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Midterm

Midterm I Lecture Summary.docx

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Department
Biology
Course
BIOL 359
Professor
Jonathan Witt
Semester
Winter

Description
Topic I: Science and Intelligent Design Theory Intelligent design theory: Alternative “scientific theory”? To promote the presence of an intelligent designer, promoted by the Discovery Institute and Center for Cultural Renewal, an alternative to Darwinian Evolution?? - Religious school board members asking for it to be included in science classes against parents - Of Pandas and People = Supplemental Biology Text - William Paley (1802): Complex eye  Eye maker - Micheal Behe: Irreducible complexity, cannot function if any protein is removed, hence there is no way there are any functional precursors that has arisen through selection e.g. the flagella o Eel sperm contains no outer dynein & no central pair complex, yet it functions just fine Scientific terms vs. Vernacular terms - Scientific o Fact: Repeatedly confirmed observation, accepted as “true”, never final, will always undergo modification o Scientific Theory: Explanation of some aspects of the natural world (Facts) that incorporates facts, laws & tested hypotheses, must be falsifiable & internally consistent o Scientific Hypothesis: Statement that leads to deductions/predictions that can be tested. If tested to be incorrect, original hypothesis is abandoned or modified o Scientific Law: Descriptive generalization about how some aspects of the natural world behaves under specific specified circumstances (Prescriptive) - Vernacular o Facts are about the same o Hypothesis: Similar to a guess o Law: Descriptive to prevent someone doing certain things Science vs. ID Theory - If we observe a structure that’s complex, then we should invoke the existence of something that’s even more complex to explain its existence?  Internally Inconsistent - Why are the designs so lousy? E.g. the Human appendix Topic II: A Short History of Evolution - Evolutionary biology began in the 1859s after the publication of the On the Origin of Species - Before evolution, Plato  Aristotle, God’s creation following a plan “The Great Chain of Being” o Changing would imply imperfection - Linnaeus “Father of Taxonomy” – Homosapiens - Lamarck: The 1 person to explore the issue of evolution, Inheritance of acquired characteristics (e.g. giraffe’s neck)  Spontaneous generation, and evolve towards a perfect form - Erasmus Darwin: Species are modified descendants of earlier forms - Georges Cuvier: Supporter of catastrophism “Earth’s features had been primarily modeled by great catastrophes that resulted from forces that no longer operates today”, popular POV until modern geology o Tries to reconcile geological history with the age of the Earth according to the Bible - James Hutton: Father of modern geology, responsible for the Principle of Uniformitarianism “today, same as we see operating in the past”, evidence presented by Charles Lyell, ended the era of catastrophism - Charles Darwin: Naturalist on the H.M.S Beagle ship  Finches o Worked on his idea for 20 years until he received a letter from Alfred Wallace, announced idea at Linnean Society in London in 1858  All species have descended without interruption from 1 or few original forms of life  Theory of natural selection to explain - The evidence for evolution was well accepted, but the mechanism of inheritance was unknown - Johann Gregor Mendel: Basis for modern genetics, compatible with natural selection - The Origin of Species + The Theory of Genes  Modern Synthesis/Neo-Darwinian Synthesis o Natural selection acts on genetic variation in populations “Population Genetics” 1 - Present molecular developmental genetics reveals deep homologies in genes controlling development Topic III: Evidence for Evolution - Evolution: Descent with modifications, or change in population of allele frequencies - Homology: Similarity from common ancestry, despite differences in function - Analogy: Similarity due to similar in function, not common ancestry - Special creations vs. Evolution o Special creations: Species do not change over time, each species created separately, young earth o Evolution: Species change over time, common ancestor, old earth o E.g. Domestication of Dogs, all are descended from wolves through phylogenetic analyses, result of selective breeding by humans (lots of biological changes in minimal geological variations) - The 2 modes of evolution: o Microevolution: Small changes within species (e.g. changes in allele frequencies) o Macroevolution: Larger phenotypic changes that is sufficient to place an organism in a different higher level taxon (combination of microevolution over time) - Descent with Modification o Soapberry bugs: Short beaks are descendants of long beak bugs o House sparrows: Rapid spread over North America, populations evolved differences in body size & coloration o Vestigial structures & organs: Useless structures that serve no functions in the organisms that possess them, but do have functions in closely-related species  Snakes legs from reptiles with limbs; Flightless bird wings from birds that can fly  Human coccyx from ancestor with tails; Human erector pili muscle from furry ancestors - The Fossil Record o If there is no evolution, same organisms should exist throughout the entire Fossil Record o If there is evolution, organisms inhabited the Earth change & there should be strong geographic patterns with respect to similar organisms  E.g. Extinct organisms: Irish elk & Trilobites  Law of succession: Fossils in a given geographic region are more closely related to the extant fauna of that region than they are to organisms in a different geographic region  Extant organism (Living) vs. Extinct organism (Fossil)  Transitional forms: Intermediate forms between the past & present organisms  E.g. Archaeopteryx, between dinosaur & bird (birds are descendants of didnosaurs)  E.g. Basilosaurus, between mammals & whales (with rudimentary pelvis bones)  Relatedness: The mockingbirds, finches, shared ancestry within phylogenetic trees - Phylogenetic Trees (Different rotation but essentially the same*) o Phylogenetics: Study of ancestory/descendent relationships o Phylogeny: Hypothesis of ancestory/descendent relationships  The closer in time the species shared a common ancestor, the more closely they are related  Polygon: If all 3 species are equally related to each other, they are sister taxa o Homology: Common ancestry, tested with pseudogenes  Genetic Homology  Pseudogene: A copy of the parent gene with no introns & no promoter regions “no expression”, they are free to accumulate mutations @ a rapid rate, used to determine the age of the organism o More species share the older processed pseudogenes o Human only share the most recent 3 with chimps & gorilla  Humans would be much better off with their own set of genetic codes “immune to diseases transmitted across species” 2 o rRNA sequences are one of the most conserved region of the genome  was chosen to construct the tree of life  Structural Homology  Vertebrate arms, natural selection tinkers the basic plan  variations  Plants with the same basic structure  Developmental Homology  Similar embryonic forms branches into different adult forms  Hernias: Intestine protrudes into the scrotum sac due to weakness in the groin - Ring species: Single species in the process of diverging into 2+ species o E.g. Siberian Greenish Warbler: Can no longer recognize/mate with each other - Analogy: Similar in function, independent evolution - The age of the Earth (Uniformitarianism vs. Catastrophism) o Uniformitarianism: Assigned dates to various rock strata  relative dating scale  Radiometric Dating: Rate of decay not influenced by temperature, weather or anything else  Measured as in half-lives, potassium-argon dating for volcanic rocks (argon = gas = bubbles out)  Earth is about 4.6 Billion years old (same for meteroids or moon rocks) o Plate tectonics: Fossils of the ostrich bird, correspondence between fossil, biological & geological data Topic IV: Introduction to Natural Selection - Darwin’s great contribution: The formal development of a mechanism that explains how evolution can occur - Natural selection: Differences in the survival & reproduction of phenotypes results in different contribution to the next generation, hence a change in the frequency of heritable phenotypic variations in population o Not just survival of the fittest but must also contribute to the next generation - More offspring “universal”  Struggle for existence  heritable variation in phenotypes due to genotypes  Those best adapted to current conditions are more likely to survive & reproduce o Changes in allele frequencies & gene frequencies are NOT the same o Only changes in population allele frequencies results in evolution - Population genetics: The study of allele and genotype frequencies & their changes in entire populations - Evolutionary fitness: The # of offspring an individual contributes (more offspring = greater fitness) o Viability/Mortality Selection: Ability to survive to reproductive age o Sexual Selection: Ability to procure a mate (Mating success) o Fecundity Selection: Family size, measures the # of female gametes produced (e.g. litter size)  Excess fecundity is universal in nature  E.g. About 2 eggs per female Atlantic cod survive to reproductive success - Adaptation: Trait that increases an individual’s fitness compare to those that doesn’t have the trait o Natural selection  Adaptive evolution “↑ # of frequencies of that trait in the next generation” - Darwin’s Theory of Natural Selection (4 Postulates) o Individuals within species are variable, some of these variations are heritable, more offspring are produced than survive, the survival & reproduction of individuals is not random but are naturally selected  Heritability: The proportion of trait variation in a population that is attributable to genetic factors, not environmentally induced differences (slope from 0 to 1)  E.g. Pepper selection by rats, the mild ones are eaten compare to the hot ones & the composition of the population changes from 1 generation to the next  E.g. Finches on Daphne Major, different beaks mostly due to variation in food “feeding polymorphism” 3  Species flock: Ancestor that originally colonized the land and diverges off into more different species  They have variable beak size, body weight & wing span, variation has a genetic basis (measured heritability, strong correlation), drought selection, only a fraction of the population survived to reproduce, since seed availability changed o Drought caused the abundance of small seeds to decrease  After the drought there is an increase in average beak depth o NS does not produce new variations on its own, it simply acted on heritable phenotypic variations & altered the frequencies of different phenotypic variants (mutation & recombination produces new variations)  Natural selection is dynamic: Phenotype favoured in one generation can be very different than those favoured in a subsequent generation  Introduction of The Cane Toad to Australia  South America, introduced to Australia to control Sugar Cane Beetle populations  Possess skin glands that secrete highly toxic substances, predators died in large #s  Snakes with large jaws & stout bodies were able to ingest cane toads & they were eliminated from the population  ↓ in jaw size & ↑ in slenderness (non-random) - Natural selection: o Acts on individuals, but consequences occur in populations o Acts on phenotypes but results in changes in allele frequencies (environmental – 0 heritability vs. genetic components – 1 heritability) – NOT GENOTYPE FREQUENCIES o Backward looking, acts on the parents, offspring are better adapted in the environment that their parents lived in (always a generation behind, DOES NOT anticipate the future) o Can produce new traits via mutation o Does not lead to perfection, all organisms are equally successful in their own environment  E.g. Gonopodium, bigger is preferred by females but it creates drag when it swims  Antagonistic selection: 2 component of NS acting in opposition to each other, can’t optimize both at the same time, resulting in compromises between the 2 forces “equilibrium” o Non-random & not progressive: Goal is to increase adaptation, but doesn’t lead towards some predetermined goal, no trend towards more advanced forms of life o Does not act for the good of the species (E.g. Geladas Baboons  Infanticide) - Human Induced Selection in Natural Populations o Only animals over a certain size can be taken o E.g. Ram Mountain Alberta, only restriction is that horns must be greater than a minimum specified size, hunting season is prior to breeding season  Larger horns = Less fitness  Mean male horn length declined over a 30 years period o E.g. Evolution of bacterial resistance to antibiotics: MDTB Topic v: Mutation & Genetic Variation - Mutation: The ultimate source of all genetic variations, provides raw material for other evolutionary forces such as NS or GD. It is any heritable change in DNA (Germ-line mutations not somatic mutations) o Point mutations: Synonymous “No AA change” or non-syrdnymous “changes AA”, many are synon
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