The formation of eusocial groups: partner choice, conflict and the role of the market

Lead Research Organisation: University of Sussex
Department Name: Sch of Life Sciences

Abstract

In eusocial or cooperatively-breeding groups of animals, some individuals act as helpers, rearing the offspring of other individuals (queens or breeders). Examples include honeybees, ants, naked mole-rats and meerkats. How and why these groups form is a key question in biology. The main testing-grounds are so-called primitively eusocial species, in which queens and helpers are not morphologically differentiated so that all individuals still have the option of independent reproduction outside the group. Paper wasps (Polistes) are the best studied insect system. In spring, overwintered females, known as foundresses, initiate new nests alone or in groups. On multiple-foundress nests, one 'dominant' female lays most of the eggs, while the others act as helpers, foraging to feed the dominant's larvae. However, although there is a well developed theoretical framework for understanding why individuals become helpers, the process of group formation itself has been little studied. Building on previous work, this proposal will combine three novel manipulative experiments with DNA profiling to investigate group formation in Polistes.

The work will:

(1) Test critical assumptions implicit in previous work: what options do foundresses have, in terms of alternative partners to join, and is there conflict between residents over group membership?
(2) Manipulate market forces - the supply of pre-existing groups available to potential joiners - to reveal the effect on major features of eusociality such as partner switching, helping effort and group productivity.
(3) Test the importance of partner choice in determining group productivity, partitioning of reproduction and cooperative behaviour.

Results will provide the most comprehensive understanding of group formation in a primitively eusocial insect, and allow a critical evaluation of previous models and data.

Planned Impact

WHO WILL BENEFIT FROM THE RESEARCH?

The project is blue-skies research to investigate fundamental questions about social evolution. Apart from other academics, the main beneficiaries will be the public through widening participation activities. Indeed, public understanding of science is essential to maintain science funding and scientific literacy.

Activities will be targeted towards:
- students (and their teachers) at schools and further education colleges taking subjects in Biology and Computer Science/ICT
- visitors to museums/exhibitions

There are at least two reasons why the proposed research should stimulate public interest:
1. Although we will use a social insect model to investigate the decision to cooperate, this decision is also a central feature of everyday human interactions, from house-mates cleaning a shared kitchen to drivers choosing whether to give way in a narrow street.
2. The public are intrinsically curious about social wasps, both because they are social and because wasps are seen as being dangerous.

HOW WILL THEY BENEFIT FROM THE RESEARCH?

Understanding the science behind their own behaviour.

The success of popular science books on cooperation, such as Rock, Paper, Scissors (Fisher 2009), and TV programmes on human behaviour, such as the BBC's Human Planet, indicate that the general public is very interested in behaviour that can be related to humans, and so would be receptive to learning about topics related to the proposed research. The interactive approach to be implemented via the Pathways to Impact plan seems particularly appropriate to stimulate interest.

Learning about social wasps.

Many people think that wasps are just a nuisance or even dangerous. By overcoming these misconceptions, and showing that wasps make complex decisions about cooperation, we can stimulate curiosity about the natural world, which will ultimately make us better able to conserve it. Furthermore, we can foster future generations of scientists by helping students to understand how even "scary" animals can not only be interesting, but also help us to understand our own behaviour.

Fisher L. 2009. Rock, Paper, Scissors: Game Theory in Everyday Life. New York: Basic Books

Publications

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Field J (2016) Cooperation between non-relatives in a primitively eusocial paper wasp, Polistes dominula. in Philosophical transactions of the Royal Society of London. Series B, Biological sciences

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Grinsted L (2017) Biological markets in cooperative breeders: quantifying outside options. in Proceedings. Biological sciences

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Grinsted L (2018) Predictors of nest growth: diminishing returns for subordinates in the paper wasp . in Behavioral ecology and sociobiology

 
Description In eusocial or cooperatively-breeding groups, some individuals act as helpers, rearing the offspring of others (queens or breeders). Examples include honeybees, ants and meerkats. How and why these groups form is a key question in biology. In paper wasps (Polistes dominula), overwintered females, known as foundresses, initiate new nests alone or in groups. All foundresses can potentially reproduce, but on multiple-foundress nests, only one 'dominant' female lays most of the eggs, while the others (helpers) forage to feed her larvae. Although there is a well developed theoretical framework for understanding why individuals become helpers, the process of group formation itself has been little studied. Previous work has traditionally been framed in terms of an individual choosing whether to become a helper in a particular group or being forced to reproduce alone. Since breeding alone is often unfeasible, this leads to the prediction that helpers will accept a high workload and only a small share of the reproduction in order to remain in the group, since they effectively have nowhere else to go. A critical objective in this proposal was test whether there is instead a 'market', where foundresses have a choice of groups to join, and where residents might choose between multiple joiners.
Our first experiment forced helpers to reveal their alternative options, by removing their current nests and nest-mates. Nearly all joined other groups, and almost none was forced to breed alone. However, when we removed helpers from groups, they were not replaced, suggesting that there is not an unlimited pool of potential helpers. These first experiments indicated that there is the potential for market forces to operate, and led on to our second key objective. This was to test experimentally whether helping effort would change if we altered market forces at the population level, for example by removing nests to create nest-less wasps as potential partners to nest with. The result, again consistent with market theory, was that helpers on unmanipulated nests began working less hard compared with controls. Effectively, by giving helpers more options, we forced dominants to accept a lower price in exchange for allowing them into the group. More generally, our findings imply that in order to predict the level of help provided, it is necessary to take into account the state of the surrounding market, not just within-group variables such as the helper's social rank. Key questions for the future will be to investigate how helping levels are enforced, and how individuals assess the state of the market.
Our third objective, to investigate the importance of partner choice, suggested that wasps do not discriminate between different partners at a fine scale, probably because they lack sufficient information. Beyond our original objectives, we also uncovered the mechanism by which the dominant's identity is determined in P. dominula, a critical piece of information that has previously been lacking. Our work has so far been published in three leading international science journals (e.g. Nature Communications), with a fourth paper currently in revision and others in preparation.
Exploitation Route This research is primarily of interest to other academics in fields such as evolutionary biology, animal behaviour and human behaiour. However, we also created a hands-on game to illustrate our work as part of our Pathways to Impact plan, which we demonstrated, along with a talk and videos of wasp behaviour, at ca. 10 high schools. Structured feedback we obtained showed, for example, that these engagement activities enthused students about careers in science, and because the postdoctoral demonstrator was female, gave particular confidence to female students that they could succeed in science.
Sectors Environment

 
Description Competition 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Schools
Results and Impact We ran a competition for sixth-formers to suggest a format for a computer game app based on our research. The student with the winning entry visited our University to meet us and see our actual research, and we have arranged for her to have a day at a commercial game developer to work towards producing a real app (this will be later in spring 2016).
Year(s) Of Engagement Activity 2015
 
Description STEM netowrking event (Brighton University) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Our presentation was a talk then a physical activity (a participatory game simulating our research) that participants could potentially use in their own work. The session sparked questions and discussion, about both the specific topic and its applications.
Year(s) Of Engagement Activity 2015
 
Description School visit (Blatchington) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Our presentation was a talk then a physical activity (a participatory game simulating our research). The session sparked questions and discussion, about both the specific topic and about academia and scientific research in general.
Year(s) Of Engagement Activity 2015
 
Description School visit (Chichester College) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Our presentation was a talk then a physical activity (a participatory game simulating our research). The session sparked questions and discussion, about both the specific topic and about academia and scientific research in general.
Year(s) Of Engagement Activity 2015
 
Description School visit (Downlands Community School) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Our presentation was a talk then a physical activity (a participatory game simulating our research). The session sparked questions and discussion, about both the specific topic and about academia and scientific research in general.
Year(s) Of Engagement Activity 2015
 
Description School visit (Midhurst) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact Our presentation was a talk then a physical activity (a participatory game simulating our research). The session sparked questions and discussion, about both the specific topic and about academia and scientific research in general.
Year(s) Of Engagement Activity 2015
 
Description School visit (Seahaven) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Our presentation was a talk then a physical activity (a participatory game simulating our research). The session sparked questions and discussion, about both the specific topic and about academia and scientific research in general.
Year(s) Of Engagement Activity 2015
 
Description School visit at Longhill High School, Brighton 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact Our presentation was a talk then a physical activity (a participatory game simulating our research). The session sparked questions and discussion, about both the specific topic and about academia and scientific research in general.

According to the teacher who was involved at the school (Martyn Newman): "It was great for the students to be able to discuss real scientific research with real scientists; many of these students had aspirations to study science further after their GCSEs"
Year(s) Of Engagement Activity 2014
 
Description Session for School Teachers, 13.12.13 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Presentation sparked interest in a game, simulating our research, that we are developing for use in schools

Teachers showed interest in the game, and in us visiting their schools
Year(s) Of Engagement Activity 2013