Parthenogenesis: Definition, Types, Facts, Introduction, Significance, Topics

What Is Parthenogenesis?

Parthenogenesis refers to the kind of reproduction in which the development of offspring occurs from an unfertilized egg. With this process, one is in a position to come up with offspring without the involvement of male gametes. All the offspring resulting from parthenogenesis are identical to the parent genetically.

Features Of Parthenogenesis

1. Asexual Reproduction: Parthenogenesis is a kind of asexual reproduction since it doesn't include the fusion of male and female gamete.

2. Genetic Uniformity: All the progeny achieved through parthenogenesis are similar to the mother and are genetically identical. Parthenogenesis occurs in many organisms, including some insects like aphids, reptiles like certain lizards, and plants.

3. Environmental Triggers: Parthenogenesis can also be induced by environmental cues, such as the absence of males or adverse conditions for fertilization.

Types Of Parthenogenesis

There are several types of parthenogenesis: obligate parthenogenesis, wherein it is the only way of reproduction; and facultative parthenogenesis, wherein it may happen in the absence of males, but sexual reproduction is also possible. Types of Parthenogenesis Parthenogenesis can be broadly classified into many types based on the involved mechanisms.

Obligate Parthenogenesis

In obligate parthenogenesis, the species only reproduce through parthenogenesis; there is no sexual reproduction. This happens in specific aphid species and some reptiles.

Facultative Parthenogenesis

In facultative parthenogenesis, a population can reproduce both sexually or asexually. For example, some female lizards can reproduce through parthenogenesis when males are absent.

Cyclic Parthenogenesis

Cyclic parthenogenesis refers to the alternating production of sexual and asexual offspring depending on environmental conditions. This can be illustrated by some species of aphids that reproduce sexually when conditions are favourable and then switch to parthenogenesis when the going gets hostile.

Mechanisms Of Parthenogenesis

Parthenogenesis may result from several mechanisms, which include the following:

Automixis

In automixis, the egg undergoes a meiosis process but some of the cells fuse to restore the diploid state. It could donate some degree of genetic diversity in its offspring.

Apomixis

Apomixis is when an embryo develops directly from the egg cell without meiosis. Offspring produced are identical in their mother's characteristics.

Examples Of Parthenogenesis

Insects

Parthenogenesis is common in many insects, as in aphids and some species of bees. For instance, the females of aphids give rise to offspring without mating and the populations exhibit high growth rates.

Reptiles

Some reptiles, such as the Komodo dragon and the whip-tailed lizards, have parthenogenesis, where females produce healthy offspring without the participation of males.

Plants

Some flowering plants, such as dandelions and some species of ferns, can naturally develop seeds without fertilization through parthenogenesis.

Merits Of Parthenogenesis

1. Rapid Population Growth: It can bring about an increase in population quickly when males are lacking in a particular environment.

2. Genetic Uniformity: The daughter organisms that emerge are more or less genetically identical to the mother, thus ensuring that positive traits that have developed get passed on.

3. Independence from Mates: Parthenogenesis is a means of reproduction without males and in very adverse or isolated conditions may be useful.

Disadvantages Of Parthenogenesis

1. Lack of Genetic Diversity: Offspring formed will have almost similar genetic material, making them be affected almost similarly by various diseases or changes in the environment.

2. Adaptability: Since the offspring produced are genetically similar; therefore, the population may face difficulty adapting to changes in the environment.

3. Inbreeding Potential: Since parthenogenesis occurs in some populations in the total absence of sexuality, inbreeding is possible, reducing general fitness.

Conclusion

Parthenogenesis is that particular mode of reproduction in which an organism reproduces asexually without fertilization. This occurs in different species of the animal and plant kingdoms, and it has its associated advantages as well as disadvantages. The knowledge of parthenogenesis enhances our understanding of the reproductive strategies and evolutionary adaptations that have allowed species to colonize diverse environments.

Recommended video on Parthenogenesis