A team at the University of Sydney has revealed that monogamy in ancestral eusocial insects, which produced highly related individuals, is key to the evolution of eusociality in insects, the "Science" journal reported.
"Multiple mating by females is common, in fact usual, across the animal world. Thus it is quite startling that our analysis shows that monogamy was the ancestral condition for all of the modern social insects," according to one of the researchers Prof Ben Oldroyd.
The researchers combined the mating frequencies of 267 species of living social hymenoptera with advanced statistical technique that reconstructs ancestral states, to infer just how many males the ancestral social insect females mated with.
In every group that they looked at, the researchers found that the ancestral females were always monogamous. This is a surprising result, given the extreme polyandry (females mating with many males) of many living social insects.
Prof Oldroyd said, "Sociality has evolved repeatedly in the Hymenoptera and the Thysanoptera (thrips). These orders of insects have an unusual mechanism of sex determination in which males are haploid (one set of chromosomes) and females are diploid (two sets of chromosomes like humans). This haplo-diploidy generates very high relatedness among sisters."