There are several variants of sexual reproduction, the differences of which are related to the peculiarities of the fertilization. Parthenogenesis -

Origin of parthenogenesis [advantages]

There are several variants of sexual reproduction, the differences of which are related to the peculiarities of the fertilization. Parthenogenesis — is the only way of sexual reproduction without fertilization in which the development of the embryo begins from an unfertilized egg.

While studying the diversity of methods of sexual reproduction the question arises: why nature has such a strange way of reproduction as parthenogenesis? It is evident that amphimixis is the most reliable and effective way of sexual reproduction. As it turned out, this strange way of sexual reproduction gives to organisms some advantages. No coincidence that many mass-occurring plant and animal species are “fans” of parthenogenetic method of reproduction.

If we analyze the prevalence of parthenogenesis, it turns out that it is inherent in many massive and numerous representatives of the world fauna. This way of propagation have Hymenoptera, which are one of the most species-rich groups of very numerous insects, as well as many species of earthworms, aphids and daphnia, which are a significant mass of living matter, and play an important role in ecosystems. Obviously, such prevalence of parthenogenetic reproduction is associated with some special properties that this method of reproduction gives to organisms.

The reasons for haploid parthenogenesis of Hymenoptera still aren’t figured out, but the circumstances of origin of cyclic parthenogenesis and clonal are much clear. Its main reason — is the inability of the normal course of meiosis in some organisms. It turns out that individuals that consistently reproduce in naturally by parthenogenesis — are a hybrid of closely related species, often found in earthworms, daphnia, aphids, goldfish, lizards and in many other species groups. Due to the fact that their karyotype is presented by chromosomal sets of different parental species, they have broken chromosomes conjugation, resulting gametes formation not by meiosis but due to mitosis, and thus they are diploid. This means that at a certain maturity or signals from the outside (for example, when interacting with alien sperm) diploid eggs begin to divide and form a new organism. Taken from http://worldofschool.org

The fact that parthenogenesis gives certain advantages to its owners follows at least from the fact that this phenomenon is widespread in animals’ and plants’ world. At least because of this reason it can be argued that many species have become so widespread only because of the virgin reproduction. It is known that organisms reproducing via parthenogenesis, although limited in their evolutionary possibilities, however, are endowed with features that allow them obvious advantages over amphimictic fellows. It turns out that they are better adapted to life in the harsh continental climate (that is why there are less of them in the tropics). It is proved that parthenogenesis contributes to the rapid spread of the species. Experience shows that it is enough of one earthworm individual, accidentally imported in a pot with house plant, to become this species mass in another continent. This happened with the parthenogenetic form of pasture worm (the worm that crawls out of their burrows after rain). In the middle of the XX century it was imported from Europe to Australia, where he settled down well. Parthenogenetic individuals are capable of living rarefied, whereas amphimictic reproducing organisms necessary need a concentration of individuals in the certain territory.

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