What is the term for the speciation that occurs without geographical separation?

The correct term for speciation that occurs without geographical separation is sympatric speciation. This process takes place when populations of a species become reproductively isolated while inhabiting the same geographic area. This can result from factors such as polyploidy, which is common in plants, where an increase in chromosome numbers can lead to reproductive isolation. Other mechanisms include behavioral changes, shifts in habitat preference, or temporal isolation, where different populations breed at different times.

In contrast, allopatric speciation requires geographical barriers to separate populations, leading to divergence and eventual reproductive isolation. Parapatric speciation involves adjacent populations that are not completely geographically separated but have limited contact and interact along a boundary. Peripatric speciation is a form of allopatric speciation that occurs when a small population becomes isolated at the edge of a larger population's range.