Taxonomic surrogacy in biodiversity assessments, and the meaning of Linnaean ranks

Copyright © 2006 The Natural History MuseumThe majority of biodiversity assessments use species as the base unit. Recently, a series of studies have suggested replacing numbers of species with higher ranked taxa (genera, families, etc.); a method known as taxonomic surrogacy that has an important potential to save time and resources in assesments of biological diversity. We examine the relationships between taxa and ranks, and suggest that species/higher taxon exchanges are founded on misconceptions about the properties of Linnaean classification. Rank allocations in current classifications constitute a heterogeneous mixture of various historical and contemporary views. Even if all taxa were monophyletic, those referred to the same rank would simply denote separate clades without further equivalence. We conclude that they are no more comparable than any other, non-nested taxa, such as, for example, the genus Rattus and the phylum Arthropoda, and that taxonomic surrogacy lacks justification. These problems are also illustrated with data of polychaetous annelid worms from a broad-scale study of benthic biodiversity and species distributions in the Irish Sea. A recent consensus phylogeny for polychaetes is used to provide three different family-level classifications of polychaetes. We use families as a surrogate for species, and present Shannon–Wiener diversity indices for the different sites and the three different classifications, showing how the diversity measures rely on subjective rank allocations.Y. Bertrand, F. Pleijel and G. W. Rous

Outer Bristol Channel marine habitat study : 2003 investigations and results

This report describes the investigations undertaken by the British Geological Survey (BGS) and the National Museums and Galleries of Wales (NMGW) during 2003 for the Outer Bristol Channel Marine Habitat Study, and the results and interpretations completed by March 2004 for the elements of the study funded by the Sustainable Land Won and Marine Dredged Aggregate Minerals Programme of the Office of the Deputy Prime Minister. The complete study is a three year programme which is planned to end in March 2006. The other principal funder of the study is the Aggregate Levy Sustainability Fund for Wales, which is administered by the Welsh Assembly Government. The Crown Estate and the British Marine Aggregate Producers Association have also supported the study with some funding and contributions of data. Pressure on marine resources in the Bristol Channel continues to develop with a number of issues including aggregates, fisheries and wind farm developments. There are also legislative obligations with regard to marine conservation, in a European context with the Habitats Directive and in national initiatives such as the designation of Carmarthen Bay, the Pembrokesire Coast and Lundy as candidate Special Areas of Conservation (cSACs). To inform the policy and decision making process in terms of developments in the marine environment requires knowledge of its current physical state. This includes the morphology, geology, biology and sediments of the seabed. Baseline information on these is essential for strategic management and the conservation of biological diversity. Responsible stewardship requires an understanding of the way the marine environment functions and how the sea may respond to human activity. It also means involving stakeholders as an integral part of policy making. The Bristol Channel Marine Aggregates: Resources and Constraints Research Project (Posford Duvivier & ABP Research, 2000), indicated significant gaps in the biological and geological data available for the Outer Bristol Channel area. The only comprehensive study of the benthic invertebrates (Warwick & Clark 1977) was carried out in 1972-1973 and British Geological Survey maps of the area were based on surveys undertaken from 1971 to 1976

Revision of Aberranta Hartman, 1965 (Aberrantidae : Annelida), with descriptions of new species from the Mediterranean and Hong Kong

Andrew S. Y. Mackie, Fredrik Pleijel, Greg W. Rous

Biological geography of the European seas: results from the MacroBen database

This study examines whether or not biogeographical and/or managerial divisions across the European seas can be validated using soft-bottom macrobenthic community data. The faunal groups used were: all macrobenthos groups, polychaetes, molluscs, crustaceans, echinoderms, sipunculans and the last 5 groups combined. In order to test the discriminating power of these groups, 3 criteria were used: (1) proximity, which refers to the expected closer faunal resemblance of adjacent areas relative to more distant ones; (2) randomness, which in the present context is a measure of the degree to which the inventories of the various sectors, provinces or regions may in each case be considered as a random sample of the inventory of the next largest province or region in a hierarchy of geographic scales; and (3) differentiation, which provides a measure of the uniqueness of the pattern. Results show that only polychaetes fulfill all 3 criteria and that the only marine biogeographic system supported by the analyses is the one proposed by Longhurst (1998). Energy fluxes and other interactions between the planktonic and benthic domains, acting over evolutionary time scales, can be associated with the multivariate pattern derived from the macrobenthos datasets. Third-stage multidimensional scaling ordination reveals that polychaetes produce a unique pattern when all systems are under consideration. Average island distance from the nearest coast, number of islands and the island surface area were the geographic variables best correlated with the community patterns produced by polychaetes. Biogeographic patterns suggest a vicariance model dominating over the founder-dispersal model except for the semi-closed regional seas, where a model substantially modified from the second option could be supported.