Banca de DEFESA: JAQUELINE DE OLIVEIRA MONTEIRO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : JAQUELINE DE OLIVEIRA MONTEIRO
DATE: 31/05/2023
TIME: 09:00
LOCAL: Instituto de Biologia
TITLE:

Understanding the diversity of anuran amphibians in elevation gradient in Chapada Diamantina, northeastern Brazil

KEY WORDS:

Amphibia; Anura; Caatinga; composition; diversity; richness; environmental variables

PAGES: 70
BIG AREA: Ciências Biológicas
AREA: Ecologia
SUBÁREA: Ecologia de Ecossistemas
SUMMARY:

Mountainous regions have unique morphoclimatic characteristics, with endemic areas and singular biota, housing approximately 87% of amphibians, birds, and mammals distributed on the planet. It is well known that the structure of amphibian communities may vary depending on environmental characteristics, but additional studies are needed to explain the compositional variation of these communities as a function of elevational gradients under different physiographies. In this context, this study aimed to test the hypothesis that environmental variations along elevational gradients can explain variations in richness, abundance, and composition of anuran species in lotic environments without canopy coverage within the Caatinga biome. The study area is inserted in Chapada Diamantina National Park (PNCD) and the regions around it. We sampled 20 sample units (SU) in two sample periods (higher and lower rainfall), distributed along a 400 m to 1300 m elevation gradient. We seek (i) replicas' structuring patterns as a function of environmental variables through the analysis of principal components (PCA) and (ii) ordination patterns of the anuran community through the non-metric multidimensional scaling method (NMDS). Using multiple linear regression analysis, we tested the research hypothesis that the sampled environmental variables (independent variables) can explain the distribution pattern of anuran species (dependent variable) along environmental gradients. We registered 613 specimens of anuran amphibians distributed in five families, nine genera, and 21 species. The NMDS solutions (one and two dimensions, 1D and 2D, respectively) generated stronger results than those randomly expected. The projection of the NMDS-1 axis (dependent variable) on the first principal component (PC1, independent variable) indicated that species composition and abundance change along the elevational gradient. In relation to the richness of the species, we verified that it decreases according to the increase in elevation. Analysis of the principal components (PCA) resulted in the four most representative principal components (eigenvalues > 1.0) and represented 80.6% of all variance after varimax rotation. The first principal component (PC1) accounted for 40.3% of the total variance and was mainly associated with climate and vegetational variables; PC2 (14.5%) had as the variable of most prominent contribution 'depth of the water body'; PC3 (13.5%), 'woody density'; and PC4 (12.3%), variables related to vegetation and river. Multiple regression analysis indicated that the measured environmental variables could explain anuran species' composition/abundance patterns along the elevational gradient in 1D and 2D solutions, emphasizing climate variables and marginal vegetation of lotic environments. The projection of the individual scores of PC1 and NMDS axes and the number of species per replica (dependent variables) separately on elevation (independent variable) showed that both environmental variables and composition/abundance and richness of anuran species responded positively to increased elevation. Even considering an elevation gradient of just over 900 m, our results pointed out that changes in environmental variables follow the gradual increase in elevation, and the latter can explain the changes in richness, abundance, and substitution patterns of anuran species that inhabit lotic environments without canopy coverage (open habitats). Our results highlight the need for conservation of the entire elevational gradient to maximize the conservation of amphibian species. As our sample universe was restricted to only an elevational gradient in the Caatinga biome, we understand it is essential to test this hypothesis and prediction in other elevational gradients in the Caatinga biome so that it is possible to make generalizations. In addition, it should be noted that we use climate and vegetation variables locally measured instead of using georeferenced global data and maps available on digital platforms. We understand that it is important to contrast the results obtained here with results from the exclusive use of digital platform data to understand which type of environmental data is the most efficient in identifying biotic variation patterns, in this case, anurans, along elevational gradients in the Caatinga and other biomes.

COMMITTEE MEMBERS:
Presidente - 1349793 - MARCELO FELGUEIRAS NAPOLI
Externa à Instituição - MARIA LUCIA DEL-GRANDE - UESB
Externo à Instituição - MIRCO SOLÉ KIENLE - UESC