Survival of the Fittest

14 May 2010

www.sciencedaily.com/releases/2010/05/10051010533.htm from a paper in Nature May 9th ... researchers used entire islands in the Bahamas to test the theory, survival of the fittest. Competition among lizards was found to be more important than predation by birds and snakes when it came to survival. They covered several small islands with bird-proof netting while others were left open, and on some islands snakes were added to expose the lizards to a greater degree of predation. They found that death by predators was a random event as far as traits such as body size and running ability or general manoevrability were concerned. When the population of lizards on an island became dense it consistently created strong natural selection favouring larger size and faster running ability - to reach food sources quicker and more agressively. In high density situations pressure of food resources became critical - which caused bigger lizards to survive at the expense of the smaller ones.

At www.sciencedaily.com/releases/2010/05/100512131513.htm another paper in the same issue of Nature is said to confirm Darwin's proposed theory of universal common ancestry, linking all forms of life by a shared genetic heritage from single celled micro-organisms to humans and elephants. A biochemist study confirms Darwin, a study that rests on several simple assumptions about how the diversity of modern proteins arose. First, it was assumed the genetic copies of a protein can be multiplied during reproduction, such as when a parent passes a copy of a gene to several offspring. Secondly, it was assumed the process of replication and mutation over long periods of time may modify the proteins from their ancestral initial versions. These two factors, it was thought, should have created the differences in the modern versions of the proteins that can be seen in the modern world. Thirdly, it was assumed genetic changes in one species do not affect mutation in other species - for example, genetic mutations in kagaroos do not affect humans. What he did not assume was quite how far back such processes go in linking organisms genealogically. It was found that the processes linked humans to other animals, and animals to enkcryotes, to bacteria and indeed to all forms of life on the earth.