Islands make animals tamer

Francesca Sajedi

Author: Ed Yong 

Date Published: January 8th, 2014

URL: http://www.nature.com/news/islands-make-animals-tamer-1.14462

Summary:

        

William Cooper Jr. of Indiana University has tested 66 different species of lizards from around the world to test Charles Darwin's idea. Darwin's idea was that when animals live on a remote island with no predators they be come tamed. When Darwin went to the Galapagos Islands, he made note of how unafraid of people the animals are even to the extent that he said that “a gun is here almost superfluous”. He swatted at birds with his hat, pulled the tails of the iguanas and sat on giant tortoises and it didn't make them run away.  These are Darwin’s ideas that Cooper used.

Cooper showed his idea that when there are no predators on the island you have an easier time approaching them, but when a predator is introduced the animal is faster to run away from you. He got data from the Eurasian lizard all the way to the Galapagos marine iguana.  Cooper took an old idea and showed evidence for it. His results showed that island lizards are much more human approachable then mainland ones. The further the island is away from the main land the easier it is to approach them. These are what the results were and what they showed.

Cooper also showed that different lizard species, even when the lizards are closely related have different behaviors of escaping depending on where they live.  Also, the lizards with skittish behavior where predators are not abundant will be expected to die down due to natural selection. Especially when there are limited resources because the skittish ones would be afraid of the other ones. These are ways that natural selection happens in the wild.                  

Relevance: 

This article relates to our evolution unit because it talks about a real world example of natural selection and how populations adapt to their environments. All the species of lizards Cooper tested on the islands were closely related to the closest mainland ones that he tested. Some how the ones from the mainland spread to the near by islands. Once the couple of them got to one of the islands the population started to grow and change after each generation. Eventually, they became less scared of different things approaching them because there were no predators that they had to worry about. The idea that the further away the island is from the mainland the approachability is higher is shown in this article. This happens because the lizard goes to the nearest island and the population adapts, then a predator comes and a group goes to the next nearest island where there may be no predators. The population becomes more docile and this process keeps on happening. Also the idea of natural selection was mentioned. Cooper thought that the more skittish of the population where the environment has limited resources and no predators will die out and the population will all be tolerant to things touching and/or walking up to them. The skittish ones will die out because the environment needs populations that will not be scared of others who are trying to use their limited resources. Copper shows what we have been talking about in class in the real world.