Rate of Evolution Metrics Observed

eldavojohn notes an article up at Science Daily on research demonstrating that smaller animals with warmer blood evolve faster than larger, colder animals. From the article: "Across species from fish to mammals, they found that rates of protein evolution showed the same body size and temperature dependence as metabolic rate. Specifically, their mathematical model predicts that a 10-degree increase in temperature across species leads to about a 300 percent increase in the evolutionary rate of proteins, while a tenfold decrease in body size leads to about a 200 percent increase in evolutionary rates."

Comments

Correlation, not causation?

[2nd Post!]

I wonder if this has to do with survival rates; shorter lifespan vs longer lifespan, more active vs passive animals, more energy vs less energy?

Re:Correlation, not causation?

[king-manic]

I wonder if this has to do with survival rates; shorter lifespan vs longer lifespan, more active vs passive animals, more energy vs less energy?

I think it's about generation time. Larger animals tend to live longer, reproduce less, and have a much larger generation time. But there might be some subtle link between higher body temperature and a more readily mutable genome. As chemical reactions occur more often and faster at higher temperatures, thus the mutation rate would be higher.

Re:Correlation, not causation?

[discontinuity]

Larger animals tend to live longer

I can't say on a general scale, but the exact opposite of this is true for dogs. Small dogs like terriers can live upwards of 20 years, larger ones like mastiffs are lucky to hit 10. I have a feeling there are other exceptions as well, but I'm not familiar with what they might be.

IIRC, average heart rate and/or metabolic rate is a better predictor of average life span for a species than is size. Not sure if that explains the disparity among dogs. It just happens that large size tends to correlate to slower metabolisms/heart rates when looking at many species.

Also, dogs are a bizarre case since they are so radically inbred. Very little natural selection going on there. There was a PBS special on dogs about 6-12 months ago (the Nature series, I think) in which they point out that two very different dog breeds (e.g., a mastiff and a terrier) have more DNA in common than the average human cousins.

Humans have lower body temp than most mammals.

[eht]

Interesting to note that humans have a lower body temperature than most mammals, actually that's one of the reasons we can get leprosy and almost no other animal can carry it, armadillos being the exception, it thrives in cooler temperatures.

Re:Captain Obvious

[Anonymous Coward]

except there are many small animals that have long lives as well, particularly birds.

"Predict", not "Demonstrate"

[R2.0]

A computer model, or any model for that matter, doesn't "demonstrate" anything, other than the fact that that model will give those results with this input. By definition, a model isn't really the phenomenon it represents. Models "predict", it's only by measurement of the actual phenomena is a prediction or hypothesis demonstarted to be true/accurate.

This is why a lot of folks are uncomfortable with the "fact" that global warming is caused by human generated greenhuse gasses - the only "fact" is that computer models show this. We can't test that theory in any meaningful way, so we need to work with what we've got, but I can't help but think the Goreacle and Leonardo DiHybrido would do better by not focussing on "proving" something that essentially can't be proven until after the results are in - i.e. a thousand years from now.

Re:dinosaurs

[Jugalator]

So that means the dinosaurs (huge cold blooded reptiles) were an evolutionary dead end? Actually, there's a theory that if it wasn't for a possibly pretty huge meteroite impact that destroyed the environment, dinosaurs like the Troodon could have evolved further into a form of humanoid reptiles.

Re:Misleading

[tgibbs]

The rate of evolution can reasonably be expected to depend upon the mutation rate, selection pressure, and the generation time. It is certainly possible to set up conditions in the laboratory in which the mutation rate is limiting. I'd like to see the actual paper to see why they concluded that the mutation rate is limiting in the wild.

Re:But... but...

[GreyPoopon]

Evolution is just a theory! I live in Kansas and my teacher was forced to tell me that!

I know you meant that as a jab at Intelligent Design, but Evolution (as is traditionally discussed) is indeed in the scientific sense just a theory. It is a logical explanation that can be tested. Remember that we are talking about evolution on a macro-scale. I think only the most dimwitted people would deny that organisms evolve or adapt at a micro-level. You can actually watch and see that happen. Fruit flies are a really good example of adaptability that can be watched. However, on a macro scale (over millions of years), we have only a bunch of dots of evidence that seem to be connected (and thus fit the model); the amount of evidence required to prove Evolution beyond any reasonable doubt makes that task nearly insurmountable. And in that respect, those who call for requiring to make it clear to students that Evolution is a theory are correct in doing so, even if some may disagree with their motives. It's very important for students to come to an understanding that there is a difference between the incontrovertible fact that 2 + 2 = 4, and the likelihood that birds are one branch of an evolutionary path from a distinct group of dinosaurs. One is intrinsically true, whereas the other has some exceptionally convincing evidence, but too many alternative possibilities to be solidly provable without a time machine and a very dedicated research team. Students need to know the difference.

So how did we get here?

[trybexus]

I knew from the article this would turn into a creation vs evoloution conversation. But this really does bring up a rather intresting question. If large species take longer to evolve then how can it be possible that human beings "being rather large in comparison" be more advanced then smaller animals, who first of all have been on th eplanet alot longer then upright standing . Is it simply a matter of brain mass. Would it not make sense that they would have evolved to have oposable thumbs before us?

Re:dinosaurs

[E 99]

And dinosaurs didn't really disappear. They just look different now. Step outside and look at all those feathered things flying around. Those are modern dinosaurs.

By this method of classification, plants ans animals should be called "modern bacteria."

Re:dinosaurs

[porcupine8]

This really came as a surprise to me when I toured the new evolution exhibit at the Chicago Field Museum last year. When I was a kid (in the 80s), the line was that dinosaurs branched into two evolutionary paths, reptiles and birds. Now this exhibit plainly states many times, "Dinosaurs were birds." Not being quite as into dinos as I was when I was seven (and obsessed), this was news to me.

Re:This explains everything!

[glitch23]

Well, that explains why Republicans don't believe in evolution; it occurs too slowly for them to notice.

The Democrats always make fun of the Republicans for having faith in something that can't be seen and yet there are Democrats who believe in evolution. Weird! Oh, and hypocritical too. And if you think evolutionary evidence can be seen, there are millions of Republicans who will tell you they see a great deal of evidence that God exists.

What's the guy even trying to say?

[adatepej]

"There is an ongoing debate about what is driving the forces of evolution, and this is one of the clearest studies that say mutation is a driving force," said Dan Graur, Ph.D., the John and Rebecca Moores professor of biology and biochemistry at the University of Houston, who was not involved in the research. "If you want to put a catch phrase on it, it is not so much the survival of the fittest, but survival of the luckiest. The outcome is not determined by the 'fitness' of a particular trait, in terms of whether the trait affects an animal's ability to compete and survive. The author says "If you want to put a catch phrase on it, it is not so much the survival of the fittest, but survival of the luckiest."
--That's right, survival of whoever is luckiest to set of genes. And when those genes are the ones that allow you to "compete and survive", those are the lucky ones. If a mutation was part of that package of lucky genes, and you reproduce successfully, and that mutation becomes standard equipment, we've just seen evolution.

Then the author says "the outcome is not determined by the 'fitness' of a particular trait, in terms of whether the trait affects an animal's ability to compete and survive."
--That's wrong! Like above, it's mutation, from whatever cause, that "drives" evolution, if you will, but it's natural selection which "channels" that drive into actual evolution.

He's right when he says mutation is a driving force in evolution. But he's wrong when he seems to write off the other hypothesized "driving force" in evolution: environment, i.e. necessity.

But, when do these "protein mutations" actually manifest in evolution that actually changes the whole of a group of organisms? When that mutation is something useful in the environment!