BSC 2011 UNIT III STUDY GUIDE: PART AUNIT III: Evolution and Population Genetics1. Discuss the following various views people held about life’s diversity (how it arose) and the age of the earth (old? young?) before evolution was suggested:(a) Essentialism/idealismPlatoGod created all thingsAll things have a constant, perfect essence "ideal form"Variation is an imperfect reflection of the inner essenceNo potential life was left unrealizedSpecies don't change; no new speciesAristotle and the "Scala of Nature" (Scale of Nature)All living things are fixed in a linear hierarchyNothing was left out of the hierarchya.k.a species can't, won't and shouldn't change(b) Natural theologyNatural Theologians (monotheistic Western Christians educated around 1600s - 1700s)Studied the natural world to better understand God's PlanAll species were divinely created perfectly all at the same timeAround 6000 years ago based on Judeo-Christian book of Genesis from the Old TestamentIslam and Hindu religions also have similar creation storySide Note: As early as 4th century Saint Augustine wrote God probably only created simple life forms and these developed over timeCarolus Linnaeus (~1750)Organized life into a nested classification system based on similar appearanceEach type of organism had a 2-part binomial scientific name (Genus & Species)Either Italicized or UnderlinedCharles Darwin (1809-1882)Attended Cambridge to become a minister and a naturalist1831: unpaid naturalist on 5 year voyage on the HMS Beagle1. He observed that organisms on same continent more similar than ones on different continents2. He saw a correlation between location and similarity and this suggested common ancestry.Extended Malthus ideas to plants and animalsPopulations in nature are capable of far greater growth than natural resources can supportIdea of a conflict between limited natural resources and reproduction was the seed of Darwin’s idea of evolution by natural selection.NS was Darwin’s proposed mechanism to explain how/why species can change over time (i.e., evolve)Thomas Malthus (1766 – 1834)Demographer and political economistHe said the fate is the poor is inescapable because their reproduction exceeds their means of sustenance (e.g. higher infant mortality and childhood mortality)This was the first suggestion of resource limitation & competition leading to “survival of the fittest”Alfred Wallace 1858Sends Darwin an example of his manuscript outlining his similar view of evolution by natural selection, which forces his hand in publishing his manuscript, On the Origin of Species(c) CatastrophismGeorges Cuvier (1769 - 1832)One of the early Paleontologists also a natural theologianAccepted divine creationBelieved in a relatively young age for EarthSporadic catastrophes caused the appearance and disappearance of organisms the fossil recordE.g. Local floods wiped out existing species and neighboring species moved inNo Evolution(d) UniformitarianismJames Hutton (1726-1797)Geological gradualismGeological features were formed slowly and gradually over a long period of time, not by catastrophes. (e.g. erosion and sedimentation)Charles Lyell (1797 - 18Mechanisms of geological change are constant over time “uniform”The same processes that happen today happened in the past, at the same rateTherefore: The earth must be very old to accumulate all of the geological changes that have occurred.Jean Baptiste Lamarck (1744 - 1829)Species evolve by gradually changing to adapting to their environmentEvolutionary relationships among animalsRight idea wrong mechanism1. "Use and disuse" – if used, body parts become stronger; if not, they deteriorate and eventually disappear.2. "Inheritance of acquired characteristics" - the traits that are acquired through lifetime by responding to the environment can be passes to their offspring. (NOT SO!)2. (a) What is the biological meaning of the term “evolution”?Species change over time and new species arises by the modification of earlier species. (i.e. decent with modification)(b) Contrast microevolution with macroevolution.Microevolution: The gradual evolution of traits within a population of a species over time; populations evolve not individuals.Macroevolution: The evolution of an entirely new species.There is no debate over microevolution.There is a debate over macroevolution between scientists and creationists.3. Describe/explain how each of the following served as evidence at the time of Darwin that evolution could be a means by which life’s diversity arose:(a) Artificial selectionNew species “created” from common ancestor via selective breeding by humans.Different breeds of dogs have arisen by artificial selection & selective breeding but are still the same species (Canis familaris). Microevolution.(b) Comparative AnatomyComparing the anatomy of different organisms supports the idea of descent with modification from a common ancestor.G. Buffon (1707 – 1788) – suggested that species could be similar because they descended from a common ancestor.The same bones and their same relative positions in vertebrate forelimbs suggest they evolved from a common ancestor who had this basic ground plan, but later evolved different functions.Homologous, analogous, & vestigial structures(c) GeologyAdaptive radiation: when populations of an ancestral species “radiate” into several new species, each adapted by natural selection to a distinct environment or life style.Ex. Finches, mainland ancestor finch was an insect eaterConvergent evolution: when unrelated species evolve to look similar not because of common ancestry but because they adapted to similar environments in similar ways.Ex. Sugar glider and flying squirrel,(d) PaleontologyFossils reveal intermediate species leading to modern species.Fossils also reveal other related lineages that did not survive (extinct)Evolution is not “goal oriented”(e) Comparative embryologyEarly embryos of different vertebrates share many “general” features.As development proceeds, similarity persists only among more closely related vertebrates.E.g., Reptiles vs. MammalsVan Baers’s Law4. (a) How can molecular biology provide evidence for evolution?The more recently two species shared a common ancestor, the more similar their proteins & DNA.(b) Provide two examples.1. Percent of amino acids that are identical to those in a human hemoglobin polypeptide. (human, monkey, mouse, chicken, frog, lamprey).2. Phylogeny: the evolutionary
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