Author response: Topological constraints in early multicellularity favor reproductive division of labor

Does the evolution of division of labour require accelerating returns from individual specialisation?

“…We follow Yanni et. al, and a number of previous models, by assuming that individual fitness is the product of individual viability, which is the chance of surviving to maturity, and individual fecundity, which is proportional to the number of offspring if the individual reaches maturity (Cooper & West, 2018;Michod, 2006;Yanni et al, 2020). We examine the specific case of reproductive division of labour between helpers and reproductives, where helpers are more cooperative, contributing to a higher viability for group members, and reproductives are less cooperative, contributing to higher individual fecundity.…”

“…Specifically, reproductive division of labour could arise in topologically constrained groups-where each cell in a spatially structured group shares cooperative benefits with only their direct neighbours (Staps & Tarnita, 2020;Yanni et al, 2020). Their analyses suggested that this is particularly likely to occur in sparsely structured groups, where cells have a small number of neighbours (Yanni et al, 2020). This is a novel result.…”

“…In contrast, Yanni et al found that division of labour between helpers and reproductives can sometimes be favoured even when there are diminishing (concave) returns from individual specialisation (Yanni et al, 2020). Specifically, reproductive division of labour could arise in topologically constrained groups-where each cell in a spatially structured group shares cooperative benefits with only their direct neighbours (Staps & Tarnita, 2020;Yanni et al, 2020). Their analyses suggested that this is particularly likely to occur in sparsely structured groups, where cells have a small number of neighbours (Yanni et al, 2020).…”

“…(B) In contrast, an accelerating return from more cooperation (or reproduction) favours reproductive division of labour, with some individuals specialising in high levels of cooperation (helpers) and others in low levels of cooperation (reproductives) (Cooper & West, 2018;Michod, 2006;Schiessl et al, 2019). In contrast, Yanni et al found that division of labour between helpers and reproductives can sometimes be favoured even when there are diminishing (concave) returns from individual specialisation (Yanni et al, 2020). Specifically, reproductive division of labour could arise in topologically constrained groups-where each cell in a spatially structured group shares cooperative benefits with only their direct neighbours (Staps & Tarnita, 2020;Yanni et al, 2020).…”

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Recent theory has overturned the assumption that accelerating returns from individual specialisation are required to favour the evolution of division of labour. Yanni et al (2020) showed that topologically constrained groups, where cells cooperate with only direct neighbours such as for filaments or branching growths, can evolve a reproductive division of labour even with diminishing returns from individual specialisation. We developed a

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