Speciation occurs when the population of a single species splits into two, such that the two newly formed groups cease sharing the same gene pool. The said split can occur as a result of many things; reproductive isolation being one of them. Interestingly, reproductive isolation doesn’t just help in speciation, but also maintains the integrity of a species by preventing interbreeding and resultant production of hybrid species.
The mechanisms of reproductive isolation are divided into two groups: prezygotic and postzygotic mechanisms, which are further divided into various types. Gametic isolation is one of the five types of prezygotic mechanisms.
Gametic Isolation Meaning
How Does it Work?
When it comes to sexual reproduction, the sperm cell (male gamete) is fused with an egg or ovum (female gamete) to form a zygote―the earliest developmental stage of the embryo. For the zygote to form, the sperm cell and egg have to be compatible. If they are not, then fertilization will not occur, which, in turn, will inhibit the formation of the zygote. If the sperm cell of a particular species comes in contact with an egg of a different species, it will simply fail to penetrate the egg as a result of its chemical makeup. Thus, the fusion of the sperm and egg will not happen, and that, in turn, will prevent hybridization.
Gametic reproductive isolation is especially seen in species that reproduce externally, primarily marine species and species of flowering plants. In most marine species, for instance, females just release their eggs into the water, in what is known as broadcast spawning, while the males follow with their sperm cells. At times, the sperm cells are simply carried around in the water, as a result of which they come in contact with eggs of other species. In such a scenario, the chances of their fusion to form hybrids cannot be ruled out. It’s here that gametic isolation kicks in and prevents the same.