Duplication is one of the most important mechanism for evolving gene and genome complexity. The availability of complete genome sequences greatly facilitated its study. In this book, the molecular duplication process is investigated via aspects of transcriptional regulation and gene function. In transcriptional regulation, how cis-regulatory elements evolve is studied via a comparative genomics approach in fungi and fruitfly species. The study in fungi species demonstrates that the dominant fate of cis-regulatory elements after duplication is the emergence of new binding sites and...