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.