Biology › Definitions › Classification, biodiversity and conservation

Classification, biodiversity and conservation definitions

Every term defined in this unit, lesson by lesson, in the same words the lessons use, with a link to the notes where you will see it used.

25 terms

Classification, phylogeny and molecular evidence

Taxonomy: The naming and classifying of organisms into a hierarchy of groups.
Taxon: Any one group in the taxonomic hierarchy: Mammalia, Primates and Homo are all taxa.
Binomial: The two-part international name of a species: genus then specific name, italicised, genus capitalised.
Phylogeny: The evolutionary history of a group: which lineages split from which, and in what order.
Phenetic classification: Grouping organisms by observable similarity, without regard to how they are related.
Phylogenetic classification: Grouping organisms so that each group contains a common ancestor and all of its descendants.
Homologous structures: Structures with the same underlying plan, inherited from a common ancestor, whatever they are now used for.
Analogous structures: Structures with the same function and different origins, produced by convergent evolution.

Kingdom: The largest of the taxonomic groups within a domain, and the level at which organisms are separated by features such as the presence of a nucleus, the material of the cell wall and the method of nutrition.
Saprotrophic nutrition: Feeding by secreting enzymes onto dead organic material outside the body and absorbing the soluble products, which is how fungi and many bacteria feed.
Autotroph: An organism that makes its own organic molecules from inorganic ones, in almost all cases by photosynthesis.
Heterotroph: An organism that obtains organic molecules by consuming other organisms or their remains.
Morphological species concept: The definition of a species by shared observable structural features, used where interbreeding cannot be tested, as with fossils.
Ecological species concept: The definition of a species by the niche its members occupy, useful for organisms that reproduce asexually.
Virus: An acellular particle consisting of nucleic acid inside a protein capsid, sometimes with a lipid envelope, which can reproduce only inside a living host cell.
Capsid: The protein coat that encloses the nucleic acid of a virus.

Species richness: The number of different species in a community.
Species evenness: How equally the individuals are shared out between the species in a community.
Species diversity: Richness and evenness together, usually expressed as an index.
Genetic diversity: The number of different alleles present in the gene pool of a population or species.
Endemism: Being found naturally in only one place, such as a single island or region, and nowhere else; a species like this is endemic to that place.

In situ conservation: Conserving a species in its natural habitat, so that the community and the conditions it is adapted to are conserved with it.
Ex situ conservation: Conserving a species outside its natural habitat, in a zoo, a botanic garden, a seed bank or a captive breeding centre.
Endangered species: A species at very high risk of extinction in the wild, as assessed against criteria such as the IUCN Red List's.
Extinct in the wild: A species surviving only in cultivation, captivity or as a population well outside its past range.