Evaluating kin and group selection as tools for quantitative analysis of microbial data

Kin selection and multilevel selection theory are often used to interpret experiments about the evolution of cooperation and social behaviour among microbes. But while these experiments provide rich, detailed fitness data, theory is mostly used as a conceptual heuristic. Here, we evaluate how kin and multilevel selection theory perform as quantitative analysis tools. We reanalyse published microbial datasets and show that the canonical fitness models of both theories are almost always poor fits because they use statistical regressions misspecified for the strong selection and non-additive effects we show are widespread in microbial systems. We identify analytical practices in empirical research that suggest how theory might be improved, and show that analysing both individual and group fitness outcomes helps clarify the biology of selection. A data-driven approach to theory thus shows how kin and multilevel selection both have untapped potential as tools for quantitative understanding of social evolution in all branches of life.

Automated summary

Kin selection and multilevel selection theory are often used to interpret experiments about the evolution of cooperation and social behavior among microbes, but they are mostly used as conceptual heuristics. This study evaluates how these theories perform as quantitative analysis tools, finding that the classical fitness models of both theories are often unsuitable for microbial systems due to strong selection and non-additive effects. Analyzing both individual and group fitness outcomes can help clarify the biology of selection and reveal untapped potential for understanding social evolution in all branches of life.