Week 3 Notes
Week 3 Notes 82669 - BIOL 3350 - 001
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80887 - BIOL 3150 - 001
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This 8 page Class Notes was uploaded by Abigail Towe on Friday September 4, 2015. The Class Notes belongs to 82669 - BIOL 3350 - 001 at Clemson University taught by Lisa G Rapaport in Fall 2015. Since its upload, it has received 43 views. For similar materials see Evolutionary Biology in Biological Sciences at Clemson University.
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Date Created: 09/04/15
O 0 Evolutionary Biology Biol 3550 Week 03 Lecture Outline Historv of Evolutionarv Thouqht Early ideas about species A Plato s notion of the type 1 Ideal form existence of an ideal form eidos Q visible world was a manifestation of that form with imperfections 2 Fixity ideal form does not change fixity of species B Aristotle 1 Scala naturae Scala Naturae or the Great Chain of Being 2 Implications of Aristotle s scale of life 0 progression from most complex to least complex 0 every organism is ordered in relation to humans which are at the apex Q organisms are unchanging since they are created in perfect form 0 change would imply imperfection in the original creation 0 impossible for new forms to have arisen since creation or for existing forms to have gone extinct C The Renaissance in Europe European thought during the Renaissance 1 Stasis the earth was full and as it should be 0 the result of God s grand design D The age of expansionism amp the scientific revolution The Scientific Revolution 1 Why did this period usher in different thinking about species and our place in nature Expansionism discovery and exploration of new areas examples South and North American and Central amp Southern Africa so people started to see unimaginable things hard to describe sights and knowledge they tried describing new creatures Advances in Science and Technology Astronomers IO 0 I O 000 00 I00 Copernicus determined earth revolved around Sun huge change because people thought earth was center of universe Galileo and Kepler later supported Copernicus theory Galileo ltalian wasn t allotted for his discoveries Mathematicians Descartes French man developed geometry and studied some anatomy to learn functions of body usually people thought of spirits for explanations Newton Printing Press helped to spread new information so much faster than before Gutenberg 2 Carolus Linnaeus published Systema Naturae in 1735 Developed the modern classification scheme that we still use today a strict believer in the fixity of forms deal form does not change fixity of species ll Discovering a world in flux A Comparative biology 1 George Cuvier lived in 18th century Renaissance unity of structure each species had its own harmony of parts species are discrete entities he thought that perhaps groups of species that look similar to each other could have common harmonies common harmonies extended to extinct species didn t really look at a matter of being related to each other just similar first scientists to acknowledge extinct species 2 Why was his examination of extinct forms important to his thinking B Organic Mutability 1 Evidence from artificial selection evidence that plants and animals were not constant in form species could change through artificial selection tremendous amount of variation could be harbored in a single stock 2 Gilbert White 1780 different breeds of pigeons traced back to rock doves looked at all species and how they functioned in their environment he made ecological link to certain birds to certain environments After doing this detailed study he hypothesized that the domestic pigeon came from wild blue bird some sort lmplying ancestor many diverse forms can arise from a single O POPE OO O C Principles of geology calculated extinction rates from fossil record extinction rates were relatively constant from layer to layer He asked himself why aren t all the species found today not represented in oldest strata periods of major extinctions correlated with periods of environmental change process of selection was obviously eliminating species that were unfit for new environmental conditions D Lamarck 1 Theory of inheritance of acquired characteristics 2 In what respects was Lamarck s theory innovative and correct What important link did Lyell make between extinction and the environment Inheritance of acquired characteristics Jean Baptiste de Lamarck use and disuse alter body form during an individual s lifetime organisms change form in response to changing environment E Species selection versus Individual Selection selection among species more fit specie survived less fit species went extinct evolution was differential sorting of chance variations among species One more F Theory of inheritance of acquired characteristics G In what respects was Lamarck s theory innovative and correct F Species selection III Charles Darwin A Early life and voyage on the Beagle upperclass family studied at University of Edinburgh medicine and Cambridge theology Naturalist on long term British navy expedition of HMS Beagle sma ship 18311836 this is where he did most of his observations to develop his theory Route New England South America around Cape Horn Galapagos touches Australia Indonesia Cape of Good Hope of Africa and then back to South America then back home to New England published On the Origin of Species by Means of Natural Selection in 1859 Notice he spent a lot of time examining other collections and doing experiments before publishing this book B Observations from the Galapagos mockingbirds from different islands looked like different species same was true for tortoises and finches biIIs appeared to fit remarkably well with available foods 1 tortoises 2 finches beak sizes change 3 Linking variation to the environment 0 Darwin noticed that island birds changed in character when other competitors lived on the same island The more species the more specialized their beaks Fewer species more generalized beak shapes C Postulates of Natural Selection 1 Hypothesized that individuals within species are variable 2 Certain of these variants are passed on the offspring sometimes traits are passed down but not always 3 In every generation more offspring are produced than can survive Individuals within certain species can reproduce exponentially but the environmental support for that individual is limited so some will survive but not all 4 Differential survival and reproduction struggle for existence only those individuals with favorable variations live to reproduce and contribute offspring to the next generation these individuals are NATURALLY SELECTED hence the mechanism of evolutionary change D Evidence for Natural Selection Fur color in Beach mice the Grants are studying the effect on Darwin s medium ground finch of 19761978 drought on Daphne Major of the Galapagos Islands During this study there are years where there are good rains but some years of serious droughts Tracking them taking beak size etc to study how the finches change with the environmental changes E Alfred Russell Wallace another naturalist living at the same time as Charles Darwin Came from a middle class family one of 9 kids He had to quit school at age 14 and went to work as carpenter with his brother for a while Later he went to explore and collect forms of life 1 Wallace s proposed theory of evolutionary change through natural selection sent his paper to Darwin in June of 1858 Lyell read paper by Wallace and paper by Darwin were both read at annual meeting of Linnaean Society in London later that year Darwin s was read first so it was published first Lyell and Darwin claimed that they had Wallace s permission to read and publish but Wallace said that he never gave permission Darwin published The Origin of Species in November 1859 2 Evidence Observations He did his observations in the Amazon River Basin 4 years and then Malaysian archipelago 8 years He became a collector by trade which caused him to notice variation of traits within species So he noticed all of the variation as he collected and comparedquestionedbegin to study and take notes on them 3 Biogeography the Wallace Line 90093539 Separation of Asian and Australian flora and fauna in as little as 20 miles F Darwin and Wallace s Great Idea Selection occurs among individuals not species the traits are either favored or disfavored change is gradual selection works on small differences among individuals Role of ecological change role of sexual selection Lamarck s view species arise individually complexity increases through time Darwin s view species arise through common ancestry complexity may increase through time G Evidence that Darwin Presented in On the Origin of Species artificial selection selective breeding geographical distribution of species and traits geography embryology anatomy vestigial organs fossils He wasn t comfortable publishing until learning massive amounts of information W 1 Vestigial structures humans have vestigial structures appendix coccyx goose bumps wisdom teeth amp pica semiluniminaris pink part in corner of eye 2 Fossils Darwin knew of fossils studied them in detail If evolution had taken place the fossil evidence should show intermediate species traits partway between two modern species further back in time hypothesized the existence of intermediate prehuman fossils 3 Not aware of plate tectonics or genetics the earth s landmass began as a huge supercontinent Pangaea About 245 million years ago the plates that form the earth s crust began to move apart which caused the single landmass to break apart CO H 1 No goal 2 Not necessarily progressive IV Natural Selection in Action A What is Selection A mechanism of evolution Genetic Drift is another example The process of differential survival and reproduction by those individuals in a population that are better higher survival and reproduction or more poorly lower survival and reproduction adapted to their environment selection acts on phenotypes and indirectly on the genes that produce them Thereby causing a change in gene frequencies over time or promote stability in gene frequencies so it doesn t necessarily mean change How is natural selection measured 1 Stabilizing selection Selection agai f beth extremes Enema tutjn after selection Dr igin el pepulet ien Mean value of the trait is highest More narrow distribution that centers on the mean 2 Directional selection ll m n LL 5 I r r I P I I r 39 r 1 5 39l Directional selection of beak depth in medium ground finches The mean beak size shifted to thicker beaks after drought because that s the most successful beak for finding food O OIOOOOOOOO 3 Disruotive selection HEilm g itEE WE I39 i if 39 Emma an Lilli l alt j r Eng 13 39hl lil m Individuals with mean value is selected against Extremes of trait are selectedfavored could eventually lead to speciation B The Case of Fur Color Evolution in Beach Mice beach mice from Florida come in a variety of colors light to dark Scientists have categorized them in subspecies according to color Facts old field mice beach mice Location Southeast USA Habitat sand burrows in dunes or old fields Home range 1000 mquot2 Breeding monogamous pairbonding Litters of 28 pups every 30 days Lifespan 912 months Eat vegetation and bugs Predators owl fox weasels bobcats snakes Prey on mice by sight and sound Visual predators light furred species live near white sandy beaches darker furred species live near darker beaches Question Assuming that ancestral populations of beach mouse had dark brown fur what could have happened to explain the occurrence of lightcolored coastal subspecies What mutations What kind of biochemical pathways have been affected Hypothesis light furred mice survived longer than darker ones on beaches thus they reproduced more and caused a shift in fur color 1 Ecology of fur color 2 Cell biology of fur color hair color are affected by two pigments eumelanin darker colors O O 0 When is eumelanin produced A transmembrane protein the melanocortin1receptor MC1 R is stimulated by a hormone called the alphamelanocyte stimulating hormone alphamsh to produce lots of eumelanin Can only bind to alphamsh pheomelanin lighter colors 3 Genetics of fur color The mc1 r gene is located chromosome 16 in mammals A single nucleotide substitution can lead to a change in the M01 R protein chain A single mutation of cytosine to thymine changes the amino acid in position 367 from an Arginine to a cysteine The mc1 r gene has two alleles R for arginine and C for cysteine Arginine codes for functional mc1 r protein but cysteine codes for nonfunctional mc1 r protein so 0 O 0 it prevents binding and changes the pigment pathway 4 Population genetics of fur color there are 3 possible genotypes associated with the mc1 r gene RR arginine arginine indicates that both copies of chromosome 16 has an arginine amino acid at position 67 of the mc1 r gene Eumelanin CC gt Cysteine cysteine indicates that both copies of chromosome 16 has a cysteine amino at position 367 of the mclr gene Eumelanin RC has both Is there a relationship between fur color of each mouse individuals and the allele combinations genotypes they possess 5 Simulation
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