explanation of reproductive isolation with examples
Explanation of Reproductive Isolation with Examples
Reproductive isolation refers to a set of mechanisms that prevent animals of the same group from breeding. These are reproductive barriers that do not allow the species to mate and produce offspring.
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Reproductive isolation that occurs before fertilization is known as prezygotic isolation. However, when it occurs after fertilization and prevents the fertilized egg from turning into a fertile offspring, it is known as post-zygotic isolation.- Here, the breeding or mating calls act as powerful reproductive barriers. If the closely-related species are unaware of their mating rituals (which are often bizarre), inbreeding does not occur. In behavioral isolation, despite being close to each other there is no sexual attraction between the male and female species. This happens because either of the species is unaware of special signals or the ritual that has to be performed before mating.
- Male hooded seals inflate their nasal cavities like a bubble gum to attract their female counterparts. The female seal will mate the one with the most visually appealing nasal balloon. So unless the male blows up his nasal, the female won't come near its prospective mate.
- Similarly, light production in male fireflies is necessary to draw female attention. Depending upon the flash pattern produced by the male, the female will then respond and light up to signal the mate.
- Sexual receptivity in male and female species is possible only if their breeding season is the same. In temporal isolation, mating seasons of the closely-related species do not match.
- In some animal species breeding seasons differ and arrive at different times of the year. Also, some species are sexually active in the morning while their counterparts prefer nighttime for mating. These different times of the day for remaining sexually active are also one of the isolating mechanisms of temporal isolation.
- Some species of fruit flies such as Drosophila persimilis are active in the morning, whereas its close relative Drosophila pseudoobscura prefer mating in the afternoon.
- In ecological isolation, the male and female species prefer a different habitat for mating. The difference in mating sites forms the reproductive barrier in ecological isolation. As their places of breeding do not coincide, the species prefer not to mate.
- Rana aurora, one of the species of frogs found in northern California prefer rapidly moving water streams for inbreeding. Whereas, the Rana catesbeiana species prefer the still, slow-moving waters of permanent ponds.
- An offspring that is produced from two different species is essentially called a hybrid. The term 'inviable' means something that is incapable of surviving. In hybrid inviability, the zygote formed from combining of the sperm and egg of two different species is incapable of sustaining its own life.
- The fertilized egg formed of different species does not mature beyond its early stages of embryonic development. The mating of a female cat with a male dog or rabbit may produce a fertilized egg, but it will die shortly due to genetic differences.