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by: Connor Harvey

Evolution BIOL271

Connor Harvey
GPA 3.5


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This 0 page Class Notes was uploaded by Connor Harvey on Sunday November 1, 2015. The Class Notes belongs to BIOL271 at Indiana University of Pennsylvania taught by RobertGendron in Fall. Since its upload, it has received 43 views. For similar materials see /class/233506/biol271-indiana-university-of-pennsylvania in Biology at Indiana University of Pennsylvania.


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Date Created: 11/01/15
Biol 271 Lecture Outline Gendron Origin of Species What is a species 1 Morphological Species Concept What is it problems a Cryptic species b Ecotypes 2 Biological Species concept de nition problems a asexual organisms b extinct forms c plant species often hybridize 1 ring species 3 Cohesion species concept what is a hybrid zone 4 Phylogenetic species concept page 1 4 ecotypic differentiation among populations gt gt i a LL gt10 E E r x Groveland Mather Tuolumne Meadows Big Horn Lake Grown at Stanford elevation 90 meters Height of plants cm o 1000 i 2000 3000 Elevation from which seed was collected meters Biol 271 Lecture Outline Gendron page 2 Why should it come as no surprise that it is ali icult to come up with a de nitive definitionfor species We will use the Biological Species Concept BSC throughout this lecture In the context of the BSC what is Speciation Reproductive isolating mechanisms prevent gene ow between populations 1 Habitat Isolation 2 Temporal Isolation 3 Behavioral Isolation 4 Mechanical Isolation 5 Gametic incompatibility 6 Hybrid inviability or sterility 7 Hybrid breakdown hybrids are fertile but not their offspring How do populations become reproductiver isolated in other words how do reproductive isolating mechanisms arise I Allopatric Speciation geographical 3 steps 1 2 Populations become geographicaly icnlafp Biol 271 Lecture Outline Gendron page 3 Caused by Decreased by 3 As populations diverge reproductive isolating mechanisms arise Allopatric Speciation explains the diversity of nches in the Galapagos salamanders in California and Hawaiian Drosophila 500 species What geographical barrier disappears before speeiation is complete a if tness of hybrids 2 that of parents b if hybrid tness lt pure bred tness Figure ISA Arn nal selection ln Vernal Drosophila pseudoabswm Fur managed a i l Relnforcement 1n the lab I n I w lt ln w r pzvmlssmn ofme puhllshzn 1mm Kessler was Mm interbreeding hawsen games in ea 7 Lens lntavbmz ing between pecies Biol 271 Lecture Outline Gendron page 4 Possible example in nature Damsel ies E 2 species closely related and with overlapping distributions hybridize in lab 1 IE Don t hybridize in nature in area of overlap wing transparency of males differs character displacement females choose mates based on transparency Hypothetical Scenario populations isolated during Pleistocene glaciation then remerged Postglaciation PISglaciauon w Biol 271 Lecture Outline Gendrou page 5 II Sympatric Speciation What is it eg Rhagoletis apple maggot fruit y Originally bred only on Hawthorn Hawthorn Apple Hawthorn Pop Apple Pop Genetic differences arose further isolating populations a mamas III Polyploidy What is it Polyploids may be triploid 3N tetraploid 4N etc Polyploids are phenotypically different amp reproductiver isolated from parents Polyploidy results from nondisjunction of chromosomes during meiosis Biol 271 Lecture Outline Gendron page 6 1 Autopolyploidy 2 Allopolyploidy Hybridization followed by nondisjunction Wheat amp some whiptail lizards evolved by polyploidy How many species are there 15 2 million named species 23 insects 42000 vertebrates 1314 million total mostly insects amp microorganisms in tropics Perhaps 99 of all species have gone extinct Biol 271 Lecture Outline T axonomy Phylogenetic analysis Goal of Modern Systematists 9 Problems Approaches to Classification 1 Problem Results can be subjective 9 relies on Advantage objective in that an external reality exists goal ofcladistic analysis page7 Systematics rantquot MA 1 he unmmt stmttamy between Saunas an ha expressz man tt t tt t a my um and tengttt oi tthta Th mm ts ht mzasurzmem nfuazh mama to tangtn ma wtng vein and tne yaxls gt5 tne mezsulemznt to tmgth ortima Th dislanze m Table M L b The pnmm lasst mlmn by I ncnrcs nemasl neighborquot tutttntque puts Spelles 3 wttn ma glcup duster A lhal has quotI neatest a wage netgtthot techntque puts spectcs 3 WM Kh group muster a tttat has he neamt 125 3 tat Phenalic tttmutetnents luv live spec Charamer t ttettgtn at Characler 2 ttangtn cl wtng vein a Neareshulgmwr 1 Average nnlghhal I t a 2 3 II A Biol 271 Lecture Outline Problem other types of shared characters Gendron pages derived from recent ancestor aka 7 unique to that group ancestral fin ancestor and some not all decedents Numerical taxonomists treat all characters equally amp hope they have enough so classification will be natural Cladists only work with shared derived characters phylogenetically informative The Cladistic ideal is monophyle c groups i I 7 thlngany a as mam vertebrate gmups Repules are a pavamwlehc group made up onunres lizards snake and v odiles in this pinure Ampmbia Tumes Common anccsxm A a ml U ul AJl 0 Common ancmur of I 1 and F om mun Iceslor of G md H Common anCcalm of l I and K Mammals Lizards Snakes Cmcodllss Ends Biol 271 Lecture Outline Gendron page 9 Other Problems combine features of both allows monophyletic amp paraphyletic groups uses homologies but both derived amp ancestral actually predates the other two which were developed in response to shortcomings of evol tax Conclusion Cladistics has the strongest theoretical foundation It is consistent and best re ects phylogeny But it is subject to frequent revisions and it could be used as an argument for throwing out the Linnaean system which biologists are loath to do Reconstructing Phylogenies Which of these two are most closely related amoeba magnolia chimpanzee human What does it mean to be more closely related quot7 How do you know Traits can be shared for three reasons 2 Homologies 7 of which there are 2 types a b Biol 271 Lecture Outline age 10 Gen on Magno 1a Human Chung Amoeba How do you know this isn t the correct tree Could chimp amp human be convergent Principle of Parsimony Developing a phylogenetic tree often proceeds in two steps Illustrating the difference between rooted and unrooted trees Figure 112 Unmmed m mmeu Irees oquot unramud nee for our mm 15 mmpatmle h a l m i unmqu use anezlas has 2 7 Zlnmmal mmum menlove Zr 3 Double muted u c Unlocked vee Rumc quotac Biol 271 Lecture Outline Gendron page ll Stage 1 Inferring unrooted tree Three possible unrooted trees for above example A A assume C and H share 100 characters not shared by M amp A 1st amp 2nd tree require at least evolutionary events each of these characters must have evolved at least twice H amp C branches OR they were present in the ancient ancestor and had to be lost twice M amp A branches Theoretical justi cation for Principle of Parsimony 9 e g improbable that vertebrate skeleton would evolve twice however change in nucleotide at particular site is not so improbable there are only 4 possible states Stage 2 Rooting the tree 3 methods a example a group of amniotes robin mouse turtle lizard kangaroo 9 which is ancestral amp which is derived 7 use outgroup to determine Biol 271 Lecture Outline Gendron page 12 Outgroup closely related but outside group of amniotes eg salamander or frog c fossil record Biol 271 Lecture Outline Gendron page 13 Inferring Phylogeny from Molecular Data Idea of a Molecular Clock is based on Evolution Neutral Theory of Molecular What was his argument Considerations unique to molecular data a distinction between homologyanalogy not as useful for inferring trees eg consider site 12 of cytochrome c methionine in humans chimps amp rattlesnakes glutamine in all other species also traditional systematists could use detailed anatomical study amp embryology to distinguish between analogy amp homology 7 V produces a great deal of data traditional systematists might work with 20 characters whereas a gene may be made up of several hundred nucleotides Statistical techniques for molecular data emphasize parsimony l Plck a prote1n gene that evolves at a rate appropriate for the problem Rams Di evalullun In elghl pmlems The rates are expressed as average numbers at changes pu ammo and me In IIJ years nepnmem by permission of me publisher hum Klmura l 933 Number of Amino Add Pmrem Changes x lo lyr Flhrlnun mldni 3 3 Pancreatic nbonuclease Zl LY 20 nglnbin 12 Mvoglobm 039 made dif cult w1th 1nsertions deletions amp Insulin 0M Cvmthmme c 03 inver51ons Hlslune m 001 Biol 271 Lecture Outline Gendron page 14 e only method for nding the root in molecular data can t use development or fossil record Molecular evidence has sometimes challenged previous conclusions Povpoises Dolphins d Odnnluce Sperm whales Q Ealeen Whales lMysuceu 323 Qt Odomcceti Other mammals Arthropods may be paraphyletic Coelemerales 2 I Chordates 4 Echinodevms Al Inse l Fogunuphom Erachinpud cmmn Nudlbvanch mollusk Bivalve mollusks 2 Slpunculid Biol 271 Lecture Outline Gendron page 15


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