Thread by @morrilleen

A pinch of pinscher, a dash of 'shund... a pint of pittie for good measure, and what kind of #dog do you get?
Ulti-mutt-ly: a distinct individual.

Happy to share our article on dog genomes, behavior, and MUTTS in @ScienceMagazine! @UMassChan @broadinstitute #ScienceResearch 1/n

https://twitter.com/ScienceMagazine/status/1519739580093714434

Even the most mixy of #mutts cannot escape the question: what's in the sauce? For the first time, we unravel the genomes of mutts (1500+ dogs of mixed or mystery heritage) and what they can show us about the inheritance of behavior. 2/n

Research was made possible thanks to the thousands of dogs enrolled in our Darwin’s Ark project (darwinsark.org). @darwinsarkfnd

See: dog tax attached #communityscience #citizenscience #CitizenScienceMonth 3/n

Dog breeds are iconic. From the Chihuahua to the Bernese mountain dog, these groups of dogs appear SO incredibly different.

This is no accident: we define breeds today by conformation and parentage. This gives rise to dogs of consistent looks and similarity in their DNA. 4/n

The friendly retriever. The feisty terrier. When we think of breeds, we rarely just think of form & aesthetics... breeds have "personality".

Do breeds have distinct, consistent, and inherited behaviors? See

https://twitter.com/eenork/status/1520450288095797251?s=20&t=buUEOD1E3UR3RYPW93RGNg

...and do we see these in mutts? 5/n

When dogs make puppies, they shuffle up chunks of their chromosomes (recombination). Pups inherit a mosaic of DNA from granddogs. Within breeds, a lot of DNA is shared between dogs -- shuffling doesn't end up with a super different result. In mutts, DNA gets interesting...🧬 6/n

What does a mutt's DNA mosaic look like? We recruited 27 complete mystery mutts (including the marvelous @CaraGenome) and sequenced their entire genomes (the full collection of their DNA) to find out.

We call these research stars our "Mendel's Mutts" cohort! 7/n

We confirm that, yes, mutt genomes are VERY diverse. So much so, that we needed to adopt a new technology for genetically testing more dogs. Even thousands of genetic markers wasn't gonna be deep enough. 8/n science.org/doi/10.1126/sc…

For 1,715 of our 18,000 dogs, including 1,496 mutts: We got spit, sequenced #DNA at low coverage, and imputed MILLIONS of genetic markers. Far denser than genotyping arrays, this "lowpass + imputation" method from @Gencove platform gave us the resolution we needed. 9/n

We collected a panel of 101 common breeds, each represented by 12 dogs with genetics, giving us the genetic fingerprints we needed to call breeds.

We saw all sorts of breeds across ancestries! Those with Chow had it low. A decent 'oodle of Poodle. 10/n

Common breeds were common in mutts, but mutts were by no means simple! Most carried ancestry matching to 4 or more breeds. X 11/n science.org/doi/10.1126/sc…

BUT wait just a minute! If we were SO worried about how stereotypes influence behavior reported in purebred dogs, then shouldn't we be _also_ concerned that owners can _see_ the breeds in their mixed-breed dogs? 12/n

Low-key, yeah, we worried about that. So, we launched another survey, called MuttMix, in collaboration with @IAABC, where we asked even more people (30K!) to guess the mix of 30 mutts. muttmix.org 13/n

Ruby, here, had a few common breeds detected (incl. 40% American pitbull and 10% golden retriever). 1% of people could guess two breeds she carries. NO one could guess three. And 6000 people said she's a Rhodesian ridgeback. Ruffles have ridges, but not Ruby. @deannachurch 14/n

This is Maxine. What is she? 15/n
A. Irish wolfhound
B. Kelpie (the dog breed)
C. Kelpie (the Scottish cryptid)
D. Some sort of doodle

Maxine is a DOODLE. She carries 18% ancestry from poodles, 43% from labs, and 10% from golden retrievers. The remaining third of her ancestry didn't match well to any breed. OK, phew: mixy-mutts mask their mix. 16/n

We then modeled the mixed effects of breed ancestry and other factors. We saw that ancestry tracks with aesthetics, and also affects behaviors. Increased beagle ancestry *can* make fora mutt w/ floppier ears or a smaller stature... more howling, or an independent attitude. 17/n

Still, we see wide variation in behavior among dogs carrying the same amount of any given breed. Which is, frankly, EXACTLY what we want: the mutts have been randomized! We can map their individual traits to DNA... 18/n

We found some ridiculously strong links to DNA! This is the incredible strong #GWAS signal for brindle coat pattern (spanning super weird gene cluster on chromosome 16). We replicate many previous studies on physical traits (height, coat, colors). 19/n

Another link we found? A spot on the DNA associated with HOWLING! A gene nearby, SCN3A, is important to oral motor and speech development in the brain. Big TBD on what this means for canine vocalization... 20/n

Dogs are a remarkable animal, and the natural behaviors of #dogs give us new perspectives on how #DNA works. There's so much we can find out by looking to ALL dogs... outbred dogs included. Let the #mutts shine! 21/n

SO many to my mentor @eenork and wonderful coauthors of @karlssonlab incl. @dogzombieblog @shirley_xueli41 @LindaBGoodman @Marjieal and collaborators @SMack_Lab @colabobio @umassmed_zlab for your roles in this very multi-faceted work 🐕🧬