Andrew Mongue

The Mongue lab at a conference last year.

This is the biggest project in my lab so far and wouldn't have been possible without help from lab members and collaborators @tliesenfelt.bsky.social @erincpow.bsky.social @kkbugtime.bsky.social
And my former postdoc adviser @laurarossevo.bsky.social for introducing me to scales. Thank you!!
7/7

For starters, there's not "one weird trick to ditch your X." There are multiple paths to sex determination turnover.

To read more about it, including what genes were gained or lost and how the genome looks in X chromosome scales, check out our preprint:
www.biorxiv.org/content/10.6...

6/n

Synteny across loss of X sex determination for paternal genome evolution. Colored bars next to species are chromosomes with individual colored lines tracking gene conservation between species. Where applicable, the X is the leftmost chromosome and highlighted with a dashed box.

The other loss, for PGE, is very different. Here, the X is basically intact across the transition and for several PGE groups. The biggest rearrangement only happens in true mealybugs, Pseudococcidae. In other words, the X chromosome seemed to be supplanted not lost. What does it all mean? 5/n

Synteny across loss of X sex determination for simultaneous hermaphroditism. Colored bars next to species are chromosomes with individual colored lines tracking gene conservation between species. Where applicable, the X is the leftmost chromosome and highlighted with a dashed box.

Next, we explored genomic changes across transitions. Starting with the hermaphrodites we found that the X fused to one of the 2 massive autosomes and gene order became more shuffled within and between chrs. Weirdly, the decrease in chromosome number precedes the turnover and may help enable it? 4/n

Maximum likelihood phylogeny of scale insects colored by sex determination system. Tips with a * are newly sequenced draft genomes, those with an illustration are new chromosome level assemblies.

First, we reconstructed a big phylogeny of scale insects based on ~1500 genes. We found X sex determination is ancestral (and some scales still use it!) and there have been
2 independent losses of the X, once in the hermaphrodites and again in the paternal genome eliminating clade. 3/n

We've known for 50+yrs that these alternative reproductive systems exist, but not really how they relate to the more mundane X sex chromosome system of other Hemiptera. So my lab sequenced 17 species of scale insects, getting five of those to chromosome level to explore. 2/n

An unknown scale insect from Costa Rica.

I'm back with another weird scale insect repro study. Previously I've talked about the simultaneous hermaphrodite cottony cushion scales and (functional) haplodiploidy paternal genome elimination in mealybugs. But how did these systems evolve? The Mongue lab has some answers! 1/n #genomics

U.S. government has lost more than 10,000 STEM Ph.D.s since Trump took office A Science analysis reveals how many were fired, retired, or quit across 14 agencies

The US government lost more than 10,000 STEM PhDs last year, according to an analysis by Science of newly released OPM data, with 11 departures for every hire. And many OPM calls "voluntary" separations were probably pushed. www.science.org/content/arti...

ICE agents killed a man and are disappearing the witnesses.

This line graph illustrates the percentage change in agency staff levels from the previous year for nine major U.S. federal scientific and health organizations between the fiscal years 2016 and 2025. The agencies tracked include the CDC, Department of Energy, EPA, FDA, NASA, NIH, NIST, NOAA, and NSF. For the majority of the timeline between 2016 and 2023, the agencies show relatively stable fluctuations, generally staying within a range of +5% to -5% change per year. However, there is a dramatic and uniform plummet starting in the 2024–25 period. Every agency depicted shows a sharp downward trajectory, with staffing losses ranging from approximately -15% to over -25%. The Environmental Protection Agency (EPA) shows the most significant decline, dropping to roughly -26%, while the National Institute of Standards and Technology (NIST) shows the least severe but still substantial drop at approximately -15%.

This is the most astonishing graph of what the Trump regime has done to US science. They have destroyed the federal science workforce across the board. The negative impacts on Americans will be felt for generations, and the US might never be the same again.

www.nature.com/immersive/d4...

Character displacement!

Molecular lab representation: Congratulations to One Battle After Another for all the Golden Globe wins, making it the highest profile movie in which people anxiously wait for the results of a gel electrophoresis run (...even if they skipped the PCR amplification).

This story is absolutely wild. Did you know that avocados change sex over the course of a day? And that it's controlled by a single ancient balanced polymorphism? This is flat our crazy

Love some good Caligidae!There's plenty of genomic data from salmon lice that let us do a sex chromosome evolution analysis without having to sequence a single thing. Salmon lice are in the Z chromosome club with birds and butterflies!

doi.org/10.1093/evol...

Haha well this is our NSF funded project!

And yeah she will mate and lay eggs in the bag, then kind of flop out and die. Neither sex feeds as adults and they live for a couple of days at most at that point!

Thanks @laurarossevo.bsky.social !!

Insights from the lack of an enigmatic trait: monomorphic sperm in evergreen bagworm moths and the evolution of sperm dimorphism Reproductive traits contain some of the most bizarre and unintuitive innovations seen across the tree of life. Chief among these is the sperm dimorphism of butterflies and moths (Lepidoptera). Males m...

Why this is and more is discussed here:
www.biorxiv.org/content/10.6...

Read it to see how this helps explain the bizarre evolution of dimorphic sperm!

And thanks to co-authors @petrnguyen.bsky.social @tliesenfelt.bsky.social @kkbugtime.bsky.social and Thomas Johnson for all their work on this!!

Conservation of sperm proteins across Lepidoptera. Proteins in the blue subsets are found in fertilizing sperm, those in red are from non-fertilizing sperm, and those found in both are at the overlap. Orthologous evergreen bagworm sperm proteins come (almost) entirely from the fertilizing and shared subsets.

To explore this, we've done genomics, proteomics, and a bit of cytogenetics on the evergreen bagworm.

The one sperm type looks basically like fertilizing sperm, but with some differences from other lep sperm proteomes, like a lack of proteases to break apart bundled fertilizing sperm.

Nonfertilizing sperm in Lepidoptera show little evidence for recurrent positive selection Sperm are among the most variable cells in nature. Some of this variation results from nonadaptive errors in spermatogenesis, but many species consistently produce multiple sperm morphs, the adaptive...

What's weird about bagworms is they only make one type of sperm. "That's not weird," you say, but most butterflies and moths make two types: fertilizing and non-fertilizing sperm, see for instance:
onlinelibrary.wiley.com/doi/full/10....

So bagworms are doing something different to the lep norm...

A grub-like female and two male evergreen bagworms.

But we're most interested in the adults. In this pic, the grub-like insect is an ADULT female bagworm(!!). The males look like normal moths...extreme sexual dimorphism!!

We're studying how this evolved, but that's another story. Today I want to highlight their sperm biology.

Two evergreen bagworms feeding

One abbot's bagworm hanging out

Pre-print and weird repro thread time!

I've posted here about scale insects a lot, but ~half of my research is on Lepidoptera. My lab is developing bagworm moths (Psychidae) as models for comparative genomics.

You probably know them like you see in the pics below: caterpillars that make cases.

Congrats, a great milestone!!

Aha, beat me to it with the classic, good choice!

A pedantic penguin very much not helping the cause.

This thread needs the Bible...the Perry Bible Fellowship.

Sex, males, and hermaphrodites in the scale insect Icerya purchasi* Abstract. Androdioecy (the coexistence of males and hermaphrodites) is a rare mating system for which the evolutionary dynamics are poorly understood. Here

I've written about this reproductive system, the mix of males and hermaphrodites without pure females (called androdioecy) before, here:
academic.oup.com/evolut/artic...

A male Icerya purchasi at rest

A hermaphrodite cottony cushion scale upside down on a leaf.

Talk about a life list critter, I've finally found a male cottony cushion scale insect (pic 1)!!

Male scale insects are rare in general but this species is composed almost entirely of simultaneous hermaphrodites (pic 2)! Rare pure males can occur, but we don't fully know under what conditions.

Mongue lab members at ESA.

The now traditional Mongue lab and alums photo from #EntSoc25. Crazy how much the lab has grown in two years!

A Manduca sexta adult specimen, pinned in a drawer at the Harvard Museum of Natural History

A desert landscape. Large Saguaro cacti are in the foreground. Rugged mountains in the background.

A large Datura flower with a moth inside it drinking nectar

I'll be heading to @sacnas.bsky.social #NDiSTEM later this week to shamelessly plug my soon-to-open lab (Fall 2026). If any students are interested in studying the plant-insect interactions of the Sonoran Desert, please get in touch!

New preprint! We unexpectedly discovered that some Caenorhabditis species delete parts of their somatic genome early in development, which fragments their chromosomes and eliminates key germline genes. Multiple lines of evidence suggest this bizarre process was present in the ancestors of C. elegans

I can definitely see that!