Mostof Thelargestuff Hasbeen Foundand Described

TaxonomyandClassification

Taxonomy

=thescienceofnaminganddescribingspecies

about1.5Mdifferentspeciesoflifehavebeen

described

eachyear~13,000newspeciesaredescribedmostscientistsestimatethatthereareatleast

50to100Millionactualspeciessharingourplanettoday

mostwillprobablyremainunknownforever:

themostdiverseareasofworldarethemostremote

mostof thelargestuff hasbeen foundand described

notenoughresearchersormoneytodevotetothiswork

CommonvsScientificName

manylargerorganismshave“commonnames”

butsometimes1commonnameforsameorganism

sometimessamecommonnameusedfor2ormoredistinctlydifferentorganisms

eg.daisyeg.moss

eg.mouseeg.ferneg.bug

withoutaspecific(unique)nameit’simpossibletocommunicateaboutspecificorganisms

WhatCharacteristicsareused

howdowebegintocategorize,classifyandnameall theseorganisms

therearemanywaystoclassify:

formcolor size

chemicalstructuregeneticmakeup

earliestattemptsusedgeneralappearanceieanatomyandphysiologicalsimilarities

plantsvsanimals

onlylargestanimalswerecategorizedeverythingelsewas“vermes”

today,muchmorefocusonmolecularsimilarities proteins,DNA,genes

HistoryofClassification

Aristotle

wasthefirsttotrytonameandclassifythingsbasedonstructuralsimilarities

described~520speciesofanimals;esparoundGreece

believedanameshouldreflecthiddenrealityoressenceusedphrasesorsinglewords,notconsistent

Theophrastus classifiedplantsintoherbs,shrubsandtrees

afterinventionoftheprintingpressin1400’s“Herbals”wereprintedtheyemphasizedplantswithmedicinaluses

CarolusLinnaeus,

aSwedishbotanist,

developedandpublishedthefirstcomprehensiveandconsistentclassificationsystemforbothplantsandanimals:

plants:SpeciesPlantarum1753

(describedandclassifiedall plantsknowninhistime

=7300species)

animals:SystemaNaturae1758

Linnaeus

categorizedandclassified~8000differentplantsand

~10,000animals

(including828musselsmolluscs;2100insects;4777fish,birdsmammals)

offeredthefirstcomprehensive,consistent

andmuchsimplermethodofnamingand

organizingspeciesintoacollection:

1.emphasizedmorphologicalcharacteristicsasthebasisforarrangingspecimensinacollection

2.eachspeciesisgivenauniquescientificname

whilesomespeciescanhave100’sofcommonnameseachhasonlyonebinomialname

3.eachuniquenameisabinomial

binomialname:Genus+speciesepithet

before–speciesconsistedofupto12words eg.tomato

was:Solanumcauleinermeherbaceofoliispinnatisincisisracemissimplicibus

(=Solanumwithasmoothherbaceousstem,incisedpinateleavesandsimple inflorescence)

Linnaeus:Solanumlycopersicum

mostnamesaredescriptive,latinizedorgreekforms,oftentohonorsomeone

buttherearealsosomeirreverentnames: eg.Veraepeculyaarthropod(?insect)

eg.Heerzlukenatchaarthropod(?insect) eg.Pisoneyvaearthropod(?insect)

eg.Agraphobiabeetleeg.Phthiriarelativitaefly

sometimes“overdo”thedescriptivevalueofaname:

eg. Gammaracanthuskytodermogammarusloricatobaicalensis

4.specieswerearrangedinanascendingseriesofinclusivecategoriesor‘taxa’

ieahierarcy:kingdom phylum class

orderfamily

genus–atypicalgenuscontainsabout10-12species

species

inthisclassificationschemeonly“species”isarealcategory

thespeciesisthebasicunitofclassification

theonlyrealunit

highertaxaarepurelymythicalcreationstohelpusunderstandrelationshipsbetweenorganisms

andsometimechangeasourknowledgeofthegroupincreases

eg.“lumpersandsplitters”

biologicalspeciesconcept:

species=groupoforganismscapableofinterbreeding and producing fertile offspring

butfossils

asexualreproduction

‘type’speciesiscollectedanddescribed

whenanewspeciesisdiscoveredarepresentativesampleis collectedandusedasthe“type”

thisbecomesapermanentpartofamuseumcollection itisthetypethatisdescribedandnamed

ifthereareanyfuturequestionsitcanbeexaminedfurther

whenLinnaeus1stproposedhissystemEvolutionhadnotyetbeenformallyproposed

afterDarwinandWallaceTaxonomytookonanewrole

wasalsousedtoreflectevolutionaryrelationships

systematics=determiningphylogenyofaspecies

phylogeny=evolutionaryrelationships

basedonphenotypicsimilaritiesanddifferences

theoriginalhierarchywasoriginallyusedjusttocategorizedegreesofsimilaritybetweenorganisms

afterDarwinitwasinterpretedtoshowphylogeneticrelationships

toconstructevolutionarytrees

1.lookforanatomicalandphysiologicalsimilarities

2.comparewithsimilarfossilsthatmightexist

3.studyitsembryologicaldevelopment

4.ecologicalcharacteristics

eg.classesoldercommonancestoreg.generayoungercommonancestor

Newcriteriaandterminologyforclassification:

Primitivevs Advanced

Primitivemoresimilartohypotheticalancestor

Advancedconsiderablechangefromancestor

eg.batorprimatevsmouseorshrew

GeneralizedvsSpecialized

Generalizedonestructurecanbeusedforlotsofdifferentthings

Specializedstructureismodifiedtoperformaspecific function

eg.insectovipositortolayeggs

becomesspecializedtosting,drillholes,parasitizehosts,etc

eg.leafforphotosynthesis

becomesspecializedasthorns,tendrils,foodorwaterstorage,flowerparts,etc

HomologousvsAnalogous

Homologousstructureswithsameorigin

impliesevolutionaryrelationship

eg.birdwing,humanarm,whaleflipper

Analogousstructureswithsimilarityinfunctionand

sometimesappearancewithnoevolutionaryconnection

eg.birdwing,insectwing eg.octopuseye,humaneye

butanalogousstructurescanindicate

convergentevolution

eg.cactiinAmerica,euphorbsinAfrica

eg.placentalsinwest,marsupialsinaustraliaeg.insectwingaroseseveraltimesinevolution

Cladistics

anevenmorespecificmethodofcomparisontriestoremoveevenmoreofthesubjectivity

usesonlyhomologousstructuresincomparingorganisms

eachchangein“primitive”structureisgivenequalweight

thosewiththemostchangesinthestructurearethemostdistantlyrelated

MolecularTaxonomy

morerecently,molecularevidenceisusedprovidesamoreobjectivewaytodeterminerelationships

thevariationsinstructureofproteinsorgenesonstrandofDNAcanbeusedtocalculatehowcloseofarelationshipthereisbetweenseveralorganisms

canalsobeusedtoestimatehowlongagonewgroupsevolved

generallyparallelsotherinformation butsometimesprovidesnewinsightinto

evolutionaryrelationships

Phylogeny

eachspeciesisincludedinahierarchyofclassification

eachlevelofthehierarchyismoregeneralthantheonebelow

eachlevel=ataxon

beforeDarwin

speciesnamesweregivenbasedoneg.physicalcharacteristicsor

eg.tohonoraresearcherinfield,eg.locationwherefound,etc

classificationintohighertaxawasbytheirstructuralsimilarities(morphology)

afterDarwinclassificationbecamecloselytiedtoevolutionaryrelationships(=phylogeny)

eachtaxonmustbemonophyletic

allmembersmustbefromsameoriginal ancestor