Influência do gradiente altitudinal na composição da fauna de pequenos mamíferos em áreas de Mata Atlântica
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Data
2015-08-28
Autores
Vale, Victor
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Universidade Federal do Espírito Santo
Resumo
The Atlantic Forest is the biome with the largest altitudinal gradient in Brazil, where seven of the highest mountains in the country are located, and areas in the Espìrito Santo state alone cover the whole gradient. Consequently, this singularity makes this an ideal region to investigate the effects of the altitudinal gradient on the richness, diversity and the differential composition of non-volant small mammals communities. So, the aim of this study was to test the hypothesis of changes in non-volant small mammal composition along an elevational gradient covering a span of 3000m, divided into six intervals of 500m each. In order to accomplish that, and to fulfill the whole gradient, a survey was conducted in two protected areas of Espìrito Santo state: Forno Grande State Park (PEFG) (elevation from 1000 to 2000 m above sea – an interval gap of data) and Mata das Flores State Park (PEMF) (0 to 500 m above sea). For other intervals, we used data either from the literature and/or from zoological collections databases available on-line. The total sampling effort of the conducted surveys was 4182 traps/night. Richness, relative frequency and diversity indexes for species were calculated for each altitudinal interval. The similarity of species composition between intervals and between Conservation Units (CUs) was evaluated employing analysis of the relative frequency of each species, using the Jaccard and Sorensen indexes of similarity according to UPGMA analysis and, additionally, through the Coefficient of Biogeographical Resemblance (CBR). The surveys resulted in three species (H' = 1.099) registered in PEMF and 17 species (H' = 2.833) in PEFG. Total species richness was higher at intermediate altitudes (500-1000 m), followed by the low elevation interval (0-500m); this pattern was maintained for marsupials, while for rodents highest indexes of richness were found between 500-2000m. Species diversity were higher at intermediate elevations (500-1000 m,), followed by high elevation areas (1500-2000 m). The interval between 1000 and 1500 presented lower diversity levels, when compared to the ones immediately anterior and posterior to it. The CBR analysis resulted in highest coefficients between adjacent intervals, particularly for those in higher elevations, while for the analysis with the UCs, the highest CBR was found between the PEFG (located in an intermediate interval) and the all the others. In the UPGMA analysis higher elevational gradients (2000-3000 m) were grouped separately from all others, and concerning the CUs, medium and higher elevation areas were grouped to the exclusion of areas at low elevations. The higher richness and diversity indexes found for intermediate elevations, for both marsupials and rodents, resulted from the co-occurrence of taxa in these intervals, overlapping species typical of lower and higher altitudes in addition to the ones commonly found at intermediate altitudes. Along the studied elevational gradient, the richness of marsupials is high until the 500-1000m interval, and then decreases almost linearly; while it is maintained high for rodents until 1500-2000 m, when then a pronounced decline is observed. The prominent resemblance between adjacent altitudinal reflects the pronounced faunal similarity among these intervals, and it is expected. Nevertheless, the highest coefficients were found for higher altitudes, possibly due to the fact that these areas share a greater proportion of endemics and/or habitat specialists; yet, the loss of species in disturbed areas of low altitude can also contribute to the pattern observed. An evident fauna replacement was recorded between 1500-2000 m, especially for species of the genera Akodon, Delomys, Oligoryzomys and Oxymcterus. Consequently, mountain ranges, and the above mentioned taxa, can act as good systems and operation units, in studies aiming to uncover the effects of climate change on the species distribution in the Atlantic Forest.
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Diversity , Richness , Riqueza , Similarity , Similaridade , Distribution Patterns , Padrões de Distribuição , Espírito Santo
Citação
VALE, Victor. Influência do Gradiente Altitudinal na Composição da Fauna de Pequenos Mamíferos em Áreas de Mata Atlântica. 2015. 90 f. Dissertação (Mestrado em Biologia Animal) - Universidade Federal do Espírito Santo, Biologia Animal, Programa de Pós-Graduação em Ciências Biológicas, Vitória, 2015.