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Evaluating multiple spatial scales to understand the distribution of anuran beta diversity in the Brazilian Atlantic Forest

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ABSTRACT

We partitioned the total beta diversity in the species composition of anuran tadpoles to evaluate if species replacement and nestedness components are congruent at different spatial resolutions in the Brazilian Atlantic Forest. We alternated the sampling grain and extent of the study area (among ponds at a site, among ponds within regions, among sites within regions, and among sites within regions pooled together) to assess the importance of anuran beta diversity components. We then performed variation partitioning to evaluate the congruence of environmental descriptors and geographical distance in explaining the spatial distribution of the species replacement and nestedness components. We found that species replacement was the main component of beta diversity, independent of the sampling grain and extent. Furthermore, when considering the same sampling grain and increasing the extent, the values of species replacement increased. On the other hand, when considering the same extent and increasing the sampling grain, the values of species replacement decreased. At the smallest sampling grain and extent, the environmental descriptors and geographic distance were not congruent and alternated in the percentage of variation explaining the spatial distribution of species replacement and nestedness. At the largest spatial scales (SSs), the biogeographical regions showed higher values of the percentage explaining the variation in the beta diversity components. We found high values of species replacement independently of the spatial resolution, but the processes driving community assembly seem to be dependent on the SS. At small scales, both stochastic and deterministic factors might be important processes structuring anuran tadpole assemblages. On the other hand, at a large spatial grain and extent, the processes restricting species distributions might be more effective for drawing inferences regarding the variation in anuran beta diversity in different regions of the Brazilian Atlantic Forest.

No MeSH data available.


(a) Original Brazilian Atlantic Forest distribution and the 12 sites evaluated in this study. Forest types are indicated by different shades of gray (light gray—semideciduous seasonal forest—SSF, gray—dense rain forest—DRF, and dark gray—mixed rain forest—MRF). Ubatuba (UBA) is highlighted illustrating that different ponds were sampled within sites. (b) Schematic representation of the different spatial scales addressed in this study. Arrows with solid lines consider ponds as the sampling units and the sites (SS1) or the forest types (SS2) separately as the extent. Arrows with dashed lines consider sites as the sampling units and the forest types separately (SS3) or the three forest types pooled together (SS4) as the extent. Circles represent sites, hexagons represent each region separately, and rectangle represents regions pooled. Details of the sites are in Appendix S1
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ece32852-fig-0001: (a) Original Brazilian Atlantic Forest distribution and the 12 sites evaluated in this study. Forest types are indicated by different shades of gray (light gray—semideciduous seasonal forest—SSF, gray—dense rain forest—DRF, and dark gray—mixed rain forest—MRF). Ubatuba (UBA) is highlighted illustrating that different ponds were sampled within sites. (b) Schematic representation of the different spatial scales addressed in this study. Arrows with solid lines consider ponds as the sampling units and the sites (SS1) or the forest types (SS2) separately as the extent. Arrows with dashed lines consider sites as the sampling units and the forest types separately (SS3) or the three forest types pooled together (SS4) as the extent. Circles represent sites, hexagons represent each region separately, and rectangle represents regions pooled. Details of the sites are in Appendix S1

Mentions: Here, we partitioned the total beta diversity of the species composition of anuran tadpoles to evaluate if species replacement and nestedness distributions are congruent at different spatial grains and extents across the Brazilian Atlantic Forest. This biome is home to approximately 600 species of amphibians, of which approximately 73% are endemic (Haddad, Toledo, Prado, Loebmann, & Gasparini, 2013). Recently, Vasconcelos, Prado, da Silva, and Haddad (2014) proposed that the species composition of anurans in the Brazilian Atlantic Forest can be split into four regions that are broadly congruent with the vegetation formations of the Atlantic Forest: (1) Region 1, located in Atlantic Forest inland areas, encompasses most of the semideciduous forest and transitional areas to the Cerrado; (2) Region 2 comprises the coastal Atlantic Forest in southeastern Brazil, where most of the area falls within the ombrophilous forest; (3) Region 3 is mostly congruent with the Araucaria forest in southern Brazil; and (4) Region 4 encompasses the northeastern Brazilian semideciduous and ombrophilous forests. Based on this classification, we explored the community similarity of anuran species at multiple SSs (among ponds at a site, among ponds within regions, among sites within regions, and among sites within regions pooled together; Figure 1). Our first objective was to evaluate whether species replacement and nestedness values are congruent considering similar SSs within and among regions of the Brazilian Atlantic Forest (Figure 2a). This approach will help us to understand if distribution patterns of beta diversity obtained in one study apply only to the area under investigation or whether they can emerge on other communities considering similar SSs (Lawton, 1999). Our second objective was to understand if ecological processes such as species sorting and dispersal limitation are congruent within and among different regions considering similar spatial grains and extents. To this, we evaluated four different SSs across the Brazilian Atlantic Forest (Figure 1):


Evaluating multiple spatial scales to understand the distribution of anuran beta diversity in the Brazilian Atlantic Forest
(a) Original Brazilian Atlantic Forest distribution and the 12 sites evaluated in this study. Forest types are indicated by different shades of gray (light gray—semideciduous seasonal forest—SSF, gray—dense rain forest—DRF, and dark gray—mixed rain forest—MRF). Ubatuba (UBA) is highlighted illustrating that different ponds were sampled within sites. (b) Schematic representation of the different spatial scales addressed in this study. Arrows with solid lines consider ponds as the sampling units and the sites (SS1) or the forest types (SS2) separately as the extent. Arrows with dashed lines consider sites as the sampling units and the forest types separately (SS3) or the three forest types pooled together (SS4) as the extent. Circles represent sites, hexagons represent each region separately, and rectangle represents regions pooled. Details of the sites are in Appendix S1
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ece32852-fig-0001: (a) Original Brazilian Atlantic Forest distribution and the 12 sites evaluated in this study. Forest types are indicated by different shades of gray (light gray—semideciduous seasonal forest—SSF, gray—dense rain forest—DRF, and dark gray—mixed rain forest—MRF). Ubatuba (UBA) is highlighted illustrating that different ponds were sampled within sites. (b) Schematic representation of the different spatial scales addressed in this study. Arrows with solid lines consider ponds as the sampling units and the sites (SS1) or the forest types (SS2) separately as the extent. Arrows with dashed lines consider sites as the sampling units and the forest types separately (SS3) or the three forest types pooled together (SS4) as the extent. Circles represent sites, hexagons represent each region separately, and rectangle represents regions pooled. Details of the sites are in Appendix S1
Mentions: Here, we partitioned the total beta diversity of the species composition of anuran tadpoles to evaluate if species replacement and nestedness distributions are congruent at different spatial grains and extents across the Brazilian Atlantic Forest. This biome is home to approximately 600 species of amphibians, of which approximately 73% are endemic (Haddad, Toledo, Prado, Loebmann, & Gasparini, 2013). Recently, Vasconcelos, Prado, da Silva, and Haddad (2014) proposed that the species composition of anurans in the Brazilian Atlantic Forest can be split into four regions that are broadly congruent with the vegetation formations of the Atlantic Forest: (1) Region 1, located in Atlantic Forest inland areas, encompasses most of the semideciduous forest and transitional areas to the Cerrado; (2) Region 2 comprises the coastal Atlantic Forest in southeastern Brazil, where most of the area falls within the ombrophilous forest; (3) Region 3 is mostly congruent with the Araucaria forest in southern Brazil; and (4) Region 4 encompasses the northeastern Brazilian semideciduous and ombrophilous forests. Based on this classification, we explored the community similarity of anuran species at multiple SSs (among ponds at a site, among ponds within regions, among sites within regions, and among sites within regions pooled together; Figure 1). Our first objective was to evaluate whether species replacement and nestedness values are congruent considering similar SSs within and among regions of the Brazilian Atlantic Forest (Figure 2a). This approach will help us to understand if distribution patterns of beta diversity obtained in one study apply only to the area under investigation or whether they can emerge on other communities considering similar SSs (Lawton, 1999). Our second objective was to understand if ecological processes such as species sorting and dispersal limitation are congruent within and among different regions considering similar spatial grains and extents. To this, we evaluated four different SSs across the Brazilian Atlantic Forest (Figure 1):

View Article: PubMed Central - PubMed

ABSTRACT

We partitioned the total beta diversity in the species composition of anuran tadpoles to evaluate if species replacement and nestedness components are congruent at different spatial resolutions in the Brazilian Atlantic Forest. We alternated the sampling grain and extent of the study area (among ponds at a site, among ponds within regions, among sites within regions, and among sites within regions pooled together) to assess the importance of anuran beta diversity components. We then performed variation partitioning to evaluate the congruence of environmental descriptors and geographical distance in explaining the spatial distribution of the species replacement and nestedness components. We found that species replacement was the main component of beta diversity, independent of the sampling grain and extent. Furthermore, when considering the same sampling grain and increasing the extent, the values of species replacement increased. On the other hand, when considering the same extent and increasing the sampling grain, the values of species replacement decreased. At the smallest sampling grain and extent, the environmental descriptors and geographic distance were not congruent and alternated in the percentage of variation explaining the spatial distribution of species replacement and nestedness. At the largest spatial scales (SSs), the biogeographical regions showed higher values of the percentage explaining the variation in the beta diversity components. We found high values of species replacement independently of the spatial resolution, but the processes driving community assembly seem to be dependent on the SS. At small scales, both stochastic and deterministic factors might be important processes structuring anuran tadpole assemblages. On the other hand, at a large spatial grain and extent, the processes restricting species distributions might be more effective for drawing inferences regarding the variation in anuran beta diversity in different regions of the Brazilian Atlantic Forest.

No MeSH data available.