An example of isolation reproductive mechanism between breeding at different times of the year and infertile offspring
An example of an isolation reproductive mechanism between breeding at different times of the year and infertile offspring is the case of the red deer (Cervus elaphus) and the sika deer (Cervus nippon) in Japan.
Red deer and sika deer are closely related species that inhabit the same areas in Japan. However, they have different breeding seasons. Red deer mate in the autumn, while sika deer mate in the winter. This difference in breeding times acts as a reproductive barrier between them.
If a red deer and a sika deer were to mate during their respective breeding seasons, they may be able to produce offspring. However, due to the genetic differences between the two species, the resulting hybrid offspring would be infertile. This means that they would not be capable of producing viable offspring of their own.
As a result, the difference in breeding seasons acts as a mechanism to isolate the red deer and sika deer populations, preventing gene flow between them. The limited gene exchange between the two species helps maintain their distinct genetic characteristics and prevents the merging of their populations into a single hybridized group.
One example of isolation reproductive mechanism between breeding at different times of the year and infertile offspring is known as temporal isolation. This mechanism occurs when two or more species have different reproductive periods or breeding seasons.
Here's a step-by-step breakdown of how temporal isolation works:
Step 1: Different Breeding Times
Two species have different breeding times or reproductive periods. For instance, one species may reproduce in the spring, while another species reproduces in the fall.
Step 2: No Opportunities for Interbreeding
As a result of having different breeding times, the two species do not have opportunities to mate and produce offspring together. This can be due to differences in hormonal cycles, environmental cues, or specific behaviors associated with their reproductive periods.
Step 3: Lack of Synchronization
Even if individuals from both species come into contact, they may not be reproductively receptive or compatible due to their independent breeding seasons. This lack of synchronization prevents successful mating and reproductive interactions between the two species.
Step 4: Infertile Offspring
In the rare cases when individuals from these species do manage to mate, the resulting offspring are often infertile or have reduced fertility. This occurs due to genetic differences and incompatibilities that have developed during their separate evolutionary paths.
Step 5: Reinforcement of Reproductive Isolation
The occurrence of infertile offspring reinforces the reproductive isolation between the two species. Over time, natural selection favors individuals that do not attempt to reproduce outside of their own breeding season, further strengthening the temporal isolation mechanism.
Overall, temporal isolation prevents breeding between species that have different breeding times, leading to limited gene flow and the development of distinct, reproductively isolated lineages.