Reproductive biology and bird phylogeny. Miles to go before we sleep

Reproductive biology and phylogeny of birds Part A. Phylogeny Morphology Hormones Fertilization . By G.M. Jamieson Barrie 2007 . Science Publishers , PO Box 699, Enfield , New Hampshire , 03748 USA . 609 pp. US $119.50 (hardcover). ISBN 978-1-5708-386-2 This densely informative book is Part A of the two-part, sixth volume in a series designed to explore the relationships between phylogeny and reproductive biology in selected groups of animals, in this case birds. Nine of its 10 chapters (2–10) cover a range of topics including development and anatomy of male and female gametes, reproductive structures and organs, endocrinology of reproduction, sperm competition and fertilization. However, its editor starts off badly by implying (volume Preface: vii) that birds are “done” from a taxonomic perspective (species discovery and classification) and that the total number of species is “almost ten thousand”…“that have been comprehensively catalogued”. Quite to the contrary, with the advent of modern, uniformly applied, phylogenetically compatible, lineage-based species concepts that take cognizance of combined (and properly interpreted) organismal and molecular evidence, this number is likely to double (Zink, 2004). Also, if “comprehensively catalogued” means that the bird species and genera are now placed within well-resolved, phylogenetically robust, monophyletic groupings of use in the discovery of evolutionary meaningful patterns in comparative reproductive biology and that can be interpreted in terms of the processes that generated these patterns, there is still much to do. Staying with the Preface, the editor also states that this publication “in two parts, attempts to document most of the important aspects of reproductive biology of birds and places them in a setting of phylogenetic relationships.” The first “attempt” is addressed in Chapters 2–10. This is done admirably. I know of no other single volume that covers these aspects of descriptive avian reproductive biology at anywhere near the same scope and depth, backed up by many useful illustrations. Having said this, let the reader be aware that the writing style of this book is pitched neither at general biologists nor ornithologists, but rather at specialist avian reproductive biologists. The chapters are replete with terms not generally known outside of this discipline and the book would have benefited greatly by a glossary defining them in a relatively simple manner. Also, there is considerable variation in writing style between chapters. Furthermore, the various contributors to chapters sometimes do not do this within an explicitly phylogenetic context. Having said this, a major “plus” is that these same authors often highlight key information gaps that can be filled only with novel and more classical comparative anatomical and endocrinological research. Therefore, despite the concerns expressed above, any university or natural history museum that lays claim to being a significant centre of biological research and education should have this volume and the other Parts of this series in its library. I would like to focus the remainder of this review on Chapter 1, Classification and Phylogeny of Birds, that is tasked with generating a firm phylogenetic foundation for what follows. It does not succeed in this “attempt” for two major, and other minor, reasons. The major reasons for this are not the author’s (John Harshman) fault, and he is explicit about this on page 1 of his chapter. …we do not currently know much about the [phylogenetic] relationships among birds… and then later in the same sentence …within a few years we will know most of what there is to know. I agree with this current assessment of the situation since I have done some of the recent work (e.g., Dyke et al., 2003; Crowe et al., 2006) necessary to support these statements and know the leaders and many members of research teams that are currently generating other organismal and molecular information necessary to achieve that knowledge (e.g., Ericson et al., 2006; Livezey and Zusi, 2006, 2007; Mayr, 2008). Indeed, subsequent to the publication of this book, I examined a PhD dissertation that thoroughly reviewed existing information and research on, and conducts novel research on new data to resolve, the relationships of and among palaeognathous birds [ratites (= ostrich-like birds) and tinamous], the most basal lineage of modern birds. “Indeed further”, I am aware of molecular systematics research by Harshman and a range of co-authors currently in review that challenges this new research and previous phylogenetic hypotheses. Now to the “minor” errors. First and foremost is, following (Scotland et al., 2003) Harshman’s asserts that molecular data are the primary, if not only, keys to discovering avian phylogeny. In support of this claim, he cites the too-often-cited paper by Stresemann (1959) who lamented that organismal biology had effectively “run out of gas” in the quest for a phylogeny of birds. Second, he asserts that “The cladistic revolution did little to help…” to deal with this phylogenetic uncertainty. These conclusions just do not withstand inspection of the recent literature. Some of my own research on galliform (chicken-like) birds published recently in this journal (Crowe et al., 2006) has decisively demonstrated the utility (contraScotland et al., 2003) of morphological characters analyzed cladistically in conjunction with molecular information in resolving the supra-generic relationships of birds. Despite his apparent molecular chauvinism, Harshman does call attention to a range of deficiencies still prevalent in avian phylogenetic research. These deficiencies include defence of paraphyletic and polyphyletic groups, basing phylogenetic conclusions on analyses of one data partition only, deficiencies in model-based (e.g., Bayesian) approaches, absence of measures of nodal support and, especially, inadequacies in data and analytical approaches employed by Sibley and Ahlquist (1990) in their phenetic phylogenetic “tapestry” of birds. His own research (e.g., Harshman, 1994) has featured prominently in a more appropriate reassessment of the “tapestry” and has identified many of flaws that exist and gaps that need to be filled. Nevertheless, I wish that he had not concluded his chapter (p. 25) by reiterating the view that “this trend [resolving the ‘uncertain nodes’ of the avian tree of life] will only accelerate as DNA sequencing becomes cheaper and more reliable.”, a position apparently favoured by Mayr (2008). This reminds me of a tongue-in-cheek comment by my old friend Dennis Stevenson: “DNA stands for deoxyribonucleic acid. It does not mean Don’t Need Anatomy”.

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