Though BlackBerry has less than 1% of the smartphone market share today, it once had more than 50%. The question is how such a successful company could fall so far. Journalists Jacquie McNish and Sean Silcoff provide many of the answers in their book, Losing the Signal: The Untold Story Behind the Extraordinary Rise and Spectacular Fall of BlackBerry. Wharton marketing professor Americus Reed recently had an opportunity to talk with McNish about what we can learn from the rise and fall of BlackBerry. An edited transcript of the conversation follows. Americus Reed: I want to start off with some questions about what drew you to this topic. Tell us a little bit about why you wrote this book, Jacquie. Jacquie McNish: It started with an investigation I did when I worked at The Globe and Mail here in Canada with my colleague Sean Silcoff.…