Essential idea: Species are named and classified using an internationally agreed system.

By Chris Paine

https://bioknowledgy.weebly.com/http://www.tokresource.org/tok_classes/biobiobio/biomenu/classification/index.htm

The Swedish botanist Carolus Linnaeus originally invented the binomial system to help him consistently name plants he identified. The system was eventually adopted by other scientists and remains to the accepted naming system for species. Though species may have many common names to avoid confusion scientists always use the scientific/binomial name.

5.3 Classification of biodiversity

Understandings

Statement Guidance

5.3.U1 The binomial system of names for species is universal

among biologists and has been agreed and developed

at a series of congresses.

5.3.U2 When species are discovered they are given scientific

names using the binomial system.

5.3.U3 Taxonomists classify species using a hierarchy of taxa.

5.3.U4 All organisms are classified into three domains. Archaea, eubacteria and eukaryote should be

used for the three domains. Members of these

domains should be referred to as archaeans,

bacteria and eukaryotes. Viruses are not

classified as living organisms.

5.3.U5 The principal taxa for classifying eukaryotes are

kingdom, phylum, class, order, family, genus and

species.

5.3.U6 In a natural classification, the genus and

accompanying higher taxa consist of all the species

that have evolved from one common ancestral species.

5.3.U7 Taxonomists sometimes reclassify groups of species

when new evidence shows that a previous taxon

contains species that have evolved from different

ancestral species.

5.3.U8 Natural classifications help in identification of species

and allow the prediction of characteristics shared by

species within a group.

Applications and Skills

Statement Guidance

5.3.A1 Classification of one plant and one animal species

from domain to species level.

5.3.A2 Recognition features of bryophyta, filicinophyta,

coniferophyta and angiospermophyta.

Students should know which plant phyla have

vascular tissue, but other internal details are

not required.

5.3.A3 Recognition features of porifera, cnidaria,

platylhelmintha, annelida, mollusca, arthropoda and

chordata.

Recognition features expected for the selected

animal phyla are those that are most useful in

distinguishing the groups from each other and

full descriptions of the characteristics of each

phylum are not needed.

5.3.A4 Recognition of features of birds, mammals,

amphibians, reptiles and fish.

5.3.S1 Construction of dichotomous keys for use in

identifying specimens.

5.3.U2 When species are discovered they are given scientific names using the binomial system.

5.3.U2 When species are discovered they are given scientific names using the binomial system.

5.3.U1 The binomial system of names for species is universal among biologists and has been

agreed and developed at a series of congresses.

The 21st International Congress of Zoology (ICZ)

http://iszscon2012.haifa.ac.il/

http://www.ibc2017.cn/index.html

• Carl Linnaeus orginally published Systema Natura in 1758 in which he gave binomials for all species known at that time.

• The IBC of Vienna in 1905 voted to accept his naming convention.• Since then both the IBC and ICZ have been the bodies that oversee the international

efforts to maintain consistent naming conventions and use of taxon.• Periodically the congresses meet to discuss issues affecting classification.

http://www.tokresource.org/tok_classes/biobiobio/biomenu/classification/index.htm

5.3.U2 When species are discovered they are given scientific names using the binomial system.

5.3.U2 When species are discovered they are given scientific names using the binomial system.

5.3.U2 When species are discovered they are given scientific names using the binomial system.

5.3.U2 When species are discovered they are given scientific names using the binomial system.

5.3.U2 When species are discovered they are given scientific names using the binomial system.

5.3.U2 When species are discovered they are given scientific names using the binomial system.

5.3.U7 Taxonomists sometimes reclassify groups of species when new evidence shows that a

previous taxon contains species that have evolved from different ancestral species.

Historically classification systems have been revised repeatedly based on emerging evidence.

Recent evidence from genetic studies of ribosomal RNA has shown that "prokaryotes" are far more diverse than anyone had suspected.

Previously in the second half of the 20th century all living organisms were classified into five kingdoms. This included prokaryotes being placed in one kingdom and eukaryotes were split-up into the remaining four kingdoms.

ribosomal RNA is found in all organisms and evolves slowly so is a good way to track evolution over long time periods.Recent work

http://academic.pgcc.edu/~kroberts/Lecture/Chapter%204/04-23_WhittakerTax_L.jpg

5.3.U4 All organisms are classified into three domains.

http://www.ucmp.berkeley.edu/alllife/threedomains.html

The Prokaryotae are now divided into two domains, the Bacteria and the Archaea

No one of these groups is ancestral to the others, and each shares certain features with the others as well as having unique characteristics of its own.

Bacteria and the Archaea are as different from each other as either is from the Eukaryota, the third domain.

Revision of the classification system lead to a new level of taxon called domains.

5.3.U4 All organisms are classified into three domains.

Archaea Bacteria (Eubacteria) Eukaryota

Examples are often, but always, extremophiles:• Sulfolobus sp. grow in volcanic

springs with optimal growth occurring at pH 2-3 and temperatures of 75-80 °C

• Halobacterium sp. (lives in water with high salt concentrations)

• Staphylococcus aureus (above)can cause skin infections and respiratory disease

• Cyanobacteria sp. Arephotosynthetic

• Rhizobium sp. live symbiotically with plants and fix nitrogen

Includes several kingdoms including fungi, animals and plants. Examples range from algae to Humans.

• No nuclear membrane• RNA and biochemistry distinct

from bacteria

• No nuclear membrane • Nuclear membrane

Features and examples of each domain:

http://en.wikipedia.org/wiki/Three-domain_system

n.b. viruses are not classified as living organisms in the same way that eukaryotes, archaeans, and bacteria are. They are however of considerable biological importance.

5.3.U3 Taxonomists classify species using a hierarchy of taxa.

5.3.U5 The principal taxa for classifying eukaryotes are kingdom, phylum, class, order, family,

genus and species.

Not all domains use the same taxa – the example above is for Eukaryotes

5.3.U5 The principal taxa for classifying eukaryotes are kingdom, phylum, class, order, family,

genus and species.

5.3.U5 The principal taxa for classifying eukaryotes are kingdom, phylum, class, order, family,

genus and species.

5.3.A1 Classification of one plant and one animal species from domain to species level.

Learn a mnemonic, one animal example and one plant example:

Domain Does Eukaryota Eukaryota

Kingdom Kennard Animalia Plantae

Phylum Play Chordata Spermatophyta

Class Classical Mammalia Eudicotyledons

Order Or Primates Magnoliidae

Family Folk Hominidae Ranunculales

Genus Guitar Homo Ranunculus

Species Songs? Sapiens Acris

http://commons.wikimedia.org/wiki/File:Masai_Woman.jpg http://commons.wikimedia.org/wiki/File:Ranunculus_macro.jpg

5.3.A2 Recognition features of bryophyta, filicinophyta, coniferophyta and angiospermophyta.

e.g.e.g.

e.g.e.g.

5.3.A2 Recognition features of bryophyta, filicinophyta, coniferophyta and angiospermophyta.

Leaves, roots and stems Vascular tissue

Reproductive structures

Bryophytes(mosses, hornworts and liverworts)

•No roots, but structures similar to root hairs called rhizoids•Mosses have simple leaves and

stems• Liverworts have a flattened thallus

None Spores produced in capsules, which develop at the end of a stalk

Filicinophytes(ferns)

•Roots present• Short non-woody stems.• Leaves usually divided into pairs of

leaflets

Yes Spores produced in sporangia on the underside of the leaves

Coniferophytes(conifer shrubs and trees)

•Roots, present•Woody stems• Leaves usually narrow with a thick

waxy cuticle

Yes Seeds develop from ovules in female cones. Male cones produce pollen.

Angiospermophytes(flowering plants)

• Leaves and roots variable in structure• Stems maybe woody (shrubs and

trees)

Yes Seeds develop from ovules in ovaries, insideflowers. Seeds are dispersed by fruits which develop from the ovaries.

5.3.A4 Recognition of features of birds, mammals, amphibians, reptiles and fish.

The most familiar animal from the chordata phyla belong the to subphylum vertebrata. Can you match the different classes with the images?

Fish (Agnatha,Chondrichthyes, Osteichthyes)

Birds

(aves)

Mammals

(mammalia)

Amphibians

(amphibia)

Reptiles

(reptilia)

http://commons.wikimedia.org/

n.b. Fish is not a true class it is actually a grouping of three similar classes.

5.3.A4 Recognition of features of birds, mammals, amphibians, reptiles and fish.

The most familiar animal from the chordata phyla belong the to subphylum vertebrata. Can you match the different classes with the images?

http://commons.wikimedia.org/

Fish (Agnatha,Chondrichthyes, Osteichthyes)

Birds

(aves)

Mammals

(mammalia)

Amphibians

(amphibia)

Reptiles

(reptilia)

n.b. Fish is not a true class it is actually a grouping of three similar classes.

5.3.A4 Recognition of features of birds, mammals, amphibians, reptiles and fish.

Limbs Gas Exchange Reproduction Other features

Mammals 4 Pentadactyllimbs

Lungs with alveoli

• Internal fertilization• Give birth to live young• Mammary glands secrete

milk

• Hairs growing from the skin• Teeth including living tissue

birds 4 Pentadactyllimbs, 2 limbs modified as wings

Lungs with parabronchialtubes

• Internal fertilization• Hard shells around the

eggs

• Feathers growing from skin• Beak but no teeth

reptiles 4 Pentadactyllimbs

Lungs with extensive folding

• Internal fertilization• Soft shells around eggs

• Dry scaly impermeable skin• Simple teeth – no living

tissue

amphibians 4 Pentadactyllimbs

Simple lungs with small internal folds and moist surfaces

• External fertilization in water

• Protective jelly around eggs

• Larval stage lives in water

• Soft moist permeable skin

fish Fins Gills • External fertilization inmost species

• Scales grow from the skin • with a single gill slit • Swim bladder for buoyancy

A summary of key features that can be used to distinguish between the vertebrate classes

5.3.A3 Recognition features of porifera, cnidaria, platylhelmintha, annelida, mollusca, arthropoda

and chordata.

chordata

porifera

cnidaria platylhelmintha

annelida mollusca

arthropoda

http://commons.wikimedia.org/

What about other phyla? Can you match the names with the images?

5.3.A3 Recognition features of porifera, cnidaria, platylhelmintha, annelida, mollusca, arthropoda

and chordata.

Chordata (animals with a backbone) should be easy. Try using the key to help identify the rest of the phyla.

5.3.A3 Recognition features of porifera, cnidaria, platylhelmintha, annelida, mollusca, arthropoda

and chordata.

http://commons.wikimedia.org/

Can you match the phyla with the images?

chordata porifera

cnidaria

platylhelmintha

annelida

mollusca

arthropoda

5.3.A3 Recognition features of porifera, cnidaria, platylhelmintha, annelida, mollusca, arthropoda

and chordata.

Symmetry Segmentation Digestive tract Other features

porifera(sponges)

None None No mouth or anus • Porous• attached to rocks• Filter feeder

cnidaria(corals, jellyfish)

Radial None Mouth but no anus • Stinging cells• Tentacles

platylhelmintha(flatworms)

Bilateral None Mouth but no anus • Flattened body

annelida

(earthworms,

leeches)

Bilateral Very segmented

Mouth and anus • bristles often present

Mollusca

(oyster, snails,

octopus)

Bilateral Non-visible segmentation

Mouth and anus • Most have shell made of CaCO3

Arthropoda

(ant, scorpion,

crab)

Bilateral Segmented Mouth and anus • Exoskeleton• jointed appendages

Chordata

(fish, birds,

mammals)

Bilateral Segmented Mouth and anus • notochord• hollow dorsal nerve cord• (some have ) pharyngeal slits

A summary of key features that can be used to distinguish between animal phyla

5.3.S1 Construction of dichotomous keys for use in identifying specimens.

5.3.S1 Construction of dichotomous keys for use in identifying specimens.

5.3.S1 Construction of dichotomous keys for use in identifying specimens.

5.3.U6 In a natural classification, the genus and accompanying higher taxa consist of all the

species that have evolved from one common ancestral species.

Natural classification groups together species that share a common ancestor from

which they evolved. This is called the Darwinian principle of common descent

.

Grouping together birds, bats and bees because they fly would be an artificial classification as they do not share a common ancestor and evolved the ability to fly independently.

It is expected that members of a group share important attributes or 'homologous’ traits that are inherited from common ancestors. For example Lions share more traits with Jaguars than with Clouded Leopards.

Natural classification is not straightforward as convergent evolution can make distantly related organisms appear similar and adaptive radiation can make similar organisms appear very different from each other.

Plants and fungi were once classified together because they both possessed shared characteristics such as cell walls. It is now known that this is an artificial grouping as their cell walls have a different molecular biology and they evolved separately.

5.3.U8 Natural classifications help in identification of species and allow the prediction of

characteristics shared by species within a group.

If a new species of Ant is discovered then scientists would predict that the species should possess amongst other characteristics six jointed legs, a head, thorax, abdomen, elbowed antennae, ‘antibiotic’ secretory glands. If the species does not match the expected set of characteristics this brings into question either the classification of the species or of Ants as a family.

Natural classification is very helpful when dealing with new species:

“New species of legless amphibian discovered in remote Cambodian rainforest”

http://www.abc.net.au/news/2015-01-17/new-species-of-legless-amphibian-found-in-cambodia/6022048

Dichotomous keys can be used to help identify the species. The keys can place a specimen with the most closely related species, genus, family or phyla using natural classification. To what level of classification a specimen can be placed depends on how unique it is.

Bibliography / Acknowledgments

Jason de Nys