New paper: Why do tropical Polistes wasps help neighbour nests?

In the 1960s, W. D. Hamilton introduced the world to kin selection. But whilst his paper was in review, he was far away in Brazil... watching the primitively eusocial wasp Polistes canadensis*. Surprisingly, worker wasps were moving between nests, seemingly lending a hand to the neighbours. This was odd. If wasps were supposed to be maximising their inclusive fitness, why did they seem to be squandering helping effort on more-distant relatives living next-door?

Hamilton added this strange fact to a section called 'Anomalies' in the second of his 1964 papers, and speculated that it might be explained by kin selection theory if (a) wasps are less useful at home and (b) neighbour nests are still related to some degree. Since then, two more hypotheses have been proposed. In our new paper based on fieldwork in Panama (thanks to National Geographic and the Smithsonian Tropical Research Institute for funding!), we show that these newer hypotheses don't work. We find that Polistes canadensis nests appear to experience diminishing returns to cooperation that confirm Hamilton's hunch: wasps can become less useful at home, so altruistic wasps can improve their inclusive fitness by switching nests.

This fieldwork involved working in some surprising parts of Panama, including a derelict loo. I've somehow managed to have an ode to derelict Panamanian loos posted on the Nature Ecology and Evolution blog, here: 
https://natureecoevocommunity.nature.com/posts/altruism-among-the-u-bends

The paper is here: 
https://www.nature.com/articles/s41559-020-01382-z


*a classic mistake in zoological naming, as P. canadensis lives nowhere near Canada.