5.3 Classification of Biodiversity

The binomial system of nomenclature

The formal system by which all living species are classified

Why is the binomial system valuable?

* Allows for identification and comparison of organisms based on recognized characteristics
* Allows all organisms to be named according to a universally recognized scheme
* Can show how closely related organisms are, allowing for the prediction of evolutionary links
* makes it easier to collect, sort and group information about organisms

Three domains

* Eukarya - organisms that contain a membrane-bound nucleus (protist, plants, fungi and animals)
* Archaea - prokaryotic cells lacking a nucleus and consists of the extremophiles (e.g. methanogens, thermophiles, etc.)
* Eubacteria - prokaryotic cells lacking a nucleus and consists of the common pathogenic forms (e.g. E. coli, S. aureus, etc.)

Hierarchy of Taxa

Dear King Philip Came Over For Good Soup

Domain Kingdom Phylum Class Order Family Genus Species

Animal example taxonomic rank

Animalia

Chordata

Mammalia

Primate

Hominidae

Homo

Sapiens

Human

Plant example taxonomic rank

Plantae

Angiospermophyta

Eudicotidae

Ranunculales

Ranunculacae

Ranunculus

Acris

Buttercup

Artificial classification + advantages & disadvantages

Involves randomly selecting unifying characteristics first and then grouping organisms accordingly. (e.g. bats and birds both fly)

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Advantage: Easy to develop and relatively stable (unlikely to change)

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Disadvantage: Do not generally show evolutionary relationships

Natural classification + advantages & disadvantages

Species in group evolved from common ancestor

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Advantage: Can be used to predict characteristics shared by species within a group

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Disadvantage: Highly mutable and tend to change as new information is discovered

Phylogenetic classification

Now being used to differentiate organisms based on genetics

How many phyla does the kingdom Plantae include and what are some examples?

The kingdom Plantae contains 12 phyla - which includes:

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* Bryophytes
* Filicinophytes
* Coniferophytes
* Angiospermophytes

Bryophyta (Plant phyla)

* Has no vascularisation (no xylem and phloem)
* Has no ‘true’ leaves, roots or stems
* Reproduce by releasing spores
* e.g. mosses

Filicinophyta (Plant phyla)

* has vascularisation (e.g. xylem and phloem)
* Has leaves, roots and stems
* Reproduces by releasing spores from clusters called sori on the underside of the leaves, sporangia
* e.g. ferns

Coniferophyta (Plant phyla)

* Has vascularisation
* Has leaves, roots and stems
* Reproduce by non-motile gametes (seeds) which are found in cones
* e.g. pine trees

Angiospermophyta (Plant phyla)

* Has vascularisation
* has leaves, roots and stems
* Reproduce by seeds produced inovules within flowers
* E.g. flowering plants and grasses

Two groups in kingdom Animalia

Invertebrates (no backbone) and vertebrates (most chordata)

Examples of invertebrate phyla (animalia kingdom)

* Porifera
* Cnidaria
* Platyhelmintha
* Annelida
* Mollusca
* Arthropoda

Example of vertebrates (animalia kingdom)

All vertebrates belong to the phylum chordata - however not all chordata are vertebrates

Porifera (animalia phyla)

* No body symmetry (asymmetrical)
* No mouth or anus
* May have silica or calcium carbonate
* Have pores
* E.g. sea sponges

Cnidaria (animalia phyla)

* Has radial symmetry
* Has mouth but no anus
* May have tentacles with stinging cells for capturing and disabling prey
* Examples include jellyfish, sea anemones and coral

Platyhelmintha (animalia phyla)

* has bilateral symmetry
* mouth but no anus
* flattened body to increase SA:Vol ratio
* unsegmented
* no circulatory system
* soft body
* e.g. tape worm and planaria

Annelida (animalia phyla)

* Have bilateral symmetry
* Separate mouth and anus
* Body composed of ringed segments with specialization of segments.
* Closed circulatory system
* Calcium carbonate shell
* e.g. earthworms and leeches

Mollusca (animalia phyla)

* Bilaterial symmetry
* Separate mouth and anus
* Body composed of visceral mass, a muscular foot and a mantle
* e.g. snail, slug, octopi, squid

Arthropoda (animalia phyla)

* Bilateral symmetry
* Separate mouth and anus
* Jointed legs
* hard exoskeleton
* Include insects, crustaceans, spiders, scorpions and centipedes

Chordata (animalia phyla)

* bilateral symmetry
* separate mouth and anus
* notochord and a hollow, dorsal nerve tube for at least some period of their life cycle
* e.g. mammals, birds, reptiles, amphibians and fish

Features in chordates that may persist into adulthood:

These features include a notochord, hollow dorsal neural tube, pharyngeal slits and a post-anal tail

Chordates that form a protective backbone

Go into sub-phylum (vertebrata) and include birds, mammals, amphibians, reptiles and fish

Features of fish

* Covered in scales made out of bony plates in the skin
* Reproduce via external fertilisation
* Breathe through gills that are covered with an operculum
* Does not maintain a constant internal body temperature

Features of amphibian

* Moist skin, permeable to gases and water
* Reproduce via external ferilisation
* Can breathe through skin but also possess simple lungs
* Do not maintain a constant internal body temperature

Features of reptiles

* Covered in scales made out of keratin
* Reproduce via internal fertilisation and females lay eggs with soft shells
* Breathe through lungs that have extensive folding (increase in SA:vol ratio)
* Do not maintain a constant internal body temperature (ectothermic)

Features mammals

* Skin has follicles which produce hair made out of keratin
* Reproduce via internal fertilisation and females feed young with milk from mammary glands
* Breathe through lungs with alveoli
* Maintain a constant internal body temperature (endothermic)