Chapter 22 Reading Guide Ap Biology Essays

Unformatted text preview: Chapters 22-26 Test Chapter 22: Descent with Modification: A Darwinian View of Life Darwin’s theory of evolution: Origin of Species by means of Natural Selection o Observations and Inferences- see p. 458 o Evolutionary fitness= reproductive success Lamarck o Use and disuse – the more a part is used, the larger and stronger it becomes o Inheritance of acquired characteristics – organisms acquire traits during their lives and pass them down to offspring Carolus Linnaeus o Invented binomial format for naming species o Developed nested mode of classification Thomas Malthus – influence on Darwin’s theory o Ideas about over-reproduction due to limited resources o Population decreases resulting from natural disasters, disease, illadaptation to environment, lack of necessary resources, etc. Darwin’s theory of evolution o Terminology Adaptations – inherited characteristics that enhance survival and reproduction Natural selection – individuals with some traits have the ability to outlive and reproduce more than other individuals because of that trait Descent with modification – gradual changes that occurred as life began in one ancestor, ending up with rich diversity of life today o Main components More individuals are produced than the environment can sustain. Only a fraction of the offspring from each generation will survive. Inherited traits that give some individuals a better chance at surviving and reproducing make them more fit – that is, able to create more offspring. Unequal ability to survive and reproduce leads to gradual change in a population, with favorable traits accumulating over time Evidence for Evolution o Fossil record (Chapter 25) o Comparative Anatomy Homologous structures – similar anatomical arrangement but different functions Analogous structures – features that are similar in function but different in structure, suggests convergent evolution since species originated from different species Vestigial structures – have no function in one species, remnants of a useful structure in an ancestor o Biogeography o o Continental drift isolation, new species arising Endemic species – found nowhere else in the world Biochemistry Universal genetic code Homologous genes “Vestigial genes”/pseudogenes – present in organisms but have no purpose Similar proteome (i.e. cytochrome c) Embryology – homologous structures that appear in embryos Tails – all vertebrate have a tail or rudimentary tailbone Pharyngel pouches – parts of throat and throat in humans, gills in fish Chapter 23: The Evolution of Populations Population – smallest unit that evolves, all individuals of the same species living in same area at the same time Sources of genetic variation o Mutation Most basic source but not major driving force Can invent new alleles that did not exist in gene pool o Sexual Reproduction – can produce new combinations of alleles during meiosis Random fertilization of gametes Crossing over – DNA exchange between non-sister chromatids of homologous chromosomes during prophase I Independent assortment – homologs assort randomly during metaphase I o Diploidy Two copies of each chromosome received by each cell Recessive allele protected in heterozygous forms from natural selection, passed down Balanced Polymorphism – coexistence of two or more phenotypes o Heterozygote advantage – greater selection advantage than homozygous dominant or homozygous recessive o Hybrid vigor – superior hybrid offspring produced, recessive traits that are lethal in the homozygous form are eliminated, heterozygous advantage increased o Frequency-dependent selection – phenotypes alternate between low and high frequencies, least common one temporarily has the advantage Types of natural selection o Sexual selection Male competition – contests of strengths that award mating opportunities to strongest males, leads to development of antlers, horns, manes, and similar structures Increased mating frequency confers selective advantage Female choice – leads to traits or behaviors in males that females find attractive o Stabilizing selection o o Eliminates individuals with extreme or unusual traits Common traits well-adapted Discourages species changes Directional selection Favors traits at one extreme of a range of traits, which continue to become more and more extreme in future generations Antibiotic resistance Penicillin kills normal bacteria, but some evolve as they are treated to it Penicillin loses effectiveness Resistant bacteria reproduce and passes down on resistance gene Disruptive selection Occurs when environment favors unusual traits Hardy-Weinberg Equilibrium – while it does not occur in reality, by comparing frequencies from two different generations, one can see how much a population has evolved o Equations o Phenotypic frequencies: p+q=1 p – frequency of dominant allele q – frequency of dominant allele Genotypic frequencies: 2 2 p + 2 pq+ q =1 p2 – frequency of homozygous dominant genotype 2 pq q 2 – frequency of homozygous recessive genotype – frequency of heterozygous genotype Required conditions – if not met, cause change in allele frequencies Large population – no genetic drift Random increase or decrease due to chance Effect is more pronounced in small populations Founder effect – small group isolated from a larger population has new allele frequencies Bottleneck effect – significant decrease in a population’s size, making it very susceptible to changes in allele frequencies Random mating – not choosing mates based on specific traits or geometric proximity, i.e. sexual selection, inbreeding No mutations (minor cause of changes) No gene flow – introducing or removing alleles from a population through immigration and emigration, respectively No natural selection – increase/decrease allele frequency Chapter 24: The Origin of Species Defining a species o Biological species concept Reproductive compatibility Ability to create viable and fertile offspring Comparing DNA or conserved proteins shows a sufficient similarity o Morphological species concept Based on shape and structural characteristics Disregards gene flow Somewhat subjective because it relies on human observances Accounts for both sexual and asexual organisms o Ecological species concept Based on interactions with the environment Accounts for both sexual and asexual organisms o Phylogenetic species concept Based on common ancestry Controversy over how different two animals must be to be in different species Modes of Speciation o Allopatric – geographic separation causes divergence of separated gene pools o Sympatric – barriers to or errors in reproduction cause divergence of gene pools, in same location Pre-zygotic barriers Ecological isolation – same region but different habitats separate 2 species Reproductive isolation o Polyploidy – extra sets of chromosomes resulting from accidents during cell division Autopolyploid – more than 2 chromosome sets from the same species Cell division error tetraploid cells Diploid gametes that can be fertilized through cross-pollination, making tetraploid daughter cells Also possible to mate with diploids, creating cells with 3 chromosome sets (unique new species) Allopolyploid – multiple chromosome sets from different species Sterile hybrids can only propagate itself asexually Allopolyploidy occurs when sterile organisms become fertile and can mate with others like it, but not its parents (new species) o Temporal isolation – 2 species mate at different times of the day, month, year, etc. o Behavioral isolation – unique mating behaviors (i.e. mating calls) distinguish 2 species o Mechanical isolation – morphological differences in reproductive anatomy o Gametic isolation – sperm cannot successfully fertilize egg if from different species Zone pelucida – biochemical barrier of eggs that contains receptor sites for the right sperm Chemical incompatibility – inability of sperm from one species to survive in female reproductive tract of other Post-zygotic barriers Reduced hybrid viability – interaction of parent genes results in impaired development Reduce hybrid fertility – unique (usually odd) number of chromosomes as well as structural differences deter gamete formation Hybrid breakdown – normal first generation of hybrids, but second generation is sterile or feeble Rate of Speciation o Gradualism– gradual divergence over long spans of time, accumulation of many small changes o Punctuated equilibrium – alternation between rapid bursts of change and long static periods Chapter 25: The History of Life on Earth Fossil record o Issues Animals didn’t die at the right time in order to be fossilized Favors species that have been in existence a long time Favors animals with shells or exoskeletons that facilitated fossilization o Methods of dating Relative dating – based on superposition of layers of rock Absolute dating – an estimate in years, a.k.a. radiometric dating Determine amount of radioactive isotope Carbon-14 is present and determine the age of the fossil Issues o Sedimentary rock contains fragments of old and new rocks o Carbon-14’s half-life is too short Transitional species – discovery made possible by the fossil record, between 2 species Fish and amphibians – tiktaalik Dinosaurs and birds – archaeopteryx Whales and land animals – pakicetus o Chapter 26: Phylogeny and the Tree of Life Taxonomic groups (in order of increasing specificity): domain, kingdom, phylum, class, order, family, genus species Phylogeny – evolutionary history of a species/group of species Cladistics o Classifications of groups Monophyletic – entire clade (ancestor and all descendant species) Paraphyletic – ancestor and some, but not all of its descendant species Polyphyletic – group with some members having different ancestors o Reliance on morphological and molecular data o Terminology Shared ancestral character – originated in an ancestor that is not a member of the clade Shared derived character – unique to a clade, not in ancestor Outgroup – species/group of species from an evolutionary linage that diverged before the species of interest (ingroup) ...
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Женщина сочувственно кивнула. - Поссорились. На мгновение Беккер задумался.

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