SJI Ecology and Climate Change Notes

IBBiology(SL/HL) [Notes]Topic1:Ecology&ClimateChange(I) [IBBiology-1stAssessment2025] Overview Topic1A⎯A4.2Conservationofbiodiversity● Theme&LevelofOrganization.Unityanddiversity⎼Ecosystems● GuidingQuestions. (1)Whatfactorsarecausingthesixthmassextinctionof species?(2) Howcanconservationistsminimizethelossofbiodiversity?● LinkingQuestions.(1) Inwhatwaysisdiversityapropertyoflifeatalllevelsofbiologicalorganization?(2)Howdoesvariationcontributetothestabilityofecologicalcommunities? Topic1B⎯B4.2Ecologicalniches● Theme&LevelofOrganization.Formandfunction⎼Ecosystems● GuidingQuestions.(1)Whataretheadvantagesofspecializedmodesofnutritiontolivingorganisms?(2)Howaretheadaptationsofaspeciesrelatedtoitsnicheinanecosystem?● LinkingQuestions.(1)Whataretherelativeadvantagesofspecificityandversatility?(2)Foreachformofnutrition,whataretheuniqueinputs,processesandoutputs? Topic1C⎯C4.1Populationsandcommunities● Theme&LevelofOrganization.Interactionandinterdependence⎼Ecosystems● GuidingQuestions.(1)Howdointeractionsbetweenorganismsregulatesizesofpopulationsin a community? (2) What interactions within a community make its populationsinterdependent?● LinkingQuestions.(1)Whatarethebenefitsofmodelsinstudyingbiology?(2)Whatfactorscanlimitcapacityinbiologicalsystems? Acknowledgement1. Notesadaptedfrom<SaveMyExams>https://www.savemyexams.com/dp/ [Notes]Topic1:Ecology&ClimateChange(I) 1

Topic1A⎯A4.2Conservationofbiodiversity ● Theme & Level of Organization. Unity and diversity ⎼Ecosystems● GuidingQuestions.(1)Whatfactorsarecausingthesixthmassextinctionofspecies?(2)Howcanconservationistsminimizethelossofbiodiversity?● LinkingQuestions.(1) Inwhatwaysisdiversityapropertyoflifeatalllevelsofbiologicalorganization?(2)Howdoesvariationcontributetothestabilityofecologicalcommunities? ContentStatementsA4.2.1⎼Biodiversityasthevarietyoflifeinallitsforms,levelsandcombinationsA4.2.2⎼ComparisonsbetweencurrentnumberofspeciesonEarthandpastlevelsofbiodiversityA4.2.3⎼CausesofanthropogenicspeciesextinctionA4.2.4⎼CausesofecosystemlossA4.2.5⎼EvidenceforabiodiversitycrisisA4.2.6⎼CausesofthecurrentbiodiversitycrisisA4.2.7⎼NeedforseveralapproachestoconservationofbiodiversityA4.2.8⎼SelectionofevolutionarilydistinctandgloballyendangeredspeciesforconservationprioritizationintheEDGEofExistenceprogramme A4.2.1⎼Biodiversityasthevarietyoflifeinallitsforms,levelsandcombinationsA4.2.2⎼ComparisonsbetweencurrentnumberofspeciesonEarthandpastlevelsofbiodiversity Biodiversity● Biodiversitycanbethoughtofasthevarietyoflifethatexistsinaspecified area. This can refer to global biodiversity, or to thebiodiversityofasmallerregion.● Biodiversityisveryimportant for theresilienceofecosystems.The more biodiverse an ecosystem is, the more stable andresistanttochangeitwillbe.● Biodiversitycanbestudiedatthreedifferentlevels:(i)ecosystem,(ii)speciesand(iii)genetic. [https://www.researchgate.net/figure/The-three-components-of-biodiversity-UNEP-WCMC-2015_fig1_312948089] Speciesdiversity● Speciesdiversitycanbemeasuredintwoways:○ Speciesrichnessisthenumberofspecieswithinanecosystem.○ Speciesevennessisthenumberofindividualsofeachspecieswithinanecosystem.● Foranecosystemtohavehighspeciesdiversityitmusthavehighspeciesrichnessandhighspeciesevenness.○ Anecosystemwouldnot bespeciesdiverseifithad1000species,butonlyhadafewindividualsof500ofthosespecies;thiswouldbehighrichnessbutlowevenness.○ Anecosystemwouldnotbediverseifithad10speciesandhadthousandsofindividualsofeachspecies;thiswouldbehighspeciesevennessbutlowspeciesrichness.● Ecosystemswithhighspeciesdiversityareusuallymorestablethanthosewithlowerspeciesdiversityastheyaremoreresilienttoenvironmentalchanges. [Notes]Topic1:Ecology&ClimateChange(I) 2

○ ForexampleinthepineforestsofFloridatheecosystemisdominatedbyoneortwotreespecies.Ifapathogencomesalongthattargetsoneofthetwodominantspeciesoftrees,thenthewholepopulationcouldbewipedout andtheecosystemit isapartofcouldcollapse. Geneticdiversity● Thegeneticdiversityisthenumberofdifferentallelesofgenesthatarepresent.Thiscanbeinanentirespeciesorinalocalpopulation.● Factorsthatcontributetogeneticdiversityinclude:○ Theproportionofgenesthathavemorethanoneallele.○ The number of different allelesthateachgenehas.● Therecanbegeneticdifferencesordiversitybetweenpopulationsofthesamespecies.Thismaybebecausethe two populations liveindifferentareasandsoaresubject toslightlydifferent selection pressures thataffecttheallelefrequenciesintheirpopulations.● There can be genetic differencesbetween individuals within apopulation. Genetic diversity in aspeciesisimportantasitcanhelpthepopulation adapt to, and survive,changesintheenvironment.● Asseeninthediagramontheright,there are different levels ofbiodiversity, such as ecosystem(habitat) diversity, species diversity,andgeneticdiversity. BiodiversityComparisons Biodiversitychangeovertime● Current estimatesfor global speciesdiversityvary, but recent estimatessuggestthattherecouldbearound8.7millionspeciesonEarth.Around1.2millionspecieshavecurrentlybeenrecordedandclassified,meaningthatifestimatesarecorrect,therearestillmanymorespeciestobediscovered.● ThenumberofspeciesonEarthhasnotalwaysbeenthesame.Thefossilrecordshowsthat:○ Manyspeciesthathaveexistedinthepastarenolongerpresent.Thisisduetoextinction.○ Therearemanymorespeciesalivetodaythanhavebeenaliveinthepast.Theprocessofspeciationleadstoanincreaseinthenumberofspecies.Speciationgivesrisetonewspeciesovertime,increasingglobalbiodiversity.● Whenspeciationoccursatahigherratethanextinction,globalbiodiversitywillincrease.● Despitemanyextinctionsoccurringoverrecentyears,periodsofspeciationinthepastmeanthatglobalbiodiversitylevelsarestillhigherthaneverbefore. [Notes]Topic1:Ecology&ClimateChange(I) 3

[https://en.m.wikipedia.org/wiki/File:Timeline_evolution_of_life.svg] [NOS] Classificationisanexampleof patternrecognitionbutthesameobservationscanbeclassifiedindifferentways● TheaccuracyoftheestimatednumberofspeciesonEarthisdependentontheprocessofclassification.○ Ifspeciesareclassifiedcorrectlythenestimateswillbemoreaccurate.○ Ifspeciesareincorrectlyclassifiedtogetherthenestimateswillbetoosmall.○ Ifspeciesareincorrectlyseparatedthenestimateswillbetoolarge.● Classificationcanbesubjective.Itisnotalwayseasytodeterminethepointatwhichonespecieshasbecometwo,orwhethersimilarorganismsareofthesamespecies,oraretwodifferentspecies.● Itcanbesaidthattaxonomistsareeither:○ 'Lumpers'. Lumpersfocusonsimilaritiesmorethandifferences, andaremorelikelytoclassifyspeciestogether.○ 'Splitters'. Splitters focus on differences, and are more likely to classify speciesseparately. [Notes]Topic1:Ecology&ClimateChange(I) 4

A4.2.3⎼Causesofanthropogenicspeciesextinction AnthropogenicSpeciesExtinction Anthropogenicextinction● Extinction that has been caused by human activities is referred to as anthropogenicextinction.● Scientistsbelievethatwearecurrentlyexperiencingamassextinctionevent,andthathumanactivitiesareplayingalargerole.● Therehavebeenfivemassextinctioneventsinthepast,sothecurrentroundofextinctionscouldbethesixth. Anthropogenicextinctioncasestudy:NorthIslandgiantmoas● The North Island giant moa (Dinornisnovaezealandiae) was a large, flightless,herbivorousbirdthatlivedinNewZealanduntiltheyear 1300. It was once thought to be severaldifferent species of moa due to size differencesbetweenlargerfemalesandsmallermales,hencethe image on the right is being labelled with adifferentspeciesname.● Humans arrived in New Zealand between1200-1300, andit isthought that themoaswerehuntedtoextinctionbyhumansby1300. [https://dinopedia.fandom.com/wiki/Moa] Anthropogenicextinctioncasestudy:Caribbeanmonkseals● Caribbeanmonkseals(Neomonachus tropicalis)livedintheoceansaroundthegulfofMexicoandtheCaribbean,andweredeclaredextinctin2008,thoughitisbelievedthattheymayhavegoneextinctbeforethis.● Their docilenatureandtheir habit of lyingout ontherocksmeant that thesesealswereeasyforEuropeancoloniststohuntfortheiroilandmeat. [https://naturerules1.fandom.com/wiki/Caribbean_Monk_Seal] Anthropogenicextinctioncasestudy:studentchoice●