Hymenoptera State

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As Hymenopterenstaaten are social insects of the Hymenoptera ( Hymenoptera ), respectively. What they have in common is a special genetic disposition, because the males are haploid , i. H. only have a single set of chromosomes . This fact is responsible for a number of very unusual phenomena in the Hymenoptera.

There are also numerous other state-forming animals , for example the termites or the naked mole rat ( eusociality ). But the males in them are not haploid, which is why the states there form in a completely different way. The Hymenoptera states represent a peculiarity of the eusocial way of life. Depending on the estimate, about 15 to 45% of all insect individuals live in Hymenoptera states. A large part of the earth's surface is claimed by ant colonies.

Historical

Historically, the Hymenoptera states were a major challenge in evolutionary biology and a touchstone of Darwin's theory of evolution . Charles Darwin saw in them the most serious problem in his theory - a paradox that could not be solved in his lifetime. Darwin's theory predicted that there could be no real altruism in the animal kingdom - but the sexless workers apparently do just that: they forego their own offspring and instead raise their siblings. How could such altruistic behavior be inherited if a worker who is successful with her altruism cannot pass this trait on to offspring? The explanation was only possible with the discovery of male haploidy , which still poses a multitude of interesting evolutionary and behavioral puzzles to biologists today .

It was only after Thomas Hunt Morgan discovered the function of chromosomes in 1910 that it was recognized that the sexless workers are 3/4 related to each other, i.e. closer than they could be with their own children or with their own mother. This is because they inherit half of all genetic information in an identical manner from their father, but on average only receive 1/4 of the same genes from the mother (see also recombination ). Workers therefore forego their own offspring and raise their siblings - which include the young sex animals through which they reproduce. This way of life brings with it a number of extraordinary phenomena that cannot occur in the rest of the animal world or in other state-forming organisms. From the point of view of the Hymenoptera , the world of kinship is therefore presented in a completely different way than it is from the point of view of humans or another vertebrate .

This discovery also leads the behavior of sterile Hymenoptera back to selfish interests and thus resolves the paradox recognized by Darwin. This article is intended to bundle information that will help explain this rather difficult to understand circumstance.

State-forming Hymenoptera

The state-forming Hymenoptera include

• Ants (see also wedding flight )
• Bees (see also wedding flight, drone assembly point and beekeeping )
• Wasps

Important issues

Haploidy

Haploidy does not necessarily lead to state formation. Male haploidy is only one factor favoring the evolution of Hymenoptera states, but it is neither a sufficient nor a necessary condition . There are insects with male haploidy that do not form a state ( i.e. solitary ). On the other hand, there are insect states that are not based on male haploidy (termites).

Distribution of interests within a Hymenoptera state

A distribution of interests can be found among the individuals and castes of Hymenoptera states that is difficult to compare with that in social associations of vertebrates or other eusocial creatures. The conflicting interests between the workers, the queen and the drones are considerable.

• Workers, soldiers
  • The workers are always very fraternal, but need the queen mother to make new siblings . Young queens and workers are sisters because they are descended from the same queen. Reproduction by workers themselves, which occurs occasionally (pathologically), because they are unfertilized, leads exclusively to male offspring and thus to the end of the state (via the males, however, the workers have a chance to pass their genes on to queens of foreign states) . In many species the workers prevent each other from doing so (called worker policing ). If a female worker were mated by a foreign male, the relationship to the offspring would drop to 50 percent. With the alternative transition to parthenogenesis, sexual reproduction with all its advantages would have to be given up completely.
  • An individual interest in survival is not innate in sexless workers. Their fitness is tied not to their own but to the survival of the state. They are therefore very aggressive and do not consider their own injuries or death in arguments .
• queen
  • From the queen's point of view, the extreme love of siblings in her children is not necessarily desirable. It is therefore inclined in many species to mate with several drones and split the progeny into factions. Not all siblings then have the same father and a genetic insecurity arises among them, which leads to the queen being unconditionally protected. From the point of view of any fraternal faction, the prospect of having to choose a sister of the other faction as the next queen is not very worthwhile, because it will cause one's own lineage to die out. Under these circumstances, all workers tend to defend the old queen and thus the existing conditions.
• Drones
  • From the point of view of the drones, which are fed and cared for by all their sisters, completely different interests are in the foreground. Their success depends on whether they manage to become a father, and if they do, they carry 100% of their genes into the next generation. Drones therefore only play an insignificant role in state life, as their future is decided at the drone assembly point or the wedding flight . As soon as their prospect of being successful there diminishes, they also lose the favor of their sisters and are driven out or killed by them.
• Interests of the states among themselves
  • Wars between Hymenoptera states - an everyday occurrence for the ants - are always extremely lossy. The workers mostly behave as if their own death played no role at all and as if the outcome of the dispute were merely a statistical process. Most states therefore appear completely incompatible with other insects or members of other states of their own species . They are mostly not interested in cooperation.
  • But there are also different strategies of warfare, which depend on the course of the conflict. For example, some species behave differently depending on whether they are successful. If the tide turns and the hive is in danger, there are no attempts at escape among the infertile animals. They defend themselves down to the last animal. But the fertile individuals flee.
  • Many species of ants and some bees and wasps sometimes live parasitically by invading other states and appropriating their stocks. In doing so, they implicitly make very precise calculations as to whether the attack is worthwhile in material terms - i.e. the loss of one's own individuals through the expected gain in resources is in a favorable ratio.
  • Some species of ants steal the brood of special other species ( hosts ) and let the hatching workers do their own work in the hive (slavery).
  • For some species, the establishment of new states is only possible if the young queen sneaks into the den of a host ant, kills the queen there and uses the already functioning state to raise its own offspring.

Hymenoptera are very species-rich. There are therefore many variations on this basic structure and the opposing interests of the castes are different depending on the genus and species.

Theories of the origin of Hymenoptera states

The exact processes of the emergence of Hymenoptera states have not yet been clarified, but will be clarified as genetic analyzes progress. It is already clear that Hymenoptera must have developed state formation several times independently of one another.

In The Selfish Gene , Richard Dawkins describes a conceivable course of evolution of a wasp state gradualistically :

• 1st stage: A solitary wasp builds a single nest and brings in food over the summer months . As this food emerges gradually, it lays its eggs in chronological order. This means that the offspring are of different ages and hatch from the pupa at different times . The first ones hatch while eggs are still being laid.
• 2nd stage: The hatched young daughters have the advantage of taking part in their mother's nest-building , since creating their own nest is time-consuming, but niches become free in the old nest when sisters hatch (in wood-dwelling or ground-dwelling wasps are the bitten or dug corridors). The daughters mate themselves, but lay their brood in their mother's nest. The sons, on the other hand, do not take part but leave the nest , since their reproductive success depends on the ability to mate as many females as possible.
• 3rd stage: Due to the close relationship of the sisters to one another, it is increasingly worthwhile for them to also enter food on which the mother can lay eggs in order to produce new sisters. Own offspring, on the other hand, are not so attractive if the daughters manage to enable one of them to hibernate so that they can become mothers themselves in the next year.
• 4th stage: The evolution of pheromonic communication makes it possible to coordinate the schedules and behaviors more precisely during the breeding season .
• 5th level: At this level the mother succeeds in using pheromones to get her daughters to remain completely sterile (infertile). The daughters' gross activity is only resumed if the mother is absent (death). Then one of the daughters takes the place of the mother and begins pheromonal suppression again on her part.
• Level 6: Since the mother no longer needs to leave the nest or defend it because of the many helping daughters, she has a low probability of failing. This enables most of the daughters to be phenotypically transformed and no longer have reproductive abilities themselves. Only some of the daughters - namely those born late - need to remain reproductive themselves. The sterile daughters are then very dependent on their mother and defend her with all means at their disposal. A death of the mother or the brood is equivalent to one's own death. At this level one can speak of a Hymenoptera state.
• 7th stage: The state insects evolve in different directions under the given pressure of the environment. The division of labor usually results in an enormous increase in productivity, which enables independent, often complex nest forms. Often skills are given up that are necessary for solitary wasps. Most of the ant species that most likely emerged from the wasps no longer have a stinger. As a primitive feature, the ability to fly was only preserved in the sex animals, but they are no longer very skilled at it and can only do it temporarily.