In parapatric speciation, two subpopulations of a species evolve reproductive isolation from one another while continuing to exchange genes.This mode of speciation has three distinguishing characteristics: 1) mating occurs non-randomly, 2) gene flow occurs unequally, and 3) populations exist in either continuous or discontinuous geographic ranges. This distribution pattern may be …

Speciation is the evolutionary process by which populations evolve to become distinct species.The biologist Orator F. Cook coined the term in 1906 for cladogenesis, the splitting of lineages, as opposed to anagenesis, phyletic evolution within lineages. Charles Darwin was the first to describe the role of natural selection in speciation in his 1859 book On the Origin of …

The evolution of mammals has passed through many stages since the first appearance of their synapsid ancestors in the Pennsylvanian sub-period of the late Carboniferous period. By the mid-Triassic, there were many synapsid species that looked like mammals.The lineage leading to today's mammals split up in the Jurassic; synapsids from this period include Dryolestes, more …

History. The term taxon was first used in 1926 by Adolf Meyer-Abich for animal groups, as a back-formation from the word taxonomy; the word taxonomy had been coined a century before from the Greek components τάξις (taxis, meaning arrangement) and -νομία (-nomia meaning method). For plants, it was proposed by Herman Johannes Lam in 1948, and it was adopted at the VII …

Allopatric speciation (from Ancient Greek ἄλλος (állos) 'other', and πατρίς (patrís) 'fatherland') – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model: 86 – is a mode of speciation that occurs when biological populations become geographically isolated from each other to an extent that prevents or interferes with gene flow.

Speciation occurs as the result of the latter (allopatry); however, a variety of differing agents have been documented and are often defined and classified in various forms (e.g. peripatric, parapatric, sympatric, polyploidization, hybridization, etc.). Instances of speciation have been observed in both nature and the laboratory.

A clade (from Ancient Greek κλάδος (kládos) 'branch'), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, the equivalent Latin term cladus (plural cladi) is often used in taxonomical literature.

Adaptation is an observable fact of life accepted by philosophers and natural historians from ancient times, independently of their views on evolution, but their explanations differed. Empedocles did not believe that adaptation required a final cause (a purpose), but thought that it "came about naturally, since such things survived." Aristotle did believe in final causes, but …

In biology, phylogenetics (/ ˌ f aɪ l oʊ dʒ ə ˈ n ɛ t ɪ k s,-l ə-/; from Greek φυλή/φῦλον [phylé/phylon] "tribe, clan, race", and γενετικός [genetikós] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups of organisms.These relationships are determined by phylogenetic inference methods that focus on observed ...

Common descent is a concept in evolutionary biology applicable when one species is the ancestor of two or more species later in time. All living beings are in fact descendants of a unique ancestor commonly referred to as the last universal common ancestor (LUCA) of all life on Earth, according to modern evolutionary biology.. Common descent is an effect of speciation, in …