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). Feature Domain BacteriaArchaeaEukaryota Histones associated with DNA Absent Proteins similar to histones bound to DNA Present Presence of intronsRare 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: Animalia Phylum: Chordata Class: Mammalia Order: Primates Family: Hominidae Genus: Homo Species: sapiens Kingdom: Plantae Phylum: Anthophyta Class: Magnoliopsida Order: Asterales Family: Asteraceae Genus: Taraxacum Species: 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 melanopterusTriaenodon obesus Carcharinus perezi Black-tip reef sharkWhite-tip reef shark Caribbean reef shark

Which two species are most closely related? How do you know? Canis lupus familiarisCanis lupus laniger Canis rufus Domestic dogTibetan wolf Red wolf

Application: Recognition of features of bryophyta, filicinophyta, coniferophyta and angiospermophyta. BryophytaFilicinophytaConiferophytaAngiospermophyta 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 seedsSeeds are produced and dispersed Fruits No fruits Fruits produced for dispersal of seeds by mechanical, wind, or animal methods

Application: Recognition of features of porifera, cnidaria, platylhelmintha, annelida, mollusca, arthropoda and chordata. PoriferaCnidaria Platyhelminthes MolluscaAnnelida Arthropoda Mouth/Anus No mouth or anus Mouth only Mouth and anus Symmetry NoneRadialBilateral Skeleton Internal spicules (skeletal needles) Soft, but hard corals secrete CaCO 3 Soft, with no skeleton Most have shell made of CaCO 3 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 appendage s 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.