|
Sydney:
If researchers are to be believed, the cold Antarctic
climate was responsible for the evolution of the deep
sea octopuses.
Australian researcher Dr Jan Strugnell of Queen's University
Belfast and the British Antarctic Survey has said that
formation of ocean currents around the Antarctica, some
millions of years ago provided the right conditions for
ocean creatures to evolve.
While previous research suggested that a range of deep
sea creatures had their origins in Antarctica, none of
this had even been tested before.
For her study, Strugnell decided to study the evolution
of Antarctic and deep sea octopuses. She constructed a
family tree by comparing the octopus DNA and morphological
features, including number of suckers.
Using fossils to calibrate evolutionary dates, Strugnell
found Antarctic octopuses and their relatives evolved
around 48 million years ago, and deep sea octopuses evolved
from Antarctic octopuses some time after 34 million years
ago.
"People have thought for lots of different taxa
that maybe this has happened, but no-one's really investigated
it properly," ABC Online quoted her as saying.
She also got her findings corroborated using evidence
from other different sources.
She said that at various stages in Earth's history, global
climate change depleted oxygen in the deep sea and all
the animals there went extinct. The evolution of octopuses
in the deep sea would have only been possible once those
waters became oxygenated again and Antarctic octopuses
were able to colonise them.
“Evidence for the timing comes from the movement
of the continents. About 34 million years ago, Antarctica
separated completely from South America, with the opening
up of Drakes Passage. This allowed the Antarctic Circumpolar
Current to form, which insulated the continent and allowed
it to get really cold. As cold water is more oxygen rich
than warm water, oxygen from Antarctic waters would have
been able to then diffuse into the deep seas along with
Antarctic octopuses, which then evolved into deep sea
octopuses. The opening of the Drakes Passage fits in with
evolution of the group," she said.
The research on octopus evolution was presented last
week at the Scientific Committee on Antarctic Research
meeting in Hobart. Parts of the research have also been
published in the journals Molecular Phylogenetics and
Evolution and Cladistics.
-
NewKerala.com
-
|
