More than One Potato

Paradoxically while plant breeding (either planned or unplanned) creates novel and useful genetic combinations, the widespread use of improved varieties can also reduce the overall genetic variation that is the very basis for the valuable traits that plant breeders and farmers want.  This wasn't a very big issue during most of our history as plant breeders.  If anything, localized and small scale breeding may have increased levels of genetic diversity within some crops (depending on your scale of measure).  However, more modern practices now threaten to severely diminish the pool of available genetic diversity for many of our most important crops.   Potatoes are a great example of this story.  Check out this cool video http://www.youtube.com/watch?v=q6XMTUbPwEY&feature=share&list=PL03468DEB0456E448