BIL 160: Class Notes Exam 1
BIL 160: Class Notes Exam 1 BIL 160
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BIL lecture 1 01172013 Read the Campbell text book readings on syllabus EVOLUTION Evolution change over time Organic evolution the genetic change of living organism over time Misconceptions about evolution quotEvolution is a theory of the origin of lifequot quotEvolution is like a climb up a ladder of progress organisms are always getting betterquot 0 Its more like a branching tree 0 Organisms are not better than others but more adapted to their own environments quotevolution means that life changed by chancequot 0 there is some chance but most is natural selection quotnatural selection involves organisms trying to adaptquot quotnatural selection gives organisms what they needquot quotevolution is just a theoryquot 0 theory in science a wellsubstantiated explanation of some aspects of the natural world 0 evolution is not a theory it s a process quotevolution is a theory in crisis and is collapsing as scientists lose con denceinit Biodiversity the variety of living specie on earth 0 17 million species on earth 0 Edward O Wilson Side notes Taxonomist biologists who names and classi es living things Systematist a biologist who studies the evolutionary relationship bw living organisms 0 Type material a collection of specimens of a single species that was cited in the original published description of that new species 0 Holotype the individual member of a species on whose physical description the description of the entire species is based 0 Paratypes the unlucky conspeci cs in the type collection other than the holotype o Conspeci cs members of the same species 0 Species a population or series of populations within which free gene ow occurs under natural conditions How Much Genetic Variety Are We Talking About Genome the full DNA sequence of an organism o Diploid organisms have 2 copies of their genome one from each parent 0 Nuclear genome the genome in a eukaryotic nucleus Organelle genome the genome in a mitochondrion or chloroplast Genetic diversity of earth is HUGE Why Should We Care About Biodiversity Genes Wild animals and plants are sources of genes for hybridization and genetic engineering Biological control agents Some species of living things help us control invasive species without the use of poisons Food sources Animals plants mushrooms etc Natural products Many of the medicines fertilizers and pesticides we use are derived from plants and animals We also get products such as oils adhesives and silk from natural sources Environmental services We rely on plants and animals for important processes such as soil aeration fertilization and pollination Enjoyment Biodiversity is often the subject of aesthetic interest Scienti c interest The diversity of plants and animals inspires scienti c inquiry in many different realms Evolutionary science anatomy physiology behavior and ecology are only a few examples Selfperpetuation Biologically diverse ecosystems help to preserve their component species reducing the need for future conservation efforts targeting endangered species Future potential for even more uses With new discoveries to come there will be many more practical reasons to appreciate biodiversity Inbreeding breeding bw closely related individuals Outbreeding mating bw unrelated conspeci cs This is why large populations are important Inbreeding increases likelihood that harmful alleles will be inherited causing genetic disorders Human arti cial selection an also bring along alleles of other genes that are unwanted Wilderness as a resource Anthropocentric view nonhuman species are important only in so far they can bene t humans Biocentric view nonhuman species are important to save for their own intrinsic value Ecocentric view biodiversity and ecosystems should be preserved not just individual species or populations bc it is the whole working system that maintains diversity Ecologically signi cant species Indicator species plantanimal species that by its presence abundance lack of abundance or chemical composition demonstrate some distinctive aspect of the character or quality of an environment Keystone species a species upon which many other species in an ecosystem rely for their survival Native species one that occurs in the area where it evolved Endemic species a native species to a particular area that is found no where else Exotic species one that has been introduced arti cially to an area where it did not evolve Invasive exotic species exotic species that aggressively displaces native species 0 Allelopathic producing toxic compounds that deter growth of completing plants nearby Politically signi cant species Threatened species still relatively abundant in isolated areas but likely to become more scarce usually due to habitat loss Endangered species so few individuals left that extinction is imminent expected to know Scienti c Method The Age of Things 0 Using radiometric dating techniques scientists have estimated o Universe is 1020 billion yo Solar system and earth 45 billion yo Life on earth 4 billion yo Earliest Homo sapiens 400000 yo Modern Homo sapiens sapiens 200000 yo Who s Who in Evolutionary Theory A History 0 Origin of life is not the same as evolution of life 0 Intellectual stirrings in the cradle of civilizations 0 Greek philosophers rst toyed with idea that life was constantly changing o Plato and Aristotle believed in an unchanging world in which all species had been created in a perfect state Aristotle believed that life forms were arranged in an unchanging chain of increasing complexity o Biblical Creation 0 Old testament supported Aristotle s idea 0 Natural theology the notion that science should be dedicated to studying nature in order to gure out the Grand Plan of the Creator Origin of Life The Birth and Death of Some Popular Ideas Spontaneous generation ancient romans thought the living organisms could spring fully formed from nonliving matter 0 Scientists then disproved this 0 Francesco Redi Placed rotting meat in covered and uncovered jars noted maggots formed only in uncovered jar 0 Anton van Leewenhoek Invented microscope Again spontaneous generation was revived on smaller scale Georges Buffon First to propose that earth and solar system had arisen due to natural processes John Needham Boiled to kill but didn t cover so bugs grew in water so believe spontaneous again Lazaro Spallanzani Did boil thing and sealed without air discounted bc thought needed air 0 Louis Pasteur Finally disproved with swannecked ask experiments Bc bacteria would not be able to pass through Continued on 122 0000 O O O 0 Take Pasteur s Work Out of Context to Contest Evolution 0 They claim Pasteur disproved spontaneous generation therefore evolution cannot occur NOT TRUE 0 MillerUrey The Modern Understanding o Duplicated conditions of primordial earth 0 Experiment yielded many organic building blocks of life 0 Important there was a lack of oxygen bc oxygen was very scarce earlier and this was necessary for early life Abiogenesis Recent Advances o Abiogenesis Origin of life from nonlife 0 Video Life originated from one single celled molecule and this came from organic chemistry Knew the ingredients for early life but didn t now how to put them together But know they have gured out how to make the C in RNA then plus light turns some of these Cs to Us So now know how to make half of the early RNA 0 Peanut Butter Video Disagrees with previous video but doesn t make any sense Organic Evolution once life got here how did it change into the variety of forms we see today 0 Jean Baptiste Lamarck know his name 0 Late 17005 concluded that animals could change over generations if their environment dictated that they needed to change to survive Used giraffe as example with neck Driven by quotuse vs disusequot if you don t use it you lose it n Vestigial things that we have that are not useful tail bone 0 We now know Lamarck not right because of Mendel and Darwin 0 Lamarck Rises from the Grave o Epigenetic inheritance new idea the suggests that Lamarck did not hit the mark but that the environment can paly a role in how DNA is packaged and expressed and some of those DNA are heritable Georges Cuvier 0 About same time as Lamarck was developing paleontology study of fossils 0 His reason for fossils was catastrophism fossil record were just con rmation of catastrophic events and massive destruction wrought by Creator 0 Charles Darwin 0 Most in uential scientist of all time bc origin of species arguable most important biological work ever written Mootoo Kimura 0 First to suggest not all evolution has to be Darwinian 0 His idea not all evolution result of natural selection Had neutral theory of molecular evolution read little article on page genetic drift was a population is related because of a small sample size u now understood to paly major role in evolutionary change in living populations The Darwinian Revolution Darwin s in uences 0 James Hutton challenged Cuvier s view of catastrophic event His idea was gradualism large change in earth s surface could be caused by slow processes erosion 0 Charles Lyell said earth processes had been going on for ages Proposed uniformita rianism 0 Thomas Malthus religious scholar O Wrote quotan essay on the principle of populationquot a Suggests that humanity s suffering disease war was inevitable result of overpopulation People already knew about arti cial selection dog shows were big Darwin thought should nature not operate in a similar way Voyage of the Beagle 0 Darwin born in 1809 in England 0 Dad was physician and he sent Darwin into medical school but he dropped out 0 Then went to college to become clergyman 0 000 0 Here he found biology and became star pupil of Rev John Henslow professor of botany Helped convince dad to let Darwin go one Beagle So at 22 Darwin left to map south American coastlines Took 5 years Went back to England ad married cousin Began to muse visualized evolution of life as a spreading tree 0 He termed gradual change of one species into another descent with modi cation Darwin s observations 0 All species have huge potential fertility 0 Except for seasonal uctuations populations tend to maintain a stable size 0 Environmental recourses are limited Inference 1 the production of more individuals than the environment can support leads to a struggle for existence with only a fraction of offspring surviving in each generation No 2 individuals in a population are exactly alike Much of the observed variation in a population is heritable Inference 2 survival in this struggle for existence is not random Inference 3 unequal reproduction bw suited and unsuited organisms will eventually cause a gradual change in a population 0 Theory of evolution by means of natural selection can be broken down into 4 basic tenets O O Overproduction organisms are capable of producing huge numbers of offspring Heritable variability those offspring are variable in appearance and function Competition resources limited offspring must compete for Differential reproduction survival and reproduction is not random Individuals whose inherited characteristics make them better able to compete therefore will leave more offspring Darwin slow to publish because of religious implications but friend told him too or else someone else will have same idea This almost happened Darwin got essay from Alfred Wallace with same idea Lyell to the Rescue Presented both Darwin s and Wallace s work Their ideas were identical But Darwin got credit for rst quotSurvival of the Fittestquot a misused phrase phrase coined by Spencer 0 0 he took Darwin s ideas and wrote own in terms of economics Darwinian s ttest is the one that produces the most offspring evolutionary tness differential reproduction due to organisms differing abilities to cope with environmental limitations 0 any trait may be 0 adaptive increases the likelihood that individual will leave offspring o maladaptive decrease quot 0 neutral doesn t affect the quot trait classified into one of these categories only in context of the environment in which organism exists Hence evolutionary fitness is determined by environment and organisms are selected to match the environment in which they live Use Terminology Carefully 0 Terms quotevolutionistquot or quotDarwinistquot imply that evolution is an ideology 0 Evolution observable testable phenomenon 0 Darwin a person who elucidated one means y which evolution can occur 0 Scientists who study the processes and mechanisms that lead to evolution evolutionary biologists not evolutionists Evolution Is it quotJust a Theoryquot 0 Will sometimes hear that quotevolution is only a theoryquot 0 The quotonly theoryquot argument is awed bc fails to separate 2 important things 0 Extant species evolved from ancestral forms 0 Natural selection is the main mechanism by which this occurred Darwin s conclusion based on observable evidence and subject to scienti c method 0 Evolution is an observable phenomenon o Darwin s theory of natural selection provides powerful mechanism explaining how evolution can proceed o It doesn t explain the origin of life only how it changed once it got here 0 Natural selection is not the only mechanism by which living things evolve Common Misconceptions About Evolution 0 Evolution is a theory about the origin of life 0 Evolution l a process by which organisms become better 0 Evolution is the result of life changing by random chance Organisms purposefully quottryquot to evolve traits bc they need them 0 Evolution means quotsurvival of the fittest Evolution is quotjust a theoryquot 0 Even the scienti c community can t agree The Fact of Evolution Observable Evidence 0 4 major lines of physical evidence telling us that evolution has occurred 0 observable examples of the evolutionary process 0 fossils 0 distribution in space in time o homologies similar characteristics bw species due to relatedness species and speciation macroevolution speciation o speciation the generation of 2 or more reproductively isolated new species from an ancestral species 0 reproductively isolate speciation implies that the 2 new species are no longer able to produce fertile offspring with each other 0 speciation can be quick or gradual depending on species and circumstances Microevolution a population can undergo genetic change with respect to other populations of same species but not become reproductively isolated from them Observable Example of Evolutionary Processes Evidence Microevolution Observed there are thousands of scienti cally documented cases of microevolution o 1 MRSA o 2 Antibioticresistant Mycobacterium tuberculosis Was this an example of natural selection 0 Did variation exist in the bacterial population 0 Was the variation heritable 0 did differential reproduction among variable bacteria occur 0 Did a nonrandom subset of the original population remain after selection Bergmann s Rule animals in higher latitudescolder climates tend to have larger bodies 0 This is true across species Evidence Macroevolution Observed Evidence What the Rocks and Fossils Tell Us Evidence of Evolution Homology Descent with modi cation the long process of observable evidence to support the idea that life on earth has evolved Homology a characteristic shared by 2 species that is similar because of common ancestry Morphological homology species correctly placed in the same taxonomic category show anatomical similarities Ontogenetic homology species places in the same taxonomic category show developmental similarities Molecular homology species placed in the same taxonomic category show similarities in DNA RNA and protein 1 Morphological Homology homologous structures structures derived from a common ancestral structure phylogenies evolutionary development of a species of grouping of organisms Primitive and Derived Characters 0 Primitive character one that is relatively unchanged from its original ancestral form 0 Symplesiomorphy a shared primitive character Derived character one that is relatively modi ed from its original ancestral form 0 Synapomorphy a shared derived character 0 The more recently 2 species diverged from a common ancestor the more synapomorphies they will share 0 Unique synapomorphies found only in a single group provides strong evidence for the common ancestry of members of that group Analogous structures and convergent evolution 0 Analogous similar structure in 2 different species 0 Serves the same function in 2 species 0 But is NOT derived from a common ancestral structure 0 Convergent evolution process in which 2 distinct lineages evolve a similar characteristic independently of one another Often occurs bc both lineages face similar environmental challenged and selective pressures know for test blastula and diagram 0 archenteron primitive gut o endoderm inside skin 0 ectoderm outside skin Protostomes vs Deuterostomes o Protostomes Animals whose blastopore becomes the mouth o Deuterostomes Animals whose blastopore becomes the anus Most are proto but one lineage including vertebrates are deuteron Happy Accidents 0 Stephen Gould coined term exaptation The preexistence of a character initially with no known adaptive signi cance that under changed environment quotsuddenlyquot conferred a selective advantage to those individuals exhibiting it Vestigial Characters Highly Derived and Mostly Nonfunctional o Vestigial structure one that has marginal if any use to the organism 2 Ontogenetic Homology Ontogeny Recapitulates Phylogeny o Ontogeny the process of embryo development 0 Phylogeny a species evolutionary history Haeckel was the rst to notice that the embryonic forms of different species had amazing physical similarities o similarities of embryo development of different species are remnants of the embryonic development features of those species39 common ancestor 0 Differences in ontogeny among taxa are not trivial o If it is present in the embryo of all taxa being considered it is most likely a homology 0 More complex adult forms are the result of changes in embryo development 0 Heterochrony Changes in the timing of ontogenetic events between related species 3 Molecular Homology The deepest level of homology The molecules that carry the instructions for making and running our bodies encoded in our DNA 0 The more closely related two species are the more similar their DNA sequences 0 Individual Organisms do not evolve Only Populations evolve 0 Glossary of Microevolutionary Terms Evolution change over time Organic evolution change in living organisms over time o Microevolution genetic change win a species over generations 0 Marcroevolution reproductive isolation between members of a previously interbreeding population resulting in two new daughtersibling species Population all individuals of the same species living in a de ned geographic or smaller organismal area Deme a local actively interbreeding population that shares a distinct gene pool Gene pool all the genes at all loci in every member of an interbreeding population Adaptation has different de nitions in physiology vs evolutionary biology 0 Physiological adaptation a short term change made by an individual organism in response to environmental changes 0 Evolutionary adaptation can be either the process by which a population evolves to become better suited to its environment a charactertrait that has resulted from the evolutionary process What Causes a Population to Evolve Mutation change in a gene is the raw material of evolution 0 How Do Populations Evolve Genetic variability in a population is the raw material for natural selection read more about bc missed class on this day 0 basically what she talked about don t need wisdom teeth but just because we don t need them doesn t mean that they just go away 0 Mechanisms of Evolution The Five Factors 0 Genetic makeup of population can change by means of 5 mechanisms O 0000 O Mutation Small population size Nonrandom mating Migration into or out of the population Natural selection Population Genetics Measuring Evolutionary Change Mendelian Genetics the study of genetic events at the level of the individual organism Molecular Genetics the study of genetic events at the level of the molecule and cell 0 Population Genetics the study of genetic events at the level of the population and hence genetics as it pertains to evolution Immunological polymorphism ABO blood groups in humans 0 Amino acid sequence polymorphisms 0 DNA polymorphism O Resrition site vartion o Tandem repeats O Compete sequence variation 0 Source of these polymorphisms mutation Skipped some 0 know duplications Hybrid 0 read article about hybridization and the resulting polyploidy polyploidy individuals more robust that parents difference bw gene and alleles gene a unit of inheritance o constructions on DNA for building proteins 0 genes code for same things but may not code in the same exact ways 0 there is a gene that controls pigment in eyes so the difference alleles are the different colors allele alternative forms of a gene that arise by mutation and are found at the same place on a chromosome Homozygous two same alleles aka WW or ww Heterozygous two different alleles Ww Genetics Primer link snail similar colors because of genetic drift small population with inbreeding HardyWeingberg 0 reported a mathematical rule that predicts relative genotype frequenciesgiven starting frequencies of two allelesin a population that is not evolving In summary 0 5 things that can cause populations to evolve o mutation 0 random sampling effects o nonrandom mating o migration 0 natural selection END OF MATERIAL FOR TEST 1 Classical Model 0 Mutation only way to get genetic variation 0 Reverse mutation mutations that can change back to wild type from one generation to the next 0 There are cases where a single mutation can cause reproductive isolation The Balance Model 0 read about balancing selection Frequencydependent selection occurs when the tness of a genotype depends on its frequency 0 Mimicry coral snake and coral snake when organism mimics another organism 2 basic kinds n Bastian harmless species looks like harmful one u malarian CONTINUED ON TEST 2 LECTURES Why Blue eyes considered mutant bc brown eyes most common deme subset of a population plesiomorphy primitive character with respect to ancestor v aplamorphy a derived character 0 in lecture in detail Wienberg equilibrium used to compare populations 0 Be ready to do calc on practice equation Pedogenesis l don t pay attention to on study guide Just So Stories Wrote kid stories about how animals came to be 0 Were likened to show why we have traits But have to be careful because don t actually know why we have a lot of these traits Lect1 evolution is de ned as change over time 0 organic evolution is the genetic and phenotypic change of living organisms over time o Biodiversity is the variety of living species on earth taxonomist A biologist who names and classi es living things systematist A biologist who studies the evolutionary relationships between living organisms 0 type material a collection of specimens of a single species or subspecies that was cited in the original published description of that new species or subspecies o holotype The individual member of a species in the type collection on whose physical description the description of the entire species is based 0 paratypes the unlucky conspeci cs in the type collection other than the holotype o conspeci cs are members of the same species For example all the Homo sapens in this classroom are conspeci cs 0 species a group of similar organisms that can interbreed in nature to produce fertile viable offspring genome is the full DNA sequence of an organism 0 nuclear genome the genome in a eukaryotic nucleus usually 2 nonidentical copies 0 organelle genome the genome in a mitochondrion or chloroplast may be multiple identical copies inbreeding is de ned as a mating between closely related individuals 0 outbreeding is de ned as a mating between unrelated conspeci cs Wilderness as a resource anthropocentric view nonhuman species are important only in so far as they can bene t humans biocentric view nonhuman species are important to save for their own intrinsic value ecocentric view biodiversity and ecosystems should be preservednot just individual species or populationsbecause it is the whole working system that maintains diversity Ecologically signi cant species indicator species a plant or animal species that by its presence abundance lack of abundance or chemical composition demonstrates some distinctive aspect of the character or quality of an environment keystone species a species upon which many other species in an ecosystem rely for their survival native species one that occurs in the area where it evolved endemic species a species native to a particular area that is found nowhere else on earth exotic species one that has been introduced arti cially to an area where it did not evolve invasive exotic species an exotic species that aggressively displaces native species allelopathicproducing toxic compounds that deter growth of competing plants nearby Potentially signi cant species threatened species still relatively abundant in isolated areas of its former range but likely to become more scarce usually due to habitat loss endangered species so few individuals left that extinction is imminent Lect2 Radiometric dating techniques measuring element decay in oldest rocks gave scientists a way to guess the age of earth 0 Universe 1020 billion yo 0 Our solar system 45 bil old 0 Life on earth 4 bil yo Origin of Life is not the same as Evolution of Life Plato and Aristotle believed in an unchanging world in which all species had been created in a perfect state 0 Aristotle also believed that life forms were arranged in an unchanging chain of increasing complexity a scaa naturae devised by a Divine Creator 0 natural theology the notion that science should be dedicated to studying nature in order to gure out the Grand Plan of the Creator spontaneous generation thought that living organisms could spring fully formed from nonliving matter Francesco Redi o Placed rotting meat in covered and uncovered jars noted maggots formed only in uncovered jar Anton van Leewenhoek o lnventedrnkroscope 0 Again spontaneous generation was revived on smaller scale Georges Buffon 0 First to propose that earth and solar system had arisen due to natural processes before all creationists John Needham o Boiled broth to kill but didn t cover so bugs grew so believe spontaneous again Lazaro Spallanzani 0 Did boil thing and sealed without air discounted bc thought needed air Louis Pasteur 0 Finally disproved with swannecked ask experiments 0 Bc bacteria would not be able to pass through ask MillerUrey o Duplicated conditions of primordial earth in apparatus 0 Experiment yielded building blocks of life amino acids sugars nucleotide bases 0 Most important feature was LACK OF 02 Abiogenesis Origin of life from nonlife Jean Baptiste Lamarck know his name 0 concluded that animals could change over generations if their environment dictated that they needed to change to survive Used giraffe as example with neck Driven by quotuse vs disusequot if you don t use it you lose it Vestigial things that we have that are not useful tail bone We now know Lamarck not right because of Mendel and Darwin Epigenetic inheritance the environment can paly a role in how DNA is packaged and expressed and some of those DNA re arrangements are heritable Georges Cuvier 0 About same time as Lamarck was developing paleontology study of fossils 0 His reason for fossils was catastrophism fossil record were just con rmation of catastrophic events and massive destruction wrought by Creator Charles Darwin 0 Most in uential scientist of all time bc of his theory f how evolution proceeds by natural selection 0000 Mootoo Kimura 0 His idea not all evolution result of natural selection 0 his theory states that random neutral changes in DNA at the molecular level can have profound evolutionary consequences over time 0 aka genetic drift random changes in the gene frequencies of a population from generation to generation This happens as a result of sampling error some genotypes just happen to reproduce more than other genotypes not because they are better but just because they got lucky This process causes gene frequencies in a population to drift around over time Some genes may even quotdrift outquot of a population Lect3 James Hutton challenged Cuvier s view of catastrophic event 0 His idea was gradualism large change in earth s surface could be caused by slow processes erosion Charles Lyell 0 said that such earth processes had been going on steadily and constantly for ages and could explain the appearance of the earth uniformitarianism o pushedhelped Darwin to publish his ideas Thomas Malthus religious scholar o Wrote quotan essay on the principle of populationquot 0 Suggests that humanity s suffering disease war was inevitable result of overpopulation Arti cial selection humans breeding animals and plants for desired characteristics Rev John Henslow professor of botany helped convince Capt Robert Fitzroy capt Of HMS Beagle and Darwin s dad to let Darwin go on 5 year voyage visualized evolution of life as a spreading tree and he termed descent with modi cation gradual change of one species into another inference 1 The production of more individuals than the environment can support leads to a quotstruggle for existencequot with only a fraction of offspring surviving in each generation inference 2 Survival in this quotstruggle for existencequot is not random but depends in part on the hereditary makeup of the survivors Those individuals who inherit characteristics that allow them to best exploit their environment are likely to leave more offspring than individuals who are less well suited to their environment Lect4 inference 3 Unequal reproduction between suited and unsuited organisms will eventually cause a gradual change in a population with characteristics favorable to that particular environment accumulating over the generations Theory of Evolution by Means of Natural Selection can be broken down into four basic tenets o OVERPRODUCTION Organisms are capable of producing huge numbers of offspring o HERITABLE VARIABILITY Those offspring are variable in appearance and function and some of those variations are heritable o COMPETITION Environmental resources are limited and those varied offspring must compete for their share 0 DIFFERENTIAL REPRODUCTION Survival and reproduction of the varied offspring is not random Those individuals whose inherited characteristics make them better able to compete for resources will leave more offspring than those not as well su ed Alfred Wallace had same ideas as Darwin and almost beat to publishing Herbert Spencer philosopher studying economics who coined quotsurvival of the fittest o quotsurvival of the fittestquot is a tautology or circular de nitionphrase Evolutionary tness is differential reproduction due to organisms39 differing abilities to cope with environmental limitations 0 adaptive trait increases the likelihood that the individual will leave offspring o maladaptive trait decreases the likelihood that the individual will leave offspring 0 neutral trait does not affect the likelihood that the individual will leave offspring Scientists who study the processes and mechanisms that lead to evolution evolutionary biologists not evolutionists quotOnly a Theoryquot argument awed bc Darwin39s conclusions are based on observable evidence and subject to the scienti c method four major lines of physical evidence telling us evolution has occurred 0 observable examples of the evolutionary process arti cial selection as model for natural selection 0 fossHs 0 distribution in space and time continental drift differences the time is took is extremely long 0 homologies Similar characteristics due to relatedness different leaf shapes bone structure species members of populations that actually or potentially interbreed in nature Macroevolution Speciation o Speciation the generation of 2 or more reproductively isolated new species from an ancestral species Can be quick or gradual o reproductively isolated when two new species are no longer able to produce fertile viable offspring with each other Microevolution when a population can undergo genetic change with respect to other populations of the same species but not become reproductively isolated from them Evidence of Micro evolution 0 MRSA Used to be treated with penicillins antibiotic But some evolved to be tolerant of it 0 TB In mid 20th c new antibiotics nearly eradicated TB Now new resistant strains showing up 0 Both prove natural selection bc had variation the variation was heritable differential reproduction occurred nonrandom subset of the original population remain Bergmann39s Rule animals in higher latitudescolder climates tend to have larger bodies than those in lowerwarmer places 0 Johnston and Selander House Sparrows in US descended from a few pairs in England yet the US population at higher latitudes are darker and larger than those in southern populations To become a fossil it helps to have 0 Hard body parts 0 A rapid burial 0 Protection from scavengersbacteria 0 Protection from oxygen Fossils parts of an organism s body 0 or can be trace fossils left by living things long ago burrows tracks castings gastroliths stones from inside stomach coproliths poop molds impressions casts entire body replaced by minerals o fossils can be unaltered composed of actual matter from the organism encased in preserving material mummi ed arid conditions frozen 0 or altered permineralized spaces in the tissue are lled by minerals over time mineralized tissues are fully replaced by minerals but keep their shape relative dating process of determining the chronological order of fossil deposition is known as stratigraphic column the vertical placement of rock layersunits in a particular location Principle of Superposition Older layers of sediment are covered by younger layers the most recent layers are at the top Principle of Fossil Succession If organisms evolve and change over time then speci c species found in a particular layer can be used as age markers linking even geographically distant sediments Principle of Crosscutting Relationships Intrusions that cut through sediments are younger than the sedimentary layers they cross Principle of Deformation Sedimentary rocks that have been deformed by folding lifting or other malformation must be older than the event that changed them Lect5 descent with modi cation the idea that life on earth has evolved its diversity through a long process of powerful evidence of this is homology a characteristic shared by two species or other taxa that is similar because of common ancestry o morphological homology species correctly placed in the same taxonomic category show anatomical similarities o ontogenetic homology species placed in the same taxonomic category show developmental embryological similarities 0 molecular homology species placed in the same taxonomic category show similarities in DNA RNA and protein Morphological Homology homologous structures structures derived from a common ancestral structure that may or may not be used for the same function in the species in which it occurs 0 ex skeletal structure Shared homologies allow us to devise hypothetical quotfamily treesquot of living organisms called phylogenies represented as a branching diagram called an phylogenetic tree or evolutionary tree Primitive character one that is relatively unchanged from its original ancestral form 0 Ex presence of tail in vertebrate Derived character one that is relatively modi ed from its original ancestral form 0 Ex modi ed shapes of various vertebrate tails symplesiomorphy a shared primitive character synapomorphy a shared derived character 0 The more recently two species diverged from a common ancestor the more synapomorphies they will share 0 Unique synapomorphies found only in a single group provide strong evidence for the common ancestry of members of that group analogous structure found in two different species 0 serves the same function in two species 0 but is not derived from a common ancestral structure 0 ex wing of butter y vs bat Gastrula diagram 0 Zygote l Blastula with Blastocoel in middle I Gastrulation l Gastrula o Gastrula includes Blastocoel Archenteron Endoderm amp Ectoderm Blastopore Protostomes animals whose blastopore becomes the mouth 0 Most animals including butter ies Deuterostomes animals whose blastopore becomes anus o Vertebrage including bats Stephen Gould rst coined term exaptation The preexistence of a character initially with no known adaptive signi cance that under changed environment and hence changed natural selection pressures quotsuddenlyquot conferred a selective advantage to those individuals exhibiting it 0 Ex scales to feathers vestigial structure is one that has marginal if any use to the organism in which it occurs Ontogenetic Homology ontogeny is the process of embryo development phylogeny is a species39 evolutionary history Ernst Haeckel rst to notice that the embryonic forms of different species had amazing physical similarities Heterochrony Changes in the timing of ontogenetic events between related species Molecular Homology Lect6 more closely related two species are the more similar their DNA sequences The very existence in of DNA every living thing on earth is in itself strong evidence of common ancestry Microevolutionary Terms evolution change over time manic evolution change in living organisms over time o microevolution genetic change Within a species over generations 0 macroevolution reproductive isolation between members of a previously interbreeding population resulting in two new daughtersibling species synonyms speciation cladogenesis Donulation all individuals of the same species living in a de ned geographic or smaller organismal area deme a local actively interbreeding population that shares a distinct gene pool gene pool all the genes at all loci in every member of an interbreeding population physiological adaptation a short term change in physiology morphology metabolism etc made by anindividua organism in response to environmental changes ex Seasonal fur change evolutionary adaptation can be either 0 the process by which a population evolves to become better suited to its environment 0 a charactertrait that has resulted from the evolutionary process What causes population to evolve mutation change in a gene Mechanisms of Evolution 0 Mutation 000 0 Small population size Nonrandom mating Migration intoout of the population Natural selection Mendelian Genetics is the study of genetic events at the level of the individual organism Molecular Genetics is the study of genetic events at the level of the molecule and cell 0 Population Genetics is the study of genetic events at the level of the population and hence genetics as it pertains to evolution 0 Polymorphism the existence in a population of more than one form of a particular trait or suite of related traits is known as O O O morphological polymorphism variation in physical characteristic chromosomal polymorphism karyotype is usually species speci c but in a population certain nonlethal anomalies may be common immunological polymorphism antigen speci cities may vary within and among populations 0 DNA polymorphisms O O O O restriction site variation variation in location of a restriction sequences among individuals tandem repeats multiplied repeats of a particular DNA sequence complete sequence variation electrophoretically distinguishable classes of genes that differ at a single position polymorphism in a single gene locus at different positions Genes can also vary in their polymorphism at different locations 0 The source of these polymorphisms is mutation germline cells give rise to eggs or sperm 0 heritable somatic cells make up the body itself 0 not heritable 0 Types of Mutations 0 Molecular mutations changes that occur at the level of the DNA molecule itself point mutation simplest type of molecular mutation is the an error in a single DNA base a deletion insertion substitution duplications entire genes duplicated 0 Chromosomal mutations Changes that can be seen at the chromosome level can also change the way the DNA is expressed Losses or additions of whole chromosomes n euploidy quottruequot poidy meaning the normal two members of each homologous pair are present a aneuploidy quotnot truequot poidy meaning more or fewer members than two of each homologous pair are present monosomy only one member of a homologous pair is present trisomy three homologs one too many nullisomy one entire homologous pair is missing 0 Mutations at Level of Chromosome Set a cell with one set of nuclear chromosomes is haploid a cell with two sets of nuclear chromosomes is diploid a cell with more than two sets of nuclear chromosomes is polyploid n autoooIVIoloidv results when extra chromosome sets all come from the same species a aopoypoidy extra chromosome set from a different species a A HYBRID is an organism produced by genetically dissimilar parents 0 A measure of genetic variability in populations is heterozygosity the proportion of genes in the genome that are present in heterozygous condition Genetic variability in a population can be quanti ed as average heterozygosity the average percent of loci that are heterozygous in that population HardyWeinberg Equation 0 pA qa 10 o pquot2 2pq qquot2 pquot2 predicted frequency of homozygous dominant individuals AA qquot2 predicted frequency of homozygous recessive individuals aa 2pq predicted frequency of heterozygous individual Aa o If a study population39s relative genotype frequencies for a particular locus match those predicted by the HW equation the population is NOT EVOLVING at that locus and is said to be in Hardv Weinberg equilibrium with respect to that locus 0 Hybrid individuals usually exhibit a high degree of heterozygosity which results in HYBRID VIGOR o The more closely related parents are the LESS heterozygous their offspring are likely to be 0
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