Edited by A. Solem and A. C. van Bruggen, ix+289 pp., E.J. Brill/W. Backhuys, Leiden, 1984. ISBN 90 04 074171.
Originally reviewed by D T Holyoak in 1985.
Published in Journal of Conchology (1985), Vol.32
Widespread interest in the biogeography of land and feshwater Mollusca led to a 'Colloquium on Non-marine Mollusc Biogeography' being held at the 8th International Malacological Congress in Budapest, Hungary in 1983 This collected work presents the text of the 19 main papers presented at the Colloquium.
The balance of papers in this book shows how the emphasis of studies in molluscan biogeography has mainly moved on from descriptive to analytical approaches. Thus for example there are studies of colonisation of newly emerging islands by land snails (Valovirta); of species numbers on islands (Cook, Mylonas, Solem); of equilibrium species numbers and the chemistry of lakes (Aho); as well as studies of the effects of climatic history on the faunas of tropical (Verdcourt), arid (Heller) and temperate regions (Grossu).
The role of earth history in explanation of patterns of distribution is submitted to critical analysis on several time scales ranging from the role of continental drift in explaining inter-continental differences and similarities of faunas (Meier-Brook, Walker) through analyses of details of faunal exchanges at edges of colliding plates and plate fragments (Giusti & Manganelli, Mordan, Walden), to studies of responses to climatic fluctuations in the Quaternary. Nonetheless, although several authors critically appraise the pertinent palacontological data, others do not and in some cases there is little fossil evidence to assess so that reconstructions of former patterns ol distribution may be viewed as speculative models rather than established fact.
Another trend evident in studies of molluscan biogeography is towards a blurring of traditional distinctions between ecology and biogeography, as these approaches are increasingly often shown to be complementary. In this context the paper presenting 'A world model of land snail ‘diversity and abundance' by Solem is of particular importance in identifying the need for further studies of the interaction of life-history, habitat and longer term geological history in determining the numbers of land snail species found coexisting. It is perhaps remarkable that despite the potential importance of interspecific competition (or the lack of it) in providing restraints on species numbers there have been remarkably few rigorous demonstrations of the extent of competition between natural land snails populations.
Several more traditional zoogeographical studies presented here adopt descriptive approaches and seek patterns of faunal affinity Thus, van Bruggen and Meredith describe the rapidly increasing knowledge of land snails in Malawi Szekeres describes the wider affinities as well as patterns of regional endcmism of South American Clausiliidae Smith reviews regional endemism in Australian land snails, and patterns of faunal affinity are discussed for Madeira (Walden) and Rumania (Grossu). Interpretation of patterns of distribution through inference of faunal history is the main aim of most of these studies. In contrast, Andre presents studies on the land snail faunas of Mediterranean parts of France and the Iberian Peninsula where the main aim appears to be quantitative measurement and classification (aided by computer) of the extent of similarity in numerous local faunas.
The importance of a sound basis of systematic studies is stressed by several of the authors, and exemplified by Gittenberger's review of distributional history in the Chondrininae or Mordan's for the Emdae of southern Arabia. Other authors comment that inadequate current levels of systematic understanding hinder detailed biogeographical study, as for example with Lymnaeidae.
Overall this book is to be recommended to biogeographers in general for the wealth of interesting material and different approaches it contains. Differences from the better known studies in vertebrate zoogeography are instructive because of the greater antiquity of many of the molluscan groups and their different dispersive abilities For malacologists especially interested in land or freshwater molluscs it provides a valuable synthesis in English of material that is otherwise widely scattered, along with several important new contributions. The book is well produced in paperback, with numerous maps and other figures. It is also well indexed.