Topic 5.5
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Transcript of 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