The evolution of hermaphroditism by an infectious male-derived cell lineage : an inclusive-fitness analysis

This work was supported by funding from Balliol College, the Royal Society (A.G.), and the University of Groningen (L.R.).There has been much recent interest in the role for genetic conflicts to drive the evolution of genetic systems. Here we consider the evolution of hermaphroditism in the scale insect tribe Iceryini and the suggestion that this has been driven by conflict between a female and an infectious male tissue derived from her father. We perform an inclusive-fitness analysis to show that, owing to genetic relatedness between father and daughter, there is scope for collaboration as well as conflict over the establishment of the infectious tissue. We also consider the evolutionary interests of a maternally inherited bacterial symbiont that has been implicated in mediating the tissue's establishment. More generally, our analysis reveals that genetic conflicts can drive the evolution of hermaphroditism.Publisher PDFPeer reviewe

U.S. Extended Continental Shelf Cruise to Map Gaps in Kela and Karin Ridges, Johnston Atoll, Equatorial Pacific Ocean

The objectives for cruise KM14-17 are to map the bathymetry of two gaps in two submarine ridges in the vicinity of Johnston Atoll. One ridge gap occurs along the informally named Keli Ridge (Hein et al., 2005) south of Johnston Atoll and the other ridge gap occurs north of Johnston Atoll that separates Sculpin Ridge (also informally called Karin Ridge) and Horizon Ridge, all in the central equatorial Pacific (Fig. 1). The cruise took advantage of a scheduled dead-head transit from Papeete, Tahiti to Honolulu, Hawai’i that could be extended for 5 days to include the planned mapping. The mapping is in support of the U.S. (Extended Continental Shelf (ECS) Task Force. These areas were identified by the ECS Central Pacific Integrated Regional Team as having the potential for an ECS

Evolution of Helping and Harming in Viscous Populations When Group Size Varies

Funding: Balliol College and the Royal Society.Recent years have seen huge interest in understanding how demographic factors mediate the evolution of social behavior in viscous populations. Here we study the impact of variation in group size on the evolution of helping and harming behavior. Although variation in group size influences the degree of relatedness and the degree of competition between groupmates, we find that these effects often exactly cancel, so as to give no net impact of variation in group size on the evolution of helping and harming. Specifically, (1) obligate helping and harming are never mediated by variation in group size, (2) facultative helping and harming are not mediated by variation in group size when this variation is spatial only, (3) facultative helping and harming are mediated by variation in group size only when this variation is temporal or both spatial and temporal, and (4) when there is an effect of variation in group size, facultative helping is favored in big groups and facultative harming is favored in little groups. Moreover, we find that spatial and temporal heterogeneity in individual fecundity may interact with patch-size heterogeneity to change these predictions, promoting the evolution of harming in big patches and of helping in little patches.Publisher PDFPeer reviewe

More on the genetical theory of multilevel selection

This study was supported by a Natural Environment Research Council Independent Research Fellowship (NE/K009524/1).In my article The genetical theory of multilevel selection, I provided a synthesis of the theory of multilevel selection (MLS) and the theory of natural selection in class-structured populations. I framed this synthesis within Fisher’s genetical paradigm, taking a strictly genetical approach to traits and fitness. I showed that this resolves a number of longstanding conceptual problems that have plagued the MLS literature, including the issues of “aggregate” versus “emergent” group traits, “collective-fitness1” versus “collective-fitness2” and “MLS1” versus “MLS2”. In his commentary, Goodnight suggests this theoretical and conceptual synthesis is flawed in several respects. Here, I show this is incorrect, by: reiterating the theoretical and conceptual goals of my synthesis; clarifying that my genetical approach to traits is necessary for a proper analysis of the action of MLS independently of non-Darwinian factors; emphasising that the Price-Hamilton approach to MLS is consistent, useful and conceptually superior; and explaining the role of reproductive value in the study of natural selection in class-structured populations.PostprintPeer reviewe

Hamilton's Rule

The first American Naturalist appeared in March 1867. In a countdown to the 150th anniversary, the editors have solicited short commentaries on articles from the past that deserve a second look.PostprintNon peer reviewe

The strategic revolution

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The purpose of adaptation

A central feature of Darwin’s theory of natural selection is that it explains the purpose of biological adaptation. Here, I: emphasise the scientific importance of understanding what adaptations are for, in terms of facilitating the derivation of empirically-testable predictions; discuss the population genetical basis for Darwin’s theory of the purpose of adaptation, with reference to the “fundamental theorem of natural selection”; and show that a deeper understanding of the purpose of adaptation is achieved in the context of social evolution, with reference to inclusive fitness and superorganisms.Publisher PDFPeer reviewe

The greenbeard effect

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R. A. Fisher on J. A. Cobb’s The problem of the sex-ratio

Funding: This work was supported by a European Research Council Consolidator Grant (no. 771387.The logic of the rarer-sex effect, concerning how natural selection acts to balance the sex ratio among newborns, was long supposed to have originated with Ronald Aylmer Fisher in his 1930 book The genetical theory of natural selection. However, the principle is now understood to have originated with John Austin Cobb in his 1914 paper The problem of the sex-ratio. Fisher did not provide a citation of Cobb’s sex-ratio paper, and it has been unclear whether he was aware of its existence. Here, I show that Fisher was indeed aware of Cobb’s paper in 1930, as revealed by his having cited it elsewhere that same year. Fisher’s willingness to highlight Cobb’s sex-ratio work lends support to the view that his failure to mention it in his book reflects the lax citation standards of the time rather than an attempt to deceive readers as to the provenance of the rarer-sex effect.PostprintPeer reviewe