A comparative analysis of nested subset patterns of species composition

Abstract

We present a broad comparative assessment of nested subsets in species composition among ecological communities. We assembled presence-absence data from a broad range of taxa, geographic regions, and spatial scales; and subjected this collection of datasets to common analyses, including a variety of metrics for measuring nestedness and null hypotheses against which to evaluate them. Here we identify ecological patterns in the prevalence and strength of nested subset structure, and assess differences and biases among the available methodologies. In all, we compiled 279 presence-absence matrices, of which 163 do not overlap in their coverage of species and sites. The survey includes studies on vertebrates, arthropods, mollusks, plants, and other taxa; from north temperate, tropical, and south temperate latitudes. Our results were as follows. Statistically significant nestedness was common. Assemblages from landbridge archipelagos were strongly nested, and immigration experiments were least nested. This adds further empirical support to the hypothesis that extinction plays a major role in producing nested structure. Nestedness was positively correlated with the ratio of the areas of the largest and smallest sites, suggesting that the range in area of sites affects nestedness. Taxonomic differences in nestedness were weak. Higher taxonomic levels showed stronger nesting than their constituent lower taxa. We observed no effect of distance of isolation on nestedness; nor any effects of latitude. With regard to methodology, the metrics Nc and Ut yielded similar results, although Nc proved slightly more flexible in use, and deals differently with tied sites. Similarities also exist in the behavior of N0 ("N") and Up, and between N1 and Ua. Standardized nestedness metrics were mostly insensitive to matrix size, and were useful in comparative analyses among presence-absence matrices. Most metrics were affected by the proportion of presences in the matrix. All analyses of nestedness, therefore, should test for bias due to matrix fill. We suggest that the factors controlling nested subset structure can be thought of as four filters that species pass to occur at a site: a sampling filter, a distance filter, a habitat filter, and an area filter - and three constraints on community homogeneity: evolutionary history, recent history, and spatial variation in the environment. The scale of examination can also have important effects on the degree of nestedness observed.

Influences of Island Characteristics on Plant Community Structure of Farasan Archipelago, Saudi Arabia: Island Biogeography and Nested Pattern

“…Nestedness appears to be a common phenomenon of insular flora (Kadmon, 1995;Wright et al, 1998;Honnay et al, 1999;Koh et al, 2002). Similarly, the present study detected a high degree of nestedness for the entire flora and for each ecological group.…”

“…To determine the significance of T (observed temperature) it is compared with the distribution of simulated temperatures produced by randomization of the matrix in Monte Carlo simulations (500 iterations). This method was used because of its statistical properties and because it can be directly compared among different taxonomic and ecological groups (Wright et al, 1998).…”

“…Similarly, the present study detected a high degree of nestedness for the entire flora and for each ecological group. Wright et al (1998) suggested that four filters operate to screen species occurrence in insular habitats and produce nested biotas. Among these were area and distance effects, passive sampling and www.intechopen.com The area filter appears to be the most important in Farasan archipelago.…”

“…Diverse biotic and abiotic processes are believed to generate nested distributions, including selective extinction (Atmar & Patterson 1993;Wright et al, 1998), differential colonization (Kadmon, 1995), nested habitats (Wright et al, 1998;Honnay et al, 1999), and differential environmental tolerances among species (Fleishman et al, 2007). Differences in environmental tolerances among species may interact with nested habitats to produce nestedness.…”

Checklist, diversity and distribution of testate amoebae in Chile

“…Nested analysis predicts the existence of a highly ordered system in which taxa composition in depauperated sites tend to be simple subsets of richer ones (i.e. a nested pattern) (Wright et al 1998;Fernández 2015). We used the method of Atmar and Patterson (1993) and the temperature metric (T • ) to explore the occurrence of a nested pattern.…”