O’Brien S, Hesse E, Luján A, Hodgson D, Gardner A & Buckling A (in press) No effect of intraspecific relatedness on public goods cooperation in a complex community. Evolution.
Many organisms – notably microbes – are embedded within complex communities where cooperative behaviours in the form of excreted public goods can benefit other species. Under such circumstances, intraspecific interactions are likely to be less important in driving the evolution of cooperation. We first illustrate this idea with a simple theoretical model, showing that relatedness – the extent to which individuals with the same cooperative alleles interact with each other – has a reduced impact on the evolution of cooperation when public goods are shared between species. We test this empirically using strains of Pseudomonas aeruginosa that vary in their production of metal-chelating siderophores in copper contaminated compost (an interspecific public good). We show that non-siderophore producers grow poorly relative to producers under high relatedness, but this cost can be alleviated by the presence of the isogenic producer (low relatedness) and/or the compost microbial community. Hence, relatedness can become unimportant when public goods provide interspecific benefits.
Best R, Ruxton GD & Gardner A (in press) Intragroup and intragenomic conflict over chemical defence against predators. Ecology and Evolution doi: 10.1002/ece3.3926
Insects are often chemically defended against predators. There is considerable evidence for a group-beneficial element to their defenses, and an associated potential for individuals to curtail their own investment in costly defense while benefitting from the investments of others, termed “automimicry.” Although females in chemically defended taxa often lay their eggs in clusters, leading to siblings living in close proximity, current models of automimicry have neglected kin-selection effects, which may be expected to curb the evolution of such selfishness. Here, we develop a general theory of automimicry that explicitly incorporates kin selection. We investigate how female promiscuity modulates intragroup and intragenomic conflicts overinvestment into chemical defense, finding that individuals are favored to invest less than is optimal for their group, and that maternal-origin genes favor greater investment than do paternal-origin genes. We translate these conflicts into readily testable predictions concerning gene expression patterns and the phenotypic consequences of genomic perturbations, and discuss how our results may inform gene discovery in relation to economically important agricultural products.
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Cameron Turner has joined us as a Visiting PhD Student from ANU, he’ll be working in St Andrews during 2018 on models of social learning and cultural evolution. Welcome Cameron!
As part of an agreement with the Chinese Scholarship Council (CSC), the University of St Andrews is offering 30 fully-funded 4-year PhD studentships to Chinese nationals. Full details of the scheme are available here.
I offer projects on evolutionary theory, so if you are interested in pursuing this opportunity in my research group, please do get in touch. The deadline for applications is 19 Jan 2018.
Gardner A & Úbeda F (2017) The meaning of intragenomic conflict. Nature Ecology & Evolution doi: 10.1038/s41559-017-0354-9.
Recent years have seen an explosion of interest in genes that function for their own good and to the detriment of other genes that reside in the same genome. Such intragenomic conflicts are increasingly recognized to underpin maladaptation and disease. However, progress has been impeded by a lack of clear understanding regarding what intragenomic conflict actually means, and an associated obscurity concerning its fundamental drivers. Here we develop a general theory of intragenomic conflict in which genes are viewed as inclusive-fitness-maximizing agents that come into conflict when their inclusive-fitness interests disagree. This yields a classification of all intragenomic conflicts into three categories according to whether genes disagree about where they have come from, where they are going, or where they currently are. We illustrate each of these three basic categories, survey and classify all known forms of intragenomic conflict, and discuss the implications for organismal maladaptation and human disease.
Jasmeen Kanwal has joined us to undertake a postdoc on social evolution of digital organisms. Welcome to the group, Jasmeen!
Thomas Hitchcock has joined us to pursue a PhD in social evolution theory. Welcome to the group, Thomas!
Gardner A (2017) The purpose of adaptation. Interface Focus 7, 20170005.
A central feature of Darwin’s theory of natural selection is that it explains the purpose of biological adaptation. Here, I: emphasize 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 Fisher’s ‘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.
I’m advertising a two-year postdoc position on social evolution of digital organisms. The project is very flexible and will be tailored to the skills, experience and interests of the successful candidate. If you think you may be interested do get in touch!
Lythgoe KA, Gardner A, Pybus OG & Grove J (in press) Short-sighted virus evolution and a germline hypothesis for chronic viral infections. Trends in Microbiology. doi: 10.1016/j.tim.2017.03.003
With extremely short generation times and high mutability, many viruses can rapidly evolve and adapt to changing environments. This ability is generally beneficial to viruses as it allows them to evade host immune responses, evolve new behaviours, and exploit ecological niches. However, natural selection typically generates adaptation in response to the immediate selection pressures that a virus experiences in its current host. Consequently, we argue that some viruses, particularly those characterised by long durations of infection and ongoing replication, may be susceptible to short-sighted evolution, whereby a virus’ adaptation to its current host will be detrimental to its onward transmission within the host population. Here we outline the concept of short-sighted viral evolution and provide examples of how it may negatively impact viral transmission among hosts. We also propose that viruses that are vulnerable to short-sighted evolution may exhibit strategies that minimise its effects. We speculate on the various mechanisms by which this may be achieved, including viral life history strategies that result in low rates of within-host evolution, or the establishment of a ‘germline’ lineage of viruses that avoids short-sighted evolution. These concepts provide a new perspective on the way in which some viruses have been able to establish and maintain global pandemics.