Thursday, April 10, 2008

Aquatic frog evolved backwards

This is interesting:

Lungless frog discovered
in Borneo

WASHINGTON (Reuters) - A rare and primitive frog living in a remote Borneo stream has no lungs and apparently absorbs oxygen through its skin, researchers reported on Wednesday.

The aquatic frog has evolved backwards, re-acquiring a primordial trait, David Bickford of the National University of Singapore and colleagues reported.

Studying the frog could help shed light on how lungs evolved in the first place, they wrote in the journal Current Biology, adding that illegal gold mining in the area may threaten the unique species.

"The evolution of lunglessness in tetrapods (amphibians, reptiles, birds, and mammals) is exceedingly rare, previously known only from amphibians -- two families of salamanders and a single species of caecilian (blindworm)," they wrote.

"Here we report the first case of complete lunglessness in a frog, Barbourula kalimantanensis, from the Indonesian portion of Borneo."

The frog may be endangered because of mining activity, the researchers said.



Spirula said...

The aquatic frog has evolved backwards, re-acquiring a primordial trait

As a zoologist, I disagree with this statement. Frogs already use their skin as a respiratory structure, in some cases the majority of the time. In addition, amphibians evolved from lunged fishes. Lunged fishes, in addition to lungs, also possess gills. But lunged fishes and fishes in general (eels excepted) do not use the skin as a respiratory surface (of any significance). So using the skin to breathe is not a "regression" to a primitive state. (Unless they're trying to reach back to Annelids as the reference point for exlusive use of skin as a respiratory structure.)

It is an adaptive loss of structures which hinder it's ability to live in a fast moving current where the bouyancy of lungs proved to be a hinderance.

What makes it interesting is that it is yet another example of unexpected adaptations that can occur under selective pressures.

My two cents.

Spirula said...

On the other hand, one of these, which creationists are always telling us don't exist, has been found.

Oh well, I guess god will now just have to fit into two smaller gaps.

Stardust said...

Spirula, thanks for your expert "two cents". You have such an interesting line of work. Thanks for that link. Snakes with legs. Yes, very interesting.

I know that creationists will come up with "well where's the in-between fossils that show them developing". I am not that educated in evolutionary science to explain that.