2 research outputs found
Do Small Animals have a Biogeography?
12 paginas, 4 figuras, 4 tables..It has been stated that small organisms do not have barriers for distribution and will not show biogeographic discreteness. General models for size-mediated biogeographies establish a transition region between ubiquitous dispersal and restricted
biogeography at about 1–10 mm.Wetested patterns of distribution versus size
with water mites, a group of freshwater organisms with sizes between 300 lm and
10 mm.We compiled a list of all known water mite species for Sierra del Guadarrama
(a mountain range in the centre of the Iberian Peninsula) from different authors and
our own studies in the area. Recorded habitats include lotic, lentic and interstitial environments. Species body size and world distribution were drawn from our work and published specialized taxonomic literature. The null hypothesis was that distribution is size-independent. The relationship between distribution and size was approached via analysis of variance and between size and habitat via logistic regression. Contrary to expectations, there is no special relationship between water mite size and area size distribution. On the other hand, water mite size is differentially distributed among
habitats, although this ecological sorting is very weak. Larger water mites are more
common in lentic habitats and smaller water mites in lotic habitats. Size-dependent
distribution in which small organisms tend to be cosmopolitan breaks down when the
particular biology comes into play. Water mites do not fit a previously proposed sizedependent biogeographical distribution, and are in accordance with similar data
published on Tardigrada, Rotifera, Gastrotricha and the like.This study was supported by projects EVK2-CT-2001-00121 (PASCALIS), GR/AMB/0750/2004 and CGL2005-02217.Peer reviewe