Mating with a single male is ancestral for eusociality

I read this paper with great interests! Have not touch Ecology for years~~ This short paper is really easy to understand and very convincing.

Very good review in F1000.

Laurent Keller
University of Lausanne , Switzerland
ECOLOGY

This paper is very interesting because it demonstrates that eusociality evolved repeatedly in taxa with a mating system maximizing relatedness. By conducting a comparative analysis of female mating frequencies in 267 species of eusocial bees, wasps, and ants, the authors found that mating with a single male is ancestral for all eight independent eusocial lineages investigated. This study puts to an end a recent controversy where some authors suggested that close relatedness may be a consequence, rather than a cause, of eusociality.

So, here is the paper.

Science. 2008 May 30;320(5880):1213-6.
Ancestral monogamy shows kin selection is key to the evolution of eusociality.
Hughes WO, Oldroyd BP, Beekman M, Ratnieks FL.

Institute of Integrative and Comparative Biology, University of Leeds, Leeds, LS2 9JT, UK. w.o.h.hughes@leeds.ac.uk

Close relatedness has long been considered crucial to the evolution of eusociality. However, it has recently been suggested that close relatedness may be a consequence, rather than a cause, of eusociality. We tested this idea with a comparative analysis of female mating frequencies in 267 species of eusocial bees, wasps, and ants. We found that mating with a single male, which maximizes relatedness, is ancestral for all eight independent eusocial lineages that we investigated. Mating with multiple males is always derived. Furthermore, we found that high polyandry (>2 effective mates) occurs only in lineages whose workers have lost reproductive totipotency. These results provide the first evidence that monogamy was critical in the evolution of eusociality, strongly supporting the prediction of inclusive fitness theory.

PMID: 18511689

Kin selection

From the time of antiquity field biologists have observed that some organisms tend to exhibit strategies that favor the reproductive success of their relatives, even at a cost to their own survival and/or reproduction. The classic example is a eusocial insect colony, with sterile females acting as workers to assist their mother in the production of additional offspring. Many evolutionary biologists explain this by the theory of kin selection.

The earliest expressions of the basic concepts were by R.A. Fisher in 1930[1], JBS Haldane in 1955[2], but it was W. D. Hamilton who truly formalized the concept, in works published in 1963[3]and - most importantly - in 1964[4], while the actual term "kin selection" may first have been coined by John Maynard Smith (1964)[5] when he wrote "These processes I will call kin selection and group selection respectively. Kin selection has been discussed by Haldane and by Hamilton. ... By kin selection I mean the evolution of characteristics which favour the survival of close relatives of the affected individual, by processes which do not require any discontinuities in the population breeding structure."

Kin selection refers to changes in gene frequency across generations that are driven at least in part by interactions between related individuals, and this forms much of the conceptual basis of the theory of social evolution. Indeed, some cases of evolution by natural selection can only be understood by considering how biological relatives influence one another's fitness. Under natural selection, a gene encoding a trait that enhances the fitness of each individual carrying it should increase in frequency within the population; and conversely, a gene that lowers the individual fitness of its carriers should be eliminated. However, a gene that prompts behaviour which enhances the fitness of relatives but lowers that of the individual displaying the behavior, may nonetheless increase in frequency, because relatives often carry the same gene; this is the fundamental principle behind the theory of kin selection. According to the theory, the enhanced fitness of relatives can at times more than compensate for the fitness loss incurred by the individuals displaying the behaviour. As such, this is a special case of a more general model, called "inclusive fitness" (in that inclusive fitness refers simply to gene copies in other individuals, without requiring that they be kin).