©2010.TheConcordConsortium,Inc. page1

Clipbirds*

Thishands‐onactivityallowsstudentstoexperiencevariationwithinapopulationandtheeffectof

selectionpressureonthepopulation.WhichvariationsareadvantageousforsurvivalandreproductioninEastClipland?InWestClipland?

Evolutionistheresultofnaturalselectionactinguponvariationwithinapopulation.Organismswithfavoredtraitswithinagivensetofenvironmentalcircumstanceshaveaselectiveadvantageoverindividualswithdifferenttraits.Itisthismechanismthatleadstospeciation.Itisimportanttounderstandthatfavoredtraitsareonlyadvantageouswithinaparticularsituationandmaynotaidsurvivalinanothercircumstance.Acat’slongtailmayaidinbalancingonatreebranchbutbedisadvantageousinahousewithfrequentlyclosingdoors.InthecaseofthefictitiousClipbirds,differenttypesoffoodfavordifferentbeaksizes.Onebeaksizeissuperiortoanotheronlyincontext.Theclassicbirdbeakactivityusuallyinvolveshavingstudentsattempttopickupvariousobjectswithawidevarietyof“beaks,”includingscissors,spoons,etc.Thistraditionalapproachdemonstratescompetitioninanecologicalsense,butdoesnotclearlydemonstratevariationwithinapopulation,whichiscentraltoevolution.IntheClipbirdsactivitythe“beaks”areallthesame,exceptforsize.Theproportionofbig‐,medium‐,andsmall‐beakedbirdschangesinresponsetotheavailabletypesoffood.

Vocabulary:evolution,variation,population,adaptation,advantage,characteristic,speciation,reproductiveisolation

*CreatedbyAlJanulawandJudyScotchmoor.

See:http://www.ucmp.berkeley.edu/education/lessons/clipbirds/

LearningGoals

BigIdea7:Intra‐specificdifferences

• Individualsofthesamespeciesmaydiffer.

BigIdea8:Adaptation/Evolution

• Speciesareadaptedtotheirenvironmentsandspeciesadapttochangesintheirenvironment.Iftheenvironmentchangesonlycertainspeciessurvive.

• Organismswithtraitsbestsuitedtotheirenvironmenthavebetterchancesofsurvival.• Thoseorganismscarryingtraitsthatarebettersuitedforaparticularenvironmentwillhave

moreoffspring.• Selectionpressurecouldleadtoachangeinthecharacteristicsofapopulation.• Adaptationrequiresbothvariabilityandselectionpressure.• Givenanunderstandingoftheneedsofagivenorganism,identifyparticularphysicaltraitsthat

wouldhelpittosurviveinagivenenvironment–e.g.,“Whatwould<organism>needtohavetosurvivein<environment>?”

©2010.TheConcordConsortium,Inc. page2

BigIdea11:Descentwithmodification

• Speciesevolvefromcommonancestors.• Differentspeciescouldarisefromonespeciesifdifferentgroupshaddifferentselection

pressures.

LessonPlan

1.Estimatedtime

Thisactivityshouldtakeapproximately45minutes.

2.Introducetheactivity(Engage)

DisplaytheCliplandScenetransparencyandtelltheclassafancifulbutengagingstoryabouta

populationofimaginarybirds(Clipbirds)thatliveshappilyinafarawayfictionalplace,knownasClipland.Pointouttotheclassthatsomehowthelargepopulationbecamedividedintotwosmallerpopulations,eastandwest.Perhapsamountainrangeroseupinabighurry,oraflockoftheClipbirds

gotlostandendedupontheoppositesideofapreexistingrangeofmountains.(Thisisfictional,sohavesomefunwithit.)

3.Guidedinquiry(Explore)

Note:Initially,twogroupsofsixstudentswillstartthegame.Mostoftheclasswillbeinvolvedas“offspring”areadded.

Materials

• Sixbagsof“food”(assembledbyERteam,forEastandWestClipland,Seasons2‐4)• 20largebinderclips• 20medium‐sizedbinderclips• 20small‐sizedbinderclips• 30plasticcups• 1FoodValuestransparency(pdf)• 1ClipbirdPopulationstransparency(pdf)• 1CliplandScenetransparency(pdf)• 1overheadtransparencyprojector

©2010.TheConcordConsortium,Inc. page3

Procedure

1. AskthestudentstonoticehowthebirdsinEastandWestCliplandarealikeandhowtheyaredifferentfromeachother.Helpthemtonoticethatthebeaksofthebirdsvaryinsize:big,medium,andsmall.

Besuretodiscussthedifferentsizebeaksasvariationswithinapopulation.2. Explainthatbirdsofvariousbeaksizesusuallydojustfine,butittakesmorefoodenergyto

maintainthelargerbeaksizethanthesmallersizes.3. DisplaytheFoodValuesinMegacaloriestransparency.Allowstudentstimetounderstandthat

thevariousfoodshavedifferentfoodvaluesandthatbirdsofdifferentbeakssizeshavedifferentneeds.

4. Selectsixstudentstobeeastbirdsandsixtobewestbirds.Withineachgroup,givetwostudentslargeclips,twostudentsmediumclipsandtwostudentssmallclips.Eachstudent/birdalsogetsaplasticcuptoserveasitsstomach.Tellthemthatinordertoeat,theymustusetheclipsinthecorrectclipmode(demonstrate)andtheymustputallfoodthatissuccessfullyeatenintotheir“stomachs”(plasticcups).

5. Spreadoutthefoodforthe2ndSeasonintwoplacesthatrepresentEastandWestClipland.Note:itiseasiestonacarpetedfloor,sothefooditemsdonotrollaroundtoomuch.

6. Givethem20secondstoeatalltheycan.Makesuretheydonotscrapeorshovelthefoodintotheirstomachs,asthiswillbadlyskewtheresults.

7. Afterthefeedingfrenzy,putuptheFoodValuestransparency.Askstudentstocalculatethevalueofthefoodtheyate(helpthemwithoneormoreexampleswrittenontheboard).Ifastudentdoesn’teatenoughtosurvivethenheturnsinhisbeakandsitsdown.Ifastudentateenoughtosurvivethenshecontinuesaspartofthepopulation.Eachstudentwhoateenoughtoreproducegetsanotherbillthesamesizeasherownandselectsastudentfromtheaudiencetobeheroffspring.

8. HaveacrewofstudentscleanupalluneatenfoodfromthefloorandreturntotheZiplocbag.9. PutuptheClipbirdPopulationstransparency.Record2birdsineachoftheboxeslabeled1st

Seasonbecausethatwastheinitialnumber.Askthenow‐livingeastandwestbirdstoraisetheirbeaksiftheyarenowinthegame.Includeallsurvivingbirdsandtheiroffspring.Recordthenumbersinthe2ndseasonboxes.(Note:thesearethebirdsresultingfromthe2ndseasonoffeeding.)

10. Repeatdirections5‐9withthefoodforthe3rdseason.Beforespreadingthefood,letstudentsknowthatthecontentoffoodhaschanged(i.e.,thequantityofeachfoodtypeisdifferent).

11. Repeatdirections5‐9withthefoodforthe4thseason.Beforespreadingthefood,whichhasagainchanged,askstudentswhattypesofenvironmentalpressuresmighthavecausedthischange(e.g.,drought,insectinvasionruiningthecrop,etc.).

12. Haveallstudentsturnintheirbeaksandcleanupthemess.13. PutuptheClipbirdPopulationstransparency.14. AskstudentstodescribewhathappenedtotheClipbirdpopulationsandwhattheythinkcaused

thechanges.15. Keepthediscussiongoingsothatstudentscancreatetheirunderstandingthatselectioncan

happenwithinapopulationthatcanfavoronetypeoveranother.

©2010.TheConcordConsortium,Inc. page4

4.Discusstheactivity(Explain)

Theactivitycoversanumberofimportantconcepts:

• Evolutionresultsfromselectionactingupongeneticvariationwithinapopulation.• Adaptationsoftenpersistinapopulationbecausetheyareinsomewayadvantageous.• Inheritedcharacteristicsaffectthelikelihoodofanorganism’ssurvivalandreproduction.• Evolutionactsonwhatexists.• Theproportionofindividualswithadvantageouscharacteristicsmayincreaseduetotheir

increasedlikelihoodofsurvivingandreproducing.• Speciationrequiresreproductiveisolation.

Usetheaboveconceptsasaguidetoaskingquestionsorusethefollowingquestionsattheendoftheactivity:

• DisplaytheClipbirdPopulationstransparencyandaskstudentswhatthenumberstellthem.Whatdotheynoticeaboutthebirdsoneachside?

• WhathappenedtotheClipbirdpopulationsinthetwodifferentareas?• Whichtypeofbeakwashelpful(advantageous)inEastClipland?InWestClipland?Why?• WechangedfoodbydumpingoutthecontentsofaZiplocbag.Howwouldfoodsourceschange

forbirdsinreallife?Forexample,sometimeschangesintheweatheraffecttheamountofavailablefood.InFloridainthewinterof2009‐10,therewasacoldsnapandorangetreeswereaffected.

5.Makeanevolutionarytree(Elaborate)Aftertheactivity,displaythefoodbagsinorder–WestClipland,Seasons2,3,and4ononeside;EastClipland,Seasons2,3,and4ontheother.Askstudentsaboutthecontentofthesebags.Whathappenedtothefoodsupply?Cantheycomeupwithscenariosforwhythismighthavehappened?Howdoesthistreeofbagsrelatetothe"treeoflife"intheLegoactivity?