Thank you for using the Jiskha Homework Help Forum. The first answer was posted in March:
2. (part II of #1): http://answers.yahoo.com/question/index?qid=20080301173601AAcrdIU
3. (Yahoo answer from 11 months ago): http://malaysia.answers.yahoo.com/question/index?qid=20071019143820AA6fLhP
4. (the Jiskha post from March): http://www.jiskha.com/display.cgi?id=1204387926
5. (an iPaper): http://www.scribd.com/doc/1031151/Natural-Selection-and-Adaptation
6. (free essays): http://www.bignerds.com/essays/Succession-Natural-Selection/3753.html
7. (Yahoo answer from 9 months ago): http://au.answers.yahoo.com/question/index?qid=20071216110748AAljylR
There were other answers that must be purchased and I did not include those.
I posted this back in August: 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.
Urbanization-post a 800 pg paper that defines it? explains urban population and how it affects our environment? water? explain challanges related to urban and explain the benefits? discuss how benefits outweight challanges