Search results for " species turnover"
showing 3 items of 3 documents
Diversity patterns and biogeography of Diaptomidae (Copepoda, Calanoida) in the Western Palearctic
2017
Diaptomid copepods are an important component of biodiversity in inland aquatic ecosystems worldwide but to date little is known about the historical and ecological factors that determined their current distribution. In the present paper, a critical review of the available literature on diaptomid species distribution in the Western Palearctic was performed, and a biogeographical analysis was carried out on the roles that spatial, current environmental, and historical (paleoclimatic) factors played on their actual distribution in this large area. The results show a clear pattern of colonization which is only partially overlapping what has been recently proposed for other terrestrial and aqua…
An “Uncertainty Principle” for the Mediterranean annual dry grasslands
2009
Preliminary results of diachronic researches on the spatial arrangement and species richness in Mediterranean annual dry grasslands (Tuberarietea guttatae) demonstrated that the patchiness resulted minimized and the temporal stability maximized at elevations offering the best compromise between the summer drought stress and the winter cold stress. Moreover, the temporal stability of the Mediterranean annul dry grasslands could not necessarily be related with their demographic inertia, meaning that the turnover and rearrangement of species within the community do not necessarily implicate significant changes in the average species composition over time. On the other hand, the survival chance…
Effects of temperatures on the spatial arrangement in Mediterranean annual dry grasslands
2009
Some preliminary results of diachronic researches on the spatial arrangement and species richness in Mediterranean annual dry grasslands belonging to the class Tuberarietea guttatae are presented. Our results are based on 12 permanent plots, set in three places at different heights in Southern and Central Sardinia. Sites were chosen to have annual species richness and plant density not significantly different. The relationship between patchiness and temporal stability was investigated at the scale of the square plots. We used the mean abundance divided by the SD in abundance (S = xm/r), as the measure of temporal stability of populations (Tilman 1999) and the Shannon-Wiener index to evaluat…