5.3 Classification of biodiversity
Species are named and classified using an internationally agreed
system.
The binomial system of names for species is universal among biologists and has been agreed and developed
at a series of congresses.
When species are discovered they are given scientific names using the binomial system.Q: List the common name and binomial name of 4 different organisms.
Taxonomists classify species using a hierarchy of taxa.
All organisms are classified into three domains (archaea, eubacteria and eukaryote).
FeatureDomain
Bacteria Archaea EukaryotaHistones associated with DNA
AbsentProteins similar to histones bound to
DNAPresent
Presence of introns Rare or absent Present in some genes Frequent
Structure of cell walls
Made of peptidoglycan
Not made of peptidoglycan
Not made of peptidoglycan; not
always present
Cell membrane differences
Glycerol-ester lipids; d-form of
glycerol
Glycerol-ether lipids; l-form of
glycerol
Glycerol-ester lipids; d-form of
glycerol
Taxonomists classify species using a hierarchy of taxa.
The principal taxa for classifying eukaryotes are kingdom, phylum, class, order, family, genus and species.
List the complete taxonomic classification for human beings and a dandelion.
Kingdom: AnimaliaPhylum: ChordataClass: MammaliaOrder: PrimatesFamily: HominidaeGenus: HomoSpecies: sapiens
Kingdom: PlantaePhylum: AnthophytaClass: MagnoliopsidaOrder: AsteralesFamily: AsteraceaeGenus: TaraxacumSpecies: officinale
In a natural classification, the genus and accompanying higher taxa consist of all the species that have evolved from one
common ancestral species.
Natural classifications help in identification of species and allow the prediction of characteristics shared by species within a group.
Taxonomists sometimes reclassify groups of species when new evidence shows that a previous taxon contains species that have evolved from different ancestral species.
Which two species of reef sharks are most closely related? How do you know?
Carcharinus melanopterus Triaenodon obesus Carcharinus pereziBlack-tip reef shark White-tip reef shark Caribbean reef shark
Which two species are most closely related? How do you know?
Canis lupus familiaris Canis lupus laniger Canis rufusDomestic dog Tibetan wolf Red wolf
Application: Recognition of features of bryophyta, filicinophyta, coniferophyta and angiospermophyta.
Bryophyta Filicinophyta Coniferophyta Angiospermophyta
Vegetative organs
Rhizoids, no true roots. Some with simple stems and leaves
Roots, stems, and leaves are usually present
Vascular tissue No xylem or phloem Xylem and phloem are both present
Pollen Pollen is not produced Pollen is produced in male cones
Pollen is produced in anthers by flowers
Ovules No ovaries or ovules Ovules are produced in female cones
Ovules are enclosed inside ovaries in flowers
Seeds No seeds Seeds are produced and dispersed
Fruits No fruitsFruits produced for dispersal of seeds by mechanical, wind, or animal methods
Application: Recognition of features of porifera, cnidaria, platylhelmintha, annelida, mollusca,
arthropoda and chordata.Porifera Cnidaria Platyhelminthes Mollusca Annelida Arthropoda
Mouth/Anus No mouth or anus
Mouth only Mouth only Mouth and anus
Mouth and anus
Mouth and anus
Symmetry None Radial Bilateral Bilateral Bilateral Bilateral
Skeleton Internal spicules (skeletal needles)
Soft, but hard corals secrete CaCO3
Soft, with no skeleton
Most have shell made of CaCO3
Internal cavity with fluid under pressure
External skeleton made of plates of chitin
Other features
Many pores over the surface through which water is drawn in for filter feeding
Tenatacles arranged in rings around the mouth with stinging cells
Flat and thin bodies in the shape of a ribbon
A fold in the body wall called the mantle secretes the shell
Bodies made up of many ring-shaped segments
Segmented bodies and legs or other appendages with joints between the sections
Application: Recognition of features of birds, mammals, amphibians, reptiles and fish.
Skill: Construction of dichotomous keys for use in identifying specimens.