In the Selfish Gene, Dawkins introduces the idea of social insect individuals being divided into two main classes: the bearers and the carers. The bearers are those who reproduce and the carers/workers are those who perform work and are usually infertile. Both types carry out their jobs efficiently because they do not have to cope with each other.
If the workers are unable to reproduce, why aid the queen? What’s in it for them? Dawkins states that the workers “farm” the reproductive individuals, meaning that the workers manipulate the queen to propagate the worker’s genes. The conflict in this system lies in the sex ratio. The queen favors a 1:1 females to males sex ratio whereas the workers favor a 3:1 females to males ratio.
It makes sense that the queen benefits by investing equally in both sexes, but why do workers favor females over males? A simplified answers is that males contain just a single set of chromosomes (all passed on from the mother) whereas the females contain a double set of chromosomes (obtained from the mother and father). Among the females, full sisters are identical twins as far as their parental genes, thus females benefit by “farming” their own mother into a “sister-making” machine.
Is there a winner? Trivers and Hare found that among 20 species of ants, the workers bias the sex ratio in favor of females (The Selfish Gene, pp. 176-178). However some species of ants, after defeating another colony of ants, take the unhatched ants who become slaves. These slaves, not knowing that their not related to the queen, performed as workers yet do not affect the queen’s preferences.
Subscribe to:
Post Comments (Atom)
Very good description and you explained everything very well. If the slaves were to find out that they were not related to the queen I wonder if all production in the hive would stop?
ReplyDeleteYou answered the blog very well, it was very thought out. I was confused about why the workers would favor females but you put it in very good terms to where I now understand.
ReplyDelete