Reproductive Isolating Mechanisms

Pre-zygotic barriers:

barriers before fertilization

Prevent Mating

Ecological, Temporal, Behavioural

Prevent fertilization

Gametic, Mechanical

Gametic

Males and females do copulate but sperm do not survive inside of females, and gametes do not unite

Ecological

Two species breed in the same area and during the same time, but not in the same place. One certain frog breeds In quiet streams, while the other breeds in rain pools.

Temporal

Species breed at different times or seasons, of the year. Ex. Red and Black Sea urchins release gametes at different times of the year.

Behavioural

Some individuals might not find certain behavioural characteristic of another individual attractive, such as mating rituals, birdsong,

Mechanical

When the sex organs are not compatible, or when pollen of a plant cannot occur due to certain structures. ex. Bird beaks have to be long, or short enough to pollinate a flower.

Post-Zygotic

After fertilization

Zygote Mortality

No fertilized zygotes or embryos develop to maturity

Hybrid Inviability

Gametes unite but genes are not compatible and result in weak offspring

Hybrid Sterility

Offspring does get born and is healthy, but cannot reproduce