Speciation is the term used by biologist for how new species evolve from an origin species. A species is a group of animals that can interbreed and produce viable offspring, species can split into two by means of allopatric and sympatric speciation. First, allopatric speciation occurs when the two groups are geographically isolated from each other. The two species gradually change their genetic make-up through a process known as genetic divergence, this process is due to natural selection and the forces of genetic drift. Secondly, sympatric speciation occurs when two subgroups of a species evolve into two different species without a geographical barrier. The two species must become reproducibly isolated from each other, this commonly occurs in species that are polyploidy. Species that aren’t polyploidy can still under go this type of speciation if the subgroups of the population use different habitats or resources within the geographical area. The subgroups will adapt to what is needed most through natural selection, over a long period of time the genetic make-up of the two subgroups will change drastically. Speciation fully occurs when, regardless if the subgroups are separated by resources or habitat, the two groups would not be able to interbreed.

References:

https://www.khanacademy.org/science/biology/her/tree-of-life/a/species-speciation