Predicting the distribution of creatures great and small

Jul 17, 2008

In studying how animals change size as they evolve, biologists have unearthed several interesting patterns. For instance, most species are small, but the largest members of a taxonomic group -- such as the great white shark, the Komodo dragon, or the African elephant – are often thousands or millions of times bigger than the typical species. 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.

"The model is remarkably compact, " says Aaron. "It also omits many traditional ideas from evolution and ecology, such as population dynamics or species interactions, yet makes very accurate predictions."

Because species size is fundamentally related to so many other characteristics like metabolism, life span and habitat, the researchers' simple evolutionary model offers support to idea that some aspects of evolutionary and ecological theory can be unified.

Source: Santa Fe Institute

Explore further: Dairy farms asked to consider breeding no-horn cows

add to favorites email to friend print save as pdf

Related Stories

Field tests needed to help control feral cats

Mar 20, 2015

Local wildlife ecologists have analysed research into feral cat habitat use from around the world in a bid to better manage the pest, which is one of the major threats to biodiversity globally.

Researchers rethink how our feathered friends evolved

Mar 17, 2015

A recently published global genome study that used the data-intensive Gordon supercomputer at the San Diego Supercomputer at the University of California, San Diego, has researchers rethinking how avian lineages ...

Recommended for you

Dairy farms asked to consider breeding no-horn cows

10 hours ago

Food manufacturers and restaurants are taking the dairy industry by the horns on an animal welfare issue that's long bothered activists but is little known to consumers: the painful removal of budding horn ...

Italian olive tree disease stumps EU

Mar 27, 2015

EU member states are divided on how to stop the spread of a disease affecting olive trees in Italy that could result in around a million being cut down, officials said Friday.

China starts relocating endangered porpoises: Xinhua

Mar 27, 2015

Chinese authorities on Friday began relocating the country's rare finless porpoise population in a bid to revive a species threatened by pollution, overfishing and heavy traffic in their Yangtze River habitat, ...

A long-standing mystery in membrane traffic solved

Mar 27, 2015

In 2013, James E. Rothman, Randy W. Schekman, and Thomas C. Südhof won the Nobel Prize in Physiology or Medicine for their discoveries of molecular machineries for vesicle trafficking, a major transport ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.