Time filter

Source Type

Edinburgh, United Kingdom

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. Source

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. Source

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. Source

Simon M.F.,Embrapa Recursos Geneticos e Biotecnologia | Pennington T.,Royal Botanic Garden Edinburgh
International Journal of Plant Sciences | Year: 2012

A recent controversy concerns whether plant traits that are assumed to be adaptations to fire originally evolved in response to selective factors other than fire. We contribute to this debate by investigating the evolution of the endemic woody flora of the fire-prone Cerrado of central Brazil, the most species-rich savanna in the world. We review evidence from dated phylogenies and show that Cerrado lineages started to diversify less than 10 million years ago. These Cerrado lineages are characterized by fire-resistant traits such as thick, corky bark and root sprouting, which have been considered to have evolved as adaptations to drought or nutrient-deficient soils. However, the fact that the lineages carrying these features arose coincident with the rise to dominance of flammable C4 grasses and expansion of the savanna biome worldwide, and postdating the earlier origin of seasonal climates and the nutrient-poor, acid Cerrado soils suggests that such traits should be considered as adaptations to fire regimes. The nature of these features as adaptations to fire is further suggested by their absence or poor development in related lineages found in fire-free environments with similar edaphic conditions to the Cerrado and by their repeated independent origin in diverse lineages. We present evidence to demonstrate that the evolutionary barrier to entry to the Cerrado is a weak one, presumably because of the ease of evolution of the necessary adaptations to fire regimes for lineages inhabiting neighboring fire-free biomes. © 2012 by The University of Chicago. All rights reserved. Source

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. Source

Discover hidden collaborations