Topic 5.5

Topic 5.5

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Classification

Why Classify?1. How many

‘different sorts’ of living things are there on the planet?

How many species are there in the world?

Let’s start with some classification!

Take 5 minutes to write down ways in which we can classify the students in class todayKey features of a classification key are that it must be clear, consistent, and easily implemented

Why Classify?In order to sort out and compare living things, we need to organise them into ‘manageable’ categoriesA good classification system allows us to make generalisations AND organise our ideas about organismsClassification involves giving every organism an AGREED NAMEClassification involves arranging organisms into apparently related organisms

The American Robin

(Turdus Migratorius)

The European Robin

(Erithracus Rubecula)

What is taxonomy?

Taxonomy is the process of (scientific) classification

Taxis: Greek for ‘Arrangement or Division’

‘Nomos’: Greek for ‘Method or Law

http://www.youtube.com/watch?v=F38BmgPcZ_I

Systems used to classify living organisms

Linnaean Binomial Nomenclature systemCladistics (Ancient Greek –Branch)Phylogenetics

The evolution of taxonomy…

The Linnaean classification system was created long before scientists understood that organisms evolved. Because the Linnaean system is based on morphology (form and structure) rather than on evolutionary theory Most biologists are switching to a classification system that reflects the organisms' evolutionary history

• Phylogenetic tree

• Cladogram

CladisticsA taxonomic system based on common evolutionary ancestryThe Method of choice for classifying organisms, since it recognises and involves evolutionary theory

Developed since 1958Any group of organisms are related by descent from a common ancestor.

There is a bifurcating pattern of cladogenesis.

Change in characteristics occurs in lineages over time.

Cladistics introduction

Phylogenetic treeAn ‘Evolutionary Tree’Shows inferred evolutionary relationship among species based on similarities/differences in their genetic material or physical appearance

Linnaean ClassificationDeveloped by Carl LinneausSwedish botanist & taxonomistIs still used today, basis for classification and naming of all new species.Based on physical traits, most of his classifications are still accurate.http://www.youtube.com/watch?v=F38BmgPcZ_I

Binomial NomenclatureEach species is assigned a two part scientific name.Written in italics If handwritten, underline the nameFirst word is capitalized (Genus): NOUN

Second word is lowercase (Species): ADJECTIVE

Binomial Nomenclature

Homo sapiens

Modern human

Hawksbill Turtle(imbricate: arrange so that they overlap like tiles)

Genus species

The genus name can be abbreviated if you have already used the full name in your text

Eretmochelys imbricata

Linnaeus also defined four groups of humans, and the divisions were based on both physical and social traits. By 21st-century standards, his descriptions can be regarded as racist. How does the social context of scientific work affect the methods and findings of research? Is it necessary to consider the social context when evaluating ethical aspects of knowledge claims?

There are seven (err, actually 8) levels of

classificationBiological taxonomy is hierarchicalAs we move from kingdom (domain) to phylum, all the way to species, organisms share more and more characteristics.This system allows us to group organisms while also assigning unique species names.

(Domain)KingPhilipCame Over For GoodSpaghetti

How is Life Classified?Pre-1969: Life is classified into 2 Kingdoms:

Plantae and Animals1969 – 1999: Life is classified into 5

Kingdoms: Monera, Protista, Plantae, Fungi, Animalia: using Linnaean Classification System – based on anatomy, morphology, embryology and cell structure

BUT: The Traditional 5 kingdom System does not explain how kingdoms may be related through evolutionary relationships among the kingdoms

The Three DomainsKarl Woese discovery of Archae

The 3 domains were proposed by Dr Karl

WoeseDogma The eukaryote-prokaryote dichotomy was the

central dogma of biology. Woese was making a claim of extraordinary scope. He was saying that we had missed one-third of all living things. People did not like that (5). "I hadn't been trained as a microbiologist, so I didn't have this bias" [about impossibility of bacterial classification]. (Woese)

Classification is a ‘messy’ branch of

science…Just compare the University of Oxford and the University of Berkeley…

Oxford University Museum of Natural

History5

Kingdoms: one

prokaryotic, four

eukaryotic

University of California Berkeley

Classification in the Animal Kingdom

Kingdom AnimaliaContains organisms as diverse as coral and mice….

Classification in the Plant Kingdom

Plant Classification (UMCB)

From Kingdom…Linnaeus originally

divided living things into 2 (then 3) kingdoms…

AnimaliaVegetalia (Plants)Mineralia (Minerals, since abandoned)

We now widely recognise FIVE kingdoms:

1. Kingdom Plantae (the plants)2. Kingdom Animalia (the

animals)3. Kingdom Fungi (the fungi and

moulds)4. Kingdom Protocista

(protozoa and alga)5. Kingdom Prokaryote

[Monera] (the euBacteria and archebacteria)

Kingdom AnimaliaEukaryoticMulticelluarHeterotrophicTerrestrial and aquaticSexual (a few are asexual)Motile (a few are non-motile)

Kingdom Plantae1. Eukaryote2. Multicellular3. Autotrophic4. Mostly terrestrial5. Sexual and asexual6. NonmotileMosses, Ferns,

flowering plants, conifers

Kingdom FungiEukaryoticHeterotrophicUnicellular and multicellularMainly terrestrialAsexual and sexualNon-motile

Mushrooms, puffballs, yeasts, rusts, water moulds

Kingdom prokaryotae (Monera)

ProkaryotesHeterotrophic and autotrophicAnaesrobic and aerobicAquatic, terrestrial and aerosolMostly asexualMostly non-motile (one kind are motile)

Kingdom Protoctistae (Protists)

EukaryotesHeterotrophic and autotrophicUnicellularMostly aquaticMostly asexualMotile and non-motile

Protozoa, slime moulds, algae

Brown Algae

…To SpeciesA group of organisms which can interbreed and produce fertile offspring.Species are named: Genus species

Heliconius charithonius

The smallest taxonomic group, though many subspecies are recognized.

Might potentially interbreedif a barrier or other challenge was removed (ie: distance)

Test yourself

Classification of the malaria parasite,

Plasmodium falciparumKingdom Protista(Subkingdom) ProtozoaPhylum: ApicomplexaClass: SporozoasidaOrder: EucoccidioridaFamily: PlasmodiidaeGenus: Plasmodium

Species: falciparum, malariae, ovale, vivax

Classification of the malaria vector: Aedes Aegyptae

Kingdom: AnimaliaPhylum: ArthropodaClass: InsectaOrder: DipteraFamily: CulicidaeSubfamily: CulicinaeGenus: AedesSpecies: Aegyptae

Now your turn: IB Classification Requirements5.5.2: List seven different levels in the

hierarchy of taxa: kingdom, phylum, class, order, family, genus and species, using an example from two different kingdoms for each levelScenic Oregon Hierarchical ClassificationUse the Scenic Oregon I-animal website to write information about an animal of your choiceUse the University of Berkeley Website to write information about a plant species of your choice

5.5.3 Distinguish between the following phyla of plants,

using simple external recognition features

Resources:Clegg, P. 165 – 168Evolution Drop-down menu in the Blog has resources on all major plant phyla

5.5.4 Distinguish between the following phyla of animals, using simple external recognition features: porifera, cnidaria, platyhelminths, annelida, mollusca and arthropoda

Resources:Clegg, P. 165 – 168Evolution Drop-down menu in the Blog has resources on all major invertebrate phyla 

Classification of the Kingdoms: Synonyms

One prokaryote kingdom

Bacteria

Monera

• No nucleus

• Divide by binary fission (asexual)

Four eukaryote Kingdoms

Protoctista

Fungi

Plantae

Animalia

Dichotomous Keys

From classification to dichotomous keys…

Classification and identification go hand in hand. Once identified, organisms can be classified by placing them in groups that have similar characteristics. To determine the scientific name of an organism, taxonomists use a process of elimination, called keying, to assist them. A dichotomous key is constructed so that pairs of contrasting characteristics are set up in a precise sequence. Each step in the identification process involves the selection of a characteristic from each pair.

Now try some yourselves…

Dichotomous keys trees of oregonFlorida Keys Flowershttp://www.pbs.org/wgbh/nova/nature/classifying-life.htmlSimple Tree dichotomous key

Wednesday/ ThursdayStarting on Topic G3: Impacts of Communities on Ecosystems