5.3 Classification of Biodiversity Flashcards
Carl Linnaeus originally published Systema Natura in 1758 in which he gave binomials for all species known at that time.
Based on physical characteristics
Binomial Nomenclature
two named naming system
Species are named:
Genus species
Species level is the smallest taxonomic group, though many subspecies are recognised
subspecies may potentially interbreed if a barrier or other challenge was removed (such as distance)
The Prokaryotes are now divided into two domains
the Eubacteria and the Archaea
Eubacteria and the Archaea are as different from each other as either is from the
Eukaryote, the third domain
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.
Eubacteria
histones associated with DNA: absent
Presence of introns: rare or absent
structure of cell walls: has peptidoglycan
nuclear membrane: none
Archaea
histones associated with DNA: proteins similar to histones are bouded to DNA
Presence of introns: present in some genes
structure of cell walls: not made of peptidoglycan
nuclear membrane: none
eukaryota
histones associated with DNA: present
Presence of introns: frequent
structure of cell walls: not made of peptiglycan, not always present
nuclear membrane: present
A kingdom is the largest & most general taxon, while
a species is the smallest taxon and includes only 1 type of organism.
The smaller the taxon, the more
similar the organisms within it are to each other.
hierarchy of taxa:
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
Natural classification groups together species that share a common ancestor from which they evolved. This is called
the Darwinian principle of common descent
It is expected that members of a group share important attributes or
homologous’ traits that are inherited from common ancestors.
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.
Convergent evolution
may cause distantly related species to appear superficially similar
Adaptive radiation
can make closely related species appear very different
Recent evidence from genetic studies of ribosomal RNA has shown that
“prokaryotes” are far more diverse than anyone had suspected.
ribosomal RNA is
found in all organisms and evolves slowly so is a good way to track evolution over long time periods.
Dichotomous keys (upcoming) 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.
artificial classification
do not share a common ancestor
advantages of natural classfication
Identifcation of species is easier. since new species may not have identifiable traits
Because all of the members o a group in a natural classifcation
have evolved from a common ancestral species, they inherit similar characteristics.
A dichotomous key is a tool to
identify unfamiliar organisms.
kingdom plantae
non vascular plants:
- Bryophytes
Vascular plants
- Filicinophytes
- Coniferophytes
- Angiospermophytes
Bryophytes (mosses, hornworts and liverworts)
- no vascular tissue
- No roots, but structures similar to root hairs called rhizoids
- Mosses have simple leaves and stems
- Liverworts have a flattened thallus
- Spores produced in capsules, which develop at the end of a stalk
Filicinophytes (ferns)
- vascular tissue
- Roots present
- Short non-woody stems
- Leaves usually divided into pairs of leaflets
-Spores produced in sporangia on the underside of the leaves
Coniferophytes (conifer shrubs and trees)
- vascular tissue
- Roots, present
- Woody stems
- Leaves usually narrow with a thick waxy cuticle
- Seeds develop from ovules in female cones. Male cones produce pollen.
Angiospermophytes (flowering plants)
- vascular tissue
- Leaves and roots variable in structure
- Stems maybe woody (shrubs and trees)
- Seeds develop from ovules in ovaries, inside flowers. Seeds are dispersed by fruits which develop from the ovaries.
porifera (sponges)
Symmetry: none
Segmentation: none
Digestive tract: No mouth or anus
skeleton: internal spicules
Other features:
Porous
attached to rocks
Filter feeder
cnidaria
(corals, jellyfish)
Symmetry: radial
Segmentation: none
Digestive tract: mouth but no anus
skeleton: soft but corals are hard
other:
Stinging cells
Tentacles
platylhelmintha (flatworms)
Symmetry: bitlateral
Segmentation: none
Digestive tract: mouth only
skeleton: soft, none
other:
Flattened body
annelida
(earthworms, leeches)
Symmetry: bilateral
Segmentation: very segmented
Digestive tract: mouth and anus
skeleton: internal cavity with fluid under pressure
other:
bristles often present
Mollusca
(oyster, snails, octopus)
Symmetry: bilateral
Segmentation: non visible segmented
Digestive tract: mouth and anus
skeleton: have shells mostly
other:
Arthropoda
(ant, scorpion, crab)
Symmetry: bilateral
Segmentation: segmented
Digestive tract: mouth and anus
skeleton: Exoskeleton, jointed appendages
other:
Bony ray- finned fish
Scales
gills
no limbs (fins only)
eggs+ sperm for external fertilisation
remain in water all life
does not maintain body temp
swim bladder for buoyancy
amphibians
skin moits and permeable
simple lungs, moist skin for gas exchange
4 pentadactyl limbs
4 legs when adult
eggs+ sperm for external fertilisation
larval stage in water, adult on land
does not maintain body temp
eggs in protective jelly
reptiles
impermeable skin with scales
lungs with extensive folding
4 pentadactyl limbs
4 legs
sperm passed into female for internal fertilisation
females lay eggs with soft shells
teeth
does not maintain body temp
birds
skin with feathers
lungswith parabronchial tubes
4 pentadactyl limbs
2 legs 2 wings
sperm passed into female for internal fertilisation
female lays eggs with hard shells
beak, not teeth
maintain constant body temp
mammals
skin has follicles with hair
lungs with alveoli, ribs and diaphragm
4 pentadactyl limbs
4 legs or 2 legs and 2 wings/arm
sperm passed into female for internal fertilisation
give birth to young and feed with milk from mammary glands
teeth
maintain constant body temp
