Mann D.G.,Royal Botanic Garden Edinburgh
Plant Ecology and Evolution | Year: 2010
Background - Now and in the past, species discovery in diatoms begins, and often ends, with a survey of morphological variation to find breaks in the variation pattern that allow diagnosable entities to be defined and named. For this process to be effective, it needs to be informed by an understanding of the mechanisms that generate variation and many mistakes were made in the early 19 th century because of poor knowledge of the diatom life cycle and phenotypic plasticity; some taxonomically important life-cycle characteristics were not properly documented until 1932. Acceptance of the Darwinian view of species as taxa arbitrarily set along a continuum of divergence was accompanied in the late 19 th and early 20 th century by description of many varieties and forms; most recently described taxa, on the other hand, have been species. The neo-Darwinian emphasis on reproductive isolation as an important factor in speciation, introduced during the 'New Synthesis' of the 1940s, did not become influential in diatom taxonomy until the 1970s. It has since been a source of controversy, some seeing it as having no place in taxonomy, others regarding it as a useful aid to the detection of species boundaries, alongside character-based approaches, both morphological and molecular. Review - This paper discusses changes in how species have been discovered and circumscribed in diatoms, and seeks to establish whether there is a basis for consensus in future work in this field. Conclusion - Whereas morphology is currently still the primary tool for discovering diatom species diversity, molecular methods may be more cost-effective in future and are the only practical means of exploring cryptic (including pseudocryptic) diversity, which appears to be widespread. By treating species as separately evolving metapopulation lineages, as recommended by de Queiroz, different approaches can be accommodated (including tests of reproductive compatibility), providing a framework within which conflicting results can be analysed and reconciled.
Mill R.R.,Royal Botanic Garden Edinburgh
Edinburgh Journal of Botany | Year: 2014
The taxonomic history of the genus Podocarpus (Podocarpaceae) is reviewed as the first part of a revision of the genus. The major taxonomic and other works relating to the genus published during nine time periods (before 1800, 1800-1850, 1851-1875, 1876-1900, 1901-1926, 1927-1947, 1948-1967, 1968-1987 and 1988-present) are briefly but critically discussed. Three landmark works are those by Pilger (1903), Buchholz and Gray (between 1948 and 1962) and de Laubenfels (1985). The paper ends with an outline plan of the revision of the genus to which the paper forms an introduction. Copyright © Trustees of the Royal Botanic Garden Edinburgh 2014.
McNeill J.,Royal Botanic Garden Edinburgh |
McNeill J.,Royal Ontario Museum
Taxon | Year: 2014
As specification of a holotype has only been necessary for valid publication of a name of a species or infraspecific taxon since 1 January 1990, for names published before that date it is often uncertain if a holotype exists, and, if it does, where it is located. The rules governing holotype recognition are outlined and suggestions for best practice are made. © International Association for P.ant Taxonomy (IAP.) 2014.
Ellis C.J.,Royal Botanic Garden Edinburgh
Perspectives in Plant Ecology, Evolution and Systematics | Year: 2012
The forest canopy is fundamentally important in biodiversity conservation and ecosystem function. Cryptogamic epiphytes are dominant tree bole and canopy elements in temperate and boreal forests, though remain neglected by mainstream forest ecology. This review makes ecological information on cryptogamic epiphytes available to a non-specialist audience, to facilitate their integration in forest biodiversity and ecosystem studies more generally. The review focuses specifically on lichen epiphytes, highlighting their diversity and ecosystem role. A principal task is to explore pattern and process in lichen epiphyte diversity - species composition and richness - therefore demonstrating the utility of lichens as an ecological model system. The review examines key themes in previous research. First, the extensive literature used to resolve species response to, and community turnover along environmental/resource gradients, consistent with the habitat niche. Second, the evidence for dispersal-limitation, which may constrain community composition and richness in isolated habitats. Third, these two processes - the habitat niche and dispersal-limitation - are used to explain stand-scale diversity, in addition to the role of neutral effects (habitat area). Fourth, the review moves from a taxonomic (pattern) to a functional (process) perspective, considering evidence for autogenic succession evidenced by competition and/or facilitation, and non-random trends in life-history traits. This functional approach provides a counter-point to an assumption that lichen epiphyte communities are unsaturated and non-competitive, a situation which would allow the long-term accumulation of species richness with temporal continuity. Finally, the review explores landscape-scale impacts on lichen epiphytes, with recommendations for conservation. © 2011 Perspectives in Plant Ecology, Evolution and Systematics.
Ellis C.J.,Royal Botanic Garden Edinburgh
Systematics and Biodiversity | Year: 2011
This Perspective examines progress, challenges and emerging directions in bioclimatic modelling. The field of bioclimatic modelling provides a toolkit which is widely used to examine the biodiversity response to climate, including future scenarios of climate change. Bioclimatic modelling has been the subject of intense research in statistical ecology; here I trace its development from a highly researched statistical foundation towards a framework that increasingly incorporates the ecological detail of a species' climatic sensitivity. However, as models become more complex (with greater ecological realism) a choice emerges between two approaches: (i) greater model complexity and biological realism - especially where applied to specific conservation problems; and (ii) acceptance of simple bioclimatic tools as a useful albeit limited component, within a mixed evidence-base to assess climate change threat and conservation action. I conclude that whole-organism biologists working at museums and botanic gardens should claim an increasing stake in the bioclimatic framework, especially as the field develops towards an improved biology, towards the integration of new forms of evidence (evolutionary biology, long-term monitoring, expert knowledge, etc.), and in order to force the expansion from model systems (e.g. birds, butterflies, trees), to biodiversity more generally. © 2011 The Natural History Museum.