Unusual island evolution happens faster than thought

Sep 20, 2006

In evolutionary circles, giant rats and miniature elephants have long been accepted as the products of accelerated evolution in isolated environments such as islands, but McGill paleontologist Virginie Millien has been the first to establish just how quickly these odd-shaped animals got that way.

In fact, island mammals evolve about three times faster than their mainland counterparts, says Dr. Millien, who based her findings on an analysis of the documented evolutionary rates of 88 island mammal species, about half of which were rodents.

The data looked at species that evolved on islands in the Mediterranean, Indonesia, the United Kingdom, California and British Columbia, among others. Dr. Millien's research paper on the topic, "Morphological Evolution Is Accelerated among Island Mammals," will appear in the October issue of the Public Library of Science (PLoS Biology).

"We know that strange things happen on islands – elephants become dwarves, for instance – but what we didn't know for sure is how fast it happens," explained Dr. Millien, curator of paleontology and zoology at the Redpath Museum. "Everybody since Darwin has assumed that it must happen very fast, because it's so shocking to see something like a one-metre-high elephant."

Isolation, climate differences, the absence of natural predators and, in some cases, adequate food sources all contribute to the unusual evolution of island mammals such as the dwarf elephants whose fossilized remains have been found on the Italian island of Sicily, Dr. Millien noted. It is known, for instance, that mammals in cold environments grow larger than those in warmer environments, she explained, citing the difference in size between black or brown bears, which live in warmer climates, and the larger polar bears that populate the North.

Dr. Millien next hopes to study similar evolutionary differences between mammals in Quebec's southern and northern regions, and to further explore the role of climate change in evolution.

Source: McGill University

Explore further: EU must take urgent action on invasive species

add to favorites email to friend print save as pdf

Related Stories

Islands spark accelerated evolution

Sep 12, 2006

The notion of islands as natural test beds of evolution is nearly as old as the theory itself. The restricted scale, isolation, and sharp boundaries of islands create unique selective pressures, often to dramatic ...

Recommended for you

Adventurous bacteria

30 minutes ago

To reproduce or to conquer the world? Surprisingly, bacteria also face this problem. Theoretical biophysicists at Ludwig-Maximilians-Universitaet (LMU) in Munich have now shown how these organisms should ...

Japan lawmakers demand continued whaling

1 hour ago

Japanese lawmakers on Wednesday demanded the government redesign its "research" whaling programme to circumvent an international court ruling that described the programme as a commercial hunt dressed up as ...

Revealing camouflaged bacteria

2 hours ago

A research team at the Biozentrum of the University of Basel has discovered an protein family that plays a central role in the fight against the bacterial pathogen Salmonella within the cells. The so cal ...

User comments : 0

More news stories

Adventurous bacteria

To reproduce or to conquer the world? Surprisingly, bacteria also face this problem. Theoretical biophysicists at Ludwig-Maximilians-Universitaet (LMU) in Munich have now shown how these organisms should ...

Revealing camouflaged bacteria

A research team at the Biozentrum of the University of Basel has discovered an protein family that plays a central role in the fight against the bacterial pathogen Salmonella within the cells. The so cal ...

How kids' brain structures grow as memory develops

Our ability to store memories improves during childhood, associated with structural changes in the hippocampus and its connections with prefrontal and parietal cortices. New research from UC Davis is exploring ...

Gate for bacterial toxins found

Prof. Dr. Dr. Klaus Aktories and Dr. Panagiotis Papatheodorou from the Institute of Experimental and Clinical Pharmacology and Toxicology of the University of Freiburg have discovered the receptor responsible ...