Characters, units and natural kinds : an introduction -- A history of character concepts in evolutionary biology / Kurt M. Fristrup -- An episode in the history of the biological character concept: the work of Oskar and Cécile Vogt / Manfred Dietrich Laubichler -- Preformationist and epigenetic biases in the history of the morphological character concept / Olivier Rieppel -- Character replication / V. Louise Roth -- Characters as the units of evolutionary change / David Houle -- Character identification: the role of the organism / Günter P. Wagner and Manfred D. Laubichler -- Functional units and their evolution / Kurt Schwenk -- The character concept : adaptationalism to molecular developments / Alex Rosenberg -- The mathematical structure of characters and modularity / Junhyong Kim and Minhyong Kim -- Wholes and parts in general systems methodology / Martin Zwick -- What is a part? / Daniel W. McShea and Edward P. Venit -- Behavioral characters and historical properties of motor patterns / Peter C. Wainwright and John P. Friel -- Homology and DNA sequence data / Ward Wheeler -- Character polarity and the rooting of cladograms / Harold N. Bryant -- The structure of a character and the evolution of patterns / Paul M. Brakefield -- Characters and environments / Massimo Pigliucci -- The genetic architecture of quantitative traits / Trudy F.C. Mackay -- The genetic architecture of pleiotropic relations and differential epistasis / James M. Cheverud -- Homologies of process and modular elements of embryonic construction / Scott F. Gilbert and Jessica A. Bolker -- Comparative limb development as a tool for understanding the evolutionary diversification of limbs in arthropods : challenging the modularity paradigm / Lisa M. Nagy and Terri A. Williams -- Origins of flower morphology / Peter K. Endress -- Origin of butterfly wing patterns / H. Fred Nijhout -- Perspectives on the evolutionary origin of tetrapod limbs / Javier Capdevila and Juan Carlos Izpisá Belmonte -- Epigenetic mechanisms of character origination / Stuart A. Newman and Gerd B. Müller -- Key innovations and radiations / Frietson Galis