ABSTRACT:
In this article , we will discuss the development of egg without fertilization and it’s types . We will see that how this developmental process safes an organism from wasting its energy in mating . We will study its types and how this process help honey bee , wasps and many social insects to increase their number. As we move down deep in topic we get to know that the development of egg without fertilization is now significantly applicable by artificial means ,this is how human beings find it beneficial . We will also harness the significance of this process.
INTRODUCTION:
The mode of sexual reproduction in which egg is developed without the fertilization is Known as the parthenogenesis .In animal parthenogenesis is development of embryo from unfertilized egg cell however in plant it involve the process of apomixes . In algae however the development occur from either male or female gamete. https://www.jstor.org/stable/983715
PARTHENOGENESIS IN ANIMALS:
PARTHENOGENONE/PARTHENOTE:
The organisms which develop through parthenogenesis is called parthenogenone or parthenote . Example : certain insects as Hymenoptera, Homoptera , rotifers and also some vertebrates such as several desert lizards, turkeys and some mammals are example of organisms in which development of egg without fertilization occur .
TYPES:
It is of two types: natural parthenogenesis and artificial parthenogenesis.
1. NATURAL PARTHENOGENESIS:
In certain animals the development of egg without fertilization occurs regularly, constantly and naturally in their life cycles and is known as the natural parthenogenesis. It is of two types: complete or obligatory and partial or cyclic pathogenesis.
a. COMPLETE PARTHENOGENESIS:
Some organisms have only one gender that is they have no male ,they completely depend on development of egg without fertilization for reproduction. For example: It is found in some species of earthworms, badelloid rotifers, grasshoppers, roaches, phasmids, moths, gall flies, fishes, salamanders and lizards.
b. INCOMPLETE OR CYCLIC PARTHENOGENESIS:
The incomplete development of an egg without fertilization is also called cyclic development because it involve the alternation of sexual generation and parthenogenetic generation. Diploid egg develop into female and unfertilized egg produce male .
This may be of two types: Haploid parthenogenesis and diploid parthenogenesis.
a. HAPLOID PARTHENOGENESIS:
When the haploid eggs are not fertilized by the sperms this is haploid development of egg without fertilization. The individual developed is also haploid . For example: In Bees the unfertilized egg develop into male bees called drones and fertilized bees develop to queen female bees .
b. DIPLOID PARTHENOGENESIS:
When the diploid eggs remain unfertilized it develop into a diploid female . The individual can may be either male or female but most probably it is female . Example : aphids are example of diploid development of egg without fertilization. Following types of diploid parthenogenesis have been found :
1. AMEIOTIC PARTHENOGENESIS:
Ameiotic mean absence of one meiotic phase however the second reduction division usually occur . Such eggs contain diploid number of chromosomes and develop Into new individuals without fertilization. This is also called apomiotic or ameiotic parthenogenesis. Example : mollusca , weevils and long horned grasshopper.
2. MEIOTIC PARTHENOGENESIS:
The oogenesis occur normally but at certain stage, chromosome doubling occur. Hence diploid egg are produced which develop into diploid individual.
The diplosis may occur by following methods:
By auto fertilization ( the ootid and secondary polocyte formed during meiotic division of oocytes , sometimes unit to form diploid egg which give rise to diploid individual).
By restitution (sometimes the karyokinesis is not followed by cytokinesis, the chromosomes of both daughter nuclei produced in the primary oocyte karyokinesis are arranged on the equator and undergo a second meiotic division to form diploid ootid and diploid polocyte. Diploid ootid form diploid individual).
2. ARTIFITIAL PARTHENOGENESIS:
This may be held artificially via controlling the physical or chemical factor.
a. PHYSICAL MEANS:
Temperature, electric shock, Ultraviolet lights and pricking of egg by needle.
b. CHEMICAL MEANS:
Chloroform, Hypertonic and hypotonic sea water, Chlorides of k+, Ca++, Na++, Mg++, Urea and sucrose.
CONCLUSION:
Parthenogenesis refers to the natural phenomenon of an egg developing without the need for fertilization. This unique reproductive strategy allows for the continuation of a species without the involvement of a male counterpart. It serves as a fascinating example of asexual reproduction, highlighting the remarkable adaptability of certain organisms. Artifitial and natural development of egg without fertilization are the methods of this sexual reproduction.
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