is a phytogeographical term denoting a state when two or more closely related (naturally occurring) taxa, originating from a common ancestor, replace/represent each other in the wild

Most often, these are species that are represented in one range of the genus. Vicariating taxa (vicariants) arose either by disintegration and independent development in part of the original range, or by adaptation to different conditions during migration.

• Geographical vicariance
  These are species of an originally common range that now inhabit two or more different ranges.
• Vertical vicariance
  This is the representation of species at different altitudes.
• Ecological vicariance
  These are related species of a common genus range separated by ecological conditions. Species are represented by their occurrence in different ecological conditions.