EBIO Test 1 Study Guide
EBIO Test 1 Study Guide EBIO 1010 - 02
University of Louisiana at Lafayette
Popular in Evolutionary Biology
Popular in Science
Joseph Merritt Ramsey
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This 23 page Study Guide was uploaded by Lauren Notetaker on Tuesday February 2, 2016. The Study Guide belongs to EBIO 1010 - 02 at Tulane University taught by Bruce Fleury in Spring 2016. Since its upload, it has received 116 views. For similar materials see Evolutionary Biology in Science at Tulane University.
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1 EBIO TEST ONE Categories Within 1) terms 2) people 3) things he said we needed to know in class TERMS • prebiotic evolution - evolution of complex networks of organic compounds before the origin of life; - possible sources: - -UV light - -Lightning - -Heat - -Radiation • spontaneous generation - early attempt to answer the question of where life came from; life is an innate property of organic matter - Idea originated with Epicurus, made popular by Lucretius (The Nature of Things) - Refuted by Francesco Redi • Stanley Miller - grad student at University of Chicago; did experiment in prebiotic synthesis based on a reducing atmosphere • Miller/Urey experiment - mixed water with methane, ammonia, hydrogen; passed electric sparks through mixture to imitate lightning strikes; amino acids spontaneously formed in mixture • panspermia - the theory that life was seeded on earth and other planets from outer space - - Idea originated with Greek philosopher Anaxagoras Word “panspermia” was coined by Tyndall (who discovered why the sky is blue) - Original meaning was that the air on Earth was full of microscopic organisms riding on tiny particles of dust 2 • chain of being - theories that species are fixed, distinct types that could be arranged in linear sequence • argument from design - theory that all of nature is designed in accord with predetermined, benevolent, and supernatural plan • System of Hybridization - theory that new species must be hybrids of existing species • Lamarck - one of the first people to realize that organisms were shaped by environments, could evolve; best known for Inheritance of Acquired Characteristics (changes in the living body could be passed on to descendants); first person to study invertebrates; also coined term biology • -heory of Organic Progression theory that once generated, organisms changed along fixed and parallel paths • Charles Darwin - author of the Origin of Species. also known as the father of evolution; went on voyage on HMS Beagle; broke with Argument by Design, Chain of Being; variation=not noise but information; evolution=selective process; explained branching pattern of evolution->descent from common ancestor; switched the view of species as fixed and distinct types to viewing species as groups of local populations that varied from each other; stressed importance of geographic isolation and distribution (biogeography); believed in blended inheritance • HMS Beagle - scheduled to go to South America in 1831 to map southern coast, explore interior, visit tropical islands and native tribes; • Captain Robert Fitzroy - captain of the HMS Beagle; did not get along with Darwin • Origin of Species - published in 1859 by Darwin and revealed the theory of evolution by natural selection; growth with reproduction, inheritance; variation in populations; struggle for existence; natural selection in certain varieties; change in proportion of those 3 - varieties in the next generation; extinction of poorly adapted forms; could not explain gaps in fossil record or physical basis for heredity • Thomas Malthus - published An Essay on the Principle of Population as a counterargument that social progress could be achieved through a better understanding of nature; argument=very mathematical: populations would increase but resources would not increase at same rate->growing gap btw too many people and too few resources=struggle for existence; greatly impacted Darwin's ideas • struggle for existence - over time, population would increase geometrically, but resources could only increase arithmetically -> leads to growing gap btw too many people and too few resources • survival of the fittest - Herbert Spencer's idea that winners are the individuals who are better equipped to survive in the struggle for existence • natural selection - well-adapted species that are equipped to prevail in struggle for existence would have more offspring than others and pass on their variation to next generation • Gregor Mendel - experimented with garden peas and discovered mechanism for heredity • blended heredity - gradual and continuous process where tiny particles called gemmules carried information for heredity and floated to different parts of the body and knew how to make body parts; gemmules moved to reproductive organs during sex. • gemmules - tiny particles that theoretically carried information of heredity all over the body; part of theory of blended inheritance • allele - different versions of the same genes; ex: W=purple(dominant) w=white(recessive) • dominant allele - allele that masks the effects of another allele of the same trait • recessive allele - allele that is masked by the dominant allele of the same trait 4 heterozygous • - if two different genes come together (ex: Ww) • homozygous - if two similar genes come together (ex: WW or ww) • mutation - changes in genetic information; mendel stressed the importance of these • modern synthesis - fusion of abstract models of genes moving through populations with the population perspective of field biologists • variation - when species are different from one another in certain ways; is constantly generated by mutations bc they replenish genetic variability that is constantly being reduced by natural selection • evolution - change in gene frequency over time (differential reproduction) • species - local groups of individuals, all of whom varied from one another in certain ways; are just groups of populations that vary from one another • -peciation begins when small parts of larger population are geographically isolated from the parent population; differences in local conditions favor different varieties in isolated population whose gene pool is subset of original population; can only interbreed with one another • Darwin's theory of evolution by natural selection - Growth with reproduction, inheritance - Variation in populations - Struggle for existence - Natural selection of certain varieties - Change in proportion of those varieties in the next generation - Extinction of poorly adapted forms - As Darwin realized, natural selection ultimately depends on variation 5 • biological species concept - species are populations of similar organisms that can interbreed with one another, but are reproductively isolated from other such populations by one ore more isolating mechanisms • homologous chromosome - two copies of each chromosome--one from each parent; contain same genes at same loci; same loci may have different alleles on each _____ _____ • chromatid - complete strand of DNA; sequence of genes; gene = simple segment of ____ that codes for the creation of a particular protein • amino acid - linear series of these make up proteins; genes code for the sequence of ___ ___ to build each protein; each of the 20 ___ ___ is coded for by sequence of three nucleotides (codon) • protein - made up of linear series of amino acids • nucleotide - organic compounds that code for amino acids; attached to backbone of sugar and phosphate molecules - Adenine-Thymine (urasil in RNA) - Guanine-Cytosine • -NA deoxyribonucleic acid; two strands in a coiled helix, each made up of series of organic compounds called nucleotides • RNA - ribonucleic acid; single strand of nucleotides • codon - sequence of three nucleotides that is coded to make amino acids • mutation - replenish the genetic variability that is constantly being reduced by natural selection - - are random alterations in genetic information relatively rare, usually have a small effect - positive, negative, neutral - can occur when DNA replicates - can also occur in chromosomes: - Change in the amount of genetic information (polyploidy, ex. 2N to 4N) 6 - Rearrangement of genetic information (deletions, duplications, inversions etc.) • genetic recombination - meiosis shuffles existing variations into infinite new combinations • sexual recombination - sexual reproduction creates an incredible number of new beings from relatively small number of alleles • mitosis - regular cell division that simply replicates cell • meiosis - cell division that reduces chromosome number in gametes to 1N • haploid - organisms with one type of each chromosome • diploid - organisms with two types of each chromosome • reduction division - first division in meiosis; turns diploid cell into two haploid cells; homologous chromosomes line up at center and are physically joined together for short amount of time; one homologous chromosome goes to each daughter cell • -ndependent assortment direction each chromosome takes during reduction division is random • Hardy-Weinberg equilibrium - see below “people” • gene frequency - how often a certain gene is in the gene pools; affected by natural selection • population genetics - the genetic composition of biological populations • gene flow - genes in a population are not static bc populations change due to immigration and emigration; occurs between local populations; depends on dispersal ability • immigration - entering a population 7 • emigration - leaving a population; (e)xit • inbreeding - breeding within one particular population • monogamy - mating with one partner for a certain amount of time • serial monogamy - mating with solely one partner for an entire lifetime • polygamy - mating with more than one partner at a time • polygyny - one male mating with multiple females • polyandry - one female mating with multiple males • founder effect - the gene pool of an isolated population will be a random subset of the gene pool of the parent population; shows that chance events can affect gene frequencies in unexpected ways; is special case of genetic drift • -enetic drift change in allele frequencies in small isolated populations due to random events; has nothing to do with adaptation or natural selection; just a statistical phenomenon • isolating mechanisms - any factor that acts to reduce or block the flow of genes between two populations: -geographic -reproductive - temporal - mechanical - behavioral - ecological • -eographic isolating mechanism isolating mechanism in which the populations are in two different locations, therefore no flow of genes - speciation starts with this 8 • reproductive isolating mechanism - speciation ends with this - prevents the members of two different species that cross or mate from producing offspring or which ensures any offspring that may be produced are sterile • temporal isolating mechanism - isolating mechanism where population becomes isolated in time; ex. fixed breeding season • behavioral isolating mechanism - isolating mechanism where changes in behavior, especially courtship and mating behavior; mechanical isolating mechanism • - isolating mechanism in which the parts no longer fit together • ecological isolating mechanism - isolating mechanism where if two populations don't meet, they don't mate; ex: specialized to live in particular habitat • allopatric speciation - speciation begins with geographic isolation; most speciation is of this variety • sympatric speciation - speciation begins within larger population in same geographical area • -species Only when populations become isolated will small changes in variation cause them to diverge into new species - largest group of organisms • directional selection - average value of a trait is shifted in particular direction (higher or lower) • stabilizing selection - acts to stabilize population around some average value • disruptive selection - the environment selects for the two extremes, against the average, splitting the population in two or more types • industrial melanism - replacement of light morph by dark morph in industrialized area 9 • microevolution - evolution at or below level of the species • macroevolution - evolution above the level of the species (orders, classes, etc.) • adaptation - the very rapid change in response to strong selective pressures • homologous structures - structurally and developmentally similar structures between two species, but are used for different purposes; derived from common ancestor (ex: wings of bird vs wings of bat) ; are evidence for divergent evolution analogous structures • - structures that are superficially similar, but structurally and developmentally different; sometimes share same purpose; result of convergent evolution • divergent evolution - divergence from common ancestor • convergent evolution - convergence on a common type or adaptive shape/structure • Six Kingdoms - bacteria; archaea; protista; animalia; plantae; fungi - BAPAPF (babies are perfect and pretty faced) • phylogeny - evolutionary history of an organism • taxon (-a) - any rank in classification, a collection of related organisms • taxonomy - description, naming and classification of living organisms • cladism - current scheme of classification. • -ladogram tree of life • clade - branch on the tree of life; determined by traits they share, traits that are different from ancestors 10 • synapomorphy - shared derived characteristics that determine clades • monophyletic - taxon contains the common ancestor of all its descendants • paraphyletic - contains common ancestor but only some descendants (most similar) - like a family with one kid that looks different and they take a family pic and leave him out • polyphyletic - taxon contains some descendant species but no common ancestor • three domains - Eukarya, Archaea, Bacteria • domain - Life is divided into three Domains - Archaea - Bacteria Eukarya - everything else kingdom • - First two domains each consist of a single kingdom, four other kingdoms make up Domain Eukarya • phylum - Phylogeny of protists still a real mess - We assume they rose from certain groups of archaeans - Protists are so different from one another, most may represent several early independent lineages of eukaryotes - As many as 50 phlya recognized • taxonomic rank (in order) - domain, kingdom, phylum, class, order, family, genus, and species • Linnaeus - collected and classified plants based on reproductive structures; believed species were fixed and distinct types and therefore could not change; created the System Natura and new system for classifying organisms with binomial nomenclature Domain Archaea - archaeans Domain Bacteria - bacteria 11 Domain Eukarya - everything else (eukaryotic cells) Kingdom Archaea - methanogens, halophilic archaens, thermophilic archaeans Kingdom Bacteria - bacteria, cyanobacteria (Nostoc, Anabena, Oscillatoria) • motile - can move about • bacillus - rod shaped • coccus - sphere shaped • spirillum - spiral shaped • prokaryote cell - Primitive cells, unicellular - Lack a cell nucleus (no nuclear membrane around chromosomes) - Lack cellular organelles bound by membranes (no chloroplasts, no mitochondria, etc…) - bacteria and archaeans • eukaryote cell - Complex cells, multicellular (some are unicellular) - Nucleus (enclosed by a nuclear membrane) - Cellular organelles enclosed by membranes (mitochondria, chloroplasts etc…) - all higher organisms (Eukarya) • endosymbiosis - life shared within • autotroph - self-feeder, “self energy”; autotrophic organisms produce their own energy - Sunlight (photosynthesis, use H O) 2 - --> 6CO +212H O +2light => C H O +6612O 6 6O 2 2 - biproduct is atmospheric oxygen - Chemical reactions (chemosynthesis, ex. H S) 2 • heterotroph - fed by other\s, heterotrophic organisms eat other organisms to survive - herbivorous - plants 12 - carnivorous - meat - omnivorous - both • photosynthetic - cyanobacteria are this - once called blue-green algae - ones you look at in the lab: nostoc, anabena, oscillatoria • chemosynthetic - the biological conversion of one or more carbon molecules (usually carbon dioxide or methane) and nutrients into organic matter using the oxidation of inorganic (e.g. hydrogen gas, hydrogen sulfide) or methane as a source of energy, rather than sunlight, as in photosynthesis. saprobe • - heterotrophs can be - get energy form dead and decaying organic matter • nitrogen fixation - turn atmospheric nitrogen (N2) into a form that plants can use (NH3 - ammonium) • root nodules - bacteria form these on legumes like clover, soybeans, alfalfa - associate with symbiotic nitrogen-fixing bacteria. • heterocyst - enlarged structure where nitrogen fixation takes place • stromatolites - thick mats, go back 2.7 billion years, one of the first ecosystems on Earth formed by a biofilm - sugar membranes that are stuck to other bacterias; resistance to antibiotics with new understanding of biofilm and bacteria vs lab solution and bacteria Kingdom Protista • Protozoa = heterotrophic protists • Phylum Euglenozoa - (Euglena) • Phylum Dinoflagellata - dinoflagellates (Ceratium, Gonyaulax) • Phylum Apicomplexa - (Plasmodium - malaria) 13 • Phylum Ciliophora - (Paramecium, Blepharisma) • Phylum Amoebozoa - (Amoeba) • Phylum Foraminifera - foraminifera • Algae = autotrophic protists • Phylum Phaeophyta - brown algae (Fucus, Sargassum, kelp) Phylum Bacillariophyta - diatoms • • Phylum Rhodophyta - red algae (Polysiphonia, Nemalion) • algae - autotrophic protists - Photosynthetic - Many referred to as “seaweeds” - Gave rise to higher plants - Phaeophyta, Bacillariophyta, Rhodophyta, Chlorophyta • protozoa - heterotrophs - Motile - Cilia – Ciliophora - Flagella - Dinoflagellata, Euglenozoa - Pseudopodia – Amoebozoa, Foraminifera - Non- motile - Apicomplexa (Plasmodium) - Gave rise to higher animals diffusion • - passive movement of molecules from area of higher concentration to area of lower concentration - results from the random movement of molecules - two edged sword; those relying on this are very small • phagocytosis - how protists eat - Engulf food in cell membrane - Pinch off membrane to form a vacuole/vesicle - Vacuoles store food, water, enzymes, wastes • pseudopodia - Amoebozoa, Foraminifera • 14 • carrageen - thickening agent also extracted from cell walls of red algae, used in making ice cream, lunch meats, cosmetics, and paint • diatomaceous earth - shells form deposits called this - used in abrasives, talc, and chalks • red tide - algal blooms of dinoflagellates are the cause of red tide - 20 species produce potent toxins People Stanley Miller and Harold Urey • Modeled Earth’s primordial atmosphere in the lab; put chemicals together that thought were present and made lightning with electricity • Harold Urey (nobel laureate) was a prominent chemist at the University of Chicago • Stanley Miller was a young grad student, looking for a thesis project • Miller had heard of experiments in prebiotic synthesis • Prebiotic evolution – evolution of complex networks of organic compounds before the origin of life • Miller asked Urey for permission to try an experiment in prebiotic synthesis based on a reducing atmosphere • Urey was less than impressed • Urey suggested a much safer alternative, measuring the amount of Thallium in meteorites Fortunately, Miller stuck to his guns, finally convinced Urey to give him one year • to get useful results • Miller mixed water with methane, ammonia, and hydrogen, and passed electric sparks through the mixture to imitate lightning strikes • Amino acids spontaneously formed in the mixture Epicurus / Lucretius/ Francesco Redi • spontaneous generation • early attempt to answer the question of where life came from; life is an innate property of organic matter 15 • Idea originated with Epicurus, made popular by Lucretius (The Nature of Things); Ancient Greeks and Romans wrote about evolution (Lucretius) • Refuted by Francesco Redi Francis Crick and Leslie Orgel / Fred Hoyle • Original meaning was that the air on Earth was full of microscopic organisms riding on tiny particles of dust • Francis Crick (co-discoverer of DNA) and Leslie Orgel carried pansperrmia much further Directed panspermia - life was intentionally seeded on Earth and other planets by an • intelligent race of aliens, or by their robotic probes • Idea was popularized by the astronomer Fred Hoyle in The Black Cloud • Hoyle claimed that interstellar dust was teeming with bacteria, seeding life everywhere throughout the cosmos Aristotle • The Chain of Being dates back to Aristotle • Also known as the scala natura, the ladder of nature Carolus Linnaeus • The Swedish botanist Carolus Linnaeus (1707-1778) set out to reveal part of the divine plan by collecting and classifying plants; focused on reproductive organs of flowers Later got his revenge on his critics by naming the most noxious and stinky weeds after • them • Believed species were fixed and distinct types, and therefore could not evolve or change • Grouped similar plants together, based on their reproductive structures • His Systema Natura (1735) is still used by modern botanists • Organisms were grouped together as Classes, Orders, Genera (Genus), Species • Invented binomial nomenclature, our modern scientific names - Genus species • System of Hybridization - new species must be hybrids of existing species Jean Baptiste de Lamarck • was one of the first to realize that organisms were shaped by their environment, could evolve in darwinian since • Best known for his theory of the Inheritance of Acquired Characteristics • Changes in the living body could be passed on to descendants (ex. giraffes’ necks) 16 • Frequently belittled by textbooks for his mechanism of evolution • One of the greatest naturalists of all times, as great as Darwin • First person to study animals without backbones, coined the term invertebrate • Coined the word biology • Thought that evolution had to be both predetermined and progressive • He was a materialist - revived the idea of spontaneous generation • Once generated, organisms changed along fixed and parallel paths - Theory of Organic Progression Darwin Rejected the idea of a divine plan behind nature • • Broke with the Argument from Design and the Chain of Being • Believed that adaptation resulted from ordinary laws of nature, no divine intervention, no cosmic blueprint • Darwinian revolution removed man from the center of creation, as the Copernican revolution had removed the Earth from the center of the universe • Man was just another organism, evolved through gradual change from lower animals • A very unlikely and very unwilling revolutionary • Family was wealthy, well educated, professional • Went to medical school at Edinburgh, but soon dropped out, couldn’t stand the sight of blood • Transferred to Christ’s College, Cambridge, to prepare for the Anglican ministry • Spent most of his time partying, even gambled away his semester’s tuition! • Father was pretty disgusted with him: “You care for nothing but shooting, dogs, and rat-catching, and you will be a disgrace to yourself and all your family” William Bailey became his mentor • • Finally got his B.A., looked like he would settle down at 22 as a minister…but something very unexpected happened • The H.M.S. Beagle was about to set sail for South America, and the captain was seeking a gentleman naturalist; mapping - Beagle set sail for South America in December 1831 - Beagle was to map the southern coast of South America, explore the interior, visit tropical islands and native tribes along the way - Unfortunately, Darwin and Fitzroy did not get along - Fitzroy was moody, contentious, intensely devout - Beagle finally reached the Galápagos Islands in September of 1835 - Isolated group of volcanic islands off the coast of Peru, far from the mainland - Classic tale of scientific discovery - Each island had one or more species of finches - Each species of finch was adapted to the environment of each individual island • It was tortoises, not finches, that started him thinking about evolution 17 • It was mockingbirds, not finches, that helped Darwin make his critical insight into the nature of evolution • Realized that evolution must be tied to variation due to The Essay by Malthus • Species were really just local groups of individuals, all of whom varied from one another in certain ways • This focus on species as groups of populations was very revolutionary • Darwin realized that evolution was a selective process, what he called natural selection • 3 other people came up with that at the same time but he wrote big thing first • Darwin’s theory was essentially complete by 1839; set aside for 20 years - Lacked any mechanism for heredity - Realized he’d be branded a heretic or worse, his family would also suffer - Darwin experimented with a variety of plants for several years, trying to discover the secrets of heredity - Even fooled around with the common garden pea, used by Mendel - Unlike Mendel, couldn’t figure it out Got a chronic disease : Most common answer is Chagas disease, tropical disease • caused by a trypanosome • Published The Origin of Species in 1859, started a great debate - Debate was mostly over the mechanism of evolution, not its existence - Heard through a colleague that the naturalist Alfred Russel Wallace was about to publish the same theory, even hitting on the same name • Darwin’s Theory of Evolution: - Growth with reproduction, inheritance - Variation in populations - Struggle for existence - Natural selection of certain varieties - Change in proportion of those varieties in the next generation - Extinction of poorly adapted forms - What Darwin accomplished: - Broke with the Argument from Design - Broke with the Chain of Being - Variation not “noise” but information - Evolution is a selective process - Explained branching pattern of evolution - descent from a common ancestor; lemark hit on branching scheme • What Darwin accomplished: - Switched the view of species as fixed and distinct types to viewing species as groups of local populations that varied from one another - Stressed the importance of geographic isolation and geographic distribution (biogeography) • Darwin’s theory could not explain: - Gaps in the fossil record (saw evolution as gradual, continuous - how could there be gaps?) - Physical basis of heredity - remained a scientific enigma • Darwin believed in blended inheritance - gradual and continuous process 18 • Tiny particles called gemmules carried the information of heredity - Gemmules floated in different parts of the body, knew how to make that body part - Gemmules moved to the reproductive organs during sex = blended inheritance - Heredity was like mixing paint - not much more sophisticated than “pee in a cup” - Makes Lamarck’s mechanism look downright sophisticated by comparison - As Darwin realized, natural selection ultimately depends on variation Thomas Malthus • In 1838, Darwin read An Essay on the Principle of Population, published in 1798 by Thomas Malthus – and it gave him the answer he had been looking for… • Social evolution followed natural evolution, nations could evolve into utopias Dad was a “free thinker” (atheist), believed that the utopians were correct; disagreed • • Malthus studied theology at Cambridge 1776 to 1782 , was ordained into the Church of England in 1788 • Access to parish registers of births and deaths, gave him statistical data on the growth of the local population, which was booming • Malthus published his Essay on the Principle of Population in 1798 - It was a runaway bestseller - Population would increase geometrically, but resources could only increase arithmetically - Over time, this would lead to a growing gap between too many people and too few resources - Out of this gap came what Malthus called “the struggle for existence” - Ideas were a major influence on Darwin, who reasoned that what was true of humanity must also apply to other animals as well - a struggle for existence Herbert Spencer • The winners must be those individuals better equipped to survive, what Herbert Spencer was to later call survival of the fittest Gregor Mendel • The answer that Darwin sought was actually found in his lifetime; Darwin never heard about Mendel’s results; pages were uncut • In 1866, experimented with garden peas, discovered the mechanism of heredity • Published his data in an obscure journal, article was ignored, few read it, none appreciated or understood it • Not a very good student - failed his teacher’s exam twice • Entered an Austrian monastery, eventually became the abbot 19 - Began his famous experiments on garden peas in the monastery garden - Focused on discontinuous variation, all or none, unlike Darwin (continuous variation) • Mendel showed that: - The physical units of heredity came in pairs, one unit from each parent - Heredity was particulate, not blending of fluids (contrast with Darwin) - Variation was not continuous, but discontinuous - Geneticists discovered that evolution really meant a change in gene frequency over time • Mendelists stressed the importance of mutations - changes in genetic information • Natural selection was only a passive filter for good or bad mutations, not an active and creative force as Darwin envisioned it • As Mendelists realized, new variations were constantly generated by mutations H.B.D. Kettlewell • thought that the color protected the moths from hungry birds • Marked a sample of moths of each color under their wings • He released equal numbers of each morph in a polluted area (Birmingham) and a clean area (Dorset) • He later returned and recaptured as many moths as he could at both sites • Dorset (clean) 6% black 12.5% light • Birmingham 40% black 19% light • Twice as many light moths survived in clean areas, twice as many black moths survived in polluted areas To determine if hungry birds were the selective pressure, he put equal numbers of • moths on light and dark tree trunks • those eaten: • Dorset (clean) 164 black 26 light • Birmingham 15 black 43 light • Each variation was adapted to its own local conditions • Both morphs were well adapted in one environment, and poorly adapted in the other Cyril Clarke • collected 17,300 peppered moths over a 35 year period - only two were on the trunk of a tree Peter Grant and Rosemary • Populations can change very rapidly in response to strong selective pressures 20 • One of the best-documented examples involves one of Darwin’s finches, the medium ground finch - Geospiza fortis • Studied by Peter Grant and Rosemary - The Beak of the Finch (Pulitzer Prize winner) Grant was studying finches on Daphne Major (an island), trying to determine what • factors shaped their communities • Darwin’s finches differ mainly in the size and shape of the beak • These differences are adaptations to the local food supply Bradshaw and Jowett • studied bentgrass (cosmopolitan weed, everywhere on the planet) Wales has many lead and copper mines • • Mines produce heaps of tailings (wastes) • Tailings are toxic - heavy metals • Bentgrass grows on mine wastes • Bentgrass on mine wastes has evolved tolerance to heavy metals • Transplanted grass from mine wastes to normal soil , and grass from normal soil to mine wastes; neither did well at all • Wild type did better in normal soil, metal-resistant plants did better on mine wastes • Two separate races of bentgrass have evolved in about 400 years of mining • Plants in California evolved a copper resistant race in less than 70 years • Evolution can happen very quickly G. Weinberg and G.H. Hardy • G. Weinberg (German doctor) and G.H. Hardy (British mathematician), made an interesting discovery in 1908 • If large populations mate randomly, the proportion of two alleles will never change • In other words, they discovered that evolution is mathematically impossible • Hardy-Weinberg Equilibrium - For any two alleles (Aa), let p and q represent the frequency of those alleles (so p = AA, q =aa, 2pq = 2Aa) - If all three possible genotypes mate with one another, in the next generation the 2 2 frequencies will be equal to p + 2pq 2q = 1 - [simple binomial equation, (p + q) ] - Let all genotypes mate again, the result will be exactly the same - Works with any number of alleles - (p + q + r) = 1 - Gene frequencies will always be in equilibrium - Hold the phone!! - Evolution is change in gene frequency over time 21 - Gene frequencies never change over time - Therefore evolution cannot occur • We know that evolution occurs - One or more assumptions must be wrong - In fact, they’re all wrong! • that’s the whole point of the hary-weinberg equilibrium • The model tells us that variation is not enough for evolution to occur • The Hardy-Weinberg Equilibrium is nothing less than a road map to evolution • It shows us the forces that drive evolution • Hardy-Weinberg only works for large populations • Strange things can happen in small populations • Genetic drift is one more source of variation that nudges gene frequencies away from the tidy equilibrium of Hardy-Weinberg model Specifically Said Was Important In Class Species were fixed, distinct types, that could be arranged in a linear sequence, like links in a chain - The Chain of Being Linnaeus System of Hybridization - new species must be hybrids of existing species Lamarck is best known for his theory of the Inheritance ofAcquired Characteristics Changes in the living body could be passed on to descendants (ex. giraffes’necks) Once generated, organisms changed along fixed and parallel paths - Theory of Organic Progression Darwinian revolution removed man from the center of creation, as the Copernican revolution had removed the Earth from the center of the universe Population would increase geometrically, but resources could only increase arithmetically Over time, this would lead to a growing gap between too many people and too few resources Out of this gap came what Malthus called “the struggle for existence” In any struggle, there would be winners and losers The winners must be those individuals better equipped to survive, what Herbert Spencer was to later call survival of the fittest 22 Darwin experimented with a variety of plants for several years, trying to discover the secrets of heredity Even fooled around with the common garden pea, used by Mendel Darwin’s Theory of Evolution If two similar genes come together we call the plant homozygous (TT or tt) If two different genes come together we call the plant heterozygous (Tt) Alleles are different versions of the same genes (original “wild type”, mutated form) Geneticists discovered that evolution really meant a change in gene frequency over time Higher organisms have two copies of each chromosome, one from each parent = homologous chromosomes Each of the 20 amino acids is coded for by a sequence of three nucleotides (codon) - code word, add to the chain Organisms with two of each type of chromosome (2N) are called diploid Organisms with one of each type of chromosome (1N) are called haploid In mitosis, the object is to make two identical diploid daughter cells Chromatids replicate before division Chromosomes line up at the center Chromatids separate, go to daughter cells Daughter cells are now identical In meiosis, object is to turn one diploid cell into four haploid daughter cells (gametes) In meiosis there are two complete cell divisions Need to reduce the chromosome number - first division is a reduction division, turns diploid cell into two haploid cells Microevolution is evolution at or below the level of the species Macroevolution is evolution above the level of the species (orders, classes, kingdoms, domains etc…) KNOWALLTHE SELECTIONS WELL; WILLBEATEST QUESTION Directional Selection - average value of a trait is shifted in a particular direction (higher or lower) Disruptive or Diversifying Selection - the environment selects for the two extremes, against the average, splitting the population in two or more types 23 natural selection types stabilizing, disruptive, directional (fill in or all at once) Evidence of Evolution (know in general sort of way what they’re all about and list them out) Biodiversity Biogeography Fossil record Embryology Comparative anatomy Molecular evolution Homologous structures are structurally and developmentally similar, even though they may be put to very different uses; Homologous structures are derived from a common ancestor The wing of a bird and the wing of an insect are analogous structures; Analogous structures are superficially similar, but structurally and developmentally different Three Domains of Life – Bacteria,Archaea, Eukarya Six Kingdoms of Life – Bacteria,Archaea, Protista,Animalia, Plantae, Fungi big question at the end of the test: types of natural selection, line of evidence for evolution, most of material comes form micro macro lecture!! Allopatric - speciation begins with geographic isolation Sympatric – speciation occurs within a larger population in the same geographical area (ex. polyploidy in plants) Most speciation is allopatric
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