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Two
new river turtle species described
Two
new river turtle species described
Date:
April 24,
2014
Source:
University of Vermont
Summary:
The alligator snapping turtle is the largest river
turtle in North America, weighing in at up to 200 pounds and living almost a
century. Now researchers have discovered that it is not one species -- but
three. By examining museum specimens and wild turtles, the scientists uncovered
deep evolutionary divisions in this ancient reptile.
..............................
The alligator snapping turtle is the largest river turtle in
North America, weighing in at up to 200 pounds and living almost a century. Now
researchers from Florida and the University of Vermont have discovered that it
is not one species -- but three.
Examining
museum specimens and wild turtles, the scientists uncovered deep evolutionary
divisions in this ancient reptile.
Once heavily
hunted for turtle meat -- alligator snapper was the main ingredient of
Campbell's Turtle Soup in the 1960s -- the riverine populations have been
deeply depleted and are of conservation concern. The new discovery indicates
that these animals are more imperiled than previously understood.
The two new
species both live in the southeastern United States. The Suwannee alligator
snapping turtle is found in Florida and Georgia -- and lives only in the famed
Suwannee River; it has been a distinct species for at least five million years,
the scientists discovered. The Apalachicola alligator snapping turtle lives in
Florida, Georgia, and Alabama -- in and around the Apalachicola River -- and
developed as an independent species at least three million years ago.
The genetics
work to identify the new lineages of turtles was completed by Joe Roman, a
conservation biologist at the University of Vermont, and colleagues. The
research was led by Travis Thomas, a Florida Fish and Wildlife Commission
scientist, and is reported in the April 9 edition of the journal Zootaxa.
Suwannee
secret
"We
found a surprising result: these really deep divisions between each
river," Roman says. "Unlike common snappers, these turtles do not
move from river to river; they're isolated and have been for millions of years,
through many glacial ages."
Roman and
his colleagues caught turtles in rivers throughout the Gulf Coast region and
collected blood samples from their tails. ("Watch out!" Roman says,
"some people claim they can snap a broom handle," with their powerful
jaws -- and one of his friends said getting his finger caught by a young turtle
was like "getting it caught in a car door.") From these samples they
collected DNA to determine that both male and female snappers in the rivers
were genetically isolated from other populations.
"The
Suwannee River turtle is way different from the others; it's been isolated --
as an independent species -- into the deep past," Roman says.
The
molecular revolution that began in the 1980s has used DNA to redraw many
boundaries between species. But to be fully confident in the genetic evidence
they had gathered, the scientists also examined the turtles for differences in
body shape and size. Close studies of the skulls and shells of museum specimens
confirmed that "each of the three genetically distinct Macrochelys
lineages can be diagnosed morphologically," the team writes in their new
paper. In other words, experts can look at the turtles, particularly the back
edge of the shell, and tell the species apart.
Out of
turtle soup
Until early
in the 20th century, alligator snapping turtles were plentiful from headwaters
in the Midwest into swamps of the Deep South, but "river turtles were hit
hard in the 1960s and 1970s," Roman says. Hunters, often smalltime
operators, "could clean out a stretch of the river in a few weeks time by
just setting traps and waiting," he says. Florida was the first state to
shut down commercial trapping and eventually all other states followed -- the
last one being Louisiana.
"Turtle
soup was traditionally served to politicians at political dinners," Roman
says, "so a senator in Louisiana fought against protecting them."
Today, Roman sees bipartisan support for protecting the turtles against current
threats like water pollution, illegal harvest and collection for the pet trade,
and river drawdowns upstream. "These are the symbols of their
rivers," he says, "and part of the cultural history of bayous and backwaters."
But they're also deeply connected to the ecological and economic health of
these regions, he notes. "As top predators, they're a key part of the
ecosystem," Roman says. "By protecting the rivers and their unique
species, you're protecting fisheries, oyster beds and the recreation economy
that people living there depend on."
About a
decade ago, Roman's work led to analysis of turtle meat sold in Louisiana,
which uncovered widespread fraud. "Approximately one in three samples of
turtle meat sold in the state were actually alligator," he says. In 2012,
the Center for Biological Diversity and others filed a petition with the
federal government to protect the alligator snapping turtle and fifty-two other
reptiles and amphibians, under the Endangered Species Act. Reacting to the new
species discovery, on April 16 the advocacy group sent an additional appeal to
the U.S. Fish and Wildlife Service.
"Now we
know alligator snappers in the Suwannee River are a unique species found
nowhere else in the world," Collette Adkins Giese, a biologist with the
Center for Biological Diversity, said in a statement. "And the much-needed
Endangered Species Act listing for these turtles would help ensure that the
Suwannee River is protected for the turtles -- and for humans."
Alligator
snapping turtles are secretive and so slow-moving that algae grow on their
backs. A sit-and-wait predator, they have a wormlike lure on their tongue that
draws in fish, "and then snap!" says Roman. "They hardly ever
come onto land, and they don't swim in seawater either," he says, which
helps explain how a distinct species arose, in the case of the Suwannee
alligator snapping turtle, in just one river.
Story
Source:
The above
story is based on materials provided by University of Vermont. The original article was
written by Joshua E. Brown. Note: Materials may be edited for content and
length.
Journal
Reference:
- TRAVIS M. THOMAS, MICHAEL C. GRANATOSKY, JASON R. BOURQUE, KENNETH L. KRYSKO, PAUL E. MOLER, TONY GAMBLE, ERIC SUAREZ, ERIN LEONE, JOE ROMAN.
Taxonomic assessment of Alligator Snapping Turtles
(Chelydridae: Macrochelys), with the description of two new species from
the southeastern United States
. Zootaxa, 2014; 3786 (2): 141 DOI: 10.11646/zootaxa.3786.2.4
Cite This
Page:
University of Vermont. "Two new
river turtle species described." ScienceDaily. ScienceDaily, 24 April
2014. <www.sciencedaily.com/releases/2014/04/140424102057.htm>.