Dissertação
Podem pequenas variações na altitude e na ordem de riachos influenciar a estrutura das comunidades de moluscos?
Fecha
2012-05-31Registro en:
SÁ, Roger Lopes de. Can small changes in altitude and order of streams, influence the community structure of mollusks? 2012. 69 f. Dissertação (Mestrado em Ciencias Biológicas) - Universidade Federal de Santa Maria, Santa Maria, 2012.
Autor
Sá, Roger Lopes de
Institución
Resumen
The influence of small gradients of altitude (0-500 meters) and order (1st to 4th) in the
spatial distribution of mollusk communities was studied, based on 40 samples collected in a
watershed of a temperate climate region, in Brazil. Richness was higher in lower ranges of
altitude (0-100), and increased with the increase of orders, independently of altitude.
However, composition and proportional abundance of species of the communities were not
structured by the environmental gradients. The small influence of landscape factors on the
spatiality of many abiotic factors, and the tolerance of many species to variations in the
environmental factors analyzed determined these results. The proximity of the lower of
altitudes with a transitional relief area, and the large width of the 4th order streams, which
favored a higher number of ecological niches, provided higher complexity to the sites
localized in these areas, allowing the occurrence of higher richness. The existence of patchy
spatial structured pattern in good environmental conditions determined the absence of the
proportional abundance of species. However, few landscape heterogeneity and possibly,
interference of vertebrate vectors in the dispersion of the freshwater mollusks hinder to find
clear patterns of spatial distribution.