Introduction Species are widely considered a fundamental unit in biology, and this explains to a large extent the continuous efforts to estimate species numbers, both globally and at various taxonomic and geographic levels ( Caley et al., 2014 ; Larsen et al., 2017 ). Speciesrichness is a key
Parasitoid assemblages infesting Yponomeuta species in the Netherlands were investigated. Parasitoid species richness and community composition were related to host species, habitat, temporal and spatial variation. Both community structure and species richness did not differ among habitats. There was no significant difference in species richness between years (1994 and 1995) but there was a significant difference in community composition. Community composition and species richness both differed among host species, although this latter result was solely due to the host species Y. evonymellus. There was no significant relationship between community similarity and distance. These results indicate that the parasitoids of the moth genus Yponomeuta in the Netherlands appear to form a spatially stable, but temporally variable community. Most of the variation in community structure was, however, related to the host species. The marked difference in parasitoid species richness and community composition of Y. evonymellus when compared to the other species warrants further study.
In the study of diversity patterns, the Mid-domain effect (MDE), which explains gradients in diversity solely on the basis of geometric constraints, has emerged as a null-model against which other hypotheses can be tested. The effectiveness, measured by its predictive power, of these MDE models appears to depend on the size of the study area and the range-sizes of the taxa considered. Here we test the predictive power of MDE on the species richness patterns of birds and assess its effectiveness for a variety of species range sizes. We digitised distribution maps of 889 species of songbird endemic to the Palearctic, and analysed the emergent biogeographic patterns with WORLDMAP software. MDE had a predictive power of 20% when all songbirds were included. Major hotspots were located south of the area where MDE predicted the highest species-richness, and some of the observed coldspots were in the centre of the Palearctic, contradicting the predictions of the MDE. MDE had little explanatory power (3-19%) for all but the largest range sizes, whereas MDE performed equal or better for the large-ranged species (20-34%) compared to the overall model. Overall MDE did not accurate explain species-richness patterns in Palearctic songbirds. Subsets of larger-range species did not always have a larger predictive power than smaller-range species or the overall model. Despite their low predictive power, MDE models can have a role to play in explaining biogeographic patterns but other variables need to be included in the model as well.
The distribution of Borneo’s species across the island is far from well-known. This is particularly true for snakes which are hard to find. Given the current rate of habitat destruction and consequent need for conservation strategies, more information is required as to the species composition and richness of specific areas of potential conservation priority. An example is the Santubong Peninsula, Sarawak, Malaysia, part of which has recently been gazetted as a National Park. In this paper, the snake species richness of the Santubong Peninsula is estimated on the basis of data obtained during 450 survey-hours. Thirty-two species were recorded. Negative exponential and Weibull functions were fitted to the rarefaction curve. The Weibull function exhibited a high goodness-of-fit, as opposed to the negative exponential function. On the basis of the fitted Weibull function, the total number of snake species was estimated to be 42. A similar estimate of 40 was obtained by applying the nonparametric Chao I estimator. Thus, less than a third of Borneo’s known 139 land snakes inhabit the Santubong Peninsula. Extrapolation of the fitted Weibull function demonstrated that direct measuring of herpetofaunal species richness of species-rich tropical ecosystems is unfeasible given the required search time. I advocate that the use of estimates is unavoidable.
speciesrichness in mediterranean ecosystems of Australia Mediterranean-type Ecosystems. Specht R.L. Kluwer Academic Publishers Dordrecht 1988 149 155 A Data Source Book Specht R.L. Clifford H.T. The invasion of higher plants into soil seed banks: control by water and nutrients Biogeography of
. Species-richness was estimated on the basis of the species accumulation curve (e.g. Colwell & Coddington, 1994 ). In a species-accumulation curve, the cumulative number of species is plotted against a measure of cumulative sampling effort. As sampling-effort increases, the rate at which new species are
factors on the speciesrichness of native amphibians. This method of analysis is commonly used to model the abundance of a species according to one or several covariates. We here intended to use this method to model the speciesrichness, by considering species as individuals, after verifying if our data
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and Mediterranean population of annual plants grown with and without water stress. Oecologia 93: 336-342.
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Biologists have long discussed the ecological and evolutionary mechanisms underlying large scale spatial patterns in speciesrichness (Chown and Gaston, 2000 ). Reptiles generally have narrower distributional ranges than other vertebrates such as birds and mammals (Anderson