Posted by Carrie Arnold
in Weird & Wild
on November 27, 2013
Wild cats are charismatic creatures, so you’d think we’d know
them all pretty well by now. Just how little we understand—at least in
some cases—is reflected in the identification of a new species of cat
known as a tigrina in northeastern Brazil.
Scientists have discovered that two populations of tigrina previously
thought to be one species do not, in fact, interbreed and thus are
distinct, according to results published today in Current Biology.
“So much is still unknown about the natural world, even in groups
that are supposed to be well-characterized, such as cats,” says the
study’s lead author, Eduardo Eizirik of Pontifícia Universidade Católica do Rio Grande do Sul in Brazil.
“In fact, there are many basic aspects that we still don’t know about
wild cats, from their precise geographic distribution and their diets.”
Eizirik’s results have implications for conservation
efforts—particularly laws about poaching and the designation of national
parkland. Such measures are often focused on individual species.
Recognizing the northeastern tigrina as distinct means that
biologists will have to assess its conservation status and determine
what steps need to be taken so that both species of tigrina can be
adequately protected. (See “Rare Cat Captured in Camera Trap.”)
Eizirik and colleagues weren’t looking to discover a new species.
Instead, they were looking to understand the evolutionary history of
what were thought to be three species of cat from the genus Leopardus:
The Pampas cat (Leopardus colocolo) looks
like a large, heavy-set, long-haired house cat. It lives in the
grasslands and scrublands of South America, from southern Argentina and
Chile up through Peru and Ecuador along the western third of the
Geoffroy’s cat (Leopardus geoffroyi) is
roughly the same size as the Pampas cat, with a brownish-yellow or gray
coat, black spots on its trunk, and dark bands across its tail and
limbs. Like the Pampas cat, Geoffroy’s cat likes scrublands and lives
The tigrina (Leopardus tigrinus),
also known as the oncilla or little spotted cat, lives throughout much
of Central and South America. With a yellow-brown coat and black
rosettes, the tigrina looks like a house cat-sized leopard. Scientists
had previously identified four sub-populations of tigrina, including the
southern tigrina, which lives primarily in Brazil’s mountainous
forests, and the northeastern tigrina, which lives in savannahs and
grasslands. The coat of the northeastern tigrina is slightly lighter,
and the rosettes are sightly smaller, than those of its southern
relative. (Learn about National Geographic’s big cats initiative.)
Eizirik and colleagues obtained DNA samples from a total of 216 different Leopardus cats
across their ranges. Analysis of the DNA sequences found in the
mitochondria, the cell’s power plant, revealed ancient interbreeding
between the Pampas cat and the northeastern tigrina.
Since an individual only inherits mitochondrial DNA from its mother,
researchers could peer into the ancient history of these two felines,
and found that they mated together frequently before the two cats split
into separate species.
Although the Geoffroy’s cat and the southern tigrina divided into
separate species over a million years ago, they began to mate together
in the more recent past in the areas of southern Brazil and Bolivia
where their habitats overlap. While the two cats interbreed regularly at
this contact zone, the mating doesn’t extend to farther areas and the
two species remain distinct.
When Eizirik and colleagues analyzed the genetics of the two
different tigrina populations, however, they were surprised to learn
that genes did not appear to be moving between the northeastern and
southern tigrinas. (See “Pictures: 7 Cat Species Found in 1 Forest—A Record.”)
“This observation implies that these tigrina
populations are not interbreeding, which led us to recognize them as
distinct species,” Eizirik says. The researchers have suggested that the
northeastern tigrina retain its current name of L. tigrinus, while dubbing the southern tigrina L. guttulus.
“Very little was—and still is—known about this species,” says
Eizirik. “There have been some initial studies on its diet, but still
most of its basic biology remains poorly known, including density,
habitat use, and population trends.”