What are the ramifications to life on Earth when the Earth's magnetic poles switch? This question is related to this question about the cause of the Earth's magnetic field switching polarity.

My question is: How does this switch in the polarity of the magnetic field affect life on Earth?  Will it have detrimental effects to living organisms?
While this does not directly answer the question, these two ideas are relevant: Rare Earth hypothesis and Mediocrity principle. 

More focused to the question, This letter to nature discusses the purposed link between evolution/mutation rate during of life and magnetic pole reversal periods. You see, when the magnetic fields reversed, it widely thought that it occurs over a period on the order of 1 - 10,000 years. During this reversal, the intensity of the magnetic field degrades to 0, and then increases from there in a reversed polarity. It is not a contentious position that during these field reversals the mutation rate (not sure about speciation rate) dramatically increases.