Ecosphere Environ Sci I
Ecosphere Environ Sci I EVPP 110
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1E1 Populations Evolution and Natural Selection EVPP 110 Lecture Instructor Dr Largen Fall 2003 2 El Historical background Evidence of evolution Darwin stheory Natural selection Microevolution 3 a Historical Background Ideas about evolution originated before Darwin mid3505 BC 15005 16005 17005 18005 4 El Historical Background mid3505 BC Aristotle noted evidence of natural similarities and relationships among organisms lead him to arrange all organisms he knew into a Scale of Nature extended from most simple to most complex visualized living organisms as being imperfect but moving toward a more perfect state 5E Historical Background 15005 fossils term coined in early 15005 to describe remains of ancient organisms of familiar living organisms in unexpected contexts marine invertebrate fossils imbedded in rocks on high mountains 6E Historical Background 15005 fossils some unlike any known form Leonardo da Vinci first interpret these finds gtgt as remains of animals that had existed in past but had become extinct 7 El Historical Background l1600s emergence of modern scientific l1700s exploration of continents discovery of new species emergence of idea natural world of living organisms must be guided by natural laws as physical world was governed by physical laws 8 El Historical Background l1800s 1809 Jean Baptiste de LamarckFrench naturalist published Philosophie Zooogique Charles Darwin born 9a Historical Background l1800s Jean Baptiste de LamarckFrench naturalist published Philosophie Zooogique in 1809 expressed most accepted view of evolution of that time all living organisms were endowed with vital force that drove them to change toward greater complexity over time organisms could pass traits acquired during their lifetimes on to their offspring gtgt example ancestral giraffe 10 E Figure 22 x4 Jeal i Baptiste Lamarck 11E Historical Background lDarwin s life and experiences led to development of his theory of evolution born in 1809 son physician sent to University of Edinburgh to study medicine at age 15 found himself unsuited for medicine transferred to Cambridge University to study theology and received his degree 12 E Figure 22 is Charles DarWih ih i859 the yearThe Origin of Speceswas published 13 El Historical Background J Darwin s life and experiences 1831 at age 22 embarked on 5year roundtheworld voyage as naturalist on H M S Beagle profoundly influenced his thinking during voyage read extensively about geology collected 1000s of specimens gtgt plants animals fossils including marine snail fossils in Andes observed unique adaptations of organisms 14E 15E Historical Background lDarwin s life and experiences 1836 returned to England at end of voyage his reading and experiences had led himto seriously doubt current thinking of the time gtgt Earth and living organisms were relatively new and unchangeable had come to believe that Earth was very old and constantly changing 16E Historical Background learly 1840s Darwin had composed an essay describing major features of his theory delayed publishing it because he knew it would cause a social furor lmid1850s British naturalist Alfred Wallace who had been doing field work in Indonesia conceived a theory identical to Darwin s 17 E Figure 22 x5 AlfredWallace 18E Historical Background lin 1858 Wallace s work and excerpts from Darwin s work werejointly presented to scientific community 19 El Historical Background l in 1859 Darwin s text On the Origin of Species by Means of Natural Selection was published didn t use term evolution at first referred instead to descent with modification perceived a unity among species gtgt all organisms related through descent from unknown organisms that lived in past 20 E Figure 22 0 Title page from The Origin of Species 21E Historical Background I In 1859 On the Origin of Species by Means of Natural Selection maintained that as descendants spread into various habitats over millions of years gtgt they that 39 39 them to diverse ways of life 22E Historical Background lDarwin s phrase for evolution descent with modification captured the idea that an ancestral species could diversify into many descendant species by 39 of different 39 39 to various 39 23 a Figure ZZl The historical context orDaiWin s iire arid ideas 24 El Evidence of evolution lEvidence of evolution fossil record biogeography comparative anatomy comparative embryology molecular biology 25 E Evidence of evolution J fossil record provides some of strongest evidence of evolution an ordered array in Which fossils appear within layers or strata of sedimentary rock each strata can bear a unique set of fossils representing a local sample of organisms that lived When the sediment was deposited younger strata are on top of older strata position of fossils in strata reveals their relative age 26 El Evidence of evolution lfossil record shows that organisms appeared in a historical sequence oldest known fossils prokaryotes dating from 35 BYA younger layers of rock reveal evolution of various groups of eukaryotes including successive appearance of various classes of vertebrates fishlike then amphibians then reptiles then mammals and birds 27 IE Evidence of evolution J biogeography geographical distribution of species first suggested to Darwin that organisms evolve from common ancestors environment of Galapagos islands resembled that of tropical islands from distant parts of world animals of Galapagos more closely resembled species of mainland South America 28 El Evidence of evolution J Comparative anatomy comparison of body structures in different species anatomical similarities among many species give sign of common descent same skeletal elements make up forelimbs of humans cats whales amp bats since forelimbs of these animals function differently would expect their designs would be different unless they all descended from a common ancestor with same basic limb structure 29 El Evidence of evolution lComparative anatomy homologous structures features that have different functions but are structurally similar because of common ancestry 30 E 31 E Figure 22 i7 Atrarisitiorial fossil lirilltirig past and present 32 El Evidence of evolution J Comparative embryology study of structures that appear during development of different organisms closely related organisms often have similar stages in their embryonic development one sign that vertebrates evolved from a common ancestor all ofthem have an 39 a 39 which quot quot gill r 39 N on sides of throat at that stage embryos of shes frogs snakes birds apes look more alike than different 33 El Evidence of evolution l Molecular biology study of molecular basis of genes and gene expression universality of genetic code is strong evidence that all life is related related individuals have greater similarity in their DNA than do unrelated individuals of same species two closely related species have a greater proportion of their DNA in common than more distantly related species 34 E Table ZZl MolecularData arid the Evolutionary Relationships of Vertebrates 35 E 36E Darwin s Theory J In The Origin of Species Darwin focused on how organisms become adapted to their environments his theory arose from several key observations all species tend to produce more offspring than environment can support individuals of a population vary in their traits organisms variations can be inherited by their offspring 37B Darwin s Theory lall species tend to produce excessive numbers of offspring overproduction production of more individuals than an environment can support leads to a struggle for existence natural resources are limited only a percentage of offspring in each generation survive and reproduce rest are starved eaten frozen diseased unmated unable to reproduce for some other reason 38E Darwin s Theory J quot ofa 39 vary 39 intheir individuals whose characteristics make them best suited adapted to their environment are most likely to survive most likely to reproduce leave more offspring than less fit adapted individuals 39E Darwin s Theory lMany of varying traits of individuals in a population can be passed from one generation to the next heritable variations individuals whose traits make them best suited to an environment are more likely to survive and reproduce and traits that made them well adapted to their environment are likely to be inherited by their offspring 40 El Natural selection I natural selection proposed by Darwin as basic mechanism of evolution essence oanich is differential or unequal success in not all individuals have equal success in reproduction 41 El Natural selection lnatural selection higher reproductive success occurs in individuals that are well adapted to their environment these individuals will reproduce and pass on their traits gtgt their traits will become more heavily represented in the next generation than will the traits of poorly adapted individuals 42 El Natural selection lnatural selection lower reproductive success occurs in individuals that are poorly adapted to their environment these individuals will reproduce less gtgt their traits will become more less and less common in subsequent generations 43 El Natural selection I natural selection individuals that are well adapted to their environment can be said to be most t for that environment or the fittest hence phrase survival of the ttest natural selection leads to in subsequent generations favored traits well adapted will be represented more and more unfavored traits poorly adapted will be represented less and less 44 El Natural selection l natural selection unequal ability of individuals to survive and reproduce leads to gradual change in characteristics of a population of organisms over generations gtgt favored characteristics accumulate gtgt unfavored characteristics disappear 45 El Natural selection lartificial selection provided Darwin with evidence for his ideas on natural selection definition selective breeding of domesticated plants amp animals by selecting individuals with desired traits as breeding stock humans were playing role of environment and bringing about differential reproduction 46 El Natural selection I arti cial selection examples plants broccoli cauliflower cabbages brussel sprouts kale and kohlrabi are all varieties of a single species of wild mustard that were produced by arti cial selection animals hundreds of varieties of domestic dog a single species called Canis familiaris are result of 10005 of years of artificial selection many species of canines resulted from 10005 to millions of years of natural selection 47 E 48 E Figure 22 Mb Arti cial seiection diverse vegetabies derived from Wild mustard 49 E Figure 22 Ma Arti cial seiection cattle breeders ofaricierit Africa 50 El Natural selection lDarwin reasoned if artificial selection could bring about so much change in a relatively short period of time then natural selection over vast spans of time would result in gradual accumulation of hertitable changes that would result in evolution of new spec39es as in five species of canines thought to have evolved from a single ancestral canine 51 El Natural selection lnatural selection in action many examples have been documented peppered moth exists in two forms light colored with splotches of darker pigment where it gets its name uniformly dark variety 52 El Natural selection lnatural selection in action peppered moth feed at night rest during the day on trees amp rocks encrusted with lichens light variety is wellcamouflaged against lichens protected from predators dark variety is conspicuous therefore not protected from predators 53 El Natural selection I natural selection in action peppered moth Great Britain priorto Industrial Revolution darkvariety of moth was rare gtgt not camouflaged against lichens gtgt became prey for birds before they could reproduce and pass onto next generation their genes for dark coloration 54 El Natural selection I natural selection in action peppered moth late 1800s pollution from Industrial Revolution killed large numbers of lichens exposing darker tree bark or roc dark variety of moth became increasingly more abundant gtgt now was camouflaged against dark surface and lighter variety was not by early 1900s in some industrial areas populations consisted almost entirely of dark variety 55 El Natural selection l Population group of individuals of same species living in same place at same time in moth example it was population not individual moths that evolved population is smallest unit that can evolve 56 El Natural selection lPopulation evolution can be measured as a change in prevalence of certain heritable traits in a population over a succession of generations Darwin understood it is populations that evolve did not understand genetic basis of population change 57 El Natural selection lDarwin could not explain cause of variation among individuals making up a population perpetuation of parents traits in their offspring lDue to knowledge that came after Darwin it is now understood that mutations in genes may produce newtraits heritable traits are carried by genes on chromosomes 58 El Natural selection I modern synthesis current version of theory of evolution that includes genetics was developed in early 1940s focuses on populations as units of evolution includes most of Darwin s ideas melds population genetics with theory of natural selection requires an understanding of relationship between populations and species 59 El Natural selection lsexual species biological species group of populations whose individuals have potential to interbreed amp produce fertile o spnng 60E Microevolution lStudying evolution at population level focuses on gene pool total collection of genes in a population at any one time reservoir from which members of next generation will derive their genes can be studied by observing changes in relative frequencies of alleles over time 61 El Microevolution lFor most genes there are 2 or more alleles varieties la population at a given time can be described by relative frequencies of a particular set of alleles lover time relative frequencies of particular alleles in population can change as result of natural selection leads to microevolution change in gene pool as in moth example 62E Microevolution lfrequency of each allele in gene pool will remain constant unless acted on by other agents population to which this applies is said to be in HardyWeinberg equilibrium 63 El Microevolution lHardyWeinberg equilibrium suggests that something other than sexual reproduction is required to alter a gene pool by changing allele frequencies from one generation to next lOne way to determine what factors can change a gene pool is identify conditions necessary to maintain genetic equilibrium 64 E Figure 23 3a The Hardereinberg theorem 65 E Figure 23 3b The Hardereinberg theorem 66E Microevolution J HardyWeinberg equilibrium following 5 conditions must be met population is very large population is isolated no movement into or out of population gene mutations do not alter gene pool mating is random all individuals are equal in reproductive success natural selection does not occur 67E Microevolution lfive conditions necessary for HardyWeinberg equilibrium my occur in nature equilibrium breaks down allele frequencies in natural populations change constantly 68E Microevolution lCauses of microevolution basically reverse of 5 necessary conditions for HardyWeinberg equilibrium l5 causes of microevolution genetic drift gene flow mutation nonrandom mating natural selection 69a Microevolution J Genetic drift change in gene pool of a small population due to chance in small population chance event can have a disproportionately large effect altering gene pool in next generation iguana example assume a small population 3 VWV 2VVlNand 5 ww gtgt an earthquake kills 3 iguana gtgt 3 dead iguanas were all VWV gtgt frequency of Wallele in next generation would be reduced 70E Microevolution lGenetic drift two subtypes bottleneck effect founder effect 71 E M icroevol ution J Genetic drift subtypes bottleneck effect results from event that drastically reduces population size event kills large numbers of individuals unselectively produces small surviving population that is not likely to have same genetic makeup as original population gtgt certain alleles will be present at higherfrequencies other alleles will be present at lower frequencies 72E 73 El Microevolution J Genetic drift subtypes founder effect results from random change in a gene pool that occurs in a small colony colonization of a new location by a single pregnant individual or a small of individuals gene pool of subsequent generations will be derived from just these few individuals thought to have been important in evolution of many species in Galapagos Islands 74 E Figure 23 4 Genetic drift 75 El Microevolution lGene flow gain or loss of alleles from a population by movement of individuals or gametes occurs when fertile individuals move into or out of a population gametes are transferred from one population to another minimizes genetic differences between populations 76E Microevolution l Gene flow reduced by reproductive isolation which increases genetic differences between populations increased by migration wars 77E Microevolution J Mutation random change in an organism s DNA that creates a new allele rare event for any given gene occur once per gene locus per 105 to 106 gametes little effect on large population in a single generation over time vital to evolution because ultimate source of genetic variation serves as raw material for evolution 78E Microevolution lNonrandom mating selection of a mate other than by chance random mating chance would require every male female in population have an equal chance of mating with every female male in population is rare in nature nonrandom mating is the norm in most populations for example in humans short males tend to marry short females 79E Microevolution lNatural selection fifth agent of microevolution differential success in reproduction most likely to result in adaptive changes in a gene pool 80E Microevolution I Some genetic variation seems to have a trivial impact on reproductive success therefore may not be subject to natural selection 81E Microevolution J neutral variation hypothesis proposes that species have some alleles that confer no selective advantage or disadvantage frequencies of these alleles may increase or decrease as a result of chance genetic drift but natural selection will not affect them human fingerprints are probably an example of neutral variation 82E Microevolution lEvolutionary fitness contribution an individual makes to gene pool of next generation relative to contribution made by other individuals fittest individuals in an evolutionary context are those that pass on the greatest number of genes to the next generation 83 El Microevolution llndividuals with a high degree of fitness those whose phenotypic traits enable them to reproduce and contribute genes to more offspring than other individuals lFavored genotypes those whose positive phenotypic effects outweigh any harmful effects they may have on reproductive success of organism lBy culling less fit individuals natural selection also cus unfavored genotypes 84E Microevolution 85E lnatural selection can alter phenotypic variations in an idealized population three main ways stabilizing selection directional selection diversifying selection 86E Microevolution 87E lstabilizing selection favors intermediate variants typically occurs in relatively stable environments where conditions tend to reduce phenotypic variation probably prevails most of time in most populations 88E Microevolution lDirectional selection EVPP 110 LecTure Learninq Guide 14 Fall 2012 Physical EnvironmenT Volcanoes Bloom s Revised Taxonomy REMEMBERIN6 0 Define o Volcano o VenT in crusT of EarTh Through which magma reaches surface 0 Lava o Magma ThaT reaches surface 0 Magma o MolTen rock locaTed under The surface 0 Lahar o MixTure of pyroclasTic maTerial rocky debris and waTer o PyroclasTic flow 0 FasT moving currenT of hoT gas and rock 0 STraTovolcano o A volcano madeup of several layers made up of cooled layers of layer Tall Can have boTh violenT and quiTe erupTions 0 Shield volcano o A volcano ThaT is made up of dried layers of lava The lava Travels fasT and far before cooling 0 Cinder cone volcano 0 Same as sTraTo buT sTeeper 0 Ring of Fire 0 A chain of volcanoes locaTed in The Pacific rim 0 Volcanic explosiviTy index 0 A measure of how explosive a volcano is IT measures The plume heighT and volume of releases 0 Mudslide O o Landslide 0 When a large parT of a volcano collapses Bloom s Revised Taxonomy UNDERSTANDING Explain lisT sTaTe o STaTe The causes of volcanoes o Converging plaTe boundaries which resulTs in subducTion The subducTed plaTe accumulaTes wiTh The magma which causes The magma needing To be released DivergenT common sense EVPP 110 LecTure Learninq Guide 14 Fall 2012 Explain The relationship beTween volcanoes and TecTonic plaTe boundaries Explain how The movemenT of plaTes relaTive To one anoTher resulTs in The producTion of earThquakes and volcanoes STaTe The general locaTions of volcanoes 0 Near and around belTs siTuaTed on plaTe boundaries LisT The Three Types of releases from volcanoes o EjecTa 0 Liquid lava o Gases LisT The gases ThaT can be released by volcanoes 0 C02 0 WaTer vapor o Sulfur Dioxide LisT The effecTs of volcanoes o Lava flows 0 Ash deposiTion o Mud slide aka lahar o Landslides o Lahars o PyroclasTic flow 0 BlasT zones 0 Toxic gas 0 Tsunamis o ATmospheric dusT Explain how can a volcano impacT climaTe o The ash will bloT ouT The sun Baom s Revised Taxonomy APPL YIN6 PracTice InTerpreT a diagram To deTermine The Type of volcano being illusTraTed uesTions 1 Which of The following are Types of volcanoes discussed in class a sTraTovolcano b shield volcano c cinder cone volcano a and b only 2 Which of The following are Types of releases from volcanoes discussed in class a ejecTa b liquid lava c gases d a and c only EVPP 110 LecTure Learninq Guide 13 Fall 2012 Physical EnvironmenT Earthquakes Bloom s Revised Taxonomy REMEMBERIN6 0 Define o EarThquake A sudden release of energy in The earTh s crusT o FaulT A disconTuniuTy in rock formaTion caused by The movemenT of The crusT 0 Focus The poinT of origin of an earThquake o EpicenTer The poinT in The surface direchy above The focus poinT o Foreshocks Tremor preceding an earThquake o AfTershocks A smaller earThquake following The main shock of an earThquake o Seismograph A device used To measure The movemenT of The earTh Usually used To measure The effecTs of an earThquake o Seismogram A graph generaTed by a seismogram IT is a record of ground movemenT o RichTer scale A scale used To raTe The amounT of energy released by an earThquake o Mercalli scale A scale used To scale The inTensiTy of an earThquake o Tsunami An indirecT effecT of an earThquake IT is caused by a large and sudden displacemenT of waTer which resulTs in The formaTion of a series of large waves 0 Seiche An indirecT effecT of an earThquake A wave in an enclosed body of waTer o Landslide An indirecT effecT of an earThquake The failure of a slope which resulTs in a large mass of earTh sliding o LiquefacTion When waTer is mixed in dry mass This resulTs in solid mass moving like waTer Bloom s Revised Taxonomy UNDERSTANDIM 0 Explain whaT causes earThquakes 0 When plaTe boundaries converge and cause a sudden release of energy in The earTh EVPP 110 Lecture Learninq Guide 13 Fall 2012 List the primary effects of an earthquake 0 Effect on 0 People 0 Buildings damage collapse 0 Bridges damagecollapse o Overpasses damage collapse 0 Dams damage collapse 0 Pipelines damage Explain what causes the primary effects of earthquakes o The movement of earth disrupts the foundations of infrastructure which damages them and sometimes leads to human death List the secondary effects of an earthquake o Tsunami o Seiche o Landslides o Liquefaction 0 Fire 0 Disease Explain what causes the secondary effects of earthquakes Explain how can an earthquake lead to increases in disease Explain the relationship between earthquakes and tectonic plate boundaries State what the Ritcher scale measures State what the Mercalli scale measures Explain the relationship between different units on the Ritcher scale Bloom s Revised Taxonomy APPL YIN6 Calculate the difference in severity of two earthquakes with different Ritcher scale ratings Practice uestions 1 The is the initial rupture point of an earthquake within the Earth whereas the is the point on the Earth39s surface that is directly above the of the earthquake a focus epicenter focus no9 divergentplate epicenter focus plate boundary epicenter focus epicenter epicenter plate epicenter