Evolutionary Conservation of Developmental Mechanisms

Wiley-Liss, 1993. $98.00 (xii + 219 pages) ISBN 0 471 58843 1 As we learn more about the mechanisms that control development, it becomes possible to consider how they may have evolved. The title of this volume reflects current interest in the topic. The same is not always true of the articles it contains! Four papers in this compendium do make some serious attempt to consider evolutionary questions. Weisblat and his colleagues spell out the approach most explicitly: 'to understand which embryological phenomena constitute primary characteristics uniting a large group of species, and which are derived characteristics that set apart smaller groups of individual species'. 'What concerns us here', they say, 'is a third level of homology' (beyond the conservation of primary sequence, and the secondary level of conserved biochemical function). This third level is 'the phylogenetic conservation, not just of single genes, but rather of sets of genes interacting with one another in a reciprocal or hierarchical manner'. This approach subsumes a multitude of questions that are ripe for attack, from the specific to the general. Where on the phylogenetic tree do G-protein - coupled transduction mechanisms first appear? What was the primitive role of