Distribución y partición aditiva de la diversidad de las comunidades de moluscos de agua dulce en arroyos del Sur de Brasil.

Abstract

Additive partitioning of species diversity is a promising approach for analyzing patterns of diversity in mollusk communities, especially their spatial distribution. Our aims were to assess the distribution of mollusk communities in Southern Brazilian streams, and to evaluate the partitioning of community diversity at different spatial scales. The study was carried out in the lower course of the Toropi River, one of the main tributaries of the Ibicuí River Basin, in Southern Brazil. Four microbasins were considered: Sertão da Mata, Ribeirão, Tororaipi and Chiniquá, and sampling were undertaken in autumn, April and May 2009. Six sites were sampled in each stream: two in 1 st -order segments, two in 2 nd -order segments, and two in 3 rd -order segments. All species found and the community as a whole, exhibited a clumped distribution. However, the variance-to-mean ratios for the Drepanotrema kermatoides and Heleobia bertoniana were higher than those of other species, suggesting a higher degree of aggregation. The additive partitioning of the species richness showed that the observed richness at smallest scale (α=within streams) represented 20.7%, and among-streams (β 1 ) represented 10.5% of the total richness. The richness and Shannon diversity index observed at the alpha scale, were higher than those observed at the first level of beta diversity scale (β 1 =among-streams). The interaction between passive dispersal, tolerance to changes in some environmental variables, abiotic factors, and clumped distribution might have determined the spatial distribution of the communities studied. The greatest variation at the larger scales of analysis, involving among-orders and among-microbasins (β2 and β3, respectively) components, was expected, considering that the increase in distance leads to greater differences in richness (higher beta diversity). In conclusion, our results showed that the clumped distribution influenced the partition of the diversity of the mollusk communities in the streams studied. Dispersal methods and tolerance to variations in abiotic factors also have important roles in determining high alpha diversity. The partitioning of diversity showed that to preserve limnetic mollusks, it is important to preserve local areas, i.e., streams. Accordingly, conservation of streams on a local scale will contribute to conservation of the entire basin and maintenance of regional diversity (gamma). Rev. Biol. Trop. 62 (1): 33-44. Epub 2014 March 01.Key words: distribution, Neotropics, spatial scale, beta diversity, clumped.Species diversity in an area is important for examining many important questions in ecology as well as for the development of management actions for conserving biodiversity (Engen, Saether, Sverdrup-Thygeson, Grotan & Odegard, 2008). However, spatial patterns of species diversity change over multiple scales (Collier & Clements, 2011). The pattern observed within a local community might be very different from these found over broader areas such as landscapes or regions (Crist, Veech, Ger...

The genus Anisancylus Pilsbry, 1924 (Planorboidea, Ancylinae) in South America: species distribution and new records

“…7). ARGENTINA: Córdoba (Rumi et al 2006, Rumi et al 2008, Ovando et al 2014; Cabana (Ovando et al 2014 ; Alegrete ; Toropi River Basin, Toropi (Martello et al 2014). CHILE (ANSP 124236, USNM 573469): Aconcagua: Estero San Isidro, Quillota; Estero San Pedro, Quillota Lanzer 1994, Santos 2000); Capilla Caleu (Ohlweiler and Lanzer 1993, Santos 1994, Santos 2003a (Ohlweiler and Lanzer 1993).…”

Effects of spatial distances on the assemblage dissimilarity of macroinvertebrates with different dispersal pathways and abilities in southern Brazilian streams

“…Macroinvertebrates were preserved in 70% ethanol and archived in the collection of Aquatic Insects of the Federal University of the Pampa (UNIPAMPA, São Gabriel campus [RS], Brazil). Previous studies conducted in the same area have separately addressed the spatial distribution of some of the taxa included in this study (Braun, Pires, Kotzian, & Spies, 2014;Figueiredo, Pires, Davanso, & Kotzian, 2013;Martello, Hepp, & Kotzian, 2014;Martello, Kotzian, & Erthal, 2017;Maxwell et al, 2020;Sá, Santin, Amaral, Martello, & Kotzian, 2013).…”