and pharyngeal pouches
front 34 Vestigial organs	back 34 remnants of structures that served important functions in the organism's ancestors structures of marginal, if any, importance to an organism
front 35 example of vestigial organs	back 35 some snakes have remnants of pelvis and leg bones
front 36 Molecular homologies	back 36 shared characteristics on the molecular level

front 37 examples of molecular homologies	back 37 all life forms use the same genetic language of DNA and RNA amino acid sequences, coding for hemoglobin in primate species, shows great similarity (indicating a common ancestor)
front 38 Convergent evolution	back 38 two species develop similarities as they adapted to similar environmental changes NOT because they evolved from common ancestor explains why distantly related species can resemble one another
front 39 The likenesses that result from convergent evolution are considered...	back 39 analogous, not homologous
front 40 examples of convergent evolution	back 40 torpedo shapes of penguin, dolphin, and shark = solution to movement through aqueous environment sugar gliders and flying squirrels occupy similar niches in their respective habitats "similar problems have similar solutions"

front 41 paleontology	back 41 the study of fossils
front 42 Fossil record	back 42 shows that evolutionary changes have occurred over time provide evidence of the origin of major new groups of organisms succession of forms!
front 43 transitional fossils have been found that...	back 43 link ancient organisms to modern species
front 44 Biogeography	back 44 the geographic distribution of species

front 45 Species in a discrete geographic area...	back 45 tend to be more closely related to each other than species in distant geographic areas
front 46 example of biogeography (as evidence for evolution)	back 46 In South America, desert animals are more closely related to local animals in other habitats than they are to desert animals of Asia
front 47 Continental drift & the breakup of Pangaea	back 47 can explain the similarity of species on continents that are distant from each other today
front 48 Endemic species	back 48 found at a certain geographic location and nowhere else

front 49 example of endemic species	back 49 Marine iguanas - found on Galápagos Islands and nowhere else
front 50 phenotypic variation often reflects...	back 50 genetic variation
front 51 examples of phenotypic variation	back 51 having / not having attached ear lobes range in height
front 52 Mutations	back 52 result in genetic variation on which natural selection can act only source of new genes and new alleles

front 53 only mutations in cell lines that produce...	back 53 gametes can be passed to offspring
front 54 Point mutations	back 54 changes in one nucleotide base in a gene can have a significant impact on phenotype
front 55 Example of a point mutation	back 55 sickle cell disease
front 56 Chromosomal mutations	back 56 delete, disrupt, duplicate, or rearrange many loci at once usually harmful, but not always

front 57 gene duplications can...	back 57 result in an expanded genome with new genes may accumulate mutations over generations and take on new functions
front 58 most genetic variations within a population result from...	back 58 the sexual recombination of alleles that already exist in a population
front 59 sexual reproduction...	back 59 shifts existing alleles and deals them at random to produce individual genotypes
front 60 three mechanisms for the shuffling of alleles	back 60 crossing over (prophase I of meiosis) independent assortment of chromosomes during meiosis fertilization

front 61 Population	back 61 a group of Individuals of the same species that live in the same area and interbreed, producing fertile offspring
front 62 Population genetics	back 62 the study of how populations change genetically over time
front 63 Gene pool	back 63 all of the alleles at all loci in all the members of a population
front 64 How many alleles does for a particular gene does each Individual have (diploid species)	back 64 two (and the individual may be heterozygous or homozygous)

front 65 Fixed (pertaining to a gene)	back 65 all members of a population are homozygous for the same allele only one allele exists at that particular locus in the population
front 66 the greater number of fixed alleles...	back 66 the lower the species' genetic diversity
front 67 Hardy-Weinberg equation	back 67 used to describe a population that is not evolving states the frequencies of alleles and genes in a population's gene pool will remain constant unless acted upon by forces other than Mendelian segregation and recombination of alleles
front 68 Hardy-Weinberg Equilibrium	back 68 1) no change in allelic frequency due to mutation 2) random mating 3) no natural selection 4) extremely large population size 5) no migration

front 69 What is the Hardy-Weinberg equation good for?	back 69 provides an excellent null hypothesis (conditions are seldom met in natural populations) if Hardy Weinberg analysis shows change in allelic frequency, can figure out which condition isn't being met
front 70 three major factors that alter allele frequencies... (and bring about the most evolutionary change)	back 70 natural selection genetic drift gene flow
front 71 Differential Reproductive Success	back 71 individuals with variations that are better suited to their environment tend to survive and produce more offspring than those with variations that are less suited
front 72 Adaptive evolution	back 72 organisms adapted to their environment

front 73 Genetic Drift	back 73 unpredictable fluctuation in allele frequencies from one generation to the next random, unadaptive change in allele frequencies
front 74 the smaller the population...	back 74 the greater the chance there is for genetic drift
front 75 two examples of genetic drift	back 75 founder effect bottleneck effect
front 76 Founder effect	back 76 a few individuals become isolated from a larger population and establish a new population whose gene pool is not reflective of the source population

front 77 Example of the founder effect	back 77 a mat of vegetation washes up on the shore of a Pacific island, host to a small population of lizards its gene pool is randomly different than that of the source population
front 78 Bottleneck effect	back 78 a sudden change in the environment that drastically reduces the size of a population the few survivors that pass through the restrictive bottleneck may have a gene pool that no longer reflects that of the original population
front 79 Example of the bottleneck effect	back 79 The population of California condors was reduced to nine individuals
front 80 Gene flow	back 80 occurs when a population gains or loses alleles by genetic additions or subtractions from the population (often by migration) results from the movement of fertile individuals or gametes

front 81 gene flow occurs when...	back 81 alleles between different populations are mixed, resulting in a reduction of genetic differences between the populations
front 82 gene flow tends to reduce the...	back 82 genetic differences between populations, making them more similar
front 83 converse of gene flow	back 83 isolated populations do not experience it, tend to adapt to their unique environments and may have significant genetic differences from the ancestral population
front 84 Relative fitness	back 84 the contribution an organism makes to the gene pool of the next-generation relative to the contributions of other members

front 85 fitness in the context of evolution is only measured...	back 85 by reproductive success
front 86 natural selection acts more directly on the...	back 86 phenotype
front 87 natural selection acts more indirectly on the...	back 87 genotype
front 88 Three ways in which natural selection can alter the frequency distribution of heritable traits	back 88 directional selection disruptive selection stabilizing selection

front 89 Directional selection	back 89 shifts the overall makeup of the population by favoring variants that are at one extreme of the distribution
front 90 Example of directional selection	back 90 darker mice are favored because they live among dark rocks
front 91 Disruptive selection	back 91 favors variants at both ends of the distribution
front 92 Example of disruptive selection	back 92 mice that colonize a patchy habitat made up of light and dark rocks, mice of an intermediate color are at a disadvantage

front 93 Stabilizing selection	back 93 removes extreme variants from the population and preserves intermediate types
front 94 Example of stabilizing selection	back 94 environment consists of intermediate color rocks, both light and dark mice selected against.
front 95 Sexual selection	back 95 individuals with certain inherited characteristics are more likely than other individuals to obtain mates
front 96 Sexual dimorphism	back 96 a difference between the two sexes in secondary sex characteristics such as differences in size, color, ornamentation, and behavior

front 97 How is genetic variation preserved in a population? (Why doesn't natural selection eliminate all unfavorable alleles?)	back 97 diploidy heterozygote advantage
front 98 Diploidy	back 98 because most eukaryotes are diploid, recessive alleles are hidden from selection in heterozygotes
front 99 Heterozygote advantage	back 99 occurs when two individuals who are heterozygous at a certain gene locus have an advantage for survival
front 100 Example of heterozygote advantage	back 100 In sickle cell disease, individuals homozygous for normal hemoglobin are more susceptible to malaria, whereas homozygous recessive individuals suffer from complications of sickle-cell disease. Heterozygotes benefit from some protection from malaria and do not have sickle-cell disease (mutant allele remains relatively common)

front 101

Why does natural selection not produce perfect organisms?

back 101

Selection can only edit existing variations
evolution is limited by historical constraints
adaptations are often compromises
chance, natural selection, and the environment interact