evolution and extinction

[woodpam]

We keep hearing about species being endangered or becoming extinct. Has anyone heard of any new species coming into existence by evolving from others. I'm thinking some creatures with a short life cycle must have lived fro hundreds of generations since records began. Is this time to evolve into a new species?

[j2buttonsw]

I think the problem with a question like this is how one defines a new species? Biologists have used empirical methods of defining a species for generations usually based on visible differences rather than genetic ones. One may have a certain genetic mutation rate which alters the genetic makeup of a species over time but when do you decide what is enough mutation to warrant a new species? You may be interested in this article I came across: http://www.evolutionfairytale.com/articles_debates
/mutation_rate.htm

[sddsddean]

I remember there was a white moth that lived in the North of England. As all the trees got covered with soot, the moth 'evolved' in to a black one to maintain its camoflague. Now after all the clean air campaigns etc., it has become white again.

[woodpam]

Thanks for some great answers - I wish I knew enough about science to be able to judge whether a theory as on the evolutionfairytale site is sound. The urban fox idea was also very interesting - I wonder if it could translate to humans living in different environments!

[incitatus]

microbes and viruses do this all the time, of course, but as their reproduction is asexual it is difficult to know if they are a species or not (one of the criteria being that a species can only breed with itself successfully). An example in nature is the london plane tree, which is a very succesful adaptation to city life. I believe that some of the species of galapagos tortoise have come into existence since records began too, but need to look this up. Races of rat, such as the harvard rat, are probably now species due to their forced deviation from the norm for use as lab animals.

[woodpam]

I don't normally rate answers as it spoils the sequence, but these have really given me a lot to think about, thanks