Niche Separation in Community Analysis: A New Method

Abstract

The design and objective of a community study imply the selection of the appropriate ordination technique in terms of species response models and weighting options. In this paper, we start from the observation that existing two‐table ordination techniques and related measures of niche breadth inevitably weight a sample in proportion to its abundance. We introduce a new multivariate method, which gives a more even weight to all sampling units, including those which are species poor or individual poor. We use this new method of analysis which we call OMI (for Outlying Mean Index) to address the question of niche separation and niche breadth. The Outlying Mean Index, or species marginality, measures the distance between the mean habitat conditions used by species (species centroid), and the mean habitat conditions of the sampling area (origin of the niche hyperspace), and OMI analysis places species along habitat conditions using a maximization of their mean OMI. Therefore, the position of the species depends on their niche deviation from a reference, which represents neither the mean nor the most abundant species, but a theoretical ubiquitous species that tolerates the most general habitat conditions (i.e., a hypothetical species uniformly distributed among habitat conditions). We demonstrate that OMI analysis is well suited for the investigation of multidimensional niche breadths in the case of strong limiting factors (e.g., meteorological conditions) or strong driving forces (e.g., longitudinal stream gradient). Furthermore, the analysis helps in finding which ecological factors are most important for community structure and organization and provides a separation of species based on their niche characteristics.

Rates of ecological divergence and body size evolution are correlated with species diversification in scaly tree ferns

“…Details of the modelling procedure are outlined in the electronic supplementary material. The outlying mean index (OMI) [38] multivariate ordination was used to study the separation of species' niches in a multivariate ecological hyperspace. Basically, OMI estimates the deviation of a species' ecological niche from a reference centre representing the general environmental conditions encountered by the sampled community [38].…”

“…The outlying mean index (OMI) [38] multivariate ordination was used to study the separation of species' niches in a multivariate ecological hyperspace. Basically, OMI estimates the deviation of a species' ecological niche from a reference centre representing the general environmental conditions encountered by the sampled community [38]. We performed OMI on a presence/absence matrix of species and a matrix of environmental conditions (see electronic supplementary material, Methods).…”

Ecological segregation of bark beetle (Coleoptera, Curculionidae, Scolytinae) infested Scots pine

“…Although many studies have addressed the effects of biotic interactions on the populations of species from different taxonomic groups (e.g. Mysterud 2000;Julliard et al 2006;Dole´dec et al 2008;Young 2008), only a few publications have been conducted related to bark beetles. A few studies describe the biotic interactions of insects from the subfamily Scolytinae in spruce Picea abies L.…”

Indices of Biodiversity Pattern Based on Presence-Absence Matrices: A GIS Implementation

“…Ideally, integration should also strive to express theoretical relationships among different views of biodiversity, preferably in a statistical or mathematical way. It is already possible to analyze statistically multiple views of biodiversity, as it has been demonstrated by a number of authors (Doledec et al 2000;Doledec et al 1996;Leibold et al 2010). In this way a fuller understanding of how different aspects of biodiversity are related, and how, can be achieved.…”