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koryos:

I don’t know if honeybees “know each other personally,” but they can recognize who is related to them and who isn’t. Research has shown that bees can recognize full and half-sisters even if they’ve never met them, which suggests that they have a genetic, inborn means of recognizing their relatives. They can even discriminate between full and half-sisters, preferring to help raise and groom their full siblings, which makes sense according to inclusive fitness theory. (More recent research has disproved this; it’s more beneficial for different patrilines to work together and individual preferences are generally overridden by the group.)

For those who do not know, bees use haplodiploidy as a sex determination system. Haplodiploid females receive two copies of each chromosome, one from each parent (which is customary). However, males only receive one set of chromosomes from their mother- which is why they have no fathers! (But they do have grandfathers.) This causes all females with the same father to be more closely related than usual, since they all get the exact same copies of his genes. Conversely, it causes females with different fathers and males to be much less related to them. This is likely the reason that haplodiplod social insects primarily use females in their worker castes, because closely-related females are more likely to cooperate than distantly-related males and females.

However, there is also evidence that bees learn to recognize their nestmates, likely due to scents shared throughout the nest via grooming. During swarming and while guarding the hive, honeybees are more likely to use nonheritable cues to recognize their nestmates. This is probably because there is little cost incurred by cooperating in either of these situations (and a lot of benefit).

As for the second part of your question, there are in fact many social insects that do not use haplodiploidy as a sexual determination system. The biggest example would be the termites. However, their eusocial behavior is still supported by inclusive fitness theory because they are purely monogamous, with a single “king” and “queen” in the nest. This means that all of the several million individuals in the nest are full siblings (barring the death of one parent; however, termite kings and queens can live for nearly fifty years). This is likely why, unlike honeybees, termite worker castes are composed of both males and females.

Not only are worker termites full siblings, they’re usually highly inbred full siblings, meaning that they’re more related than normal siblings. They might be even more closely related than haplodiploid siblings.

Termite colonies also occasionally employ “secondary reproductives,” where lower-caste males and females develop reproductive organs and start producing eggs if the king and queen die, or if the colony gets very old/large. They can set up their own smaller satellite colonies to expand the colony’s foraging rage, and in very old nests may actually produce the majority of offspring.

Female secondary reproductives are usually produced via asexual reproduction by the queen- meaning they are her clones. Not only that, but since all unmated males in the colony are their brothers (though in terms of genetics, they’re actually more or less their sons!)… guess who these sub-queens mate with? “All in the family” takes on a whole new meaning.

The evidence we have now actually suggests that monogamy is a more powerful selecting force than haplodiploidy for inclusive fitness; in fact, haplodiploid insects were probably ancestrally monogamous. I talked about this in a great more detail in this article, but for now, here’s some reading.

References:

Downs, S. G., & Ratnieks, F. L. (1999). Recognition of conspecifics by honeybee guards uses nonheritable cues acquired in the adult stage. Animal behaviour, 58(3), 643-648.

Frumhoff, P. C., & Schneider, S. (1987). The social consequences of honey bee polyandry: the effects of kinship on worker interactions within colonies. Animal behaviour, 35(1), 255-262.

Getz, W. M., & Smith, K. B. (1983). Genetic kin recognition: honey bees discriminate between full and half sisters.

Husseneder, C., Brandl, R., Epplen, C., Epplen, J. T., & Kaib, M. (1999). Within-colony relatedness in a termite species: genetic roads to eusociality?. Behaviour, 136(9), 1045-1063.

Matsuura, K., Vargo, E. L., Kawatsu, K., Labadie, P. E., Nakano, H., Yashiro, T., & Tsuji, K. (2009). Queen succession through asexual reproduction in termites. Science, 323(5922), 1687-1687.

Page, R. E., Robinson, G. E., & Fondrk, M. K. (1989). Genetic specialists, kin recognition and nepotism in honey-bee colonies. Nature, 338(6216), 576-579.

Thorne, B. L., Breisch, N. L., & Muscedere, M. L. (2003). Evolution of eusociality and the soldier caste in termites: influence of intraspecific competition and accelerated inheritance. Proceedings of the National Academy of Sciences, 100(22), 12808-12813.