Jeff Groh

MKado: a toolkit for McDonald-Kreitman tests of natural selection https://www.biorxiv.org/content/10.64898/2026.03.02.709122v1

I'm super excited to share that this article was published today in Science! www.science.org/doi/10.1126/...

All made possible by the fantastic group of donors, volunteers and scientists at The American Chestnut Foundation (tacf.org), HudsonAlpha Institute for Biotechnology, and our collaborators.

Davis Summer Population Genomics Program Want to learn population genetics? Please fill out this form to indicate your potential interest in a 2-week intensive online summer population genetics course taught by Jeffrey Ross-Ibarra and Graham...

Fun news! @gcbias.bsky.social and I are teaching a 2-week online population genetics workshop this summer to raise money for the Center for Population Biology at UC Davis. We're trying to gauge interest -- please fill this out if you might be interested! And please share broadly!

New paper! From Sam Snodgrass and @genomeofforrest.bsky.social, w/ @druncie.bsky.social, @gcbias.bsky.social, and a collaboration with Andres Moreno and @santiagogmm.bsky.social. Can we quantify the impact of humans on maize dispersal?

Plant yourself in a comfy chair and lend me your ear:

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Our paper on the mysterious Devonian organism Prototaxites has now finally been published! See the paper here (www.science.org/doi/10.1126/...) and our explainer thread below!
Prototaxites reconstruction by Matt Humpage

New preprint is up!

Not going spoil the results for you 🤓 but we looked at some “bird” vs “bee”-pollinated Penstemon hybrid zones and came away with some pretty unexpected results!

… Bernie Sanders statement: “Donald Trump has, once again, shown his contempt for the Constitution and the rule of law….”

thanks, the post refers to sexual function at the level of the entire plant, within a single day, so it's not incorrect. how this results from the action of individual flowers over consecutive days is described in more detail in the paper

The alleles are ancient (~44 million yrs old!) maintained by disassortative mating. They regulate same behavior in other spp & are found in 10s-100s more wild relatives of avo, tropical trees for which it would be burdensome to even observe this behavior, but we can predict it's there from their DNA

Whether a plant is A/B depends on the alleles it inherits from its parents at 1 transcription factor, a gene that regulates many other genes in flowers. Expression of the alleles is rhythmic with the day/night cycle and the dominant allele has a phase delay corresponding to flowering time difference

In this time-lapse video of the 'Hass' variety, you can see two sets of flowers opening and closing at different times of day. The 1st set is functionally female, the 2nd set is functionally male. B-type varieties show the complementary pattern

Balanced polymorphism in a floral transcription factor underlies an ancient rhythm of daily sex alternation in avocado In avocado and certain wild relatives in Lauraceae, pollination occurs via a synchronized rhythm of floral sex timing between two hermaphroditic flowering types. A-type plants present female-phase flo...

Did you know there are 2 types of avocado varieties? A-types switch from female to male, B-types male to female, within a single day. This reciprocal sex alternation promotes cross-pollination and has a simple genetic basis. Read more in this recent preprint from the final chapter of my PhD thesis 🥑

In this time-lapse video of the 'Hass' variety (A-type), you can see two sets of flowers open and close at different times of day. The first set is functionally female, the second set is functionally male. B-types show the reversed pattern

pictured above are Eric Focht and Mary Lu Arpaia, two of the co-authors on the new study

Congrats @jeffgroh.bsky.social et al. Some avocado trees open female-phase flowers in the morning & then male in afternoon. Others show complementary pattern (m->f), to synchronize pollination of two types. Jeff show this to be a >45Mya polymorphism at a transcription factor across 100s of species.

surely karma for misspelling my name in my exit seminar announcement

I’ll never look at avocados in quite the same way: The latest from UC Berkeley Miller Fellow Jeff Groh who sits in my lab and Ben Blackman’s lab. He works on balancing selection and molecular mechanisms underlying the coevolutionary phenomenon of mating type alternation (PhD with Graham Koop).

Rapid evolution of synteny associated with multiple origins of dioecy and XY sex determination Chromosomal rearrangements are a major driver of evolutionary innovation, shaping processes including local adaptation, speciation, and sex chromosome evolution. Multispecies synteny datasets are rich...

Very excited to share the capstone of my postdoc work with @stepheniwright.bsky.social, co-led by Wright lab grad student Cassandre with contributions from many others.

We combined new methods with high-quality Rumex assemblies to dive into the remarkable history of rearrangement in this genus.

🧬 Just out in Bioinformatics Advances: “tskit arg visualizer: Interactive plotting of ancestral recombination graphs.” 

Read the full paper here: https://doi.org/10.1093/bioadv/vbaf302

Authors include: @kitchensjn.bsky.social, @yanwong.bsky.social

Research Associate-Fixed Term - East Lansing, Michigan, United States Position Summary The Lowry Lab at Michigan State University is searching for a postdoctoral research associate to conduct molecular and physiological experiments to understand the causes of genetic va...

I am currently searching for a new postdoctoral researcher to study the evolution, genetics, and physiology of cold acclimation and freezing tolerance in switchgrass at Michigan State University. This work will be funded by a newly funded five-year DOE grant. careers.msu.edu/jobs/researc...

With @aconga.bsky.social we wrote a short Dispatch to highlight two awesome companion papers in @currentbiology.bsky.social by @jeffgroh.bsky.social, @gcbias.bsky.social and by Liu et al. on how the control of heterodichogamy is going nuts in the Juglandaceae :

www.cell.com/current-biol...

Hermaphroditic plants also use TIME ⏰🌿 to avoid selfing.

Two new @currentbiology.bsky.social papers explore the rapid turnover of this trait in the wingnut family.

Both @vincentcastric.bsky.social and I summarized these findings 👉 authors.elsevier.com/a/1m2MA3QW8S...

#Evolution #PlantBiology

Distinct haplotypes and reversed dominance at a single-gene balanced polymorphism controlling heterodichogamy in two genera of wingnuts In the angiosperm mating system of heterodichogamy, two hermaphroditic morphs temporally alternate between male and female flowering phases, promoting…

Congratulations to @jeffgroh.bsky.social on the publication of his paper on an ancient balanced polymorphisms controlling heterodichogamy in two genera of wingnuts. The paper shows the putative turnover & reversal of dominance of a mating type polymorphism
www.sciencedirect.com/science/arti...

Distinct haplotypes and reversed dominance at a single-gene balanced polymorphism controlling heterodichogamy in two genera of wingnuts In most species within the walnut family, two genetically determined morphs alternate between male and female flowering phases in time. Groh et al. identify a distinct locus for this dimorphism in two...

Sharing our new paper, "Distinct haplotypes and reversed dominance at a single-gene balanced polymorphism controlling heterodichogamy in two genera of wingnuts". Genomics & evolution of a mating type system involving two morphs with alternating sexes in walnut relatives www.cell.com/current-biol...

We're excited to be recruiting an NIH funded postdoc to work in the Coop lab at UC Davis. We're specifically interested in candidates who are want to work at the intersection of human genetics, GWAS, and population genetics modeling. Please RT

A species interaction kick-starts ecological speciation in allopatry | PNAS Adaptation to different environments is thought to play a key role in speciation. However, speciation typically begins in allopatry, where reproduc...

Work led by Marius Roesti, "A species interaction kick-starts ecological speciation in allopatry" now published - Varying degrees of divergence associated with presence/absence of a single interacting species predicts strength of prezygotic RI in freshwater stickleback www.pnas.org/doi/10.1073/...

New Article: "Ginger genome reveals the SMPED1 gene causing sex-phase synchrony and outcrossing in a flowering plant" rdcu.be/eJPdX

SMPED1, located in a dichogamy-determining region in Alpinia species, controls the timing of sex-organ synchrony.

Quantitative system drift https://www.biorxiv.org/content/10.1101/2025.09.17.676933v1

Please share broadly: I am looking for a postdoctoral fellow to work on a collaborative project on the temporal population genomics of invasive Capeweed (using contemporary and herbarium genomics), with ‪‪@shaky-dingo.bsky.social‬ and colleagues

tskit_arg_visualizer: interactive plotting of ancestral recombination graphs Summary: Ancestral recombination graphs (ARGs) are a complete representation of the genetic relationships between recombining lineages and are of central importance in population genetics. Recent brea...

Excited to share our new preprint for the tskit_arg_visualizer Python package! ARGs can sometimes feel like a black box, so
@yanwong.bsky.social and I have been developing a method to programmatically drawing these graphs.

🔗 arxiv.org/abs/2508.03958

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