Angel Rajput will describe about science( biology ) subject topics, genetics , some helping tools like calculator, screen recorder, image resizer and many more.
Parthenogenesis
It is the modification of sexual reproduction in which an egg develops into a complete offspring without fertilization.
It is mono parental.I is found in many nonvertebrates e.g rotifiers, aphids, bees and crustaceans.
I is also found in a few vertebrates.
Types:- Parthenogenesis is of two types:-
i) Natural ii) Artificial
1) Natural Parthenogenesis:- It is a regular phenomenon in the life history of some animals. It may be complete. incomplete or peadogenetic.
a) Complete (obligatory Parthenogenesis):- It occurs in some rotifiers and a few vertebrates. There are no males at all. So there is no biparenteal sexual reproduction. The females develops exclusively by parthenogenesis. e.g rock lizard, Lacerta sexicola armaniaca, Indian snake Typhlina brahmina shows complete parthenogenesis and there are no males.
b) Incomplete (cyclic) Parthenogenesis:- some animals have both sexual and parthenogenetic individuals, whic may alternate. In these animals, female can produce unfertilized and fertilized eggs, depending upon the environmental conditions. Example - In Daphnia, a water crustacean, female lays unfertilized eggs that develop parthenogenetically under favourable conditions and fertilized eggs during the time of environmental stress. In Honey bee, unfertilized eggs develop into male bee(drones) with haploid cells, and fertilized eggs give rise to females(Queen bee and worker bees) with diploid cells.
c) Paedogenetic Parthenogenesis:- In certain insects , Larvae lay eggs which develop parthenogenetically into a new generation of larvae. Parthenogenesis in larvae is called paedogenesis ( pais- child, genesis- origin).
2) Artificial Parthenogenesis:- Eggs of certain animals, such as annelids, mollusks, starfish, frog, hen, rabbit etc. , can be induced to develop parthenogenetically by artificial stimuli. Artificial stimuli may be i) physical, which may be , pricking of needles, electric shock, change in tempreature or pH (ii) Chemical stimuli such as addition of urea, fatty acids, ether, chloroform, to water.
