Summary

This document reviews key concepts in evolution, including sexual selection, speciation, and coevolution. It discusses the interplay between traits like anisogamy and sexual selection, and the concept of codiversification among interacting species. It concludes by touching on the concepts of diversification and key innovations.

Full Transcript

13 SexualSelection Anisogamy Gametesize is thefundamentaldifferencebetweenfemalesandmalesinplants animals Anisogamy iswhatgeneratesdifferencesbetweensexes sexualdimorphism and shapeshowtheyevolve sexualselection Shapeshowtheyevolve whichthere isdifferentselectionpressures that can beexerted on an...

13 SexualSelection Anisogamy Gametesize is thefundamentaldifferencebetweenfemalesandmalesinplants animals Anisogamy iswhatgeneratesdifferencesbetweensexes sexualdimorphism and shapeshowtheyevolve sexualselection Shapeshowtheyevolve whichthere isdifferentselectionpressures that can beexerted on an organism thatproducesmanysperm vs on an organismthathas toinvestalot of time andenergyintodeveloping a small oflargeregg Extreme Anisogamy Estes'sm inf stufffilthiest.tn goihgffsfehd it oftimeprotecting theegg whichmeans hermobilitywill bealsoextremelyreducedcomparedto amale kiwi whodoesn'thave to investas muchtimefor agivenegg Femalekiwi vs male kiwi are an example of extreme anisogamy Sexdeterminingsystems Reptileshavean environmental sexdeterminationmeaningdepending on thetemperature at which anegg is incubated as implications for whether that eggwilldevelopasmaleor female mammals willhave an Xy vs xx sex determination Forbirds butterfliestheyhave a Zw sex determination somales are homocomedic whereas females are heterocomedic Sothecombination of sex determiningsystems in anisogamy where youhavedifferences ingamatesizessetsthestagefor an important process called sexualselection Primaryvs secondary sexual traits Sexualselection isfocused on a characteristicthat is involved in eithermaleattraction or reproductionprocessitself Primarysexualtraits actualorgansinvolved in sexual reproduction theycan undergosexualselection Secondarysexualtraits involved in mateattraction but don'tplay a directrole inreproduction Darwinrecognized thatthesetwotraitslikelyevolvedvia a differentmechanism than strictnaturalselection sexualselection SexualSelectionselectioncaused competitionfor matesamongindividuals of the same sex by Sexualselection is similar tonaturalselectionexcept it is notdirectlytied to survival or adaptationto the environment but insteadtied to mates sexualselection isn'tdirectlytied to survival or somecharacteristics or adaptation of theenvironmentitselfbut its insteadtied to matesandtheabilityto obtainmates and produceoffspring Anexample the longtailedwidowbirds drastically in an experimentwouldchange theirtailfeatherlength so whentheir tail feather are shortened theyhavesignificantlylower theirnesting numbers whereas whentheyhave enlongated tails thenesting s increasedsignificant sothen naturallywe ask whydon't we seelongertails in animals this iswherethere is sometradeoff betweenthebeneficialeffects ofhavinga longtail showing off to femalesand yourabilitytokind ofnavigatethe environment over a longterm thekeyis that this trait canevolvedbysexualselectionincreasesmale'soverallfitness even if it decreasessurvival Fitnessin sexualselection is a compromisebetweensurvival andmatingsuccess So with the longtailedwidowbirdfemalespreferlongtails so thatfavor increases it beyondwhat is idealfor matesurvival HOWEVERmediumtail is bestformale survival Bateman'sPrinciple inthe idea of anisogamy sincematesarecapableof producing millionsofspermcellswithlittleeffort a trait that increasesthe ofmates that he can aquire isfavoredbyselectionandso willspreadThismeansselectioncan act on traits that increasemalematingsuccessFemalesbycontrast can oftenfertilize all of her eggswith a singlemating and thus there is littleselectionfor traitsto increase matenumber Male male competition Maleshaveevolvedhorns or antlers topreventothermales fromobtainingmates 20 of deersobtain someform ofinjuryfrommale malecompetition tradeoff indeers 50 ofmales sometimes don'tgetto reproducethat year Anotherexample of male malecompetition is spermcompetition Spermcompetition the penisof maledamselflieshave astructurethatresembles verysmallscoop thejob is toremovespermfrom a previousmale thathavemated gun thatfemale FemalechoiceandPrimarySexualTraits Evolutionaryconflict is demonstratedby thegenitaliaof many duck species Maleduckphallusescoil cow whereas the femaleduck oviductscoil Thisarisesfrom the fitnessbenefitof females avoidinginseminationfrom so males Somefemaleshavethe ability to choosesperm that will inseminate theegg this is an exampleof coevolution basically where sexualselectionoccurs on the primarysexualcharacteristics FemalechoiceandSecondarySexualTraits maleBetafish are colorfuland haveverylongfins whereasfemales very look a lot moresimplierthey'resmaller and shorter thereare no connection to theenvironmentas to why a beta fish needsthesecolors this all has to dowithfemalechoiceandsexualselection 3modelsof SexualSelection DirectBenefits thismeansthefemalechoosing some characteristicof a potentialneed wherethere is some directbenefit that the male is offeringthat willincreasefirstsurvival andreproductivesuccess Example morman Crickets spermatophores are what male crickets create with a lot of time andeffortTheyshow them off tofemalecrickets so that theycan approve it and take it This is an injection of resource so she takes it to sustain herselfduringthe reproductiveprocess producingoffspring So this is a directbenefit she ischoosinga modelmalecricketbased on thespermatophore that he's produced and that will sustain her that is directbenefit She is assessingamongstmales what characteristics and in this casethe spermatophores which is a directbenefit Directbenefit is when resources that increases the femalessurvivaland reproductive success Sensory Bias this is when the characteristics of the male tap into some innatepreferences that thefemaleschoose to mate with an individual with that trait Ex inswordtails femalesprefermales with long colorfultails Latentmatepreference when a preferencefor something is existingbefore the preferenceitself isexisting Solike when the swordtailfish mate with the female Priapella thepriapellaprefertheswordlong tail even thoughthe malesof theirgroupdon'tproducelongtails Directbenefitmaybe lesscommon butmoreintuitiveHOWEVERsensorybias is quitecommonand lessintuitive GoodGenes Goodgenesmodel is a combinatition of sensorybias and directbenefit with mashIemmore depthas to whya female would choose a male a female is producing an offspring 50 female 50 male and those 50 male are likelygoingto inherit that trait that was one of the traits that she can choose in her own mate Malesmayhave honestsignals that indicatetheir quality Ex a sticklebackredness is obtainedfromcarotenoids from their diets and appearto be a goodindicator of how well their offspring will fighttapeworm infections So if you're afemalechoosingbetweenmales you can use this outwardindicator the redness of that male as an honestsignal of who youaregoingto mate Wsfseciation SexualSelection thespeciation by where havedifferentpopulations process you evolvingdifferenttraitsindifferentdirections Speciationbeginswhengroupsbecomeseparatedinspaceor becomedifferent in uninformed behaviorthatindividualsfromonegroupnolongerrecognizeindividualsoutsidethegroup 14 CoevolutionandInteractions Co evolution thejointevolution of two or more ecologicallyinteractingspecieseach of which evolvesinresponse to selectionimposedby the other co evolutionoccursw biologicalorganismsthatcanevolve infandom think of co evolutionin thetensofreciprocalselection So selection on onespeciesfeedsbackintotheselection on the otherspecies co evolutionbothplayers are evolvingintandem Ex ofcoevolution theevolution ofstrongertoxicityof a butterflyinresponsetopredator becomingmore resistantAKAreciprocalco evolution Codiversification co speciation occurswhen interactinggroups such as hostandparasitesspeciatein tandem generatingcongruentdiversificationpatternsandphylogenies Ex aphidshaveanearperfectassociationbetweenbranchingpatternsof thehostaphidsand theirendosymbioticbacteria booknara whichimplies co evolution whenthere is a perfectmirroringpattern inthephylogenictreesthenyouknow co diversifica andco speciationhappened Youdon'tsee a perfectco speciationwiththe non hostspecificparasiticwasp so instead youget a lot of crosswires animalsandtheirpathogens coevolve at a smallscale EvolutionaryArmsRace snakeandnewt newtsproduce a potentdefenceagainstpredators tetrodotoxin TTX theTTXamountsinnewtsvariesgeographicallyand it is correlatedto the presenceof garnersnakes thereissomepredator outtherethat hasevolved tofeed onroughskin newtsThis in turn led to theevolution of the strongneurotoxin Garnersnakesare commonpredatorsof the roughskin newts thegarnersnakesevolvedsomeformofresistancestowardsthenewts thenewtsthemselveshavevariousamountsof neurotoxins whichcorrelatesto the snaks resistances EvolutionaryArmsRacewhichis wherewehave acertainpopulations of preythat haveevolvedhightoxicityandtherehavebeenrecipricalevolutionin thepredator toevolve additionalresistance So in the heatmapsshown outsidetherange of thenewtssnakeshave no TTX resistan But within theoverlap area resistancevariesdirectlywithtoxicity therearesomepopulationsofsnakesthathavemoreresistancethanneeded themoleculareffectsofTTX ittargetsan importantsodiumpump in snakesand it appears asthoughdifferentpopulations of snake overlapwiththenewts evolvedindependent aminoacidchangesconferringresistance EcologicalCharacterDisplacement Anindirectaction of fitnessservicebestexampleshownwithdarwin'sfinches in thisexamplethere is afitnessserviceswherespecieshaveeither alargebillswillhave higherfitness or thosespecieswithsmallerbillswillhavehigherfitness SOOVERTIMEyou'dexpecttwospeciesco occurring thattheywouldclimbthefitnesssurface andthattheindividualfromthespeciesingreenwould potentiallyhavehigherselection higherfitnesswithgettingsmallerbills thebluespecieswouldhavehigherfitnessbyevolvingslightlylargerbills So overtimewe'dexpectthattherewouldbelessoverlapbetweenthe twospecies Overlap inresources canleadtothedivergence in importantecologicalcharacter in this case forthesmall largebillfinches iftheyarecompeting for a similarresource theywon'tbeabletoobtainthesameamountof resources iftheywerejuston their own cuznowthey'recompetingwithanotherspecies thisideais nowplayedout on the Galapagoswhere on theislandtheydon'tco occur andthereismoreoverlapintheir billdepthWheretheydoco occur andcompeteforresources thesmall mediumbillfinchesThere is more overlapwhentheyare on separateislands compare towhentheyareonthesame islandthereis nooverlap Sowhen we'retalkingaboutthis incontext of a singlepopulation in asinglespeciesand that sort of hadthe extremeendsof the fitnesssurfacewhichhadthesort ofhigher fitness it is anexampleof disruptiveselection in the instanceofecologicalcharacterdisplacementthereis nohybridizationhappening Thereisno interbreeding in this instancebetweensmall billedfinchesandlargebilled finches thedivergenceintheirbuildswheretheyco occur ispurely a resultofcompetition forthe sameresources BatesianMimicry Toxicbutterfliesevolvebrightwarningcolorationto warn off predators BatesianMimicsgainprotectionbylookinglikethe toxicspecies but actuallybeing palatable Millerian mimicry everyone istoxic butit is geographicallyrestricted everyone istoxic butit'sbettertobelocallycommon geographicallylocalizedselectionforconvergence strongselectionfor everyoneto bethe same 15 EvolutionofDiversity Diversification an evolutionaryincrease in the numberof species in a clade usuallyaccompaniedbydivergence in phenotypiccharacters diversemeans ofspecies diversificationrate means alongthe lineage of birds inthiscase how manyspeciesare beingproduced over a given timeperiod keyAdaptation Innovation keyinnovations orkeyadaptations allowinvertebratesto sort ofopenup a new worldofecologicalopportunities so inthisexamplethesea archinesthey compared to theircloserelativestheyevolve muchstrongerjaws eatgreatervarietyoffood so bycontrastthe sanddollarsand hearturchinstheyactuallyevolve innoveltyecologySotheyspecializedintoburrowing intosand wheretheyfeedon fineparticulate filterfeeders Howeverthesezoneswerenotbeingoccupiedbyothercloselyrelatedspecies becausetheymoved into newecologicalzonestheycoulddiversifyintospecializing on thedifferenttypesoffoodthat thesestrongerjawsallowthemto eat Shift in diet and habitat shift is calledecologicalopportunity becausethesenovelinnovationsopenedup a new worldthatallowedthemto specialize diversify it isthought that thisresultedin an increasein the ofspecies thatweremaybespecializing ondifferenttypesoffood theseevolutionsonlyhappenedonceso testingforthem isverychallenging Sisterclades sisterspecies twocladesof highertaxathat arederivedfroman immediate commonancestorandarethereforeoneanother'sclosestrelatives Backto keyAdaptations Anotherexample of keyadaptation islatexin plants plantsproducethis as a defenseaganistherbivorousplants theevolutionof thisdefensehascorrelatedwiththeevolution ofthe ofspecies oneapproachtostudyingkeyadaptation isthroughsisterclades anotherwayisthrough lineagesthroughtime LineagesThroughTime studydiversificationpatternsthroughtimeandlookingatphylogenyis calledlineagesthrough thineageaccumulaterapidlyover time diversificationslowsdownandstarts toleveloff initiallytherewillbe a burstofspeciationwherelineagesarerapidlyaccumulatingover timeButthentowardsthe morerecentperiod thediversificationstarts to sortofleveloutand 2 0 fifersification slowsdowndue tokeyinnovation soevolvenewhabitats but overtime theprocessoflineagessplittinganddiversifyingthe sortofhowmanyspeciesyoucanpack intotheworld ofbeing a warblerexspeciesbecomes smaller Soovertimethesespeciesform buttheyeventuallyplateauovertime Evenratethroughtime is species isbeingproduced at roughlythesamerateovertime Sogenerally it'san increasebutthere's no obviouschangein the rate at the baseofthetree vs theshapeof thetree Earlyburstofspeciation incontrastthere's a lot oflineagesbeingaccumulated overashortperiodof timehoweverthereis a plateaulikethe warblers Lateburstofspeciationwherethereare probably oneortwolineagesexistingfor a longperiodoftime sonotproducingmanyspeciesbutthenthere'sarapidburstsotheyhave a lot ofspecies beingproducedover a veryshortamountoftime netdiversificationgenerallyincreasesbutsomeslowdownincertaincladesfromnichefilling but overallincrease AdaptiveRadiation evolutionarydivergenceofmembersof asinglephylogenticlineageinto a variety ofdifferent adaptiveforms usuallythe taxadiffersintheuseof resourcesorhabitatsandhavediverged over a relativelyshortintervalofgeologicaltime Adaptive ecologicallydiversity vianaturalselection Radiationmanyspecies relativetobaseline manyadaptiveradiationoccuron islands EcomorphsandconvergentEvolution Divergentandconvergentevolution inAnolislizardswhichhavediversifiedintodistinctecomorphs specializedforwelldefinedforagingniches whenthespecieshave adistinctmorphology thatis predictablebasedonwheretheylive theyareknownasdistinctecomorphs sotheyhavemorphologiesthatareadaptedandsuitedto aspecificecology what is convergentevolution LatitudinalGradientSpeciesDiversity atlowerlatitudesmoreof mountainsandelevationcanbe inhabitedbyplantsandanimals Sohighertempsmountainsareeasilyaccessible incontrastto the rockymountainswhichhave lowtemperaturesso itsbasicallytreelinesanduninhabitabletundraandmuchlowerelevation Forvertebratesweseehigherdiversitybelowtheequatorwhereasfor marinelifethere are higher of speciesin higherlatitudesorabove theequator twohypothesis Cradleofdiversity museumofdiversity Cradle speciationrate isfasterinthetropics Museum extinctionrate islowerinthetropics Speciation rate is actuallyhigher at highlatitudes 16 GenomeEvolution Howdo genesoriginate mostcommonlythroughduplicationofpreviousgenes Duringthegenereplicationprocess sometimes there'serrors Sometimestheseerrorsstickaroundandgetsduplicated Geneduplicatescanshow up in genomes AMY alsoknown asamylasewhichis an enzymethatbreaksdownstarch there isdiversityin thenumberofduplicates duplicationprocess can result in divergenceofthegeneandthegenefunctionitself 3DivergenceofDuplication Subfunctionalization there's a divisionoflabor yougettheoriginaltemplatediversified so onefunctiongetstwosetswhilethe other twogetthemissingset Hemoglobinduplicationforfetusevolves via subfunctionalization developingfetusandhashigheroxygenaffinitythanthe adultversion jeopardy offffaf.fm new characteristic newfunctionthatthisgeneduplicateevolvesto do geneduplication of RNASE1 to RNASEIB which is a new variant thatfacilitatesdigestion egiietat.in iie iia Duplicatedoesn'tprovide a redundant in thesystemand it anynewfunction it is is eventually lost if thegeneresults in redundancy then it may not beusefulto have a 2ndcopy theduplicatedgenemaythenaccumulatemutations cuz it is not expressed can't bepurged naturalselection e g the prematurestopcodon ourgenes are litteredwithpseudogenes formerlyduplicatedgenes formerlyduplicatedchromosomalregions without a promoter is known as pseudogenes pseudogensarenottranscribedtranslatedtheylackapromoter theydohoweverevolve at a fasterratebecausetheyarenotconstrained byselection Evolutionofgeneexpression 1 codingchanges 2 Expressionofchanges the amountandpotentiallylocation oftheexpression ischanging Formosquitoesforexample theevolutionofthedomesticformappearstodifferintheexpression of an ordorantreceptor intheirantennae theydon'thavea no codingsequencedifferenceindomestic forestformofmosquitoesHOWEVE theirgeneexpressionsaredifferent manygenesdiffer inexpression morethanexpectedbychance GenomeSize PoweredFlight sizeofgenomesvarydramaticallywithintaxonomicgroups humangenome isjustover 3billionbasepairs prokaryoteshavemuch onaverage lower genomesizes Strong correlationbetweengenomesize codingsequences i.e genenumber forsingle celledorganisms thiscorrelationdoesnotholdformulticellularorganismsduetojunkDNA there is no correlationbetweenthe sizeofthegenomeandtheoverallcomplexity of an organism TransposableElements are selfishDNA or geneticparasite Aluforex transcribesitselfintoRNAandisthenreversetranscribedintoDNAandinserted elsewherein thegenome theyarebasicallystrandsofDNAthathavecharacteristicsthatallowthemtoreplicate anddiversify inthegenomesof their host Genomesizeseemstoevolvequitefreely ineukaryotes w otoomanyconstraints but isassociated withsomeinterestingphenotype Ex smallgenomes are associatedwith organismesthatflylikebirds bats Smallgenome size associatedwiththeropoddinosandmayhavebeen a requirementforthe evolutionofflight 17 Evolution andDevelopment Evo Devo Heterochrony Pedomorphosis connectionbetweengenotypeand phenotypeoccursthrough a developmental process transitiontogenotype to phenotype

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