Defining fitness in natural and domesticated populations / James S.F. (Stuart) Barker -- Genetic architecture of reproductive fitness and its consequences / Richard Frankham -- Fitness traits in animal breeding programs / Michael Goddard. Discussion / John W. James -- Maintaining genetic variation in fitness / William G. Hill and Xu-Sheng Zhang -- Spherical cows grazing in flatland : constraints to selection and adaptation / Mark Blows and Bruce Walsh -- Maintaining fitness by within breed selection / Peter Bijma. Discussion / Michael Goddard -- Some evolutionary consequences of niche construction with genotype-environment interaction / Kathleen Donohue -- Genotype by environment interaction with farm animals / John W. James -- Drosophila and selection in nature : from laboratory fitness components to field assessments / Ary A. Hoffmann. Discussion / Keith Hammond -- Strategies to exploit genetic variation while maintaining diversity / Brian P. Kinghorn ... [et al.] -- Managing genetic diversity, fitness and adaptation of farm animal genetic resources / Louis Ollivier and Jean-Louis Foulley -- Livestock genetic resources : preserving genetic adaptations for future use / John P. Gibson. Discussion / Frank W. Nicholas -- Stuart Barker's contributions to population genetics and animal breeding : exploring fitness, evolution and animal genetics / Frank W. Nicholas and Keith Hammond.