Protist Diversity and Geographical Distribution (Topics in Biodiversity and Conservation, 8)

There is still a widespread belief that microscopic organisms, such as bacteria, fungi, protists, and small multicellulars, have a cosmopolitan distribution due to a presumed easy dispersal by wind and water. However, the contributions collected in this book – ranging from protists to rotifers and mosses – show that microorganisms have community structures and biogeographies similar to those found in animals and vascular plants, although the ranges of many can be wider and local endemism is rarer. Accordingly, the cosmopolitan distribution model of Finlay & Fenchel is to be replaced by the moderate endemicity model of Foissner, which assumes that one third of microscopic organisms are morphological and/or genetic endemics. This has far-reaching consequences for estimates of the number of species and their conservation. There is convincing evidence that we know only about 20% of the actual diversity in many protist groups, especially saprotrophs and heterotrophs such as amoebae, flagellates, and ciliates. It is probable that this great diversity of microscopic organisms is caused by low extinction rates over geological time, and short generation times which foster dispersal of genetic variants. That the great diversity of microorganisms has remained unrecognized for such a long time has several reasons, of which the most serious is a shortage of taxonomists. Considering the dramatic losses of habitats occurring, especially in the tropics, a large portion of the Earth’s protist biodiversity will disappear before it has been discovered. Reprinted from __Biodiversity and Conservation__, volume 17:2 (2008) Conservation and biodiversity of protists The conservation of biodiversity is not just an issue of plants and vertebrates. It is the scarcely visible invertebrates and myriads of other microscopic organisms that are crucial to the maintenance of ecological processes on which all larger organisms and the composition of the atmosphere ultimately depend. Biodiversity and Conservation endeavours to take an holistic view of biodiversity, and when the opportunity arises to issue collections of papers dealing with too-often neglected groups of organisms. The protists, essentially eukaryotes that cannot be classi?ed in the kingdoms of animals, fungi, or plants, include some of the lea- known groups of organisms on earth. They are generally treated as a separate kingdom, commonly named Protista (or Protoctista) in textbooks, but in reality they are a mixture of organisms with disparate a?nities. Some authors have hypothesized that the numbers of protists are not especially large, and that many have extraordinarily wide distributions. However, the p- ture that unfolds from the latest studies discussed in this issue is di?erent. There are many species with wide ranges, and proportionately more cosmopolitan species than in macroorganism groups, as a result of their long evolutionary histories, but there are also de?nite patterns and geographical restrictions to be found. Further, some protists are linked to host organisms as mutualists or parasites and necessarily con?ned to the distributions of their hosts. Front Matter....Pages I-VII Protist diversity and distribution: some basic considerations....Pages 1-8 Distribution and diversity of aquatic protists: an evolutionary and ecological perspective....Pages 9-25 “Missing” protists: a molecular prospective....Pages 27-42 Diversity, dispersal and biogeography of bryophytes (mosses)....Pages 43-50 Myxomycete diversity and distribution from the fossil record to the present....Pages 51-67 Diversity and endemism in Rotifera: a review, and Keratella Bory de St Vincent....Pages 69-82 Diversity and geographic distribution of benthic foraminifera: a molecular perspective....Pages 83-94 Diversity and biogeography of testate amoebae....Pages 95-109 Diversity and geographic distribution of ciliates (Protista: Ciliophora)....Pages 111-129 The “ Tetrahymena pyriformis ” complex of cryptic species....Pages 131-146 Diversity and geographic distribution of desmids and other coccoid green algae....Pages 147-158 The diversity and distribution of diatoms: from cosmopolitanism to narrow endemism....Pages 159-171 Dinoflagellate diversity and distribution....Pages 173-184 Dispersal and biogeography of silica-scaled chrysophytes....Pages 185-192 Conservation of protists: is it needed at all?....Pages 193-209 Back Matter....Pages I-I Europe is certainly the most intensively inventoried region of the world. This book brings together a selection of original studies submitted to "Biodiversity and Conservation" that address biodiversity and conservation in Europe