Question

21. Species can remain separate for 3 distinct reasons: geographic isolation, temporal (timing) isolation and behavioral isolation.
Which of those mechanisms isolates two populations of similar frogs that are separated by the Cascades Mountain Range. . Explain your answer
Give an example of how the other two mechanisms could isolate populations from each other.

Answer 1

Reproductive isolation occurs when barriers prevent two populations from interbreeding – keeping their gene pools separate

There are two main categories of reproductive isolation barriers:

Prezygotic isolation – occurs before fertilisation can occur (no offspring are produced)

Postzygotic isolation – occurs after fertilisation (offspring are either not viable or infertile)

Prezygotic isolation barriers can be temporal, behavioural, geographic / ecological or mechanical; whereas postzygotic isolation barriers include the inviability, infertility or breakdown of hybrid organisms

Reproductive Isolation Mechanisms

reproductive isolation

Temporal Isolation

Temporal isolation occurs when two populations differ in their periods of activity or reproductive cycles

Example:  Leopard frogs and wood frogs reach sexual maturity at different times in the spring and hence cannot interbreed

Behavioural Isolation

Behavioural isolation occurs when two populations exhibit different specific courtship patterns

Example:  Certain populations of crickets may be morphologically identical but only respond to specific mating songs

Geographic Isolation

Geographic isolation occurs when two populations occupy different habitats or separate niches within a common region

Example:  Lions and tigers occupy different habitats and do not interbreed (usually)

i hope this helps