EVS 1101 NOTES from the textbook.docx

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Environmental Science
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Danielle Fortin

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EVS 1101 NOTES from the textbook Chapter 3 Evolution Biodiversity and Population ecologyGolden toads of Monteverde have not been observed since 1989 They lived in cloud forests and would appear during the early part of the regions rainy seasonThey became extinct due to global warming and have not been found since 1989Evolution change over time but scientists refer to it as biological evolutionBiological evolution genetic change in organisms across generations often leads to modifications in the appearance functioning or behaviour of organisms comes from random genetic changes or directed by natural selectionNatural selection traits that enhance survival and reproduction are passed on more frequently to future generationsDarwin realized that organisms produce more offspring thancan survive some more likely than others individuals that had an advantage in surviving and reproducing might be inherited by their offspringIndividuals of the same species vary in their characteristicsWe now know that difference is due to differences in genes genes and the environmentThe same genes that make an organism well suited in one env may disable it in another envPunctuated equilibrium evolutionary change that occurs quickly in short bursts separated by long periods of stabilityA parent that is long lived and produces many offspring will pass on genes to more offspring than a weaker shorterlived parent with few offspringIn the next generation the offspring will be better adapted and prevailAdaptive trait a trait that confers greater likelihood that and organism will reproduceMaladaptive trait that reduces successHeritable traitsgenes in organisms DNA must code for the traitAccidents may occur that change the DNA and cause genetic variation in DNAMutations accidental changes in DNA from addition deletion or substitution of single nucleotides to the insertion or deletion of large sections of DNAIf mutation occurs in a sperm or egg cell it can arrive in the next generationRecombination produces combinations of genes generating variationDirectional selection trends towards larger or smaller faster or slowerStabilizing selectionproduces intermediate traits preserves status quoDisruptive selectiontraits diverge from their starting condition in two or more directionsEnvironment will put pressure on natural selection on an organismConvergent evolution two completely separate and distinct species evolve similar traits generally as a result of adaptation to selective pressures from similar environments or habitatsover time the organisms respond to selective pressures exerted by the physical characteristics in the environmentadaptive radiation burst of species diversification that occurs in response to environmental change natural selection allows for the development and diversification of traits leading to emergence of new species and new organismsartificial selection breeding organisms artificially selection conducted under human directionselective breeding same as artificial selection exaggerate traits we preferbiological diversity the sum of all organisms in an area taking into account the diversity of species genes populations and communitiesspecies particular type of organisms or a population or group of organisms who are similarpopulation group of individuals of a particular species that live in the same area Speciationnew species are generatedallopatric speciation emergence of a new species as a result of physical separation of populations over some geographic distancedivergent evolutionover time populations diverge or grow different and can no longer mate with each other populations can be separated in many ways glacial sheets moving across continents major rivers may change course drying climate may evaporate lakes warming or cooling of temperature plants move in order for speciation to occurpopulation need to be isolated for thousands of generationsif the glacier recedes or the river returns to normal etc the populations can come back togethermoment of truth if the populations have not diverged enough the individuals will interbreed and reestablish gene flow mixing the variations and gone back to normalif the pops have diverged enough then they will not reproduce togethersympatric speciation species from populations that become reproductively isolated in new niche and in same geographic areain plants speciation has occurred as a result of hybridizationphylogenetic trees explain how divergence took place relationships between speciesextinction disappearance of species from Earthextinction is natural process but humans have impacted the rate at which it occursthe loss impacts humans because it lowers our resourcesextinction generally occurs when environmental conditions change quicklyendemic native or restricted to a particular geographic region only occurs in one place and nowhere else eg Monteverde cloud forestmass extinctionwiped out 5095 of out planets species at a time th biologist and scientists alike believe that we are starting our 6 mass extinction by humans
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