Distribution Of Creatures Great And Small Can Be Predicted Mathematically

Science Daily ^ | 7/19/2008

[Soliton]

Now for the first time two SFI researchers explain these patterns within an elegant statistical framework.

"The agreement between our model and real-world data is surprisingly close," says SFI Postdoctoral Fellow Aaron Clauset, who, along with SFI Professor Douglas Erwin, presented the findings in a July 18 Science paper.

In Clauset and Erwin's model, descendant species are close in size to their ancestors, but with some amount of random variation. But, this variation is constrained, first by a hard limit on how small a species can become, due to physiological constraints, and second by a soft limit on how large a species can become before becoming extinct. After millions of virtual years of new species evolving and old species becoming extinct, the model reaches an equilibrium in which the tendency of species to grow larger is offset by their tendency to become extinct more quickly.

By using fossil data on extinct mammals from up to 60 million years ago to specify the form of the model, the researchers showed that this evolutionary process accurately reproduces the diversity of 4,000 mammal species from the last 50,000 years.

[Coyoteman]

Cool!

[Soliton]

Ain’t it beautifu when a plan comes together!

[TASMANIANRED]

Without even looking at the numbers....I’ll predict.

Food species are most numerous, reproduce the fastest and tend to be smaller...

Predator species tend to be larger, reproduce more slowly and have longer lives...

[JamesP81]

By using fossil data on extinct mammals from up to 60 million years ago to specify the form of the model, the researchers showed that this evolutionary process accurately reproduces the diversity of 4,000 mammal species from the last 50,000 years.

I hate to point out the semi obvious here, but it looks to me like they're doing nothing more than copying what's already there. I write computer software for a living. This doesn't strike me as any different than if someone wrote a complex mathematical formula down on a piece of paper, and looking at that formula I wrote a program to emulate it. Of course the program would produce the same results as the equation on paper, at least to within the decimal precision the particular computer was capable of.

[Sacajaweau]

Sounds like this guy never did any fishing.

[tbw2]

And big species like the mammoth and giant sloth require more space for each, so there are fewer numbers of them overall. A big temperature shift or upsurge in predation, and they are more likely to die out because there are fewer of them in general.
Kill 90% of a rat colony, they can bounce back fast in a generation or two. Kill 90% of a rat terrier population, and being far fewer at the start, it might make it impossible for the breed/species survivors to find mates and breed.

[TASMANIANRED]

Exactly.

Mice, rats and rabbits breed so prolifically because so many things have them on the food chain.