title: The difficulty of agreeing about constraints.
authors.affiliation: Institute of Evolutionary and Ecological Sciences, University of Leiden, P.O. Box 9516, 2300 RA Leiden, The Netherlands.
authors.forename: Patrícia
authors.initials: P
authors.lastname: Beldade
authors.forename: Paul M
authors.initials: PM
authors.lastname: Brakefield
mesh_terms: D005075:Biological Evolution; D019521:Body Patterning; D004626:Embryology; D012641:Selection, Genetic