Reproductive isolation of populations can be temporal, behavioural or geographic
In various situations populations of members of the same species (same gene pool) can be stopped from reproducing together because there is an insurmountable barrier between them. These barriers can be geographical, temporal, behavioural or related to the infertility caused by hybridization.
Geographical Isolation - Occurs when physical barriers (e.g land or water formations) prevent males and females from reaching each other, hence interbreeding is impossible.
Temporal Isolation - Refers to incompatible time frames that prevent populations or their gametes from encountering each other. For example if the female parts of the flowers of one populations of plants reach maturity at a different time compared with the release of pollen of another population, the two will have great difficulty producing offspring together. Hibernation or late return from migration are other temporal barriers between two gene pools.
Behavioural Isolation - Occurs when one populations lifestyle and habitats are not compatible with those of another population. For example many bird species rely on a courtship display in order for one sex to copulate with the other. If the males has a version of courtship display that is significantly different to that of another population, the females might not find it seductive enough to be potential mates. Hence no or little reproduction is likely to occur between the two populations due to behavioural differences.
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