Evolution by Natural Selection
Evolution by Natural Selection Biology201
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Date Created: 11/01/15
Evolution by Natural Selection Wednesday October 21 2015 Chapter 22 Lecture 16 The Darwinian revolution challenged traditional views of a young Earth inhabited by unchanging species 1 1859Darwin published The Origin ofSpecies a noted that current species are descendants of ancestral species b Evolution descent with modi cation i Both a pattern and process 2 Scala Naturae and Classi cation of Species a Scala naturae view of species developed by Aristotle b Old Testament holds that species were individually designed by God and therefore c Carolus Linnaeus interpreted organismal adaptions as evidence that the Creator had designed each species for speci c purpose d Founded taxonomy e Developed the binomial format for naming species i Categorize species 2 Ideas About Change over Time a Fossils remains or traces of organisms from the past usually found in sedimentary rock which appears in layers called strata b Paleontology study of fossils i Developed by Georges Cuvier b Abrupt boundaries between strata represent catastrophic events i Catastrophism b James Hutton and Charles Lyell perceived that changes in Earth39s surface can result from slow continuous actions still operating today and at the same rate 2 Lamarck39s Hypothesis of Evolution a b inheritance of acquired characteristics c Species evolved to match their environments 2 Darwin39s Research a Voyage of the Beagle i Goes to south America ii Found fossils that resembled living species from the same region and living species resembled other species from nearby regions iii Experiences an earthquake in Chile and saw a landslide and the uplift of a strata iv Galapagos islandsbirds with different peaks can eat different things Adaptation to the environment and origin of species Natural selection mechanism off descent with modi cation but did not introduce his theory publicly i Process in which individuals with favorable inherited traits are more likely to survive and reproduce nO39 ii Alfred Russel Wallace Monday October 26 2015 Lecture 17 Chapter 22 1 Evolution is supported by an overwhelming amount of scienti c evidence a New discoveries continue to ll in the gaps b i Direct observation ii Homology iii Biogeography iv Fossil records b Arti cial selection species modi ed by selecting and breeding individuals with desired traits i Wild mustard plants 2 Natural Selection and Adaptation a Natural selection process in which individuals with favorable inherited traits are more likely to survive and reproduce i De ned by Darwin from inferences from two repeated observations a Observation 1 i Members of a population often vary in their inherited traits b Observation 2 i All species can produce more offspring than the environment can support and many of these offspring fail to survive and reproduce b Inference 1 i Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to leave more offspring than other individuals b Inference 2 i This unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the populations over generations b Individuals do not evolve populations evolve over time i Natural selection only increases or decreases heritable traits that vary in a population 2 Direct Observations a Natural selection in response to introduced plant species b The evolution of drugresistant i Staph infections ii MRSA methicillin resistant Staph strain 1 Uses different gene than what methicillin kills ii Within two years of penicillin being developed there were resistant strains 1 The strongest strains live through the drug ii Methicillin works by inhibiting a protein used by bacteria to produce cell walls iii Basically creates quotsuper bacteriaquot b Natural selection does not create new traits but edits and selects for traits that are already present in the population c The current local environment determines which traits will be selected for or selected against in any speci c population i If environmental conditions change so does the selective pressure on traits 2 Homology a Homology similarity resulting from common ancestry i Not what they do but how they39re built ii Lizard bird human whae yes iii Octopus sea starno b Homolooous structure anatomical resemblances that represent variations on a structural theme present in a common ancestor i Human cat whale bat b Comparative embryology reveals anatomical homologies not visible in adult organisms c Vestigial structures remnants of features that served important functions in the organism39s ancestors i At the molecular level are genes shared among organisms inherited from a common ancestor b Evolutionarv trees phvlooenies hypotheses about the relationship among different groups i Tree shaped diagrams that shows how species are related based on common ancestors