Wednesday, October 15, 2008

Tawk Amongst Yah-selves

Anyone seen an old SNL skit called Cawfee Tawk, where Mike Myers, dressed as a women, hosted a talk show? Every once in a while s/he became vaclempt, and would throw out a topic to discuss. Tawk amongst yah-selves s/he would say, before collecting him/herself.

I keep a few topics for discussion in mind, for different situations (not directly from SNL, those were much funnier than my bio-geek stuff). Still, they are quite useful for breaking out of one of those awkward silences that can occur when a group of semi-strangers is talking together. I'll throw one out at a conference or at a bar, and think "Tawk amongst yah-selves". I usually like to sit back and listen, whether vaclempt or not.

If I am with a group of physiologists or evolutionists, I throw out this one:

Why has bioluminescence evolved SO many times in the marine environment, but almost never in freshwater environments?

Or, if you're more interested in one for a bar that includes someone other than a biologist -

Why are all the best rock bands British, but all the best individuals of rock n roll American?


Nick (Matzke) said...

Um...there's a lot more dark in the marine ecosystems. And diversity in general. Many freshwater systems are (a) shallow, i.e. no non-photic zone, (b) turgid, (c) recent (i.e. post-glacial), and they are all way, way smaller than the marine ecosystems available (i.e. <1% I think).

You're on your own with the bands though... ;-)


Bjørn Østman said...

It seems to me that there is a trend, but that it is only that the Brits do bands much more than individual performers. I don't see there being anything like it in the US.

Lynyrd Skynyrd.
The Doors.
Beach Boys.
Red Hot Chili Peppers.
Creedence Clearwater Revival.

David Bowie.
Eric Clapton.

(This list is not intended as an endorsement of any kind.)

Todd Oakley said...

Nick - I agree with your list as reasons for a lower proportion of f.w. bioluminescence, compared to marine. However, there is essentially NO f.w. bioluminescence. This seems pretty extreme.

It raises questions like - have bioluminescent organisms ever invaded freshwater? ie is bioluminescence lost in f.w. or is it that bioluminescent organisms don't make that move. If they don't make that move, is there some physiological constraint?

I think there is some bioluminescence in Lake Baikal, the oldest f.w. body, so this would be consistent with your age hypothesis. At the same time, bioluminescence is so labile phylogenetically, that there must be cases of very recent origin - so why not in f.w.?

Eric Heupel said...

Aren't there a few freshwater mollusks with bioluminescence? I think one group was native to Australia?
Still the exception to the rule only adds more intrigue... why this one group and no where else...

Todd Oakley said...

Eric - it's a freshwater limpet. Latia is the genus. They live in New Zealand streams. I've been unable to confirm my dim memory of bioluminescence in Lake Baikal, so my last comment might be off...

Todd Oakley said...

Lynard Skynard = American; Beatles=British.

Eric Heupel said...

Aerosmith = British, can't leave out Blue Oyster Cult

Do you have an approx time for the most recent bioluminescent origin?

Todd Oakley said...

Actually, Aerosmith are from near Boston. They're one of the exceptions, for sure.

Youngest bioluminescent origin? I'd have to think about that for a while. That would be a good review/synthesis paper.

ajna said...

There is freshwater biolum in some amphipod or another. What about the idea of co-option of antioxidant proteins for use in bioluminescence? Freshwater may have been invaded after oxygen levels rose, so these reactions didn't get a chance to reevolve. But that doesn't explain the number of bioluminescent organisms on land...

Bjørn Østman said...

Todd, the greatest band ever is British, but it seems a little unfair in this context to use them for comparison.

Back in the early days (50's) there were many more individual artists in the US, and once things got off the ground in England bands were in (in the 60's). So perhaps the trend can be explained by... Elvis?

Kevin Zelnio said...

First you have to recognize that bioluminescence has evolved multiple times throughout many different types of organisms from bacteria to fish. Bioluminescence in mulitcellular fauna is either biological derived through a symbiosis with bacteria or chemically through one of several independently derived chemicals with one of several independently derived enzymatic pathways. Bioluminescence is also (probably) as common in the terrestrial environment as in the marine environment. Several fungi and insects are characterized by the chemical pathways. So maybe an interesting question is why do we see a lack of symbiotic luminescence in the terrestrial environment as opposed to the marine environment where there are many luminescent symbioses as well as chemical ones in eukaryotes.

But it is interesting, why haven't terrestrial luminescence invaded into freshwater systems? This is explained in part by following the organisms who are exhibit this phenotype. Fungi are very poorly known in freshwater systems and insects and earthworms are mostly terrestrial, at least the luminescent phases. Interestingly, freshwater Vibrio are bioluminescent (the same bacteria genus in squid). I thought there was a freshwater ostracod (a Vargula species?) that was luminescnet?

Lastly, luminescence doesn't always have a purpose. It could be a side reaction from an enzyme (give off light to release energy). Luciferins and luciferases could have other functions than to provide light. What is amazing is how this reaction came to be harnessed by several eukaryotic fauna for several totally different ecological purposes.