In this fascinating, witty, and vividly written book, Menno Schilthuizen illuminates these questions, showing how biologists and zoologists over the last two centuries have responded to them, assessing our current knowledge of species, and proposing his own solution to Darwin's mystery. Using the sometimes-vicious academic debates and the powerful personalities of scientists as background, Schilthuizen explores the meandering path of species research and sets it out in the clearest possible terms. From looking at how we define a species, to exploring how geographical isolation and sexual selection contribute to making new species, to showing how species may appear gradually or instantaneously, 'Frogs, Flies, and Dandelions' offers a comprehensive account of this evolutionary drama. Along the way, we get to know a remarkable cast of characters from the plant and animal kingdoms, from the copper-loving monkey flower to sockeye salmon, fire-bellied toads, lyrebirds, apple maggot flies, and many others. Most important, we get a clear picture of all the conditions necessary for one species to give birth to another.