Species = group of organisms which are able to breed freely to produce fertile offspring.
Courtship behaviour = precursor behaviour to mating. Courtship behaviours are often species-specific and therefore aid in species recognition.
• Process by which we allocate living things to groups
• Arranged into groups of increasing similarity
• This can be done artificially
• For our convenience
• E.g. – Flower guide by colour
• Or Naturally
• Basic unit of natural classification is species
• Natural classification reflects evolutionary relationships
• Closely related species can be grouped together
• These groups can be grouped together
• These groups are then arranged into a series of ranked and interconnected groups
• Forms a hierarchy
PHYLOGENY
• The study of evolutionary relationships between organisms
• Group of organisms arranged by how closely related they are
• The closer they are related, the closer they are on the tree
• Common ancestors are shared by groups
• The closer the lines, the more recent the ancestor
• All common ancestors are extinct
• Species that belong to the same phylogenetic group are called monophyletic
• Humans and gorillas are monophyletic
TAXONOMY
• Study of the principles of classification
• Study of differences between species
• Species usually grouped according to physical similarities
• Similar species are place together
DOMAINS: WHY DO WE CLASSIFY THINGS?
• To order them
• For our convenience
• To make studying them easier
• To make identification easier
• To help us to see relationships
CURRENT CLASSIFICATION SYSTEM
• Species is basic unit of classification
• As you rise through hierarchy, more variation is shown
• The taxa (sing. taxon) are:
• Domain
o All living things categorized in 1 of 3
o Bacteria, Archaea, Eukaryote
• Kingdom
o 5 Kingdoms
• Phylum
• Class
• Order
• Family
• Genus
• Species
CLASSIFYING A SPECIES
• At higher levels, differences are greatest
• It is easiest to distinguish between these groups
• As you move to lower groups, it becomes increasingly difficult to separate closely related species accurately
• More and more detailed description is needed
• When referring to a species, we use its genus and species
• E.g. Homo sapiens
USING BIOCHEMISTRY IN SYSTEMS
• Biochemistry is increasingly used in classification
• Determines the degree of relation
• Differences reflect evolutionary relationships
• Cytochrome C
• Use in most organisms for respiration
• Made from smaller sequences of amino acids
• If the sequence is similar, two organisms are closely related
• If it is different, they are not
• DNA
• DNA found in all living organisms
• Always provides the genetic code
• More similar the sequence the more closely related the species