haplodiploid

cool facts abt bees bc im all excited abt them now

  • most bees are solitary; the only social bees are european honeybees and the stingless social bees native to australia and south america (see previous post)
  • theyre technically called “eusocial” because theyre not just social in the sense that they aggregate together, which many insects do, but because they have cross-generational stratified social systems with rigidly-divided labour and reproductive activities. there are RULES yo
  • the only other eusocial insects are ants, which belong to the same taxonomic order as bees and wasps; and termites, which belong to the same order as the cockroaches
  • so it’s accurate to say that “bees and ants are social wasps” and “termites are social cockroaches” which is cool to me for some reason
  • eusocial insects communicate to each other using INTENSELY complex pheromone systems ie. they talk to each other using smells
  • e.g. an alarm pheromone released by a scared bee is what tells all her bee friends to come form a swarm of death
  • ants and bees both use haplodiploid sex determination mechanisms, whereby the females have 2 sets of chromosomes and the males only have 1
  • the way this works is: the queen can decide which sex of offspring to produce based on whether or not she fertilises her eggs. females are produced from fertilised eggs, and have genes from both the queen and her mate; males are produced from unfertilised eggs, so ONLY have their mother’s genes (and only half of them)
  • yes it’s true that only female bees do any work. the males (drones) literally just sit in the hive and do. nothing. i dont know why evolution did this. 
  • same for ants actually. all the ants in antman should have been female but what can u expect from the mcu amirite
  • i lie when i say that males do nothing because there is one (1) important event in their life and that is: going on an Epic Icarian Journey vertically up into the sky to discover which of them will be the Chosen One and win the heart (chromosomes) of the princess
  • by which i mean: when she’s ready to mate, the princess leaves the hive and flies upwards into the sky. all the males follow her. she keeps flying up and up and up as the males fall away one by one and the last male still flying beside her wins and becomes the father of the new hive. then he dies
  • (cool but irrelevant fact abt termites: in termites the male doesnt die,but stays on to live in the nest. this gives termite colonies both a king and a queen. animorphs lied to u im so sorry)
  • only female bees can sting because the sting is formed from a modified ovipositor (the egg-laying organ). males don’t have it so they cant sting
  • having said that, most bees WONT sting (in fact pretty much only honeybees will, though the fun part of that is that their stings also happen to be barbed and envenomated so they really make it count)
  • most of the native australian bees (which are the only ones i really know about) won’t sting you unless really really really scared, and the social ones literally can’t because their stings evolved to be useless for,, whatever reason. they can still bite, but it’s really just annoying more than painful. however they do somehow know to go for the eyes and nose which i can testify to from personal experience
  • we do have a date for the evolution of eusocial bees (i cant remember the exact number but i think it was sometime in the triassic??) whatever the cool part is how they discovered it, because as u can imagine it would be pretty difficult to find explicit fossil evidence of a group of bees living together in a rigidly-stratified generationally-overlapping labour- and reproductively-divided social system
  • OR so we thought because,,, the very fact of bees living together brings about morphological changes. specifically, the abdomen of worker bees will be smaller, compared to the abdomens of solitary female bees, because workers dont have to lay eggs. they have queens for that
  • so essentially: the way we got the earliest current date for the evolution of eusociality is,, someone found a tiny bee fossilised in amber, with a tiny sting (so we know its female) and a tiny abdomen (so we know she couldnt lay eggs)
  • hence: social bee
  • PALAEONTOLOGY IS GR8

anonymous asked:

Do all workers bees in the hive know each other personally? According to inclusive fitness theory and I want to know if there is any other social insect live with each other and don't have the sexual determination system similar to that of bees

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.