Which I think is a cool angle on the much modelled evolution of cooperation.
In addition to @caritalindstedt.bsky.social and @abhay-gupta.bsky.social, we also have Nina Gerber on the modelling side and Raphael Ritter on the data collection side, all in all a wonderful cooperation!

So as a whole, there’s quirks about haplodiploidy in here, but the broader question is about heterogeneity not only in helper fates but also in the recipients. To somewhat oversimplify: if everyone is identical, it may be harder to observe help than if there’s mixed groups in one sense or another.

Males in this species may be created with sisters nearby (if their mother did mate) or without (if she did not). The two types of brood differ in whether a focal individual has kin nearby who have different prospects than ‘self’ has.

Answers are complex (biased sex ratios in haplodiploids play a role) but a big thing is that helping is particularly favoured when someone with poor prospects can help someone with better prospects survive. Prospects = what happens as an adult.

In our case helping occurs among the juvenile life form so the question is suddenly not trivial. Why on earth would a son help siblings less than a daughter, if they’re all in a pile trying to survive together, and their life is not yet sex-specific at all?

Scientists actually know quite a bit about sex differences in helping but our system allows a finer look at the who-helps-whom question. The species is haplodiploid, and many haplodiploids form colonies where the recipient of help is by default a female.

Puking is a predator defence trait expressed by larvae of pine sawflies, and the grand question is who contributes to collective defence when it’s cheaper to the individual to freeride on others’ defense effort. Tantalizingly, females in this species contribute more.

And here is another fruit from the same delightful collaboration! academic.oup.com/evolut/artic...