Andy Gardner

@andygardner.bsky.social

1021 Followers 744 Following

Evolution | Theory | Social Evolution | Population Genetics | Behavioural Ecology | Kin Selection | Multilevel Selection | Inclusive Fitness | Sex Ratio | Altruism | Professor of Biology at University of St Andrews, Scotland.

Figure 1 | Choosy dispersal efficiently balances the load of individuals across patches, dramatically reducing kin-competition and thereby promoting the evolution of altruism. (a) The potential for altruism as a function of dispersal rate where each disperser is assigned to a randomly chosen group (‘one option’, grey) versus where each disperser is assigned to the smaller of two randomly chosen groups (‘two options’, black). Analytical results are shown as curves and simulation results are shown as discs. Giving dispersers a choice over their destination promotes the evolution of altruism in viscous populations. (b) The distribution of individuals across patches following a bout of dispersal, where each disperser is assigned to a randomly chosen group (‘one option’, grey) versus where each disperser is assigned to the smaller of two randomly chosen groups (‘two options’, black), obtained by individual-based simulation. Allowing dispersers the choice of two groups dramatically balances the load of individuals across groups. (c) The relatedness of groupmates as a function of dispersal rate and the ability of dispersers to choose their destination; dispersal reduces relatedness according to the analytical expression r = 1/(n-(n-1)(1-d)2), and there is no effect of disperser choosiness on relatedness. (d) The scale of competition—i.e. the proportion of resource competition that occurs locally versus globally—as a function of dispersal rate and the ability for dispersers to choose their destination, as inferred from individual-based simulation data. Individuals are assigned either to randomly chosen groups (one option) or to the smaller of two randomly chosen groups (two options), with intermediate levels of choice being implemented by having a proportion of individuals being given one option and the remainder being given two options. Except for low rates of dispersal and little choice over destination, the scale of competition is rendered negligible.
AI image generated using Google's Gemini.
Photo of Chedhawat Chokechaipaisarn
Photo of Kalyani Twyman.
Programme for Part I of the Symposium "Advances in technology, mathematical and statistical models and their application in evolutionary ecology: the dawn of a new era", including talks by Hanna Kokko, Szymon Drobniak, Aurelien Tellier, Yuxin Ning and Md Ruhul Armin.
Figure 1. Unbeatable sex allocation strategy of unconstrained females (r*) as a function of proportion of constrained females (p) under local mate competition with two foundresses colonising the patch. Shown are the result for Godfray’s (1990) erroneous diploidy solution (dashed grey line), our corrected diploidy solution (solid grey line), and our haplodiploidy solution (solid black line). Overlaid are results from individual-based simulations (discs).
AI-generated image using the paper's title and abstract as input.
A slide from Tim's talk, featuring a schematic showing how haplodiploid inheritance works, with mothers contributing genes to sons and daughters, and fathers contributing genes only to daughters.
A portion of the title page of the paper. The Abstract reads: Haplodiploids—in particular, wasps—are the workhorses of sex-allocation research. This is owing to their unusual system of sex determination, which provides a ready means of sex ratio adjustment. Notably, their sexually asymmetrical mode of genetic inheritance leads mothers and fathers to come into conflict over the sex ratio of their offspring. In the simplest outbreeding scenario, a mother is favoured to employ an even sex ratio while a father prefers that all his mate’s offspring are female. An important modulator of evolutionary conflict between mating partners is genetic relatedness, raising the possibility that this sex ratio conflict is reduced in low-dispersal settings with mating occurring between relatives. However, the impact of population viscosity on sex ratio conflict in haplodiploids remains unknown. Here, we develop and analyse a kin-selection model to investigate how the rate of dispersal modulates sex ratio conflict in a haplodiploid, viscous population setting. We find that population viscosity is associated with a reduction in the extent of sex ratio conflict—the effect being very weak under density-independent dispersal and much stronger under density-dependent dispersal.
Rock art at Cueva de las Manos, Santa Cruz Province. From Wikipedia: "Cueva de las Manos (Spanish for Cave of the Hands or Cave of Hands) is a cave and complex of rock art sites in the province of Santa Cruz, Argentina, 163 km (101 mi) south of the town of Perito Moreno. It is named for the hundreds of paintings of hands stenciled, in multiple collages, on the rock walls."
Image of clown anemonefish.
A figure from the paper, showing the probability of fixation for alleles of different effect sizes in altruism versus nonsocial scenarios.
Notes and Records: the Royal Society journal of the history of science.