Scientists have discovered that the altruistic behaviour of European Paper wasps, Polistes dominulus, even towards non-related insects, actually improves their reproductive success.
P.dominulus are a species of primitively eusocial wasp, meaning that the subordinate (lower ranked) wasps have the same reproductive ability as the dominant wasp. In a group situation, however, only the dominant is allowed to reproduce. The curious aspect of the species is that wasps choose to give up reproduction in favour of helping a dominant wasp build her nest, instead of going it alone and building their own nest.
Primitively eusoical behaviour can be understood in terms of evolution if the subordinates are close relatives to the dominant, allowing their genes to pass to the next generation indirectly. European Paper wasps, however, will often help non-relatives.
A team from the University of Sussex investigated the theory that the subordinates helped dominant wasps in the hope of inheriting the nest at the end of the season. Dr Ellouise Leadbeater who worked on the study, explained; “We wanted to know how much reproduction they got [through inheritance], if they actually did better as a subordinate, waiting to see if they inherited the nest, than they would if they just went and nested all by themselves
The group of researchers studied the wasps for an entire breeding season (February – July) and recorded the reproductive success of both subordinate and lone wasps. Surprisingly they found that the subordinate wasps did at least as well as the lone wasps, and often better.
The team also found evidence of the subordinates ‘sneaking’ eggs into the nest, but the predominant reproductive success came from inheritance. “As well as inheriting and becoming the dominant, they also get to lay a few eggs as subordinates. But inheritance was the main driver... 60% of the eggs that subordinates laid, were laid after they’d inherited the dominant position.”
Click to hear Dr Elli Leadbeater discuss the findings