Positive interspecific relationships between local abundance and extent of regional distribution are among the most ubiquitous patterns in ecology. Although multiple hypotheses have been proposed, the mechanisms underlying distribution-abundance (d-a) relationships remain poorly understood. We examined the intra- and interspecific distribution-abundance relationships for a metacommunity of 13 a...

The abundance of a species is generally expected to peak at the centre of its distribution range and decline towards the range limits. Empirical evidence for such ‘abundant centre’ patterns is, however, limited, particularly for subtidal species. We tested the ‘abundant centre’ hypothesis for 8 fish species endemic to the shallow rocky reefs of south-western Australia. Fish abundances were quan...

The effect of crop species and edaphic factors on the distribution of Trichoderma species in Alfisol soil under different agrosystems was evaluated. Each soil sample was assayed for nine abiotic factors and culturable microfungal populations. Fungal abundance was determined by dilution plate technique, and the identification of fungi was based on morphological characteristics. Pearson’s correla...

Patterns in the commonness and rarity of species are a fundamental characteristic of ecological assemblages; however, testing between alternative models for such patterns remains an important challenge. Conventional approaches to fitting or testing species abundance models often assume that species, not individuals, are the units that are sampled and that species' abundances are independent of ...

Identifying factors regulating variation in numbers of individuals among populations across a species' distribution is a fundamental goal in ecology. A common prediction, often referred to as the abundant-centre hypothesis, suggests that abundance is highest near the centre of a species' range. However, because of the primary focus on the geographical position of a population, this framework pr...

the main diatomic structure-forming species of the zayandehrud reservoir was investigated by collecting samples from the surface, five, seven and 10 m depths from january 2011 to october 2012 along four linear transects. asterionella formosa hassall, cyclotella ocellata pantocsek and fragilaria crotonensis kitton were revealed as the three structure-forming species among diatomic algae in the r...

Description of vegetation patterns associated with environmental factors such as grazing, climate, landforms, substrate variables etc. are helpful for land management planning. This study used new synecological tools to investigate plants composition and to provide ecological descriptions of plants communities of communal pastures in Sahelian Ecological Zone of Niger. Vegetation and several env...

The central themes of community ecology-distribution, abundance, and diversity-display strongly marked and very general patterns. These include the log-normal distribution of abundance, the relation between range and abundance, the species-area law, and the turnover of species composition. Each pattern is the subject of a large literature that interprets it in terms of ecological processes, typ...

The methods of Maximum Entropy have been deployed for some years to address the problem of species abundance distributions. It is important to identify correctly weighting factors, or priors, to be applied before maximising the entropy function subject to constraints. The form of such priors depends not only on the exact problem but can also depend on the way it is set up; priors are determined...