Kin Selection

by

François Rousset, Laurent Lehmann

• LAST REVIEWED: 12 January 2022
• LAST MODIFIED: 12 January 2022
• DOI: 10.1093/obo/9780199941728-0083

Introduction

Kin selection theory is a formulation of natural selection theory that is particularly suitable for understanding cases of reproductive self-sacrifice. For example, sterile workers in insect societies help the queen to reproduce by rearing her offspring. This phenomenon can be favored by natural selection when the workers are genetically related to the queen and thereby help her to transmit genes identical to theirs in the queen. The origin of this idea can be traced back to anecdotal comments by Haldane and Fisher, and even to the Origin of Species, but a systematic development of the idea began with Hamilton’s development of the concept of inclusive fitness. Natural selection by way of effects on genetic relatives has been named kin selection, and can thus occur whenever relatives preferentially interact together, in family-structured or spatially structured populations. The concepts of kin selection theory now provide powerful methods for analyzing models of evolution of social behaviors, including not only reproductive self-sacrifice in social insects but also the occurrence of conflicts within such societies, and more broadly any ecological interaction that includes cooperative or competitive interactions between individuals. The theory has contributed substantially to the development of ideas in diverse fields beyond behavioral ecology, including parasitology, and to the study of epigenetic processes in developmental biology.

General Overviews

The general theory and the diversity of its empirical implications are not generally covered in a single textbook. Bourke 2011 comes closest to filling this niche. The collection of papers in Hamilton 1996 is a highly recommended reading, showing both significant early steps in the development of kin selection theory and the breadth of its empirical applications, but it is piecemeal and missing recent developments. Some monographs address applications to specific group of organisms or life history traits, largely using kin selection theory as the conceptual framework. The evolution of social insect colonies is surveyed by Crozier and Pamilo 1996, and ants are more specifically discussed in Bourke and Franks 1995. The latter book also provides an accessible introduction to many aspects of the theory itself. West 2009 reviews sex ratio evolution, a favorite topic of many tests of kin selection theory because of the relative ease of controlling the costs and benefits of alternative behaviors. Two more theoretically oriented monographs provide thorough introductions for graduate students and above: Frank 1998 emphasizes abstract general formalisms applicable to any evolutionary scenario, and Rousset 2004 emphasizes the relationship between kin selection, population genetic theory, and demography in structured populations. Marshall 2015 is a book-length defense of the general version of inclusive fitness.

• Bourke, A. F. G. 2011. Principles of social evolution. Oxford: Oxford Univ. Press.

  DOI: 10.1093/acprof:oso/9780199231157.001.0001

  Covers kin selection broadly and in reasonable depth. A more specific aim of the book is to explain in terms of kin selection theory the hierarchical organization of life, of genes in cells, of cells in multicellular organisms, and of organisms in societies.

• Bourke, A. F. G., and N. R. Franks. 1995. Social evolution in ants. Princeton, NJ: Princeton Univ. Press.

  Although the book defines ants as its topic, it includes substantial general introductions to kin selection and multilevel selection theories, and substantial discussions of major conceptual issues such as parent-offspring conflict.

• Crozier, R. H., and P. Pamilo. 1996. Evolution of social insect colonies. Oxford: Oxford Univ. Press.

  Similar in spirit to Bourke and Franks 1995, but covers a broader taxonomic range, delves more into the analysis of models, and more narrowly focuses on sex ratios.

• Frank, S. A. 1998. Foundations of social evolution. Princeton, NJ: Princeton Univ. Press.

  DOI: 10.1515/9780691206820

  The first book-length treatment of inclusive fitness theory, with broad applications and many examples. It also emphasizes regression methods for formulating various expressions for change in allele frequency, but in an abstract way so that some readers may find it difficult to appreciate the precise meaning and limits of the concepts.

• Hamilton, W. D. 1996. Narrow roads to gene land. Vol. 1. Oxford: Freeman.

  This volume collects all of Hamilton’s publications prior to 1981, including works on sex ratio that introduced concepts of game theory and of intragenomic conflict. Each paper is introduced by a commentary describing the intellectual context in which it was developed, often in the form of personal anecdotes.

• Marshall, J. A. R. 2015. Social evolution and inclusive fitness theory: An introduction. Princeton, NJ: Princeton Univ. Press.

  DOI: 10.1515/9781400866564

  Mainly an enthusiastic advocacy of the general version of inclusive fitness against recent criticisms, this book argues more through citations of previous authors than through self-contained, compact arguments. It does not discuss how kin selection arguments are used in game theoretical arguments that form the core of behavioral ecology.

• Rousset, F. 2004. Genetic structure and selection in subdivided populations. Princeton, NJ: Princeton Univ. Press.

  Merges methods of kin selection theory, game theory, and population genetics, showing in particular how relatedness relates to descriptions of genetic population structure; how this leads to results for fixation probabilities of mutants, widely used since; and how to interpret fitness costs and benefits in the presence of local competition.

• West, S. 2009. Sex allocation. Princeton, NJ: Princeton Univ. Press.

  DOI: 10.1515/9781400832019

  Extensively covers the literature on sex ratio evolution. Theoretical results are presented but not rederived, and kin selection theory is used as an interpretative tool for these results.