Classification

Classification Classification schemes sort organisms into groups based on characteristics that they share. As we progress from Kingdom to species, the organisms share more characteristics in common. The species is the basic category of classification.

Why classify Scientists use classification to help them Identify organisms by recognising characteristics shared by their group Identify relationships within the groups and look for evolutionary trends . Describe new organisms quickly and accurately Communicate more easily with other biologists Biologists who specialise in classification are called taxonomists. The study of classification is called taxonomy.

Classification schemes Classification schemes can change as we discover new organisms that don’t fit neatly into a current category eg Euglena advances in technology show new characteristics or new relationships between organisms eg chitin cell wall of fungi, DNA sequencing

Characteristics used in classification 1 1. Structural similarity (morphology) Animals - structures such as skeleton, fur, scales and body parts Plants - structures like leaves, roots or stem structure as well as means of reproduction.

Characteristics used in classification 2 Structure can be misleading as some groups may share a common feature but are from very different groups (eg bats, birds and some insects have wings), so taxonomists look at evolutionary history and supporting internal structures help make classification decisions. Sometimes they must go further and look at blood proteins, DNA and even embryos to help make decisions. Colour, size and habitat are not usually used at major grouping levels because these can vary between different populations, sexes or at different ages or stages of life.

Characteristics used in classification 3 2.  Means of reproduction (e.g. sexual, asexual, internal, external, flowers, cones, seeds, spores or fruits). Often we combine structural and reproductive features.

Classification of humans

Scientific Nomenclature Organisms are identified by two names – their Genus and species names Genus is always capitalised and species is always lower case The Genus species is usually italicized and/or underlined

Naming organisms Most names come from Latin words describing a colour or feature (eg rufus = red, macro = big, pus/pod = foot, giganteus = big, agilis = agile) Sometimes a species may be named after a person (usually the scientist that discovered it eg bernardus) Agile Wallaby   Black Wallaroo Eastern Grey Kangaroo Red Kangaroo Macropus agilis Macropus bernardus Macropus giganteus Macropus rufus

Classification keys Keys are used to help identify organisms. Dichotomous keys are ones that divide the group into twos.

Dichotomous keys Table keys Flow chart keys