Summary of the River that Flows Uphill... Day 7

This is also another online book by W.H. Calvin. I looked at this because i enjoyed his other book and wanted to read more on something i was learning in class. This book in particualr is a journal kept by Calvin on his trip down the Grande Canyon. here on day 7 he discusses one of the topics that we covered in our class: natuarl selection. In particular, Calvin concentrates on the squril population in the canyon. He notes that there is a difference in the south rim populations and the north rim populations. This is an example of the same species being divided by geological factors (the river) and changinf differently over time, sympatric speciation. (31 pages)