Most of the world's animals need to reproduce sexually in order to leave offspring, and sexual reproduction must also be a combination of male and female. However, we know that animals expend so much energy in their search for mates and during courtship that some organisms are unable to pass on their genes to their offspring.
So the question is, why do earthly creatures set up such a barrier to prevent organisms from reproducing?
<h1 class="pgc-h-arrow-right" > same-sex offspring</h1>
Ever since the birth of human civilization, we have been challenging the taboos of nature, and the same-sex offspring is one of them. In 2018, scientists obtained mice from bi-father sources for the first time through technical means, that is, lone male mice.
In the laboratory, scientists take out an egg cell from the nucleus, then inject the mouse sperm into the denucleated egg cell, and then combine the egg cell containing sperm genetic material with another sperm, at which point a fertilized egg is formed, and the mouse developed from the fertilized egg is the lone male mouse.
Listening to the description alone makes the experiment simple, but in fact, scientists found that lone male mice are difficult to develop and survive, and the developed embryos are significantly larger than normal mouse embryos.
Parthenogenesis mice use a similar process, except that the embryonic development of parthenogenesis mice is much smaller than that of a normal fetus.
The reason why the offspring of the same sex will be too largely different from the normal fetal body size is actually because of the results of the male-female game. We know that most males do not bear the pain of reproduction, and even many males are not involved in raising offspring, so it is a very cost-effective thing for males to find more opposite-sex mating. In this way, even if a part of the offspring do not survive, a part of the offspring will pass on their genes. Therefore, the strategy of males is to mate more, and let their offspring be larger and better, so that their offspring will have a higher survival rate, and the larger offspring will not consume the energy of the male, so the offspring of the lone male will be much larger than the normal offspring.
However, for females, mating does not increase the number of their offspring, because they require a lot of physical energy and energy to produce offspring, and they have to feed their cubs for a long time after the offspring are born. Therefore, the strategy of females is to have fewer eugenics, while making their offspring smaller and better, this is because the faster the embryo develops, the more energy it consumes, the more it is not conducive to its own development, so the female will enhance the genes that can inhibit the development of the embryo, and try to make the child develop smaller. Therefore, the offspring of parthenogenesis will be much smaller than normal offspring.
Because the reproductive patterns of male and female mating have evolved over hundreds of millions of years, both male and female have reached a delicate balance in the production of offspring, and the participation of the other must be involved to produce healthy offspring. Otherwise, whether it is parthenogenesis or solitary male reproduction, the resulting individuals cannot survive, let alone pass on their own genes, so the gene is eliminated in evolution.
Although scientists can achieve solitary male and parthenogenesis, the process is very troublesome, and the existing solitary male or female mice do not survive for a long time.
<h1 class= "pgc-h-arrow-right" > the benefits of sexual reproduction</h1>
Most animals today use sexual reproduction and must be both male and female to reproduce. The reason for this is actually beneficial.
At present, there are two ways of reproduction in nature, asexual reproduction and sexual reproduction. Among them, asexual reproduction mainly refers to the fact that organisms can reproduce without mating, such as viruses. The advantage of asexual reproduction is that there is no need to expend energy to find a mate, but if it is asexual reproduction with DNA as genetic material, then the genetic mutation rate of the offspring is slower, and it is easy to keep up with environmental changes, so that it is eliminated by natural selection.
The reason why viruses use asexual reproduction and can also mutate faster is because they use RNA as genetic material, and RNA has only one chain and is prone to mutation.
Compared with asexual reproduction, the advantage of sexual reproduction is that the genes of organisms will undergo genetic recombination, genetic mutations, etc. when forming fertilized eggs, so that the genes of offspring are more diverse, and genetic diversity means that they can adapt to the transformation of the environment more quickly, so that they can survive better on the earth.
If the same organism has only one sex, and both can mate at will, then in the process of evolution, there will inevitably be some individuals who only want to make each other pregnant, pat themselves on the butt and leave, and these individuals perform the strategy of males, and after a long period of evolution, they will still evolve two different genders.
Conversely, if the same organism has three sexes and needs to find three parties to mate when mating, then the mating efficiency will be greatly reduced, so that it will be eliminated by nature.
It can be seen that organisms evolve two sexes because they are the most efficient, and at the same time, they can diversify the genes of their offspring and make it easier to adapt to the natural environment. Therefore, most animals today use male and female mating to breed offspring when breeding offspring.