* Astronomy

Blobrana · L

RE: Evolution

Blobrana · L

Speed Limit To The Pace Of Evolution
Researchers at the University of Pennsylvania have developed a theoretical model that informs the understanding of evolution and determines how quickly an organism will evolve using a catalogue of "evolutionary speed limits." The model provides quantitative predictions for the speed of evolution on various "fitness landscapes," the dynamic and varied conditions under which bacteria, viruses and even humans adapt.
A major conclusion of the work is that for some organisms, possibly including humans, continued evolution will not translate into ever-increasing fitness. Moreover, a population may accrue mutations at a constant rate -- a pattern long considered the hallmark of "neutral" or non-Darwinian evolution -- even when the mutations experience Darwinian selection.

Read more

Blobrana · L

Ever since Darwin discovered that species can evolve, scientists have wondered how new species form. Answering this question is the key to understanding the diversity of all of life. A group of colourful fishes in Africa's Lake Victoria have been the focus of scientific efforts to unravel how new species form. This lake contains more than 500 species of cichlids, which play a leading role because of their rapid speciation and remarkable diversity. Still, the mechanisms involved in the rapid appearance of new cichlid species have remained elusive to scientists.

Read more

Blobrana · L

When animals evolve on islands, size doesn't matter
A theory explaining the evolution of giant rodents, miniature elephants, and even miniature humans on islands has been called into question by new research published today in Proceedings of the Royal Society B: Biological Sciences.
The new study refutes the 'island rule' which says that in island environments small mammals such as rodents tend to evolve to be larger, and large mammals such as elephants tend to evolve to be smaller, with the original size of the species being the key determining factor in these changes.
The new research findings suggest that the tendency to either evolve larger or smaller on islands varies from one group of species to another, irrespective of original size. The research team, from Imperial College London, suspect instead that a number of external factors, including the physical environment of the particular island, the availability of prey, the presence of predators and the presence of competing species all play a role in determining the size evolution of island mammals.

Read more