Abstract
In The Origin of Species, Charles Darwin described the formation of new species as the “mystery of mysteries”. More than 150 years after Darwin first posed the problem much progress has been made in discerning what creates the great diversity of life. Speciation is the evolutionary process where a group of inbreeding populations diverges into two or more reproductively isolated groups. In this chapter, we summarize the current understanding of speciation in sexually reproductive organisms. In particular, we describe how barriers to gene flow evolve and focus on the most important factors promoting speciation. Further, we integrate different perspectives by describing recent progress from many different model systems for the study of speciation. Building on this work, we emphasize new genomic approaches to the study of speciation and how advances in DNA sequencing methods will revolutionize our understanding of the genetic basis of the speciation process. We conclude by summarizing our current understanding of speciation and show that although much of Darwin's mystery is solved, many important questions remain.