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GENES & CELLS
Genes tell tale of
cat domestication
Traits differing in tame, wild
felines linked to DNA variants
BY TINA HESMAN SAEY
A peek into cats’ genetic makeup may
help reveal how hissing wild felines
became purring tabbies.
Genes involved with embryo development differ between wild and domesticated cats, researchers report November
10 in the Proceedings of the National
Academy of Sciences. The new genetic
data support a recent hypothesis about
why domesticated animals often have a
juvenile appearance.
In July, three scientists proposed
that certain physical features shared by
domestic animals, described as domestication syndrome, might all result from
mild defects in the function of cells
known as neural crest cells (SN: 8/23/14,
p. 7). Neural crest cells migrate to different parts of an embryo and give rise to
several tissues, including the bone and
cartilage that shape faces, muscles, pigment cells and the adrenal glands, which
control the flight-or-fight response.
Some of the genes identified in the
new study are involved with neural
crest cell development, supporting the
idea that changes in the cells can lead
to tameness, the researchers say. Genes
involved in memory, fear and reward
systems in the brain also differed
between domestic and wild cats.
It’s still too early to say how these
genetic changes might affect brain
development and lead to the evolution
of tameness, says Greger Larson, an
evolutionary biologist at the University
of Oxford. Many genes contribute to
domestication. The combination of the
neural crest cell hypothesis and supporting genetic evidence, such as that
provided by this study, give researchers
clues about which genes or biological
systems might be most important for
domestication, he says.
Most scientists consider cats only
semidomesticated, says geneticist
and study coauthor Wesley Warren of
Washington University School of Medi-
cine in St. Louis. Pet cats are indepen-
dent and breed freely with their wild
cousins. So the researchers were sur-
prised that they could
find genetic signatures
of domestication in the
animals at all.
Warren and his colleagues first compiled
the genome of a female
Abyssinian cat named
Cinnamon as a reference to compare with
DNA of multiple cats
and other species. To
look for genetic variants
associated with domestication, the researchers
examined DNA from 22 cats from six
domestic breeds (Felis silvestris catus),
two European wildcats (F. silvestris
silvestris) and two African wildcats
(F. silvestris lybica).
The team looked for regions of the
genome where domestic cats are genetically similar to each other but differ substantially from wildcats. The researchers
concluded that the 13 genes in five
genome regions that they found were
associated with domestication. Five of
those genes are involved in controlling
survival and migration of neural crest
cells in the embryo.
It may be that the researchers are
overinterpreting their data, says Anna
Kukekova, a geneticist at the University
of Illinois at Urbana-Champaign who
studies tame and aggressive silver foxes.
“They cannot say that the changes they
found are associated with tameness,”
she says.
Comparing the cat genome with those
of other species, the
researchers did discover
some genetic variants
that help explain some
feline characteristics,
such as cats’ keen eye-
sight and hearing.
Genes may also reveal
what it takes to be a real
carnivore. Cats are obli-
gate carnivores: Some
nutrients they need
are found only in meat.
They also have trouble
digesting plant-based
foods. “No tofu for felids,” says study
coauthor Leslie Lyons, a comparative
geneticist at the University of Mis-
souri College of Veterinary Medicine
in Columbia.
Researchers have wondered how
cats avoid heart disease when they eat
such protein- and fat-laden diets. A
genetic analysis reveals that several
genes involved in processing lipids
have evolved rapidly in cats compared
with other species. Those fat-process-ing genes help the animals stave off the
artery-clogging effects of a high-fat diet.
Polar bears also eat a lot of meat and
have developed similar adaptations, suggesting that those genetic changes may
be a signal of a carnivorous lifestyle. s
22
The number of distinct
calls in the adult giant
otter’s repertoire
SOURCE: C.A.S. MUMM AND
M. KNÖRNSCHILD/PLOS ONE 2014
JUST THE FAC TS
Otter noise
Comparison of DNA from
Cinnamon, a female Abyssinian
cat that lived at the University
of Missouri, with DNA from
other domestic and wild cats
has revealed how domestication
shaped cats’ genes.
