Question

Explain how limbless salmanders evolved according to Darwin's theory of natural selection?

Answer 1

http://salamander.uky.edu/srvoss/Nov23.pdf

Answer 2

To answer your question, you have to understand a couple of things. First, limbless salamanders are descended from limbed salamanders. In other words, limblessness isn't a primitive, but rather a derived trait for salamanders. Limbs have been lost secondarily. Secondly, you'll want to look up information on limbless salamaders (Google it, or use the library: there are lots of good books about salamanders.) There you will find infomation on the autoecology or lifestyle of these salamanders. Where do they live? How do they get around? Most importantly, what advantage might they have in their environment by NOT having limbs? Natural selection operates on populations of organisms; populations are subject to different environmental pressures (selective pressures). Forexample, animals living in caves are often blind (their ancestors could see), but have lost that ability through selection, because mutations that rendered an animal blind were not a disadvantage, and might actually be advantageous. By the way the article cited above is about neoteny, which is a fascinating case where some salamanders retain their larval characteristics yet are able to breed (imagine a giant baby that could have its own children). It doesn't address your question, though.