iiinova — where your digital self keeps evolving

Reposted by Mark Bitter

Tom Murphy 🏳️‍🌈🇵🇸 @thommurphy.bsky.social · 02/10/2026

the Perspective is a super interesting read. I haven't waded into the arcana of evolutionary theory since my days as an EEB major in college but this new data is a tremendously interesting intervention in the field and really shows how technology and statistics can overdetermine questions of theory

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Mark Bitter @markcbitter.bsky.social · 01/10/2026

Our hope with this Perspective is to open a conversation. We would love to hear what you think and what remains to be done!

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Mark Bitter @markcbitter.bsky.social · 01/10/2026

We are grateful to the many colleagues who gave us feedback on this piece, to John Kelly for suggesting the term “neo-balance,” and to all members, past and present, of the Petrov and Schmidt labs!

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Mark Bitter @markcbitter.bsky.social · 01/10/2026

And we need theory for a regime where many large-effect loci experience fluctuating selection at the same time, and for how populations can maintain them without an unsustainable genetic load.

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Mark Bitter @markcbitter.bsky.social · 01/10/2026

We also want to know whether these alleles are old or recent, whether they are broadly pleiotropic, whether they respond to specific conditions or to general ecological shifts, and how natural selection coarse-grains the environment to generate recurrent fluctuating selection.

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Mark Bitter @markcbitter.bsky.social · 01/10/2026

We need to understand what stabilizes common large-effect alleles, as fluctuating selection by itself is likely not enough. Many mechanisms are possible and we need data to tell which operate: spatially varying selection, dominance reversal, storage effects, frequency dependence?

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Mark Bitter @markcbitter.bsky.social · 01/10/2026

Where should the field go? We argue that time series data have a lot to teach us. We should use them to find and fine-map causal variants and then understand their functional and fitness effects.

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Mark Bitter @markcbitter.bsky.social · 01/10/2026

Is balancing selection of this kind common only in some species, say those with very large N, or is it pervasive, as the human ancient DNA data suggest?

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Mark Bitter @markcbitter.bsky.social · 01/10/2026

And how important is fluctuating selection on large-effect loci for demographic inference, human disease risk, how species will respond to environmental change, and patterns like Lewontin’s paradox?

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Mark Bitter @markcbitter.bsky.social · 01/10/2026

Many questions remain. For instance, how do we square GWAS findings of mostly modest effects on any one trait with the large allele frequency fluctuations, and thus strong selection, that we see in time series?

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Mark Bitter @markcbitter.bsky.social · 01/10/2026

We propose a “neo-balance” framework. It keeps most of the neo-classical model (purifying selection, positive selection, drift, linked selection) but gives balancing selection a substantial role in maintaining common, large-effect variation.

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Mark Bitter @markcbitter.bsky.social · 01/10/2026

In many of these systems, selection on the same variants changes in strength and often in direction over time. This is what you expect if fitness effects depend on context, which is the core premise of balance theory. And you can only see it by measuring allele frequencies as evolution happens.

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Mark Bitter @markcbitter.bsky.social · 01/10/2026

We also discuss similar findings from midges (doi.org/10.1093/icb/icac098), Arabidopsis in outdoor experiments (doi.org/10.1126/science.adz0777), and the Florida Scrub-Jay (doi.org/10.1101/2025.09.09.673786).

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Mark Bitter @markcbitter.bsky.social · 01/10/2026

Examples in the paper: Daphnia in a pond over 10 years (a; doi.org/10.1073/pnas.2307107121), Drosophila across seasons (b; doi.org/10.1371/journal.pgen.1004775), monkeyflowers over 23 years (c; doi.org/10.1002/evl3.308), and humans via ancient DNA (d; doi.org/10.1038/s41586-026-10358-1).

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Mark Bitter @markcbitter.bsky.social · 01/10/2026

Across very different organisms and timescales, these studies find the same thing: hundreds of common polymorphisms with large selection coefficients (often 10% or more). Under constant directional selection such variants should fix within hundreds of generations, but they have not.

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Mark Bitter @markcbitter.bsky.social · 01/10/2026

Recently a different approach has become feasible: tracking allele frequencies as populations evolve in their natural settings. This lets us measure selection on individual variants directly, without relying on signatures that may have decayed or not yet accumulated.

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Mark Bitter @markcbitter.bsky.social · 01/10/2026

And in species w/ high recombination, like Drosophila, even old balanced polymorphisms leave a signal in a region too small to detect. Brandt et al. (doi.org/10.64898/2026.01.13.698512) showed w/ simulations that over two-thirds of long-term balanced loci are missed even under favorable conditions.

doi.org

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Mark Bitter @markcbitter.bsky.social · 01/10/2026

The main static signature of balancing selection is an allele that stays at intermediate frequency for longer than expected under neutrality. In humans this means at least ~1 million years. Balancing selection that started more recently leaves no such signature at all.

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Mark Bitter @markcbitter.bsky.social · 01/10/2026

There are classic cases of balancing selection (sickle-cell/malaria, G6PD, MHC), but evidence that it is a major force genome-wide and across taxa has been lacking. We think this may be a problem of power, not biology.

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Mark Bitter @markcbitter.bsky.social · 01/10/2026

This debate has mostly been tested by inference from static, contemporary DNA sequences. This work established the central roles of purifying selection and drift and showed that positive selection is common. Scans for balancing selection found much less.

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Mark Bitter @markcbitter.bsky.social · 01/10/2026

If balance theory is right, many common polymorphisms should have large fitness effects, be maintained by selection, and switch between being advantageous and deleterious depending on context. This can happen through selection varying in time or space, frequency dependence, dominance reversals, etc.

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Mark Bitter @markcbitter.bsky.social · 01/10/2026

The main alternative is “balance theory,” championed by Dobzhansky. It rejects the idea of a single best allele. At many loci alleles are beneficial in some contexts and deleterious in others, and selection actively maintains them.

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Mark Bitter @markcbitter.bsky.social · 01/10/2026

The "neo-classical" view, today’s standard model, holds that each functional locus has a single best allele. Selection mostly removes variation: purifying selection purges deleterious mutations, and positive selection occasionally fixes beneficial ones. Most common variants are effectively neutral.

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Mark Bitter @markcbitter.bsky.social · 01/10/2026

The Perspective centers on two competing views that fueled fierce debate throughout the mid-20th century (Muller vs. Dobzhansky, among many others). That debate was never fully settled. In brief:

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Mark Bitter @markcbitter.bsky.social · 01/10/2026

With this paper, it was really fun to step back and think about the bigger picture: what do the strong selection and rapid adaptation we've quantified in D. melanogaster mean for the nature of genetic variation, and for fields like demographic inference, GWAS, and conservation genomics?

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Mark Bitter @markcbitter.bsky.social · 01/10/2026

I’m very grateful to all of them for building the experimental and conceptual system that made my work possible, and of course to Dmitri and Paul for their mentorship and support throughout.

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Mark Bitter @markcbitter.bsky.social · 01/10/2026

New Perspective w/ @petrovadmitri.bsky.social and Paul Schmidt! We ask what evolution-in-action studies tell us about an old question: what genetic variation matters for fitness, and what maintains it? ecoevorxiv.org/repository/v...

ecoevorxiv.org

Common, consequential, and actively maintained: a neo-balance view of genetic variation

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Reposted by Mark Bitter

Pleuni Pennings @pleunipennings.bsky.social · 29/09/2026

I am hiring a postdoc! Are you interested to work on population genetics/ drug resistance/ data? Want to work in Montpellier, France? Fastq files don't scare you? PhD required, start date hopefully Nov 1! (end date Sep 30 2028) Please share! abetterscientist.wordpress.com/2026/09/29/p...

abetterscientist.wordpress.com

Postdoc position on drug resistance evolution in Montpellier, France

I have some exciting news (again!). I got money from the region (Occitanie) to hire a postdoc (and later an engineer / technician) to work on drug resistance evolution in malaria (P. faciparum) and…

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Reposted by Mark Bitter

Bernard Kim @bernardkim.bsky.social · 15/09/2026

Princeton EEB is running a very broad faculty search at the Assistant Professor level. Please consider applying to join us! This is a wonderful, collaborative, cohesive department with diverse interests and amazing colleagues. apply.interfolio.com/193474

apply.interfolio.com

Apply - Interfolio {{$ctrl.$state.data.pageTitle}} - Apply - Interfolio

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Reposted by Mark Bitter

Karen Shih @karenyshih.bsky.social · 28/08/2026

Really excited to share that work from my PhD is now on bioRxiv! We ask: Is the transcriptional response to high tumor mutational burden (TMB) consistent across cancers, or does it vary by cancer type? www.biorxiv.org/content/10.6...

biorxiv.org

Transcriptional Response to Tumor Mutational Burden Is Consistent Across Cancer Types

Tumor mutational burden (TMB) shapes tumor transcriptional state, but studies typically describe this response as an average effect pooled across cancer types. Whether that average reflects a consiste...

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Moi Expósito-Alonso (MOILAB) @mexpositoalonso.bsky.social · 11/08/2026

We are looking for an **assistant professor in ecology** in our integrative biology department, a vibrant dept focused on ecology, evolution, organismal biology, with several linked centers including natural history collections! PLEASE APPLY! aprecruit.berkeley.edu/JPF05489

aprecruit.berkeley.edu

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Julia Kreiner @jmkreiner.bsky.social · 31/07/2026

uchicago.wd5.myworkdayjobs.com/External/job... The Kreiner and Carley Lab groups are hiring a shared Research Analyst to help lead wet lab protocol development and management. We're a fun group and would love to hear from you :) Get in touch with questions!

uchicago.wd5.myworkdayjobs.com

Research, Analyst

Department BSD E&E Carley Lab About the Department The Kreiner Lab (kreinerlab.com) and Carley Lab (carleylab.uchicago.edu) in the Department of Ecology & Evolution at The University of Chicag...

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Dmitri Petrov @petrovadmitri.bsky.social · 15/07/2026

Cannot be more excited about the lineup for the inaugural Function of Evolving Systems GRC conference I am co-organizing with the amazing Joy Bergelson. Less than a month away: August 9 - 14, 2026. Still a few spots left! And do check out the amazing list of speakers: www.grc.org/function-of-...

grc.org

2026 Function of Evolving Systems Conference GRC

The 2026 Gordon Research Conference on Function of Evolving Systems will be held in Waterville Valley, New Hampshire. Apply today to reserve your spot.

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Reposted by Mark Bitter

Katherine Xue @ksxue.bsky.social · 26/05/2026

Do you love amplicon sequencing? Do you want to sequence MORE amplicons, faster and at lower cost? Check out 💘CUPID-seq💘, a highly multiplexed library design that lets you sequence hundreds of amplicon samples (16S, 18S, and more!) on a single sequencing run! (1/n) 🧵 www.biorxiv.org/content/10.6...

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Society for the Study of Evolution @sse-evolution.bsky.social · 24/04/2026

We are pleased to recognize two Honorable Mentions for the SSE Presidents’ Award this year: Skylar Berardi and Miles Roberts for their papers in Evolution Letters! shorturl.at/CpcoY @evolletters.bsky.social

Text: Society for the Study of Evolution, SSE Presidents' Award Honorable Mentions: Skylar Berardi, Drosophila melanogaster pigmentation demonstrates adaptive phenotypic parallelism over multiple spatiotemporal scales, Miles Roberts, k-mer-based diversity scales with population size proxies more than nucleotide diversity in a meta-analysis of 98 plant species.

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Nandita Garud @nanditagarud.bsky.social · 31/03/2026

I am excited to share our latest paper, Uniform bacterial genetic diversity along the gut, now out in Nature Communications! www.nature.com/articles/s41.... (1/n)

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Luisa F. Pallares @luisapallares.bsky.social · 23/02/2026

Have you ever wondered 🤔... Does phenotypic variance respond to environmental perturbation? Does it have a genetic basis? Are mean and variance regulating loci exposed to different selection pressures? These and more questions are explored in our new preprint 🔥 www.biorxiv.org/content/10.6...

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Mark Bitter @markcbitter.bsky.social · 26/03/2026

Really excited to see this work out now in Ecology Letters! May be particularly interesting to those thinking about life-history trade-offs and eco-evolutionary feedbacks, and how those may interact to maintain variation within natural populations. onlinelibrary.wiley.com/doi/10.1111/...

onlinelibrary.wiley.com

Pervasive Fitness Trade‐Offs Revealed by Rapid Adaptation to Shifting Population Densities in Large Experimental Populations of Drosophila melanogaster

Trade-offs are an inherent feature of organismal biology and fundamental to the evolution of natural populations. Using experimental evolution in large, genetically diverse populations of Drosophila ...

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Nandita Garud @nanditagarud.bsky.social · 12/02/2026

I am seeking a postdoc to join my group at UCLA -- ideally the candidate would have some experience in either population genetics or microbes/microbiome (computational background needed). We have a range of projects and are happy to tailer to your interests. Please dm/email me if interested.

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Jeffrey Perkel (he/him) @jperkel.bsky.social · 11/02/2026

Scientists across the career spectrum are burnt out, & people are leaving STEM in startling numbers, particularly those from under-represented groups. A lab handbook can foster a more positive research culture. By @scattercushion.bsky.social @nature.com 🧪 www.nature.com/articles/d41...

nature.com

Lab morale got you down? Try a handbook

Documents that lay out a research group’s ethos and practical guidelines are becoming increasingly popular in the academic community.

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Noah Whiteman @nkwhiteman.bsky.social · 04/02/2026

Very excited to be going to the Annual Drosophila Research Conference @genetics-gsa.bsky.social in Chicago this March. I think #Dros26 is the hashtag. There is still time for you to register! The fly community is so welcoming and supportive—if you are new to flies please consider going.

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Rush Dhillon, PhD | Cartoonist & Illustrator @rushstudio.bsky.social · 30/01/2026

Excellent piece by Matz @heatshok.bsky.social and colleagues discussing the dire status of Caribbean reefs, and potential plans and policies that can be implemented if these reefs are to have any chance. Check it out in PNAS!

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Dmitri Petrov @petrovadmitri.bsky.social · 29/01/2026

Registration is open for the inaugural GRC conference in the Function of Evolving Systems. Aug 9-14, 2026, Waterville Valley. Truly stellar speaker lineup. Student/postdoc fellowships are available! Please come join us! www.grc.org/function-of-... @joybergelson.bsky.social

grc.org

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Joao Ascensao @joaoascensao.bsky.social · 27/01/2026

How does the strength of genetic drift evolve over long times? New preprint out 👇 www.biorxiv.org/content/10.6...

biorxiv.org

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Grant Kinsler @grantkinsler.bsky.social · 18/12/2025

Excited that SpaceBar is now out in Nature Methods!🥳 We combined clone tracing with spatial transcriptomics to untangle what drives gene expression in tumors: a cell's identity or its neighborhood? Most genes were driven by location, but some showed strong clonal patterns. rdcu.be/eVhpc

rdcu.be

SpaceBar enables single-cell-resolution clone tracing with imaging-based spatial transcriptomics

Nature Methods - SpaceBar is a cellular barcoding strategy for simultaneous analysis of cell clonal and spatial identities.

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Ricky Wolff @rwolff.bsky.social · 17/12/2025

Working on this paper fundamentally changed how I thought about bacterial evolution, and I couldn't ask for a better to Hannukah present than to see it out, at last!

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Nandita Garud @nanditagarud.bsky.social · 17/12/2025

If you are interested in this work and are looking for a postdoc position, please get in touch -- we are actively looking for someone to join our group at UCLA!

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