Date: April 7, 2014
Source: Senckenberg
Research Institute and Natural History Museum
Scientists at the
Senckenberg Research Institute in Dresden, together with an international team
of researchers, have studied the widely distributed freshwater turtle, Mauremys rivulata. In spite of
geographical barriers, the turtles are genetically very similar throughout
their vast distribution range. This would indicate that that animals cross
hundreds of kilometres of sea. The study is published in the scientific journal
Zoologica Scripta.
Mauremys
rivulata is a turtle, no more than 24 centimetres in size,
which is widely distributed in lakes and streams in the region of the Eastern
Mediterranean, from southeast Europe and Greece to western Turkey and as far as
Lebanon, Israel, Syria and the islands of Crete and Cyprus.
The wide range of the
species led the research team of Prof Dr Uwe Fritz, Managing Director at
Senckenberg Dresden to study this species of turtle genetically.
"Because of the many
geographical barriers in the range of this freshwater turtle -- especially the
Aegean Sea -- we assumed that there would be many genetically different
populations. This was based on the consideration that there was no gene flow
between the isolated distribution patches, as the sea divides the
populations," says Fritz.
The story that emerged,
however, was quite a different one: Using different genetic methods, the
scientists examined 340 turtle samples from a total of 63 localities across the
entire region of distribution. "The astonishing thing is that even turtles
living at great distances from each other display an almost identical genetic
pattern, for instance, in southeast Europe and Asian Turkey" explains
Fritz. This means that the turtles must have found a means to exchange their
genes across large distances -- and indeed over hundreds of kilometres of sea.
But how do the animals
manage to live on both sides of the Aegean without developing into an
individual species over time? "One idea is that the turtles were brought
to the different regions by humans, which meant that the gene pool could mix
constantly," explains Melita Vamberger, lead author of the study, and
adds: "Yet in contrast to other turtles, Mauremys rivulata was never popular as food, because these animals
stink terribly. There is therefore no obvious reason why these turtles should
have been transported in such large numbers."
Thus, only one other --
unexpected -- possibility remained for the researchers: "We assume that
this freshwater turtle is dispersed across the sea. It is likely that turtles
are swept repeatedly from their habitats in coastal swamps into the sea by
storms. They can obviously survive for a long time in the sea, long enough
until they are washed onto some shoreline somewhere. And this occasional
exchange is sufficient!"
In fact, some time ago a Mauremys rivulata was caught on open
water near Cyprus, which would support this theory.
And whatever a turtle can
do might also be a feasible option for others. "It might well be
possible," says Fritz, "that other turtle species take the route
across the sea. For instance, this could also explain the weak genetic
structure found throughout the widely distributed and endangered North American
diamond terrapin (Malaclemys terrapin)."
This could necessitate rethinking conservation measures for this and other
species.
Story Source:
The above post is
reprinted from materials
provided by Senckenberg
Research Institute and Natural History Museum. Note: Materials
may be edited for content and length.
Journal Reference:
Melita Vamberger, Heiko
Stuckas, Dinçer Ayaz, Petros Lymberakis, Pavel Široký, Uwe Fritz. Massive
transoceanic gene flow in a freshwater turtle (Testudines: Geoemydidae:Mauremys
rivulata). Zoologica Scripta, 2014; DOI: 10.1111/zsc.12055
Cite This Page:
Senckenberg Research
Institute and Natural History Museum. "Freshwater turtle crosses the
Aegean Sea." ScienceDaily. ScienceDaily, 7 April 2014. <www.sciencedaily.com/releases/2014/04/140407090611.htm>.