Parthenogenesis (from the ancient Greek - “woman” and “creation”) is a type of same-sex reproduction, which is characterized by the fact that the development of the fetus occurs without fertilization of the egg, and the organism born in this way is genetically identical or almost identical to the maternal one. A similar method of creating offspring was discovered in Switzerland at the end of the eighteenth century, and has now been well studied by biologists; it can be reproduced artificially in laboratory conditions. Most often in the wild, this occurs among arthropods; parthenogenesis of bees, ants, and aphids is of particular interest. Let us take a closer look at which insects are characterized by parthenogenesis, and its features in some species.
The species where same-sex reproduction is widespread are insects. The proportion of vertebrates that use this method of reproduction is very small, and is currently considered impossible even at a theoretical level, this is the point of view of official science.
Types of insects that reproduce in a same-sex way:
- cicadas;
- bees;
- ants;
- thrips;
- gallworms;
- hay eaters.
The need for insects to use this method of population reproduction is as follows:
- This helps control the number of individuals of different sexes.
This is true for those individuals who live in groups and who have a clear division of responsibilities between the sexes. For example, females work, males protect their homes, or vice versa. - Restoration of a population in the absence of individuals of any sex.
In some insects, males are often absent as a species, they either became extinct in the process of evolution, or at some certain period they could not cope with climate changes, due to which their number became so small that it was not enough to fertilize all the females. In this case, the population is saved only by the fact that females can create offspring on their own. - Reproduction in conditions where the number of remaining individuals is insufficient.
This happens when a species moves to new territories; in this case, same-sex reproduction of offspring contributes to the rapid development of the population, even though initially the number of individuals was small, because each of them can leave offspring.
It is widely believed that since only one sex is involved in the creation of offspring. But this opinion is fundamentally wrong, since the germ cells and reproductive system of the body are responsible for the development of the fetus. Therefore, this type of reproduction is classified as sexual; you can often find the name - same-sex reproduction; it is also considered correct from the point of view of the biological characteristics of this process.
Reproduction of bees by parthenogenesis
Parthenogenesis occurs in bees all the time, only with the help of parthenogenesis drones appear, but this is not the only way bees reproduce their population. The fact is that when the female has matured, she makes a “nuptial walk”, during which she is fertilized by many drones at once. The female does not consume the sperm accumulated during this “walk” immediately and does not lose it, but deposits it in a special bag located in her body and ensuring the vital activity of sperm for another three to four years after mating.
Then, when the female begins to lay eggs, and she lays up to two thousand of them per day throughout her life (just three to four years, as a rule), she can independently decide whether to fertilize the egg with sperm stored in that special sac, or No. If the egg is fertilized, it will become a new worker bee, and if not, then the male will become a drone.
Watch a video about the biology of bee reproduction.
The female makes the decision whether to fertilize the egg or not, taking into account a number of factors:
- The size of the comb in which she lays the egg. The drone honeycombs are somewhat larger, the female senses this. For example, ordinary honeycombs are approximately five and a half millimeters in size, while drone honeycombs are one and a half to two millimeters larger; the female will easily feel this difference.
- Presence of sperm in the sac. It could also either be all already used up, or it could not exist at all due to any external conditions that could affect the behavior of the drones during the mating period.
- The need to create more drones or worker bees.
For the needs of her population, a female can determine who she will produce depending on the number of individuals of a particular sex in the hive.
The mechanism of creating offspring by bees discussed above suggests that parthenogenesis in bees is not asexual reproduction, because the same cells of the reproductive system are responsible for the creation of both fertilized and unfertilized eggs. At the same time, in bees, same-sex reproduction of the population has its own characteristics that are not typical for other insects.
Characteristics of same-sex reproduction
As mentioned above, parthenogenesis is characteristic of bees, ants, and many other types of insects. In addition, this method of creating offspring is found in fish, lizards, and some other vertebrates, but it is extremely rare.
The Internet is replete with articles stating that there are facts and even examples indicating the possibility of parthenogenesis in humans. But, from the point of view of scientists, this is unlikely or even impossible. , which is mostly characteristic of organisms located at the bottom of the development chain - invertebrates. Despite a number of obvious advantages that this method of population reproduction can give to a particular species, in the process of evolution the bisexual method of reproduction has proven to be better and more promising.
The artificial method of same-sex creation of offspring has opened up a wide field for genetic research. The most appropriate way to use it would be to save endangered species. Research in this area is currently being actively conducted. Perhaps, in a few decades, the problem of endangered species will be completely resolved.
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