Different environmental gradients affect different measures of snake β-diversity in the Amazon rainforests

Abstract

Mechanisms generating and maintaining biodiversity at regional scales may be evaluated by quantifying β-diversity along environmental gradients. Differences in assemblages result in biotic complementarities and redundancies among sites, which may be quantified through multi-dimensional approaches incorporating taxonomic β-diversity (TBD), functional β-diversity (FBD) and phylogenetic β-diversity (PBD). Here we test the hypothesis that snake TBD, FBD and PBD are influenced by environmental gradients, independently of geographic distance. The gradients tested are expected to affect snake assemblages indirectly, such as clay content in the soil determining primary production and height above the nearest drainage determining prey availability, or directly, such as percentage of tree cover determining availability of resting and nesting sites, and climate (temperature and precipitation) causing physiological filtering. We sampled snakes in 21 sampling plots, each covering five km2, distributed over 880 km in the central-southern Amazon Basin. We used dissimilarities between sampling sites to quantify TBD, FBD and PBD, which were response variables in multiple-linear-regression and redundancy analysis models. We show that patterns of snake community composition based on TBD, FBD and PBD are associated with environmental heterogeneity in the Amazon. Despite positive correlations between all β-diversity measures, TBD responded to different environmental gradients compared to FBD and PBD. Our findings suggest that multi-dimensional approaches are more informative for ecological studies and conservation actions compared to a single diversity measure.

Disentangling the effects of environmental and geographic distances on lizard assemblages in Amazonian forests

“…Additionally, we used the phylosor (1‐phylosor) function of the picante R ‐package to estimate phylogenetic distances based on fractions of branch‐length shared among paired modules. By applying a simple linear regression given by functional distance = a + b (phylogenetic distance) , we found a positive relationship ( r 2 = 0.40, p < 0.00001), which indicates that functional distance is a good proxy for phylogenetic distance in our study system, consistent with snake assemblages in Amazonia (Fraga et al, 2018).…”

“…Many studies have shown turnover of species assemblages in Amazonia (e.g. Fraga et al, 2018; Rojas‐Ahumada et al, 2012), but the scale of those studies was too limited to detect neutral effects due to dispersal limitation. To increase the geographical coverage in an area with no obvious dispersal barriers, a multidisciplinary effort has been applied to provide an efficient sampling design to quantify dissimilarities among assemblages based on standardized sampling plots installed along the Madeira‐Purus interfluvial region, in the Midwestern Amazonia (PPBio, 2020).…”

“…These forest types also represent different portions of gradients in soil texture, vegetation cover and climate. Combinations of those gradients have been shown to be related to dissimilarities among assemblages of plants (Bernardes & Costa, 2011), fish (Barros et al, 2013), snakes (Fraga et al, 2018) and bats (Marciente et al, 2015).…”

Impact of recreational transformation of soil physical properties on micromolluscs in an urban park

“…According to Shelford's law, a single factor has an effect when it is at the minimum or maximum of that species' tolerance zone (Shelford, 1911(Shelford, , 1931. In most cases, species do not respond to individual environmental factors, but to complex gradients of different environmental factors (Rydgren et al, 2003;de Fraga et al, 2018). Ecoclines, which can be represented by the DCA ordination axes, are considered as the markers of complex ecological gradients (Rydgren et al, 2003).…”

Hierarchical effects of historical and environmental factors on lizard assemblages in the upper Madeira River, Brazilian Amazonia

“…In general, it is expected that habitat-specialist species find inadequate-to-optimum continuums of environmental conditions for survival and reproduction [34]. Environmental filtering has been found in Amazonia for plants, frogs, lizards, snakes, and birds [15,[35][36][37][38][39][40][41][42][43]. For lizards, local assemblages may differ due to variation in individual abundance or species turnover along gradients of distance from water courses [31,44], elevation [45], climate seasonality [46], and number of trees [43,47].…”