Octupus genome gives a clue about ice shelf collapse

The West Antarctic Ice Shelf is the largest and most unstable of the world’s ice sheets, and some climate scientists believe it could be capable of a relatively quick collapse causing a catastrophic rise in sea levels.

These Turquet’s octopuses will certainly be saying “I told you so.”

Although you wouldn’t, on first analysis, see anything that an octopus and the melting of a gigantic ice shelf would have in common, an international team from LaTrobe University would beg to differ.  In a paper recently published in Molecular Ecology the authors drew a correlation between genetic variance in Turquet’s octopus (Pareledone turqueti) and the collapse of the West Antarctic Ice Sheet as recently as 200,000 years ago.  The study looked at genetic material from many Turquet’s octopuses collected over a period of five years.  These animals are unusual in that once they reach adulthood they do not move except to flee from predators.  The researchers expected to find a lot of genetic variance between different populations for this reason, but instead discovered that octopuses from the Ross and Weddell seas (on the opposite sides of Antarctica) had startlingly similar genomes.

Study author Dr. Jan Strugnell says:

“Ocean currents would have both facilitated and hindered the flow of genes. But the Antarctic Circumpolar Current almost certainly wouldn’t have facilitated so much dispersal by octopuses that two populations have almost identical genetics.

So, we think this would only have happened if the West Antarctic Ice Sheet had collapsed.”

Normally the depth of the ocean and ocean currents have a huge effect on movement so this result was most unexpected. These octopuses are not found below a depth of 1000 meters so any populations separated by deeper water would normally never meet. Only a trans-Antarctic seaway would allow mixing between the Ross and Weddell sea octopuses, and this study provides the genetic evidence to support such a claim.

Advertisements

2 comments

  1. Hi Susan.
    Fascinating story. However I’m not clear from the illustrations how a melting ice cap would allow the two populations to be one – isn’t there still a lot of land in between the Ross and Weddell Sea?
    Bill

  2. Great question! The researchers concluded that due to ice cap melting, sea levels may have been high enough to allow a sea way that connected the Ross and Weddell seas.

Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: