Biogeography of Amazon birds: rivers limit species composition, but not areas of endemism

Large Amazonian rivers may act as dispersal barriers for animals with low dispersal abilities, limiting their distribution to certain interfluves. Consequently, the distribution of these taxa would be less affected by macroclimatic gradients. Conversely, high‐dispersal taxa would be less constrained by large rivers and may track suitable climates. We evaluate whether Zygoptera and Anisoptera, two Odonata suborders with different dispersal abilities, show differences in distribution patterns across Amazonian interfluves. We further assess the relative importance of macroclimatic and habitat factors in their community assembly. We used network modularity analyses to identify biogeographic species pools and spatial buffers to define metacommunity species pools. Then, we used structural equation models to estimate the relative importance of multi‐scale factors on species richness patterns. Zygoptera communities are more similar in species composition within than between interfluves, suggesting that large Amazonian rivers indeed limit the distribution of Zygoptera species. Conversely, the distribution of Anisoptera extends across Amazonian interfluves. Seasonality has a strong positive effect on Zygoptera and Anisoptera richness across scales. In addition, habitat integrity is negatively correlated with the regional species richness and abundance of Anisoptera and positively correlated with Zygoptera local richness. The contrasting effects of habitat integrity on Anisoptera and Zygoptera suggest that the former is favored in open habitats, whereas the latter is so in forests. Despite these differences, both suborders appear to follow similar community assembly mechanisms in Amazonia, with a strong climatic control across scales and an effect of habitat filters on local communities.

Section: Discussionmentioning

confidence: 99%

Drivers of regional and local diversity of Amazonian stream Odonata

Alves‐Martins

Calatayud

Medina

et al. 2018

“…The values of each axis of the NMDS were subjected to EBK and then assembled into a single RGB map, a routine described in detail by Oliveira et al . (). By contrast, unlike Oliveira et al .…”

Section: Methodsmentioning

confidence: 97%

“…By contrast, unlike Oliveira et al . (), who excluded the areas with less than ten records from their analysis, which could represent poorly sampled areas, we used the information from all sampling sites. We consider that the harvestman species richness is truly low at some sampling sites (i.e.…”

Section: Methodsmentioning

confidence: 99%

“…This was carried out using the metaMDS function of the R package vegan (Oksanen et al, 2017). The values of each axis of the NMDS were subjected to EBK and then assembled into a single RGB map, a routine described in detail by Oliveira et al (2017). By contrast, unlike Oliveira et al (2017), who excluded the areas with less than ten records from their analysis, which could represent poorly sampled areas, we used the information from all sampling sites.…”

Section: Species Richness and Beta Diversitymentioning

confidence: 99%

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Spatial variation in phylogenetic diversity of communities of Atlantic Forest harvestmen (Opiliones, Arachnida)

Nogueira

Bragagnolo

Dasilva

et al. 2019

The study of diversity has become increasingly sophisticated, including the use of measures of phylogenetic diversity. We calculate the spatial variation in species richness, taxonomic beta diversity, and alpha and beta phylogenetic diversity (PDα and PDβ, respectively) of Atlantic Forest harvestman communities using a data set containing 556 species from 68 sites, distributed in 12 Brazilian states. We compare the congruence of phylogenetic and taxonomic diversity patterns, and also compare PDα with null model expectations, to check for phylogenetic clustering or overdispersion in communities. Species richness and PDα are correlated, peaking in southern and south‐eastern coastal sites and decreasing towards the interior and towards the north‐east. PDα in north‐eastern sites was higher than expected, while a clustered phylogenetic pattern characterised most other sites. Communities in the southern and south‐eastern regions were dominated by species from the large family Gonyleptidae, presenting a high richness and a low PDα. As the dominance of Gonyleptidae decreased towards the north, where local communities have fewer species, but a higher PDα, they contain representatives of other families. The beta diversity was more sensitive to the compositional changes involving closely related Gonyleptidae species, while PDβ is more influenced by deeper phylogenetic compositional changes, between more distant lineages. Phylogenetic diversity may be of special importance to assess the conservation value of distantly related lineages. These species‐poor groups are less likely to influence taxonomic‐based diversity analyses, but their importance for conservation arises from their phylogenetic distinctiveness, captured by PDα and PDβ measures.

“…Beyond the geographical barrier effect mentioned above, spatially proximal locations should have a higher number of shared species (Hubbell, 2001), especially in the case of organisms with limited dispersal capacity, as in the case of most Zygoptera S anchez-Herrera & Ware, 2012). These two influences, that is: (i) distance between the sites and (ii) the influence of major rivers as geographical barriers are difficult to separate, as most of the sites in the same area of endemism area are spatially closer to one another than to sites in different areas of endemism (Dambros et al, 2016;Oliveira et al, 2017).…”

Section: Spatial Biogeographic and Environmental Conditions And DIVmentioning

confidence: 99%

Spatial, biogeographic and environmental predictors of diversity in Amazonian Zygoptera

Brasil

Oliveira

Calvão

et al. 2017

Our objectives were to assess how turnover and nestedness contribute to beta‐diversity patterns of the Zygoptera in Amazonian streams, and to relate these components of beta diversity to environmental, spatial and biogeographic predictors. Our first hypothesis is that the turnover is the most important component of beta‐diversity patterns due to the historical isolation of all or part of the areas located in the interfluves of the major Amazonian rivers. Our second hypothesis is that the interaction between environmental conditions and the area of endemism (biogeography) would be the most important predictor of beta‐diversity patterns. To test these hypotheses, we compiled data on the Zygoptera communities from 172 Amazonian streams. We used three sets of predictor variables: (i) environmental variables, (ii) area of endemism (biogeographic) and (iii) spatial filters. The turnover explained 99.36% of the beta diversity, corroborating our first hypothesis. Together, environmental and biogeographic variables were the best predictors of beta‐diversity patterns. For turnover, however, the biogeographic variables were the best predictors, contrary to our second hypothesis. We found high gamma diversity, but low alpha diversity in the Zygoptera communities. This paradox is explained by the high turnover among sites within the study landscape. This pattern of diversity is related to both historical biogeographic factors and the spatial structuring of environmental conditions in the Amazon region. In the light of our results (high turnover and beta diversity), and their correspondence with areas of endemism, adequate conservation of Amazonian Zygoptera diversity will depend on the establishment of so‐called mega‐reserves throughout the major Amazonian interfluves and, whenever possible, in the areas with adequate environmental conditions for the greatest possible number of species, otherwise, most species may be at a constant risk of extinction.