Science - USA (2022-04-29)

analysis ( 22 ), defined eight factors that ex-
plain a cumulative 24.3% of variance in be-
havior (fig. S4 and tables S3 and S4), and
scored 16,522 dogs. We named each factor
for the facet of behavior captured and es-

tablished standard terms for describing low-

and high-scoring dogs (Fig. 2A). In subse-

quent analyses, we examined the influence

of breed and genetics on each behavioral fac-

tor (Fig. 2B).

Genetic data

Nearly half of the DarwinÕs Ark cohort are

mutts, an understudied population with un-

characterized genomic diversity. We whole-

genome sequenced (mean coverage = 46×;

Morrillet al.,Science 376 , eabk0639 (2022) 29 April 2022 2 of 15

staffordshire bull terrier

siberian husky

australian shepherd

dachshund

boxer

australian cattle dog

toy poodle

border collie

golden retriever

german shepherd dog

beagle

chihuahua

labrador retriever

american pit bull terrier

2% 4% 6% 8% 10%

Breeds guessed in

MuttMix

2% 4% 6% 8% 10%

Breed ancestry

inferred in pet dogs

0-5%

5-45%

45-85%

85-100%

2% 4% 6% 8% 10%

Breeds reported in

purebred dogs

candidate

confirmed

genetic data

confirmed breed

candidate breed

sex, age & size info

surveyed

mutt

6,^1

10

1,079

2,066

1,037

LMER pool N=1,002

3,99

7

2,387

547249

GWAS pool N=1,967

ANOVA pool N=6,797

PPS pool N=18,385

9,009

3,637

14,327

2,155

9,376

18,385

0% 100%

survey completion rate

50%

# dogs

0

12,000

6000

R=0.86; p=3x10−12

416144

ankle calf knee thigh

relative height score

staff−measure

d

R=0.84; p=6x10-93

owner−measured10 106 125 83 13

hip

0

25

50

75

0

25

50

75

100

physical trait

physical trait related

motor pattern

95 other behavior

7

(^88)
Canine Health &
Quality of Life Survey
Canine Cognitive
Dysfunction Rating
putatively heritable,
breed-differing behaviors
Dog Personality
Questionaire
Dog Impulsivity
Assessment Scale
physical trait
18
44
31
6
11 8
new questions:
domestication more direct human influence on behavior
pre-zygotic selection
modern breeds
(< 20% of dogs)
selection on
breed-defining
physical traits
useful behaviors appear? present
extinct,
ancestral wolves
e.g. eye-stalk
motor pattern ~1 billion
dogs
~ 20,000 years ago
G
D E F
B C
A
Fig. 1. The ancestry-inclusive DarwinÕs Ark project collected surveys and genetic
data from a diverse cohort of dogs.(A) Selection on behavior in dogs predates
modern breeds, which have existed for ~1% of dog history ( 10 ). (BandC) Surveys
include (B) 79 published behavior questions ( 34 – 37 ) and 39 new questions about
heritable, easy-to-identify traits that fall into (C) four categories that potentially vary in
heritability, including physical traits (fig. S3). (D) Owner responses to the size question
(fig. S2) were highly correlated with measured size in 375 dogs (Pearson correlation).
Boxes and whiskers represent 25% quartile, 75% quartile, minimum, and maximum,
with horizontal line at median. (E) Owners of most dogs answered >95% of questions.
(F) Upset plot visualizing the dataset. Six horizontal bars show the number of dogs
subsetted by information type or breed category (“subsets”). Each column is a possible
intersection of subsets, with black circles indicating the inclusion of a subset and
vertical bars showing the number of dogs intersecting. Four rows (“pools”) represent
the dogs used in four major analyses. Plus signs denote the inclusion of an intersection,
with total number of dogs (N)ontheright.(G) The frequency of breeds among
purebred dogs in Darwin’s Ark (left), compared with the 14 most common breed
ancestries we detected in all dogs through global ancestry inference (middle). More
popular breeds tended to be guessed more frequently by MuttMix participants (right).
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