The emergence of a new species over geological time such that descendants and ancestors can no longer interbreed. There are three main types of speciation:
1. Allopatric speciation
Speciation takes place in small, satellite groups isolated on the peripheries of the species’s range by geographical barriers and subjected to genetic drift
2. Sympatric speciation
Speciation without geographical barriers resulting from finely graded ecological differences within the same species‚aa range or from ethological isolation based on behavioural incompatibilities
3. Chromosomal or instantaneous speciation
Speciation as a consequence of a single chromosomal mutation in populations sub-divided into small kinship groups. If appearing in a dominant male, it may then spread in a social organisation that permits a large degree of interbreeding
Other types of speciation are incipient speciation, parametric speciation of adjacent populations, peripatric speciation of peripheral populations, stasipatric speciation due to chromosomal rearrangements generating daughter species that extend their ranges, and hybrid speciation (formation of new species after hybridisation between two previously existing species and more common in plants than animals).
Developmental (or ontogenetic) timeSee Biological evolution, Founder effect, Genetic drift (or random walk), ‘Hopeful’ monsters, Incipient speciation, Macroevolution (or horizontal evolution) and microevolution (or vertical evolution), Mutation (biology), Phylogenetic (or geological time), Phyletic gradualism and punctuated equilibrium, Phylogeny