∞ generated and posted on 2016.12.23 ∞
Means of preventing fertilization that occur following sperm release.
| Gametic Isolation is something that is effected particularly by ova (eggs) that interferes with their fertilization by not very closely related sperm; this can be envisaged as a purely passive process whereby divergence in the structure of receptor molecules to which sperm otherwise much bind to achieve fertilization results in reproductive isolation between that sperm and egg's populations. |
Gametic isolation can be viewed positionally as the last of the prezygotic barriers, though in reality gametic isolation is a mechanism that does not necessarily follow mating in the sense that mating is typically envisioned. Instead, gametic isolation is important particularly under circumstances where the potential for the gametes of different species to interact is especially difficult to prevent.
This can occur, for example, upon release of sperm by organisms into the general environment rather than directly within the vicinity of , such as one sees with invertebrates as well as multicellular algae.
Mosses and ferns similarly release their sperm into the general environment. At least somewhat equivalently, plants very often can have flowers dusted in various ways by the pollen from different species, necessitating a means of avoiding fertilization by the pollen from different species.
The broader point is that it turns out that it can be important for a number of species to avoid wasting eggs to undesirable hybridizations and also to help guide wanted sperm to the right eggs. There is incentive, as a consequence, for the evolution of between eggs and sperm of the same species such that desired fertilizations are more likely and undesired fertilizations less likely, with both mechanisms contributing to gametic isolation.
The following video is fun (though difficult to make out some of the words), and does get its biology more or less right: