Rajiv McCoy

Ancient co-option of LTR retrotransposons as yeast centromeres - Nature Evolutionarily related ‘proto-point’ centromeres providing resolution to the evolutionary origins of point centromeres are identified in yeast, and comparison shows they evolved in an ancestor with re...

Our paper is now out in Nature:

“Ancient co-option of LTR retrotransposons as yeast centromeres”

www.nature.com/articles/s41...

A short thread on how retrotransposons helped give rise to yeast point centromeres.

1/14

Selection-driven color variation in the aposematic strawberry poison frog, Oophaga pumilio Aguilar-Gómez et al. use exome sequencing of 347 strawberry poison frogs to uncover the genetic basis of color variation. They identify that kit, ttc39b, and bco1 underlie blue-red, yellow-red, and gr...

The last chapter of my PhD is finally out !!!! In the same species, on neighboring islands, we see radically different warning colors emerge. Evolution in action:
Selection-driven color variation in the aposematic strawberry poison frog, Oophaga pumilio: Current Biology www.cell.com/current-biol...

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.

2 First-Gen Scientists on Curiosity, Community and Discovery Megan Dennis, associate professor in Biochemistry and Molecular Medicine, and Siobhan Brady, professor in the Department of Plant Biology and the Genome Center, are more than an just office neighbors ...

Please check out these amazing women! They are fantastic scientists, committed mentors, supportive friends and honestly super stars! 🤩@bradylabs.bsky.social @mydennis.bsky.social @ucdavis.bsky.social
www.ucdavis.edu/news/podcast...

Plasmid mutation rates scale with copy number | PNAS Plasmids are extrachromosomal DNA molecules that spread by horizontal transfer and shape bacterial evolution. Plasmids are typically present at mul...

New paper out in PNAS!!! 🎉

Do more plasmid copies mean faster evolution?

🧵 Dive into the story

www.pnas.org/doi/10.1073/...

The last work of my PhD is finally out: www.pnas.org/doi/10.1073/...! This work is about accurately estimating branch length in the Ancestral Recombination Graph (ARG), which is achieved by a really simple framework with minimal assumptions. (1/n)

Common variation in meiosis genes shapes human recombination and aneuploidy - Nature Analysis of data from pre-implantation genetic testing sheds light on the genetic basis of meiotic-origin aneuploidy, the leading cause of human pregnancy loss, identifying common genetic variants ass...

Pregnancy loss is common in humans, and chromosomal abnormalities are the leading cause. Using genetic data from ~140,000 IVF embryos, we show that maternal variation in meiosis genes influences recombination and aneuploidy risk.

First authors: @saracarioscia.bsky.social & @aabiddanda.github.io

My lab is recruiting postdocs in AI/ML for genetics & genomics through the Malone Postdoctoral Fellows program. Apply by Jan 30! Lots of other great labs across the Malone Center as well.

Embryo selection company Herasight goes all in on eugenics ...

I wrote about the bizarre case of Herasight, the embryo selection company going all in on eugenics.

Homo sapiens-specific evolution unveiled by ancient southern African genomes - Nature The genomes of 28 ancient southern African individuals dated to between 10,200 and 150 years before present offer insights into the evolution of Homo sapiens.

Our new ancient DNA paper has just been published!
We present 28 new genomes from southern Africa - several of them high-coverage whole genomes.
Exciting to be moving towards population-level representation of ancient southern African genetic diversity!

www.nature.com/articles/s41...

Observational epidemiological studies can mitigate genetic confounding with the genetic relatedness matrix Observational studies are commonly used in psychology and epidemiology to identify risk factors correlated with health outcomes. However, these studies are vulnerable to confounding when shared geneti...

Excited to share work from my postdoc with @docedge.bsky.social and collaborators Matt Pennell and @jgschraiber.bsky.social, newly out over the weekend: www.biorxiv.org/content/10.1... (1/6)

The discovery and patterns of the underlying long-standing mild-effect mutator alleles in S. cerevisiae populations Most mutations are neutral or deleterious, and mutator alleles that increase the mutation rate of an organism are considered rare and short-lived. Here, we report a genomic signature consistent with t...

New preprint with @pyjiang.bsky.social and @kelleyharris.bsky.social! The discovery and patterns of the underlying long-standing mild-effect mutator alleles in S. cerevisiae populations www.biorxiv.org/content/10.1...

Estimation and mapping of the missing heritability of human phenotypes - Nature WGS data were used from 347,630 individuals with European ancestry in the UK Biobank to obtain high-precision estimates of coding and non-coding rare variant heritability for 34 co...

First time on Bsky and first big announcement!

I am excited to announce that our new study explaining the missing heritability of many phenotypes using WGS data from ~347,000 UK Biobank participants has just been published in @Nature.

Our manuscript is here: www.nature.com/articles/s41....

How is functional variation at large-effect loci maintained in natural populations, even as environments change? In a paper led by @mkarag.bsky.social, we tracked known pesticide resistant alleles in outdoor 𝘋. 𝘮𝘦𝘭𝘢𝘯𝘰𝘨𝘢𝘴𝘵𝘦𝘳 cages & inferred selection and dominance from temporal sequencing data.

Multi-lineage natural gene therapy mediated by embryonic triploid mosaicism in the context of Fanconi anaemia Fanconi anemia is a rare inherited bone marrow failure syndrome caused by inactivation of genes in the Fanconi anemia/BRCA DNA repair pathway. We report a patient with X-linked Fanconi anemia, and aty...

Interesting story in this preprint.

A male infant was diagnosed with Fanconi anemia due to an X-linked frameshift mutation.

Three years later, his hematopoiesis became normal (without intervention). How?

www.medrxiv.org/content/10.1...

Our paper on clonal expansions in Sperm is out in Nature www.nature.com/articles/s41...
If you are interested in working at an intersection of Mendelian genomics/Population genetics/Clonal expansions +Cancer genetics/ and of course mutagenesis, please rich out about postdoc in my lab

Sperm sequencing reveals extensive positive selection in the male germline - Nature A combination of whole-genome NanoSeq with deep whole-exome and targeted NanoSeq is used to accurately characterize mutation rates and genes under positive selection in sperm cells.

Now published! Our paper on:
(1) Accurate sequencing of sperm at scale
(2) Positive selection of spermatogenesis driver mutations across the exome
(3) Offspring disease risks from male reproductive aging
[1/n]
www.nature.com/articles/s41...

How do oocytes prepare for life before life begins? 🧬
Our new review in Annual Review of Cell and Developmental Biology @annualreview explores how oocytes store proteins to support development and fertility. (1/5)
🔗 go.shr.lc/4o9hsk8

🚀 We’re hiring a Postdoc!

Join our group in Poznan, Poland to study meiotic crossover recombination in plants 🌱 Highly motivated & enthusiastic candidates are welcome!
📅 Deadline: Nov 1, 2025

🔗 ibmib.web.amu.edu.pl/wp-content/uploads/2025/09/Postdoc_position-2025-Ziolkowskis-Lab.pdf

We are excited to share GPN-Star, a cost-effective, biologically grounded genomic language modeling framework that achieves state-of-the-art performance across a wide range of variant effect prediction tasks relevant to human genetics.
www.biorxiv.org/content/10.1...
(1/n)

Pan-UK Biobank genome-wide association analyses enhance discovery and resolution of ancestry-enriched effects - Nature Genetics Genome-wide analyses for 7,266 traits leveraging data from several genetic ancestry groups in UK Biobank identify new associations and enhance resources for interpreting risk variants across diverse p...

A project many years in the process, we’re pleased to present our work on multi-ancestry meta-analysis across a boatload of traits in the UK Biobank: www.nature.com/articles/s41...

Are you interested in doing a PhD in Copenhagen? Interested in studying Neanderthals and Denisovans which live on in our genomes?
Than you are more than welcome to apply to join my group starting Jan 2026 :)

candidate.hr-manager.net/ApplicationI...

Please reach out if you have any questions!

Frequency-dependent fitness effects are ubiquitous In simple microbial populations, the fitness effects of most selected mutations are generally taken to be constant, independent of genotype frequency. This assumption underpins predictions about evolutionary dynamics, epistatic interactions, and the maintenance of genetic diversity in populations. Here, we systematically test this assumption using beneficial mutations from early generations of the Escherichia coli Long-Term Evolution Experiment (LTEE). Using flow cytometry-based competition assays, we find that frequency-dependent fitness effects are the norm rather than the exception, occurring in approximately 80\% of strain pairs tested. Most competitions exhibit negative frequency-dependence, where fitness advantages decline as mutant frequency increases. Furthermore, we demonstrate that the strength of frequency-dependence is predictable from invasion fitness measurements, with invasion fitness explaining approximately half of the biological variation in frequency-dependent slopes. Additionally, we observe violations of fitness transitivity in several strain combinations, indicating that competitive relationships cannot always be predicted from fitness relative to a single reference strain alone. Through high-resolution measurements of within-growth cycle dynamics, we show that simple resource competition explains a substantial portion of the frequency-dependence: when faster-growing genotypes dominate populations, they deplete shared resources more rapidly, reducing the time available for fitness differences to accumulate. Our results demonstrate that even in a simple model system designed to minimize ecological complexity, subtle ecological interactions between closely related genotypes create frequency-dependent selection that can fundamentally alter evolutionary dynamics. ### Competing Interest Statement The authors have declared no competing interest.

How common are frequency dependent fitness effects?

New preprint out today 👇
doi.org/10.1101/2025...

The MUC19 gene: An evolutionary history of recurrent introgression and natural selection We study the gene MUC19, for which some modern humans carry a Denisovan-like haplotype. MUC19 is a mucin, a glycoprotein that forms gels with various biological functions. We find diagnostic variants ...

Our paper on the evolution of MUC19 in humans, Neanderthals, and Denisovans is finally out today in Science!

This has been a six-year effort by 13 authors to weave together 3 separate but related evolutionary stories around this one gene (more on thread 🧵).

www.science.org/doi/10.1126/...

I built a Gradio app to illustrate how selective sweeps can be detected from population genetic data: ryangutenkunst-sweep-detection-dpi.hf.space . It can help with your first submissions to the GHIST sweep detection challenges! ghi.st #GHIST

65 Genomes Expand Our Picture Of Human Genetics Researchers closely examined the genomes of 65 individuals to paint a more complex, and more complete, picture of human genetic diversity.

Complete genomes alert! @glennislogsdon.bsky.social, @christinebeck.bsky.social, and I were on @scifri.bsky.social today talking about "Complex genetic variation in nearly complete human genomes"
📄 www.nature.com/articles/s41...
📻 www.sciencefriday.com/segments/65-...

How to get introgressed fragments in genomic data? Everything you always wanted to know you find in our review in @cp-trendsgenetics.bsky.social, led by Xin Huang:
doi.org/10.1016/j.ti...

Lab retreat at the JHU Bloomberg Center in DC

NEW pub: The role of metabolism in shaping #enzyme structures over 400 million years. Now out in @nature.com

Super grateful to have played a small role in this project - congrats to lead/corr authors Oliver, Benjamin, and Markus!

www.nature.com/articles/s41...

#alphafold #evolution #genomics

Congratulations!!