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Global Species Richness (global + species_richness)
Selected AbstractsEcology and conservation status of temporary and fluctuating ponds in two areas of southern EnglandAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 2 2009D.T. Bilton Abstract 1.A high proportion of ponds are temporary in nature, although the biodiversity value of such sites is still poorly recognized. This work explores the plant and macroinvertebrate communities of 76 temporary and fluctuating water bodies in two regions of southern England (Lizard Peninsula, Cornwall and New Forest, Hampshire) that have retained high pond densities. The ecology and conservation status of sites is examined, and comparisons made with ponds elsewhere in England and Wales. 2.Lizard and New Forest ponds supported 119 plant and 165 macroinvertebrate species respectively. Patterns of community similarity for plants and macroinvertebrates were highly concordant, taxa being related in a similar manner to measured environmental variables including pond area, depth, pH and water chemistry. 3.Patterns of pond occupancy revealed that most species were locally rare, over half occurring in less than 10% of ponds, and less than 10% being recorded from more than 50% of sites. More than 50% of ponds supported at least one nationally rare plant and almost 75% at least one nationally rare macroinvertebrate. These taxa occupied a wide range of pond types in each region, and did not have predictably different ecologies from common species. 4.Comparisons with ponds elsewhere in England and Wales revealed that Lizard and New Forest communities are nationally distinct, being most similar to ponds in areas of low intensity agriculture elsewhere in western Britain. Individual ponds in both regions supported more nationally rare taxa, on average, than ponds sampled in the national survey. 5.Ponds in the two areas have high conservation value, both regionally and nationally, supporting almost 75% of the global species richness of temporary ponds sampled across England and Wales. Within each region, many taxa are found in relatively few sites, and effective conservation of pond biodiversity will require a regional management approach. Copyright © 2008 John Wiley & Sons, Ltd. [source] A tale of two analyses: estimating the consequences of shifts in hexapod diversificationBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2003PETER J. MAYHEW I present a novel descriptive (non-statistical) method to help identify the location and importance of shifts in diversification across a phylogeny. The method first estimates radiation rates across terminal higher taxa and then subjects these rates to a parsimony analysis across the phylogeny. The reconstructions define the magnitude, direction and influence of past shifts in realized diversification rates across nodes. I apply the method to data on the extant hexapod orders. The results indicate that the Coleoptera (beetles) and Diptera (flies) have contributed large upward shifts in diversification tendency, without which, under the model employed, global species richness would be reduced by 20% and 6%, respectively. The origin of Neoptera (insects with wing flexion), identified elsewhere as a significant radiation, may represent a large positive, a large negative or zero influence on current species richness, depending on the assumed phylogeny and parsimony method. The most influential radiations are attributable to the origin of the Eumetabola (insects with complete metamorphosis plus bugs and their relatives) and Pterygota (winged insects), but there is presently only weak evidence that they represent significant shifts in underlying diversification tendency. These analyses support some but not all results of previous phylogenetic analyses and the identity of the most important shift therefore remains elusive. New methodology involving comparisons across multiple taxa is likely to be necessary. © 2003 The Linnean Society of London, Biological Journal of the Linnean Society, 2003, 80, 23,36. [source] Estimating the global species richness of an incompletely described taxon: an example using parasitoid wasps (Hymenoptera: Braconidae)BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 3 2001KONRAD DOLPHIN The need to estimate the magnitude of undescribed species richness arises from the limited resources available to the description and conservation of biodiversity, the continuous loss of diversity that we are currently experiencing, and the sheer scale of the task of accurate measurement. Several estimation methods have previously been described and discussed in some detail, but the reliability of these methods is difficult to assess. In this study, we use two independent methods to predict the global species richness of the subfamilies of the parasitic wasp family Braconidae. The first is to extrapolate from the decreasing rate of species descriptions to the point at which this rate reaches zero. The second method uses the geographical distribution of species in two well-studied taxa (butterflies and mammals) to extrapolate from our knowledge of braconid diversity in the Palaearctic. For the subfamilies which currently contain at least 50 species, there is a significant correlation between the proportions of undescribed species predicted by each method. Each method predicts an average increase of between 100% and 200% for the Braconidae as a whole. Applying the figures we obtain to the class Insecta yields an estimate of 2.05-3.4 million global insect species. [source] | ||||||||||