Functional diversity and traits measurements
We selected functional traits related to three major categories: (1)
recruitment and life-history, (2) resource and habitat use, and (3) body
size (see functional trait measurements in Supplementary Information).
We selected eight traits for fish, six for arthropods, and nine for
macrophytes (Table 1). All traits were measured by us (e.g., body
length) or by using published literature sources (see Table S1). For
each trait in each stream, the assemblage abundance-weighted trait
variances (CWV) were calculated by following Bernard-Verdier et al.
(2012) and Enquist et al. (2015). Importantly, the CWV was computed for
each assemblage separately (Table 1). CWV is a measure of trait
dispersion within a given assemblage weighted by the abundance of each
individual taxon and is considered a measure of functional trait
diversity of a given community assemblage (Enquist et al., 2015).
We also calculated a multivariate index of functional diversity based on
trait dispersions for each assemblage, i.e., functional dispersion (FD;
Laliberté & Legendre, 2010). Functional diversity of the three
assemblages had similar values between Amazonia and Uruguay streams
sites (Figure 1d). Moreover, to analyze whether intensive human
land-uses have similar effects on different traits categories, we
calculated the average indices for each trait component using average
standardized assemblage community variance values (CWV). For body size,
we used maximum length (fish and arthropods) and vegetative plant height
(macrophytes). For recruitment and life-history traits, we used traits
related to the persistence and reproduction mode of each assemblage, and
for resource and habitat use, we selected those traits that are closely
related to feeding modes of fish and arthropods, and growth form, and
nutrient acquisition to macrophytes (Table 1). Importantly, we did not
compare the traits across assemblages, but instead considered the traits
individually for each assemblage (see Table S1).