Predict the distribution characteristics of large and small species

To understand how species change in size during evolution, biologists have created interesting models. Most species are very small, but the most massive members of a classified group, such as giant white sharks, Komodo dragons or African elephants, are thousands or even larger than other species.

For the first time, two SFI researchers gave an explanation for the evolutionary types based on the statistical framework of elephants.

Aaron Clauset - a postdoctoral fellow of SFI with Professor Douglas Erwin SFI - published the results of the study on June 18 issue of Science that: 'Our model surprisingly matches data. obtained from the real world '.

The elephant god leads the whole herd.Most species are very small, but the most massive members of a classified group, such as giant white sharks, Komodo dragons or African elephants, are thousands or even larger than other species.(Photo: iStockphoto / Jonathan Heger)

In the model of Clauset and Erwin, descendants are very close in size to ancestors but carry some other random changes. But the transformation is repressed, first due to the hard limit on the small size of the species because of its physiological repressive effects; The second is due to the soft limit of a species' large size before the species becomes extinct. After millions of years of evolution of a new species accompanied by the extinction process of ancestors, the model has reached a state of equilibrium in which species tend to grow larger than a way to offset the trend of extinction. faster than them.

By using fossil data from extinct mammals about 60 million years ago to determine the type of evolutionary model, researchers have shown that the exact evolutionary process has produced Born 4,000 mammal species compared to the previous 50,000 years.

Aaron said: 'The model is really full. It also eliminates many traditional views on evolution and ecology, such as population dynamics or species interaction, while still making accurate predictions. '

Because the species size is basically related to many other characteristics such as metabolism, longevity and environment, the researchers' simple evolutionary model is only intended to support the view that some aspects of theory Ecology and evolution can merge together.