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The female fire ants broke away from the males

Imagine a world where there is no genetic connection between women and men. It turns out that this is what happens with the fire ant: the fertile females are clones of their mothers, and the males are clones of their fathers

Zvi Atzmon

Nowadays, we often hear about the "war of the sexes" in various contexts - in family counseling sections, in popular psychology literature, in movies, in politics. In the end, many sigh and agree that "it is very difficult for you (you), but it is impossible without them (without them)". But it turns out that the little fire ant actually took a big step towards a complete separation between females and males: the fertile females - the "queens" - are genetically the offspring of only their mothers, and the males are the genetic offspring of only their fathers, with no female genetic contribution. This is what Danny Fournia and his colleagues, researchers from France, New Caledonia, Japan and Belgium, found in a study reported in the June 30 issue of the science weekly Nature.

Men differ from women, among other things, in the chromosomes in their body cells. As we know, the female cells contain two X chromosomes, while the male cells contain a single X chromosome and a Y chromosome. However, the difference is smaller than this description suggests. First, in addition to these two chromosomes, each cell, both of a woman and a man, contains 44 additional chromosomes, which are classified as pairs. Half of them get a man from his mother, and so does a woman from her father. In other words, these chromosomes belong to the pool shared by men and women.

Since the genes, which dictate the hereditary traits, are included in the chromosomes, they are usually represented in pairs - one originating from the mother and one from the father. If there is a difference between them, in many cases the trait is dictated by only one of the spouses - he is called "ruling" (dominant). It does not matter the origin of the ruler - in the mother or in the father. The X chromosome is also passed between men and women and vice versa: a man's X chromosome originates from his mother, and one of a woman's two X chromosomes originates from her father. Only Y chromosomes constitute a separate population - they are passed down from white fathers, and women have no share or inheritance in them.

However, the difference in chromosomes between women and men is even narrower: in each cell of a woman's body, only one X chromosome actually functions (as in a man) - in some of the cells it originates from the father, and in another part from the mother, and this is due to a process that prevents almost all the genes on one of the X chromosomes from working. On the other hand, the Y chromosome, the "male" chromosome, has only a few genes. This tiny chromosome is what determines masculinity in a person, but overall the genetic differences between women and men are limited.

Despite this, from a biological point of view, a "species war" does exist, and as in any war, even those who seek peace are involved in it against their will. It turns out that few of the genes contained in the chromosomes shared by a woman and a man undergo "parental imprinting" (imprinting), in such a way that for those genes only one of them determines - the one that has undergone the appropriate parental imprinting, while the partner who originates from the other parent has no "right to speak", and he is not affects the attributes. "Sovereignty" does not determine in this case, but the source of the gene, the mother or the father. For example, a certain gene that dictates the growth of the fetus has a paternal imprint: the "interest" of the father is that the fetus grows as much as possible - of course, at the expense of the pregnant mother. This is not a war to hurt; Its whole purpose is to exploit the other (the woman-mother, in this case) for the benefit of the genetic interests of the father-male.

Many living creatures have reproduction and inheritance mechanisms similar to ours, and even in them there is a biological "war of the species". But there are living creatures whose reproductive mechanisms are very different, to the point that some of them can be perceived as imaginary or "perverse" at first glance, and some of them are not completely understood. For example, among earthworms (diarrhea), living in moist soil, "this whole thing" is simpler: everyone is androgynous - both male and female. As a male, he produces sperms and transfers them to his mate during mating, and as a female, he has eggs fertilized by sperms received from his mate and he lays them after fertilization. Diarrhea that has found another diarrhea does not need, therefore, to check with tassels - it mates with itself, and at the same time fertilizes and is fertilized.

Among the ants and bees, not only is there a separation between males and females, but the distinction between them is not determined by a single chromosome but by an entire set of chromosomes. The fertile females - the queens - mate with males and receive sperm from them that are stored in their bodies for a long time. An egg fertilized by a sperm develops into a female, while an unfertilized egg (with only half the number of chromosomes in a female's body cells) develops into a male. The male cells contain, therefore, only chromosomes derived from the mother; He has no father (but he has a grandfather, his mother's father). In social bees and ants, in addition to the division between the sexes, there is also a division into classes (castes): most females are barren and serve as "workers", and only a small minority are fertile females (queens), who mate with males and lay eggs. The fertilized among them develop into females (workers or queens), the unfertilized into males.

This arrangement apparently "doesn't please" the eyes of the fire ant, which is only about 1.5 mm long, its bite is very painful, and it has become a real scourge in various parts of America, as well as in Africa and Micronesia. Fornia and his colleagues found that while the workers of the fire ant normally have a mother and a father, the queens were not formed as a result of fertilization, but instead contain the same set of chromosomes as the mother queen. The young queens are, therefore, cloned products of the queen-mother (a cloned product means a new individual that is genetically identical to the individual from which it was created). It looks like a knock-out in favor of the female queens in the war of the sexes. But the males do not raise their legs and withdraw from the battle. The team of researchers points to an amazing finding, which may have no equal in the animal world: the young males carry only chromosomes that originate from their father! Is it possible that the sperms penetrating certain eggs destroy the maternal chromosomes in them? This is the opinion of the researchers, the actual war of annihilation. These eggs are used, if indeed this is the case, only as a substrate for cloning the male.

If this is indeed the case, in the fire ant the chromosomes of males and the chromosomes of fertile females never mix, and they pass parallel through the generations, as if they were two separate biological species. The mixing of the genetic material does indeed occur in the working females, but these are sterile and do not bear offspring themselves.

Imagine a similar situation in humans - parallel lineages of men and women, without any genetic connection between them...

The writer is the scientific editor of the monthly "Galileo"

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