Animals That Taste Only Saltiness

http://nautil.us/blog/the-animals-that-taste-only-saltiness

by wormold • 12 years ago

50 20 12 years ago

tieTYT• 12 years ago

When a mutation came along that made the receptor not work, that animal was just as likely to survive as one that didn’t have the mutation.”

Then shouldn't there still be a chance of having the mutation because nothing is selecting for or against it? Instead it seems the entire species can't taste sweetness so the gene was removed. Why would that happen? I don't know of any other explanation than, "there is an advantage to not being able to taste sweetness".

EDIT: I removed "50/50" from my question. That wouldn't be the right percentage.

mhurron• 12 years ago

Something else occurred that removed those that didn't have that mutation.

protonfish• 12 years ago

If the mutation only occurred once, yes. But if there is no selection pressure against a broken gene, every time it mutates it will enter the gene pool until the working version eventually disappears completely. (After many years, of course.)

whatshisface• 12 years ago

But wouldn't there be an equal chance of the mutation reversing itself? This is true in digital transmissions, why not in DNA?

sp332• 12 years ago

Maybe it's a dominant genetic trait?

Strilanc• 12 years ago

It's likely that there are many ways to turn it off, and without selection pressure they all randomize.

If there's 10 codons needed to make it work, and there's no selection pressure, then there's only a one in a million chance it's working by chance. Even when it gets close, there's a 9:1 chance that the next mutation will make things worse instead of fixing the issue. Mostly it would stay around the noise floor with ~2.5 of the codons set correctly.

That being said, I doubt it's as simple as "these 10 codons must have these values for this taste receptor to work".

walruscop• 12 years ago

Interesting. Makes me wonder how we evolved our taste buds.

baddox2• 12 years ago

I don't know the details, but it's fairly easy to imagine a series of small steps that could occur via random mutations, where each small step offered a slight fitness advantage over individuals without the mutation.

SoftwareMaven• 12 years ago

Isn't that just the definition of evolution?

jeltz2• 12 years ago

There is no mention of smell in the article. What if dolphins use their sense of smell instead?

tiglionabbit2• 12 years ago

Dolphins can't smell.

They retain all of the mammal sense-of-smell genes for smelling in air, but they are corrupted by random mutations. None of them function anymore.

jeltz2• 12 years ago

Thanks! That would have been useful information for them to add to the article. I assume Hyenas still retain their sense of smell though.

jessaustin• 12 years ago

It isn't clear how useful the salty taste would be to dolphins anyway. Wouldn't everything in their environment taste salty, to pretty much the same extent?

freiheit• 12 years ago

The salinity of the ocean isn't uniform and the ocean is connected to various bodies of fresh water. From a quick glance at the map of surface salinity[1] you can see that warmer waters are saltier. Perhaps tasting saltiness sometimes helps dolphins avoid dangerous fresh water, helps to locate different temperature waters, or generally helps them understand the current environment better? Maybe freshwater fish are unhealthy for dolphins to eat?

[1] http://en.wikipedia.org/wiki/Seawater#mediaviewer/File:WOA09...

Animals That Taste Only Saltiness

Related Stories