plants and arthropods are the main elements of biodiversity in ecosystems. in order to evaluate structural biodiversity of plants and arthropods in natural systems of arid land, a study was carried out in shirvan, mashhad and gonabad, three regions of razavi and northern khorasan provinces, iran. in each region, 10 areas of natural systems selected and sampling was done in these selected areas....

While we frequently observe that increasing species richness within a trophic level can increase the rates of predation or herbivory on lower trophic levels, the general impacts of prey diversity on consumption rates by their predators or herbivores remains unclear. Here we report the results of two field experiments that examined how subcanopy sessile species richness affects rates of consumpt...

Allen H. Hurlbert* and Ethan P. White Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA *Correspondence: E-mail: [email protected] Present address: Ethan P. White, Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT 84322, USA Abstract Species richness patterns are characterized either by overlaying species range maps or by compiling geographical...

The importance of landscape heterogeneity to biodiversity may depend on the size of the geographic range of species, which in turn can reflect species traits (such as habitat generalization) and the effects of historical and contemporary land covers. We used nationwide bird survey data from Japan, where heterogeneous landscapes predominate, to test the hypothesis that wide-ranging species are p...

Aim Patterns of species richness are often closely linked with climate, but the specific mechanisms by which species’ climatic niches underlie large-scale richness patterns remain poorly understood. It has been hypothesized that reduced temperature seasonality in the tropics promotes the evolution of species with narrow temperature niche breadths, and that this hypothesis helps explain high tro...

A major goal of research in ecology and evolution is to explain why species richness varies across habitats, regions, and clades. Recent reviews have argued that species richness patterns among regions and clades may be explained by "ecological limits" on diversity over time, which are said to offer an alternative explanation to those invoking speciation and extinction (diversification) and tim...

Why does species richness vary so greatly across lineages? Traditionally, variation in species richness has been attributed to deterministic processes, although it is equally plausible that it may result from purely stochastic processes. We show that, based on the best available phylogenetic hypothesis, the pattern of cladogenesis among agamid lizards is not consistent with a random model, with...

We study how species richness of arthropods relates to theories concerning net primary productivity, ambient energy, water-energy dynamics and spatial environmental heterogeneity. We use two datasets of arthropod richness with similar spatial extents (Scandinavia to Mediterranean), but contrasting spatial grain (local habitat and country). Samples of ground-dwelling spiders, beetles, bugs and a...