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Andy Gardner @andygardner.bsky.social · 27/08/2026

New paper: "Sexual conflict and sexual pleiotropy" (#OpenAccess), with Thomas Hitchcock (@imprintedgene.bsky.social), Tracey Chapman & Jennifer Perry (@jennyperry.bsky.social) doi.org/10.1098/rspb... @royalsocietypublishing.org @standrewsopenres.bsky.social #OA

Illustration of the distinction between sexual conflict and sexual pleiotropy. (A) Sexual conflict: a male and female disagree over a jointly produced phenotype, for example whether a female releases more eggs after mating or withholds resources for future reproduction. Releasing more eggs now costs the female but benefits the male, who will not sire her future offspring. Sexual conflict occurs when selection favours female withholding and male-induced release. (B) Sexual pleiotropy: males and females are favoured to express different values of a trait encoded by genes expressed in both sexes. An allele associated with larger body size may benefit male carriers while harming female carriers or vice versa. Antagonistic sexual pleiotropy occurs when selection favours opposite alleles in each sex.

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Andy Gardner @andygardner.bsky.social · 14/08/2026

New paper: "The evolution of socially modulated dispersal", with Chon I Kam (@chonikam.bsky.social) & Graeme Ruxton (Open Access) doi.org/10.1016/j.jt... @uniofstandrews.bsky.social @standrewsopenres.bsky.social @stagradschool.bsky.social

Forms of dispersal, when social modulation does not improve dispersal success. The 3D cube shows the parameter space for each of the evolutionary outcomes while the 2D slices are cross-sections of the cube at specific s values. For low cost of forcing (low a), high cost of dispersal (high c) and low degree of sibship (low s), only forced dispersal obtains (i.e. x* = 0, y* > 0; portion of parameter space lying behind the orange volume). For high cost of forcing (high a), low cost of dispersal (low c) and high degree of sibship (high s), only voluntary dispersal obtains (i.e. x* > 0, y* = 0; portion of parameter space lying in front of the orange volume). For intermediate cost of forcing (medium a), intermediate cost of dispersal (medium c) and intermediate degree of sibship (medium s), both voluntary and forced dispersal coexist (i.e. x* > 0, y* > 0; portion of parameter space lying within the orange volume).

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Andy Gardner @andygardner.bsky.social · 14/08/2026

New paper: "Inclusive fitness for the conflicted individual" (Open Access) doi.org/10.1093/jeb/... "internal conflict per se does not erode the adaptive integrity of the individual" @jevbio.bsky.social

The theory of inclusive fitness explains the process and purpose of social adaptation. However, the canonical derivation of inclusive fitness assumes a simple causal relationship between genotype and phenotype. In reality, different components of the genotype may have different impact upon the phenotype and different genetic relatedness to social partners, as, for example, in the case of parent-of-origin effects that have been implicated in the evolution of genomic imprinting and a diversity of pathological phenotypes. Whilst such scenarios may be framed in terms of a clash of inclusive-fitness interests of different genes or different genetic factions, it remains unclear whether and how an individual’s inclusive fitness may be defined in the context of such internal conflicts. Here, I investigate how the derivation of inclusive fitness is affected in the context of an individual suffering from internal conflict between her maternal-origin versus paternal-origin genes. I show that, in relation to a single conflicted trait, the individual’s inclusive fitness is given as a weighted average of the interests of the underlying genetic factions, with the power wielded by each faction providing the appropriate weight. This reveals that internal conflict per se does not erode the adaptive integrity of the individual. Rather, it is variation in the underlying balance of power across different traits that leads to a breakdown of the individual’s unity of purpose.

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Andy Gardner @andygardner.bsky.social · 17/12/2025

New paper: "Choosy dispersal promotes the evolution of altruism", with Emilija Barteškaitė (#OpenAccess) doi.org/10.1098/rsbl... The 'Power of Two Random Choices' principle of load balancing may explain the evolution of altruism in viscous populations @royalsocietypublishing.org #OA

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.

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Andy Gardner @andygardner.bsky.social · 18/11/2025

New paper: "A formal theory of group-level adaptation for obligate eusociality", with Kalyani Twyman (@kztwyman.bsky.social) #OpenAccess academic.oup.com/jeb/advance-... #Image #GoogleGemini @jevbio.bsky.social #OA

AI image generated using Google's Gemini.

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Andy Gardner @andygardner.bsky.social · 19/08/2025

Join us for Part 2 of the "Advances" symposium today, from 11am in Room 129+130. #ESEB2025

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Andy Gardner @andygardner.bsky.social · 18/08/2025

And Chedhawat Chokechaipaisarn, whose poster "The consequences of constrained sex allocation under local mate competition" (P02.036) is in Tuesday's session. This is based on his recent paper in Journal of Evolutionary Biology: doi.org/10.1093/jeb/... @jevbio.bsky.social @eseb2025.bsky.social

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Andy Gardner @andygardner.bsky.social · 18/08/2025

Two other members of the research group have successfully made it to @eseb2025.bsky.social ahead of me. Look out for @kztwyman.bsky.social, whose poster "A formal theory of group-level adaptation for obligate eusociality" (P01.068) is in this evening's session.

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Andy Gardner @andygardner.bsky.social · 18/08/2025

Finally on my way to #ESEB2025, a day late, following flight cancellation... Disappointed to miss 1st day of talks, but happy that S03.01 "Advances in technology..." is in @ju-morimoto.bsky.social's safe hands. Starting 10.30am, Meeting Room 129+130, with invited talk by @kokkonut.bsky.social.

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.

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Andy Gardner @andygardner.bsky.social · 09/07/2025

New paper: "The consequences of constrained sex allocation in diploids and haplodiploids under local mate competition", with Chedhawat Chokechaipaisarn: doi.org/10.1093/jeb/... @jevbio.bsky.social

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).

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Andy Gardner @andygardner.bsky.social · 07/05/2025

New paper: “The clonality window: relatedness and the group covariance effect in the evolution of division of labour”, with @kztwyman.bsky.social #OpenAccess doi.org/10.1093/evol... @journal-evo.bsky.social #Image: #ChatGPT #Evolution #OA

AI-generated image using the paper's title and abstract as input.

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Andy Gardner @andygardner.bsky.social · 17/02/2025

New paper: "Kin-discriminating partner choice promotes the evolution of helping" with Tom Scott (@tomwscott.bsky.social) & Geoff Wild (@geoffwild.bsky.social) #OpenAccess doi.org/10.1093/evol... @journal-evo.bsky.social #Image: #ChatGPT #Evolution #OA

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Andy Gardner @andygardner.bsky.social · 15/01/2025

New paper: "Kin competition drives the evolution of earlier metamorphosis", with @bingdongevo.bsky.social. doi.org/10.1002/ece3...

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Andy Gardner @andygardner.bsky.social · 07/11/2024

Chedhawat (Tim) has given an online seminar about this sex-ratio work, here: cassyni.com/events/K7vsZ...

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.

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Andy Gardner @andygardner.bsky.social · 30/10/2024

New paper: "Density-dependent dispersal reduces conflict over the sex ratio" (OpenAccess), w/ Chedhawat Chokechaipaisarn. doi.org/10.1098/rsbl... Sex-ratio optima for haplodiploid parents converge in viscous populations when dispersal is density-dependent.

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.

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Andy Gardner @andygardner.bsky.social · 01/10/2024

One of my undergraduate students, Callum Ferrando, has just published a comic in Journal of Evolutionary Biology. You can find "Taylor's famous result" here: doi.org/10.1093/jeb/... @jevbio.bsky.social @uniofstandrews.bsky.social

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Andy Gardner @andygardner.bsky.social · 27/08/2024

New paper: "Kin selection as a modulator of human handedness: sex-specific, parental & parent-of-origin effects" (#OpenAccess), with Bing Dong & Silvia Paracchini (@silparacchini.bsky.social): doi.org/10.1017/ehs.... #OA #Image commons.wikimedia.org/wiki/File:Cu...

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."

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Andy Gardner @andygardner.bsky.social · 29/11/2023

New paper: "Transmission of social status drives cooperation and offspring philopatry", with Antonio Rodrigues (Open Access) doi.org/10.1098/rspb...

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Andy Gardner @andygardner.bsky.social · 22/11/2023

New paper: "Sexual antagonism in sequential hermaphrodites", w/ Thomas Hitchcock (@imprintedgene.bsky.social) *Open Access* doi.org/10.1098/rspb... Image: commons.wikimedia.org/wiki/File:Am...

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Andy Gardner @andygardner.bsky.social · 06/11/2023

New paper: "A geometric approach to the evolution of altruism" (OpenAccess) sciencedirect.com/science/arti... Altruism alleles are disfavoured upon their first appearance in the population, when they are not yet shared by kin. This slows the evolution of altruism.

A figure from the paper, showing the probability of fixation for alleles of different effect sizes in altruism versus nonsocial scenarios.

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Andy Gardner @andygardner.bsky.social · 25/10/2023

Registration & abstract submission now open for PopGroup 57, 8-10 Jan 2024 in St Andrews: populationgeneticsgroup.org.uk

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Andy Gardner @andygardner.bsky.social · 25/10/2023

This paper is published Open Access, but it's worth pointing out that *all* of the Royal Society's journal content is freely available just now, for "Open Access Week": royalsociety.org/journals/

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Andy Gardner @andygardner.bsky.social · 28/09/2023

For more background, see: doi.org/10.1098/rstb...

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Andy Gardner @andygardner.bsky.social · 28/09/2023

New paper: "R.A. Fisher on J.A. Cobb's The Problem of the Sex-Ratio" (OpenAccess) hdl.handle.net/10023/28453 "Fisher's principle" of the sex ratio was first given by Cobb in 1914. Here I show that Fisher was aware of Cobb's paper.

Notes and Records: the Royal Society journal of the history of science.

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