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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.


Illustration of the hypotheses evaluated in this study. (a) Three scenarios for the distribution of species replacement (βjtu) and nestedness (βjne) values considering ponds as sampling unit and sites as extent (SS1): (i) Species replacement is the main beta diversity component in the three sites and dissimilarity values are similar among sites; (ii) species replacement is the main beta diversity component in the three sites, but dissimilarity values are different among sites; (iii) species replacement and nestedness values are dependent on the site and dissimilarity values are different among sites. For illustrative purpose we showed SS1, but it can be applied to all spatial scales. (b) Predictions of the relative importance of environmental variables and geographical distance explaining variation in anuran community composition at different spatial scales. Please see text to details of the predictions
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ece32852-fig-0002: Illustration of the hypotheses evaluated in this study. (a) Three scenarios for the distribution of species replacement (βjtu) and nestedness (βjne) values considering ponds as sampling unit and sites as extent (SS1): (i) Species replacement is the main beta diversity component in the three sites and dissimilarity values are similar among sites; (ii) species replacement is the main beta diversity component in the three sites, but dissimilarity values are different among sites; (iii) species replacement and nestedness values are dependent on the site and dissimilarity values are different among sites. For illustrative purpose we showed SS1, but it can be applied to all spatial scales. (b) Predictions of the relative importance of environmental variables and geographical distance explaining variation in anuran community composition at different spatial scales. Please see text to details of the predictions

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
Illustration of the hypotheses evaluated in this study. (a) Three scenarios for the distribution of species replacement (βjtu) and nestedness (βjne) values considering ponds as sampling unit and sites as extent (SS1): (i) Species replacement is the main beta diversity component in the three sites and dissimilarity values are similar among sites; (ii) species replacement is the main beta diversity component in the three sites, but dissimilarity values are different among sites; (iii) species replacement and nestedness values are dependent on the site and dissimilarity values are different among sites. For illustrative purpose we showed SS1, but it can be applied to all spatial scales. (b) Predictions of the relative importance of environmental variables and geographical distance explaining variation in anuran community composition at different spatial scales. Please see text to details of the predictions
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5383494&req=5

ece32852-fig-0002: Illustration of the hypotheses evaluated in this study. (a) Three scenarios for the distribution of species replacement (βjtu) and nestedness (βjne) values considering ponds as sampling unit and sites as extent (SS1): (i) Species replacement is the main beta diversity component in the three sites and dissimilarity values are similar among sites; (ii) species replacement is the main beta diversity component in the three sites, but dissimilarity values are different among sites; (iii) species replacement and nestedness values are dependent on the site and dissimilarity values are different among sites. For illustrative purpose we showed SS1, but it can be applied to all spatial scales. (b) Predictions of the relative importance of environmental variables and geographical distance explaining variation in anuran community composition at different spatial scales. Please see text to details of the predictions
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.