Crosswords0 min ago
evolution and extinction
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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?
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For more on marking an answer as the "Best Answer", please visit our FAQ.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
/mutation_rate.htm
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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.