Homology, genes, and evolutionary innovation / Gunter P. Wagner.

Includes bibliographical references (pages 427-465) and index.

Introduction. What this book aims to do and what it is not --
1. The intellectual challenge of morphological evolution : a case for variational structuralism --
2.A conceptual roadmap to homology --
3. A genetic theory of homology --
4. Evolutionary novelties : the origin of homologs --
5. Developmental mechanisms for evolutionary novelties --
6. The genetics of evolutionary novelties --
7. The long shadow of metaphysics on research programs --
8. Cell types and their origins --
9. Skin and a few of its derivatives --
10. Fins and limbs --
11. Digits and digit identity --
12. Flowers --
13. Lessons and challenges--
References--
Index.

This book provides the first mechanistically based theory of what homology is and how it arises in evolution. Günter Wagner, one of the preeminent researchers in the field, argues that homology, or character identity, can be explained through the historical continuity of character identity networks - that is, the gene regulatory networks that enable differential gene expression. He shows how character identity is independent of the form and function of the character itself because the same network can activate different effector genes and thus control the development of different shapes, sizes, and qualities of the character. Demonstrating how this theoretical model can provide a foundation for understanding the evolutionary origin of novel characters, Wagner applies it to the origin and evolution of specific systems.