Study Guide/Bundle BIOL 1306/1106
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This 19 page Study Guide was uploaded by Hayley Lecker on Thursday September 10, 2015. The Study Guide belongs to BIOL 1306/1106 at University of Texas at El Paso taught by Anthony Darrouzet-Nardi in Fall 2015. Since its upload, it has received 80 views. For similar materials see Organismal Biology in Biology at University of Texas at El Paso.
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Biology Bundle Important Information Professor s Email aidarrouzetnardiutepedu or anthonvdnutepedu Chapter 15 Process of Evolution reference pages 298324 151 Evolution Both Factual and the Basis of Broader Theory The changes in the genetic composition of a population is called evolution Evolutionary theory is the understanding and applications of the processes of evolutionary change to biological problems Darwin s 3 major propositions about evolution 1 Species are not immutable they change over time 2 Divergent species share a common ancestor diverged over time Darwin termed this descent with modification 3 Changes over time arecan be explained by natural selection quotSurvival of the Fittest Lecture Notes Darwin Darwin s theory became popular because of the origin of species It was readable book for the average individual to understand and his scholarship was impressive Darwin believed that evolution requires counterintuitive thinking Geometric growth acceleration of exponential process Seeing the full continuum of the variation instead of only seeing the extreme points of evolution importance of variation in species Understanding of the geological time scales evolution happens over millions of years not decades 152 Mutation Selection Gene Flow Genetic Drift and Nonrandom Mating Result in Evolution A population is a group of individuals of a single species that live and interbreed in a particular area This is importance to understand as it is used throughout the chapters Individuals do not evolve however population do Mutation generates genetic variation this builds on Darwin s term descent with modification A mutation is any change in the nucleotide sequence of an organisms DNA Most mutations are a Deleterious meaning harmful or b Neutral meaning no effect Very few mutations are beneficial to the organism An allele is a different form of a gene a variation Selection on genetic variation leads to new phenotypes Through natural selection certain genetic variations will increase in frequency of beneficial mutations in populations Adaption is a favored trait that evolves through natural selection Natural selection acts to remove deleterious mutations from a population it can be related to a safe guard so certain harmful genes do not affect multiple people This can be done by making the individual with the deleterious mutation infertile or by death Gene Flow is the migration of individuals and movements of gametes between populations The book says it is a phenomenon Genetic Drift is the random changes in allele frequencies from one generation to the next may cause large changes over time Population bottleneck is the result of environmental events which causes only a small number of a population to survive Founder effect is the random changes in allele frequencies resulting from establishment of population by a very small number of individuals Example Christopher Columbus coming to America think about the genetic changes to the population and the animals and plants introduced into new environments Sexual selection occurs when individuals of one sex mate preferentially with particular individuals of the opposite sex rather than random This can be seen in human behavior with how we pick our quotmatesquot 153 Evolution can be measured by changes in Allele frequencies Evolution can be measured by looking at changes in allele and genotype frequencies over time in a population There is an equation to measure the change in allele frequencies Allele frequency number of copies of the allele in the populationtotal number of copies of all allele in the population please note that the means divided by The frequency of an allele range from 0 to 1 Monomorphic means there is only one allele at a locus meaning the frequency is equal to 1 Polymorphic means more than one allele is at a locus Genetic structure is the frequencies of different alleles at each locus and the frequency of different genotypes in a population HardyWeinberg equilibrium is a model in which allele frequencies do not change across generations and genotype frequencies can be calculated from allele frequencies This applies only to sexually reproducing organisms If a population is at HardyWeinberg equilibrium is must meet the following criteria There must be no mutation No gene flow No selection of genotypes Infinite population size Random mating Populations in nature do not meet the strict guidelines for the HardyWeinberg equilibrium this helps explain why populations evolve Even though in populations do not meet the guidelines it is importance because it is useful for predicting genotype frequencies of a population from its allele frequencies and allows biologists to evaluate which processes are acting on the evolution of a population 154 Selection can be stabilizing directional or disruptive Qualitative traits are traits distinguished by discrete qualities Example black vs white Quantitative traits is the phenotype determined by multiple alleles Natural selection can act on quantitative traits in three ways 1 Stabilizing selection favors average individuals This reduces variation in populations but does not change the mean Keeps the gene sequence the same 2 Directional selection favors individuals that vary in one direction from the mean Individuals at one extreme contribute more offspring to the next generation Evolutionary trends may result 3 Disruptive selection favors individuals that vary in both directions from the mean Individuals at opposite extremes contribute more offspring to the next generation Increases variation in a population 155 Genomes Reveal Both Neutral and Selective Processes of Evolution Nucleotide substitution is the change in one nucleotide in a DNA sequence a point mutation Synonymous substitution this type of substitution mostly does not affect phenotypes because most amino acids are specified by more than one codon Nonsynonymous substitution is deleterious or selectively neutral Substitution rates are highest in positions that do not change the amino acid being expressed They are even higher in pseudogenes copies of genes that no longer are functional 156 Recombination Lateral Gene Transfer and Gene Duplication Can Result in New Features In asexual reproducing species deleterious mutations can accumulate the only way of removing them is death of a lineage Sexual reproduction results in new combinations of genetic material which increases evolutionary potential In the short term it can have disadvantages recombination can break up adaptive combinations of genes reduces the rate at which females pass genes to offspring and dividing offspring into genders reduces the overall reproductive rate Lateral gene transfer is the process of individual s genes organelles or genome fragments moving horizontally from one lineage to another Species can pick up DNA fragments directly from the environment genes may be transferred to a new host in a viral genome and hybridization results in transfer of many genes Gene duplication can cause genomes to can new functions Gene copies can have different fates 1 Both copies retain original function 2 Gene expression may diverge in different tissues or at different times in development 3 One copy may accumulate deleterious mutations and become functionless 4 One copy retains original functions the other changes and evolves a new function Lecture Notes Vocabulary Evolution descent with modification the idea that living species are descendants of ancestral species that were different from the presentday ones also defines more narrowly as the change in genetic composition of a population from generation to generation Natural Selection The differential contribution of offspring to the next generation by various genetic types belonging to the same population Adaptation A particular structure physiological process or behavior that makes an organism better able to survive and reproduce Artificial Selection The selective breeding of domesticated animals and plants to encourage the occurrence of desirable traits Biogeography Study of location of plants and animals in different places throughout the world Homology A similarity between two or more features that is due to inheritance from a common ancestor Analogy Similarity between two species that is due to convergent evolution rather than descent from a common ancestor Convergent Evolution Independent evolution of similar features from different ancestral traits Vestigial structure A feature of an organism that is a historical remnant of a structure that served a function in the organism s ancestors Exaptation A character previously shaped by natural selection of a particular function is coopted for a new use Intermediate Forms Fossils or organisms that show the transformation from ancestral form to descendant species form Chapter 16 reference pages 325342 Chapter 161 All of Life is connected through its Evolutionary History All life is related through a common ancestor Phylogeny is the evolutionary history of these relationships A Phylogenetic tree is a diagrammatic reconstruction of that history As the example to the left A lineage is a series of ancestor and descendant population shown as a line drawn on a time axis The only problem with the example to the left is it doesn t have an x axis to represent the 2 passage of time FTI M When a single lineage divides into two it is directed as a split or node The example to the left shows the ancestor lineage being 11 which spilt into 13 and 12 and so forth Each descendant population can give rise to a new lineage which continues to evolve The example phylogenetic tree shows that 12 gave rise to 15 and 16 A phylogenetic tree is not limited to one species it can depict all life forms major evolutionary groups small groups of closely related species individuals populations or genes The common ancestor of all organisms in the tree forms the root of the tree The splits can represents events where one lineage divides into two because of a speciation event for a tree of species a gene duplication event for a tree of genes and a transmission event for a tree of viral lineages through a host population Vertical distances between braches don t have any meaning and the order of the vertical branches is arbitrary Take 19 in the example above it gave rise to 10 and 9 those two numbers could be switched and the image would still have the same meaning Any group of species that we designate with a name is called a taxon A taxon that consists of all the evolutionary descendants of a common ancestor is called a clade A clade can be identified by choosing any point on a phylogenetic tree and tracing all the descendant Hneages Two species that are each other s closest relatives are called sister species Any two clades that are each other s closest relatives are called sister clades Before the 1980 s phylogenetic trees were mostly used in evolutionary biology and in systematics the study and classification of biodiversity Today phylogenetic trees are used in almost all fields of biology Evolutionary relationships among species form the basis for biological classification As new species are discovered phylogenetic analysis are viewed and revised this simply means that the tree is updated to reflect new insight The tree of life s evolutionary framework allows us to make predictions about the behavior ecology physiology genetics and morphology of species We can also make predictions about missing quotevolutionary links that sometimes haven t been discovered yet Any features shared by two or more species that have been inherited from a common ancestor are called homologous features They are not limited to just phenotypes but can be DNA sequences protein structures anatomical structures and even behavior Each character of an organism evolves from one condition the ancestral trait to another condition the derived trait An example of this is the vertebral column what we call our spines is a trait shared by vertebrates The ancestral trait of this was an undivided supporting rod Traits being developed it is not just between an ancestral tree sometimes unrelated groups can develop similar traits Convergent evolution is when superficially similar traits may evolve independently in different lineages In an evolutionary reversal a character may revert from a derived state back to an ancestral state An example of this is the whale whales are descendants of creatures who evolved into land walking creatures however through evolution whales became aquatic again it s key to remember that we all descendant of water creatures that eventually became land creatures thus reverting back to an ancestral state Similar traits generated by convergent evolution and evolutionary reversals are termed homoplastic traits or homoplasies Ok that was a lot of information but realize evolution is a long history and covers a lot So before going on take a break this is a lot to absorb Chapter 162 Phylogeny Can Be Reconstructed from Traits of Organisms Figure 163 Inferring a Phylogenetic Tree 39 The earliest branch in the tree 39 represents the evolutionary split between the outgroup lamprey and the ingroup the remaining I species of vertebrates 1 v 4 The lamprey is 39 x quoti designated as Lamprey lthe outgroup outgroup Common ancestor Perch V Jaws lt E z quot Derived traits are Loquot Salamander indicated along x 439 lineages in which 971 J the evotved 7 1quot Lun s x y 7777777 N x g Lizard Keratinous 7 scales 39 gt Ingroup Claws Crocodile or nails Gizzard lt Feathers Pigeon Fur mammary l d C 7 gan 5 Mouse j quotquotll Chimpanzee PRINCIPLES OF LIFE Figure 163 flf39 2012 Sinauer Associates Inc Throughout 162 we will refer back to this image so I took the liberty of including it as it is a great example to help explain The group of organisms of primary interest is called ingroup A species of group known to be closely related to but phylogenetically outside the group interest is called outgroup The Parsimony principle is used to provide explanation of observed data in the simplest way In phylogenies this entails minimizing the number of evolutionary changes that need to be assumed over all character in all group as an evolutionary change may occur multiple times the best hypothesis is the one that requires the fewest homoplasies Any trait that is genetically determined can be used in phylogenetic analysis An important source of phylogenetic information is morphology the presence size shape or other attributes of body parts If a species is extinct phylogenies depend on morphology Fossils provide evidence that helps distinguish between ancestral and derived trails the fossil record can also reveal when lineages diverged However morphology has some limitations such as 1 Some taxa see taxon for definitions in 161 show few porphological differences 2 It is difficult to compare distantly related species 3 Some morphological variation is caused by the environment When morphology cannot be depended upon we can look at development Similarities in developmental patterns may reveal evolutionary relationships Behavior some traits are cultural or learned and may not reflect evolutionary relationship example bird songs However other traits such as frog calls have a genetic basis and can be used in phylogenies Molecular data DNA sequences have become the most widely used data for constructing phylogenetic trees Nuclear chloroplast and mitochondrial DNA sequences are used however information on gene products amino acid sequences of proteins can be used as well Now we can use mathematical models to describe DNA changes over time These models can account for multiple changes at a given sequence position and different rates of change Maximum likelihood methods identify the tree that most likely produced the observed data Phylogenetic trees can be tested with computer simulations and experiments on living organisms Chapter 163 Phylogeny Makes Biology Comparative and Predictive Applications of phylogenetic trees Phylogeny can clarify the origin and evolution of traits this can help understand fundamental biological processes Figure 166 A Portion of the Leptosiphon Phylogeny L androsaceus Selfcompatibility I l L quotbicoi39orquot C Common ancestor L Marv ows I I39i3ffijrus L 39aisclttus outcmssrxg 8 loolmg taxo nomists into class L frm orus Wing quotquot09 Separate spaces as L bicolor Convergent ora morpmmgy associated with sencompatibility arose independently in three dittermt Leprosiphon 088908 L beco39or St Illa ngl L acrcui39aris 4 I quotbicolol quot quot I ransom Selfcompatibility L quotDecolor quot PRINCIPLES OF LIFE Figure 166 201 2 Sinauer Associates Inc The above image can be used to explain selfcompatibility Most flowering plants reproduce by mating with another individual this is called outcrossing Selfincompatible species have mechanisms to prevent selffertilization However other plants can be quotselfingquot which requires they be selfcompatible If you do not understand selfcompatible it means these flowers or plants can be reproduce with themselves Figure 167 Phylogenetic Tree of Immunode ciency Viruses Virus transferred from simian host to humans Q HIV1 humans Schpz chimpanzees SIVhoest L Hoest monkeys Sleun suntailed monkeys Slend mandrills Common ancestor SlVagm African green monkeys SIVsm sooty mangabeys Q HIV2 humans SIVsyk Sykes monkeys PRINCIPLES OF LIFE Figure 167 39 2012 Sinauer Associates Inc The image above can be used to explain zoonotic diseases These are caused by infectious organisms transmitted from an animal of a different species the example in the image is HIVAIDS Phylogenetic analysis helps determine when where and how a disease first entered a human population Figure 168 The Origin of a Sexually Selected Trait Evolution of male sword Xi39phophorus d Swordtail gt fishes J Platyfish Evolution of female 1 sensory bias Platyfish 0quot PRINCIPLES OF LIFE Figure 168 in 2012 Sinauer Associates Inc Some adaptations relate to mating behavior and sexual selection which are complex traits The image above is example of this Phylogenetic analysis supports the sensory exploitation hypothesis this means female swordfishes have a preexisting bias for males with long tails When reconstructing ancestral traits morphology behavior and amino acids sequences or nucleotides are used for ancestral species The molecular clock hypothesis states that rates of molecular change are constant enough to predict the timing of lineage splits A molecular clock uses the average rate at which a given gene or protein accumulates changes to estimate the time of divergence A molecular clock was used to estimate the time when HIV first entered the human population from chimpanzees The estimated date of origin is about1930 Chapter 164 Phylogeny is the Basis of Biological Classification In the 1700 s a Swedish biologist Carolus Linnaeus created the biological classification system Binomial nomenclature gives every species a unique name consisting of two parts the genus to which it belongs and the species name Example Homo sapiens Species and genera are further grouped into a hierarchical system of higher categories such as family the taxon above genus Example The family hoinidae contains humans plus our recent fossil relatives the chimpanzees and gorillas Families are then grouped into orders Orders are grouped into classes Classes into phyla singular term is phylum Phyla are finally grouped into kingdoms Linnaeus developed this system before the thought of evolution was widespread Today we use biological classifications to express the evolutionary relationships of organisms Taxa are monophyletic meaning they contain an ancestor and all descendants of that ancestor and no other organisms However there is also polyphyletic which is a group that does not include its common ancestor and paraphyletic which is a group that does not include all the descendants of a common ancestor There are also codes to follow for biological nomenclature biologists around the word follow the rules for the use of scientific names however there name be many common names for one organism or a common name for several species but there is only one correct scientific name Example There are many species of cacti however we give them all the common name of cacticactus in reality they all have an individual unique name Lecture Notes from the Week Mostly Terms Some terms may be repeated from last weeks notes or from the chapter notes these are vocabulary the professor deems important Genetic variation the differences among individuals in the composition of their genes or other DNA segments variation in DNA sequences among organisms This makes evolution possible and variations endless however levels of similarity are surprisingly high Genetic polymorphism Genetic differences that are common among organisms of the same species Genetic divergence Genetic differences that accumulate between species Neutral variation Genetic variation that does not provide a selective advantage or disadvantage Population A group of individuals of the same species that live interact and reproduce together in a particular geographic area Microevolution Change in gene pool of a population from generation to generation Macroevolution Evolution of whole lineages speciation and extinction Gene pool The entire set of genetic information all the alleles of all genes within a population the set of alleles and their frequencies within a population for a specific gene locus Hardy Weinberg Equilibrium A condition in which allele and genotype frequencies remain constant through time in a population Gene flow Exchange of genes between populations through migration of individuals or movements of gametes Genetic drift Changes in gene frequencies from generation to generation as a result of random chance processes Founder effect Random changes in allele frequencies resulting from establishment of a population by a very small number of individuals Bottleneck effect a period during which only a few individuals of a normally large population survive Stabilizing selection Selection against extreme phenotypes Disruptive selection Selection for an extreme phenotype in one direction Directional selection Selection of phenotypes at both extremes Balanced polymorphism Two different versions of a gene are maintained in a population because individuals carrying both versions heterozygous are better able to survive than those who have two copies of either version alone lntersexual individuals from one sex choose mates from the other based on impressive features lntrasexual competition within same sex for mates Biological species concept A group of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups Morphological species concept A species distinguished from others only by its morphology Operational taxonomic unit An operational species definition using percent DNA sequences similarity typically from sequencing of conserved genes such as the ribosomal 16S gene A typical cutoff would be 97 Lineage species concept A branch on the tree of life which has a history that starts at a speciation event and ends either at extinction or another speciation event Reproductive isolation and reproductive barriers Prezygotic affects behavior prior to fertilization Barriers habitat isolation temporal isolation behavioral isolation mechanical isolation gamete isolation Postzygotic reduces survival or fertility of offspring Barriers zygote mortality hybrid sterility F2 sterility Allopatric A new species formed while geographically isolated from parent population Sympatric without geographical isolation a new species forming next to parent population Adaptive radiation A period of evolutionary change in which groups of organisms form many new species whose adaptations allow for them to fill different ecological roles in their communities The powerpoint from the teacher includes Darwin s finches as an example of this as well as cichlid fish It is estimated 99 of species are extinct and the average species lifespan is about 10 million years Lecture Notes for the Week Lecture 4 Biological species concept A group of actually or potentially interbreeding natural populations that are reproductiver isolated from other such groups Morphological species concept A species distinguished from others only by its morphology Operational taxonomic unit An operational species definition using percent DNA sequences similarity typically from sequencing of conserved genes such as the ribosomal 16S gene A typical cutoff would be 97 Lineage species concept A branch on the tree of life which has a history that starts at a speciation event and ends either at extinction or another speciation event Reproductive isolation and reproductive barriers Prezygotic affects behavior prior to fertilization Barriers habitat isolation temporal isolation behavioral isolation mechanical isolation gamete isolation Postzygotic reduces survival or fertility of offspring Barriers zygote mortality hybrid sterility F2 sterility Allopatric A new species formed while geographically isolated from parent population Sympatric without geographical isolation a new species forming next to parent population Adaptive radiation A period of evolutionary change in which groups of organisms form many new species whose adaptations allow for them to fill different ecological roles in their communities The powerpoint from the teacher includes Darwin s finches as an example of this as well as cichlid fish It is estimated 99 of species are extinct and the average species lifespan is about 10 million years Other species problems are listed below Ettilhier sipeciiies cneepts edit Ecclcgical species A set ef erganisms adapted is a particular set ef reseurces callei new reseurces are divided up tend te pred uce these clusterle Helprcd uctive species T we erganisms that are able te repred uce naturallyr te pred uce is Spec E jcitatiee seeded lsclaticn species A set ef actuallyr er iszitentiall39vr interbreeding pepu latidns This is g results cit tireeding experiments dene in arti cial cenditidns mavi reference is natural peipu latidnsmquot fquotquotmiI imam Genetic species Based en similarityr ef BHA ef individuals er pdpulatidns T echnigl Echesicn species Mest inclusive pepulatidn ei individuals having the petential fer pl pepulatidns can hvhrid ize successfultv their are still distinct cehe Escluticnarilv signi cant unit Esuijl An e velutidnariliilr signi cant unit is a pepulatidn cit erganisms that Spec E jcitetiee seeded Phenetic species Based en phenetics Micrcspecies A species with very little genetic variability usuallyr ene that repre Reccgniticn species Based en shared repreductive svstems including mating tiehavic Matereccgniticn species A greup ef erganisms that are Iiil39l Wl39l te recegnise ene anether a repred uctive iselatidnlmi m Emmi Earth s Geological Time Scale TABLE ZI2 Earth s Geological History Part 2 neunva was spun ERA PERIOD ONSET MAJOR EVENTS IN THE HISTORY OF LIFE Cenozoic Quaternary 18 mya Humans evolve many large mammals become 39 Tertiary 65 mya Diversification of birds mammals flowering plal Cretaceous 145 mya Dinosaurs continue to diversify flowering plants sify mass extinction at end of period z76 c Mesozoic Jurassic 200 mya Diverse dinosaurs radiation of rayfinned fishes Triassic 251 mya Early dinosaurs first mammals marine inverteb first flowering plants mass extinction at end c z65 of species disappear C Permian 297 mya Reptiles diversify amphibians decline mass ex1 period z96 of species disappear g Carboniferous 359 mya Extensive fern forests first reptiles insects cli E Paleozoic Devonian 416 mya Fishes diversify first insects and amphibians rr end of period 275 of species disappear Silurian 444 mya Jawless fishes diversify first rayfinned fishes r colonize land Ordovician 488 mya Mass extinction at end of period z75 of spec Cambrian 542 mya Most animal phyla present diverse photosynthe 600 mya Ediacaran fauna 15 bya Eukaryotes evolve several animal phyla appear Precambrian 38 bya Origin of life prokaryotes flourish 45 bya It is important to look at the left side as it gives perspective to how long each section is Important areas to note are the mass extinction around 488mya 416mya297mya 251 mya and 145mya The chart below shows this graphically with peaks In the PowerPoint there was also a chart that showed the sea levels and mass extinction correlation this tended to be the case when the sea level were low There were a few outliers such as in 443mya when sea levels were quite high Marine extinction intensity during the Phanerozoic P Tr 542 500 450 400 350 300 250 200 150 100 50 0 Origins of Life Millions of years ago It is presumed that a primordial soup of times was the beginnings of life They believe this occurred in deep ocean sea vents because this could provide warmth The theory is that organic compounds began life which in turn increased in complexity to macromolecules and finally protocells Multicellularity was seen 1218 billion years ago these organisms had higher complexity and variation They evolved many times The ediacaran biota about 600 million years old is the first fossil we have on date Up until the Cambrian times the Precambrian era did not have many species however come 542mya there was an explosion of different species this is called Cambrian Radiation many of the species that did survive would give rise to the species we know today The area where we can find a lot of fossils of species that did not make the cut is in the Burgess Shale were 20 to 30 arthropods are unable to be placed into any modern group these species lost to us When the fossils from the Burgess Shale were first uncovered many were classified into modern groups but later reclassified as they were found to not fit any modern group First colonial First cyanobacteria photo First synthetic fossils eukaryotes of multi cellular First animals oceans F39r3t Origin of multi Formation Origin photo First cellular of Earth of life synthesis eukaryotes eukaryotes quot L BILLIONS I Y T i OF YEARS Hadean Archean Proterozoic Phan rozoic AGO i l 4 3 2 1 MILLIONS Cambrian Ordovician Silurian Devonian Carboniferous Permian Triassic Jurassic Cretaceous Tertiary Quaternary 0F YEARS I l i l I 500 400 300 200 100 Present PRINCIPLES OF LIFE 2e Figure 1810 2014 Sinauer Associates Inc Phylogenetics The study of evolutionary history of a particular group of organisms or their genes Taxonomy A scientific discipline concerned with naming and classifying the diverse forms of life Taxon A named taxonomic unit at any given level of classification There are five kingdoms Plantae plants Fungi Animalia animals Protista eukaryotes and Monera prokaryotes Each kingdom is then broken down into smaller groups the table on the next page is an example of the panther s breakdown Eukarya 1 E 1 E3 Klngdom n Animalia D Chordata a Mammalia Felidae Panthera Panthera pardus Copyright 0 Pearson Education Inc publishing as Benpamin Cummings As you can see it has a Domain then the Kingdom and each class gets smaller and smaller until we have its name A B Clade A monophyletic group made up of an ancestor and all its desendents Cladogram A branching diagram used showing evolutionary relationships among organisms Example to the right A lineage is ancestors and its descendant population this is usually shown on a time scale When a single lineage divides into two it is called a node or split as a lineage continues to spilt it forms a tree The common ancestor forms the root of the tree Sister taxa Two phylogenetic groups that are each other s closest relatives Monophyletic Describing a group that consists of an ancestor and all of its descendants Paraphyletic Describing a group that consists of an ancestor and some but not all of its descendants Polyphyletic Describing a group that contains multiple lineages not linked by a common ancestor Polytomy An unresolved branch point in a phylogenetic tree in which the evolutionary relationships amongst the descendant taxa are not clear Outgroup A species or group of species from an evolutionary lineage that is closely related to a target group under study but known to have diverged before the members of the target group Molecular clock A method for estimating the time required for a given amount of evolutionary change based on the observation that some regions of genomes evolve at constant rates Prmosmmeg V m Echinoderms IMH i L lili Il w m A i i r 2008 Leonard Eisenberg H I IV ks FISI I If 2le h W All rights reserved L quot Cuelacanth FlawJun i a Sponges y l Lungfish Amphlhlans Fuin i W l g Amoebas 39 ktl U Red Algae w i m Mi i h l I39 W lPlants l 4 g 1 my 39 i 7 kl l39 l x W 39 39 TBS L1 i xrmu Eukaryotes M l Mammals 39 39 l Archaea r w x y r l a r 7 r r 7 39 7 7 1 0M Ruvt E Bacteria r 7 EL 7 r r 39 r j 11 7 i 7 i 7 it E w 397 r 7 Earth Birth E a i lerlhuls Jana Today 65 200 250 370 440 542 700 1m 2m 3m Millions of Years Ago 3m 2m 1m m 542 440 370 250 200 65 Today All the major and many ofthe minor living branches of life are shown on this diagram lbnt only a few of those that have gone extinct are shown Example Dinosaurs extinctm 93mm Lwquot i v quot 39n El WNW In class we looked at the possible origin of head lice based on the human and chimp lineage divergence It was find out that chimp lice and human head lice lived 6 million years ago around the divergence of the chimp and human lineages We next examined the pubic lice the common ancestor between head lice and pubic is 12 million years ago so it wasn t related closely with the divergence of human and chimp So we looked at other possibilities and came to conclusion that pubic lice are most related to gorilla lice which shared an ancestor of 34 million years ago The following two examples show these findings L Host 5mm Evil M r Far ire Dupxiicatim H I F er 39i miuehumanue y y 39I39 Far it39e Extinutipn 395 NW Hakim Hugh Harm 13 Millquot EMT 1 F erfi miue snhae i Para Fritlme erljiiae Emilia F eri39i nifn his was E39W ME fair rst
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