Classification and biodiversity

• Homo sapiens.
• Classification is the process of naming and organising organisms into groups based on their characteristics.
• Phylum, class, order, family, genus and species are different taxonomic ranks.
• Each species is named according to the binomial system, the first part of the name is the genus and the second part of the name is the species.
• Organisms can be grouped into one of the five kingdoms: Animalia, Plantae, Fungi, Monera (prokaryotes) and Protoctista.
• The analysis of molecular differences in different organisms to determine the extent of their evolutionary relationship is known as molecular phylogeny.
• The data obtained by molecular phylogeny has been accepted by scientists and this gave rise to new taxonomic groupings - all organisms can be separated into one of the three domains: Bacteria, Archaea and Eukaryota.
• Gel electrophoresis, as well as DNA sequencing and bioinformatics, can be used to distinguish between species and determine evolutionary relationships.
• The findings are published in scientific journals and presented at scientific conferences.
• Scientists study the evidence in a process called peer review.
• A species is a group of organisms which can interbreed to produce fertile offspring.
• The accepted model of a species is referred to as the reproductive model.
• The reproductive model has limitations as cross-breeding occurs and some members of the same species don't interbreed due to geographical isolation but would produce fertile offspring.
• There are other models of a species, like the ecological, mate-recognition, genetic, and evolutionary models.
• Biodiversity is the variety of living organisms.
• Biodiversity can be measured in terms of species richness, which is the number of different species in a habitat.
• Genetic diversity is a measure of the genetic variation found in a particular species, in other words, the number of alleles in a gene pool.
• Diversity index is represented as D.
• Total number of organisms of all species is represented as N.
• Total number of organisms of each species is represented as n.
• Captive breeding programmes in which endangered species are carefully bred to increase genetic diversity and population size.
• Genetic diversity is maintained in captive breeding programmes via the exchange of organisms and gametes, keeping stud books, preventing inbreeding and use of techniques such as IVF.
• Reintroduction programmes aim to release animals bred in captivity into their natural habitat as well as to restore lost habitats.
• Endemism is the state of a species being unique to a particular geographical location, such as an island, and not found anywhere else.
• Seed banks store a large number of seeds in order to conserve genetic diversity and prevent plant species from going extinct.
• Storing seeds instead of plants means that a large variety of species can be conserved, and it is cheaper than storing whole plants as it takes up less space.
• Conservation can be in-situ (in an organism's habitat) or ex-situ (outside of an organism's habitat).
• The seeds are stored in cool, dry conditions as this maximises the amount of time they can be stored for and they are periodically tested for viability.
• Both methods of conservation have risks and benefits.
• Education programmes aim to educate people about the importance of maintaining biodiversity, captive breeding programmes as well as illegal trade of animal products.
• Initiatives such as National Parks and Sites of Specific Scientific Interest aim to conserve habitats and biodiversity.
• The niche of a species is its role within its ecosystem/habitat.
• Species which share the same niche compete with each other and the better adapted species will survive.
• The idea that better adapted species survive is the basis of natural selection.
• Organisms are adapted to their environment in various ways: anatomical adaptations are physical adaptations, either external or internal, such as the presence of long loops of Henlé which allow desert mammals to produce concentrated urine and minimise water loss.
• Behavioural adaptations are changes in behaviour which improve the organism's chance of survival, such as mating calls.
• Physiological adaptations are processes involving enzymes/hormones that increase an organism's chance of survival, such as regulation of blood flow through the skin.
• Natural selection is the process in which fitter individuals who are better adapted to the environment are more likely to survive and reproduce and pass on the advantageous alleles to their offspring.
• Evolution is the process by which the frequency of alleles in a gene pool changes over time as a result of natural selection.
• A variety of phenotypes exist within a population due to mutations.