Dr. Stepfanie Aguillon 😷
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s-m-aguillon.bsky.social
Dr. Stepfanie Aguillon 😷
@s-m-aguillon.bsky.social
2.8K followers 2.9K following 71 posts
Asst Prof at UCLA | genomics, hybridization, & speciation 🧬🐤🐟 | cross-stitching extraordinaire 🪡 | lover of the desert 🌵| dog enthusiast 🐕 | she/her

Opinions are my own.

www.stepfanieaguillon.com
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s-m-aguillon.bsky.social
Intriguingly, compared to other Great Plains hybrid zones, we find just a few recent-generation hybrids! With many more individuals that seem to be backcrossed with the parental species. #ornithology #hybridization #speciation #evolution
September 12, 2025 at 3:49 PM
s-m-aguillon.bsky.social
This was a really fun collaboration with Garth Spellman who collected these samples and originally sequenced them with just a few genes! We found that the hybrid zone transitions quite sharply from black-headed to rose-breasted in South Dakota. #ornithology #hybridization #speciation #evolution
A figure from the manuscript showing structure plot results. Each bar in this figure represents a different individual and the extent of a particular color shows their genomic ancestry. Most individuals with mixed ancestry are found in sites 6-9 Another figure from the paper showing the modeled clines for mitochondrial ancestry, nuclear ancestry, and the plumage phenotype of males. All match up with each other (no apparent displacement of the nuclear cline from the phenotypic!) and transition quite quickly.
September 12, 2025 at 3:49 PM
s-m-aguillon.bsky.social
The first Aguillon Lab paper is officially out in early view at Evolution!! Led by postdoc @devonderaad.bsky.social, we’ve explored the hybrid zone between black-headed and rose-breasted grosbeaks in the Great Plains. #ornithology #hybridization #speciation #evolution doi.org/10.1093/evol...
Figure 1A from the paper shows the distribution of black-headed (western) and rose-breasted grosbeaks (eastern) throughout North America. Small illustrations of males of each species are shown. Black-headed has a rusty orange breast and black head, while rose-breasted has a small reddish bib with a bright white belly. There is an inset map of South Dakota showing the transect across the hybrid zone
September 12, 2025 at 3:49 PM
s-m-aguillon.bsky.social
Excited to be heading to St. Louis for #AOS2025! Be on the lookout for talks from our lab!:
- Jenna McCullough (PD) and Jonah Alderson (grad) are up against each other on Wed. morning
- Claire Geiman (grad) will present a poster Wed evening
- Devon DeRaad (PD) will give a talk on Thur afternoon
Information on Jonah’s talk: Domestication genomics of the society finch (Wed, August 13 at 11:30-11:45 am), Genomics 2, Room Grand C Info on Jenna’s talk: is structural white color rare in birds? Wednesday Aug 13 at 11:30-11:45, in Grand Ballroom A Info on Devon’s talk: How are new species formed on islands? Superficial signals of sympatric ecological speciation actually result from massive and ongoing gene flow; Thursday, August 14 at 2:45-3:00pm, Room Grand F Info on Claire’s poster: Strong selection maintains a narrow, stable avian tension zone in the Great Plains; Wednesday evening from 7-9pm, Poster Number 2
August 11, 2025 at 11:35 PM
s-m-aguillon.bsky.social
The lab has ✨things✨! 😍
Piles of cardboard boxes, multicolored tube boxes, colored tape, sharps containers, multicolored tube racks, etc. are piled up on a gray counter. There are numerous light brown cabinets below the counter and open wall shelves above. Two pallets full of boxes stacked like Tetris!
November 19, 2024 at 7:51 PM
s-m-aguillon.bsky.social
With so many new followers, it's time for a re-introduction! Hello! I'm Stepfanie and I recently started as an Assistant Professor at UCLA. I study speciation (primarily in birds) and mostly post about science, DEI, COVID precautions, and crafts.
A photo of Stepfanie wearing a bright blue sweatshirt with "UCLA" written in bold yellow letters. Smaller white letters underneath say "Bruins." In this picture Stepfanie has medium-length brown hair and a big smile. She's sitting on a bench made from the trunk of an old tree.
November 16, 2024 at 11:37 PM
s-m-aguillon.bsky.social
I'm so excited to be starting up my new lab at UCLA! Thanks to @mwtingley.bsky.social for the official name tag!

Check out coyotebrushstudios.com for a variety of California plant and animal related artwork like this acorn woodpecker

#evolution #ornithology #NewPI
Image of the outside of Stepfanie's office showing the PI Office tag and 110D in big letters. 110D is a decal stuck to a gray glass wall. Perched on top of the large black D is an acorn woodpecker decal with an acorn in its beak. Acorn woodpeckers have striking contrasting black and white color with a bright red crown patch. A close up of the PI Office tag showing: Stepfanie Aguillon, Assistant Professor, Ecology and Evolutionary Biology
September 9, 2024 at 6:28 PM
s-m-aguillon.bsky.social
I'm excited to give an @asn-amnat.bsky.social Early Career Investigator talk at #Evol2024! Come check out the award talk session on Sunday from 4:15-5:45pm (Rm 516C) to learn about what I've been up to during my postdoc and what my lab will be working on now that it's open!
First slide of my talk titled "Understanding the speciation process through phenotypes, genotypes, and behavior." The slide includes my name (Stepfanie Aguillon), my email (aguillon@ucla.edu), and my lab website (www.stepfanieaguillon.com). Additionally my adorable lab logo which includes a flicker and a swordtail growing out of a DNA strand is included.
July 24, 2024 at 10:33 PM
s-m-aguillon.bsky.social
So exciting to see this great study led by Tris Dodge out as a preprint!! Tris explores the genetic and behavioral basis of the false-gravid spot in Xiphophorus birchmanni using an elegant suite of experiments! #evolution 🧬🖥️
Figure 1 from the manuscript, showing the gals gravid spot trait. This pigment develops in some males and is controlled by kitlga. GWAS show a clear peak on chromosome 2 near this gene.
May 15, 2024 at 4:00 AM
s-m-aguillon.bsky.social
We find that an ancient hybridization event has MOVED a mitonuclear incompatibility from one pair of hybridizing species (X. malinche & X. birchmanni) INTO our focal species (X. cortezi & X. birchmanni)!! This incompatibility causes similar phenotypic/genotypic effects in our hybrids 🧬🖥️ #evolution
F2s from our cross either have a normal developmental phenotype (75% of them!) These first two pictures show siblings from the same brood. The first shows developmentally typical individuals while the second shows embryos that are smaller and less developed. Or F2s "stall" in development (25%). These first two pictures show siblings from the same brood. The first shows developmentally typical individuals while the second shows embryos that are smaller and less developed. At the genotypic level We see that 100% of all stalled embryos are homozygous for the X. birchmanni version of ndufs5 (which interacts poorly with the X. cortezi mitochondria which all F2s possess).
April 24, 2024 at 4:25 PM
s-m-aguillon.bsky.social
We explore a ton of different reproductive barriers—from assortative mating to sperm morphology to genetic incompatibilities—between X. cortezi and X. birchmanni. We start by describing a new hybrid population and also produce F1s and F2s between these species in the lab. 🧬🖥️ #evolution
Distribution map showing the ranges of the two species with their overlap shown in gray. Images of the two species are included. X. cortezi has smaller dorsal fin and a "sword" appendage on the caudal fin, while X. birchmanni has a large, sail-like dorsal fin and a deeper body.
April 24, 2024 at 4:13 PM
s-m-aguillon.bsky.social
One surprising finding is that niche models suggest limited invasion potential in Southern California, but this differs from what community scientists are finding! There has actually been a RAPID expansion of these birds across the LA area in the last decade #ornithology
Part of one of the figures from the paper showing niche modeling results for Zosterops simplex. We used niche modeling from the native range to see where these birds might thrive in North America and we found limited overlap with Southern California eBird sightings from 2012 through 2023 showing that these birds have spread from a few sightings in Orange County in 2012 to being spread throughout the LA area and south into Tijuana by 2023
March 4, 2024 at 6:14 PM
s-m-aguillon.bsky.social
Exciting new paper led by Devon DeRaad is out today in Biological Invasions! We used genomic data to identify the source of introduced white-eyes in California and Hawaii, and perform niche modeling to understand the invasion potential in SoCal! #ornithology 🧬🖥️

link.springer.com/article/10.1...
Figure 1 from the manuscript showing: At the top, a map of Australasia with the samples indicated as colored points. There is an inset of Hawaii and southern California showing those two introduced populations. At the bottom, there is a phylogenetic network connecting the six focal Zosterops species with illustrations. Each illustration shows a small yellow/green songbird that looks nearly identical
March 4, 2024 at 6:08 PM
s-m-aguillon.bsky.social
Just opened a new houseplant game… Planted! 🌱🌱
Coffee table with a variety of cards and game mats spread out. There are bright sun tokens, green leaves, water droplets, and green thumbs. Cards have a variety of beautifully drawn houseplants, houseplant tools, and decorative houseplant gear. The game is called Planted.
February 18, 2024 at 4:49 AM
s-m-aguillon.bsky.social
I’m always cross-stitching!! 🪡🧵 Here are some recent finishes and a work in progress…
A cross-stitched purple dragon sitting atop a bookshelf. The dragon has cute round glasses and is reading a book. The piece is framed with light blue matting and a thin black frame A cross-stitched Christmas stocking that says “Dad” at the top. There is a smiling snowman next to a brown reindeer with green jingle bell harness. A variety of colorful birds and squirrels sit atop the reindeers antlers and the snowman. A different cross-stitched snowman smiling and looking upwards. There is a green present being held by red-gloved hands.
February 16, 2024 at 6:33 AM
s-m-aguillon.bsky.social
To deal with the stress of the job market, I started doing the NYTimes crossword again in March… Started getting back into it for real in May when my partner got interested again too. We’ve officially hit a 100 day streak with tomorrow’s Monday! 🧩#AcademicSky
Screenshot of the “Congratulations!” Screen from the NYTimes Crossword app. It says: “Congratulations! You finished a Monday puzzle in 5:39” There is a gold star with “100 day streak” and a blue lightning bolt with “1:20 faster than your average”
December 18, 2023 at 2:03 AM
s-m-aguillon.bsky.social
TBH I’m very impressed with my solving time for this Wednesday’s crossword 😁
Screenshot of the “Congratulations” page from the NYTimes crossword. It says “You finished a Wednesday puzzle in 7:24,” that I’m on an 11 day streak, and I finished 8:11 faster than my Wednesday average.
September 20, 2023 at 2:48 AM
s-m-aguillon.bsky.social
I’ve sadly (finally) made the decision to leave Twitter… but I’m happy so many of the folks I was missing are here!! I’ll make my first post here the same as my last post there:

I’m starting a faculty job at UCLA next summer! I’m super excited for this next stage of my career and life 🥳
Stepfanie sits in front of a tree with a bright blue sweatshirt with bold yellow letters that say UCLA. Underneath in white is written BRUINS. Stepfanie sits in front of a tree with a bright blue sweatshirt with bold yellow letters that say UCLA. Underneath in white is written BRUINS. Stepfanie’s smile is bigger in this picture!
August 20, 2023 at 7:10 PM