Evolution Key Words

Key words

adaptive radiation - when a large number of species form to occupy different ecological niches

allopatry - speciation as a result of geographical isolation

allopatric speciation - speciation occurring where organisms are initially capable of actually interbreeding but cannot because they are geographically separated

analogous structures — structures which have the same job but have different bone make up e.g. wings of a bird, bats and insects. Do not share a common ancestor

biogeography — the study of the geographic distribution of organisms

dine — a gradual variation in the characteristics of a species or population over a geographical range

co-evolution - when one species or group changes its genetic composition in response to a genetic change in another

convergent evolution - when different species living in the same environment come to look similar

divergent evolution - when one species branches to form two or three species

embryology — the study of how embryos develop, looking at which genes are turned on and when

endemic — only found naturally in a certain country or area

evolution — the gradual process by which the present diversity of plants and animals arose from earliest and most primitive organisms

genetic drift — the important random fluctuation in the frequencies of alleles due to chance events

geographic or topographic barrier — a physical barrier (for the species) that prevents gene flow. e.g. a mountain ridge may be a barrier for an insect

gradualism - slow changes between populations that occur as a result of different selection pressures

homologous structures — structures which have a similar evolutionary history but have developed to suit different functions e.g. wing of bat, flipper of dolphin and arm of human

hybrid — an individual formed by mating between genetically different populations or species

instant speciation — the formation of a new species through autopolyploid or allopolyploid. Because the chromosome numbers of the new ‘instant’ species do not match that of the original species they cannot interbreed

isolating mechanism - any mechanism that prevents interbreeding of hybrids

parallel evolution — the development of related organisms along similar evolutionary paths due to strong selective pressures acting on all of them in the same way

polyploidy - when cells have more than 2n chromosomes common in plants

punctuated equilibrium - where evolution consists of long periods of stability, followed by short rapid changes as a result of critical selection pressures

reproductive isolation — a barrier to breeding that exists due to differences in mating seasons or mating organs e.g. flowers flowering at different times of the year

ring species — two apparently distinct species that are connected by a series of intermediate geographical and structural subspecies between which interbreeding can occur

selection pressure - the environmental factors that favour certain phenotypes

speciation - a mechanism by which new species are formed

species - a group of individuals with common features and ancestry, which will interbreed

sympatry - speciation within the same area by natural selection; there are a number of niches and groups move into the niches best suited to them

temporal barrier — when gene flow is prevented due to the populations or species having different mating times of day, month or year

vestigial organ — any part of an organism that has diminished in size during its evolution because the function it serves has decreased in importance e.g. the appendix in humans

And some more (:

•Phylogenetics: the study of evolutionary relatedness between groups of organisms. Relatedness is determined by DNA sequencing data and comparing morphological data

•Phylogeny: The evolutionary development and history of a species or higher taxonomic grouping of organisms.

•Cladogram: Diagram which shows ancestral relations between organisms

•Cladistics: method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants (and nothing else).