What is the main conflict in The Beak of the Finch by Jonathan Weiner?

The Beak of the Finch is an overlook at the research that began with Charles Darwin in the Galapagos Islands and has been continued by the Grants and other scientists over twenty years by studying the islands’ finches. Giving an overview of Darwin’s evolutionary theories and the finches that were omitted from “The Origin of Species”; the book then moves on to explore two decades worth of research and observation of the finches and how that research is being applied in the last part of the twentieth century.