Five Types of Isolation in Biology

Ecological Isolation

• Ecological, or habitat, isolation is when two species that could interbred do not because the species live in different areas. For example, in the wild of India both the lion and tiger exist and are capable of interbreeding; however, the lion lives in the grasslands and the tiger lives in the forest. By living in different habitats, the two species will not encounter on another and are isolated from the other species.

Temporal Isolation

• Temporal isolation is when species that could interbred do not because the different species breed at different times. This temporal difference can be the difference between breeding during the night or during the day as some insect species. More common is breeding at different times of the year. For example, the field crickets Gryllus pennsylvanicus and G. veleti become sexually mature at different types, one in the spring and the other in the autumn.

Behavioral Isolation

• Behavioral isolation relates to the fact that many species have mating rituals that are performed prior to mating. This is a common barrier between animals. For example, certain species of crickets will only mate with male crickets that produce a particular mating song. Pheromones which are chemical compounds produced by animals will attract mates from the same species but will not be effective at attracting different species.

Mechanical Isolation

• Mechanical isolation is caused by structures or chemical barriers that keep species isolated from one another. For example, in flowering plants the shape of the flower will tend to match up with a natural pollinator. Plants that do not have the correct shape for the pollinator will not receive a pollen transfer. Chemical barriers, sometimes placed as a separate type of isolation is the prevention of gametes from forming. These chemical barriers will only allow sperm from the correct species to fertilize the egg.

Geographical Isolation

• Geographical isolation are the physical barriers that may exist that keep two species from mating. For example, a species of monkey that are located on an island cannot breed with another species of monkey on the mainland. The water and distance between the two species keep them isolated from one another and makes it impossible for them to breed.