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Land use changes are considered a significant cause of amphibian declines worldwide. However, little is known regarding which land uses have more pervasive impacts and which help to supplement the biodiversity conserved in protected areas. In addition, amphibian species respond to a broad array of geographical constraints, which may blur responses to disturbance, depending on the species' natural history.Here, we explored whether functional diversity patterns of amphibian assemblages are linked to human land use while considering spatial autocorrelation and phylogenetic relatedness among species. We surveyed tadpoles along 500 km in coastal wetlands in southern Brazil and quantified four traits related to tadpole habitat use and predator avoidance.Spatial components influenced functional richness to a greater extent than land use. Functional evenness was higher in ponds surrounded by more exotic reforestation, and to a lesser extent an effect of crop area. Functional divergence was also associated with reforestation areas.Our results showed that some land uses (reforestation with exotic species and temporary crops) have more pervasive impacts on tadpole communities. Such changes in amphibian communities occurred even at low levels of landscape change. Our findings highlight that conversion to human land use requires complementary approaches (i.e., tadpole and adult responses) to provide early warning signals about habitat modification effects. [ABSTRACT FROM AUTHOR]

Geographical patterns of phenotypic variation are the outcome of a complex array of evolutionary and environmental factors. Studies on the correlates of the geographic variation in morphological characters can be useful to understand the drivers of phenotypic differences and because intraspecific variation in morphology can impact either local adaptation of any given species or higher-level ecosystem processes. The morphology of larval amphibians responds to multiple factors, including wetland level and surrounding land use. However, understanding the relative influence of such environmental factors on the morphology of tadpoles remains challenging. We used geometric morphometrics to describe the intraspecific morphological variation in tadpoles of Scinax squalirostris (Anura: Hylidae) in freshwater wetlands ranging along the transition between the Pampa and Atlantic Forest biomes in southern Brazil. Specifically, we assessed the relative influence of spatial and environmental (aquatic predators, water chemistry and hydroperiod, crop area) factors to tadpole body size and shape. The size of S. squalirostris tadpoles was affected by spatial factors and pH. Smaller-sized tadpoles were observed in the Pampa–Atlantic Forest transition. Allometry-free changes in the shape of tadpoles were associated both to wetland and upland factors. Tadpoles in larger ponds showed globular bodies and higher ventral fins, while tadpoles in ponds with higher electrical conductivity showed smaller tails. Tadpoles in ponds surrounded by larger crop areas showed longer fins. Our results are useful to understand the importance of wetland and upland effects on the morphology of widely distributed aquatic species, especially given the ongoing scenarios of land cover modification and climate change. [ABSTRACT FROM AUTHOR]

Understanding seasonal patterns of assembly mechanisms are key to comprehending the metacommunity dynamics of organisms inhabiting temporary habitats such as wetland macroinvertebrates. However, tests of the seasonal variation in assembly mechanisms of macroinvertebrates in wetlands with differing hydroperiods are rare, especially in the Neotropical region. We tested for seasonal patterns in the metacommunity assembly mechanisms of macroinvertebrates in small subtropical highland wetlands of southern Brazil with different hydroperiods. We also tested whether patterns varied between macroinvertebrate taxa with different dispersal modes. Macroinvertebrates were sampled in 12 wetlands classified into "short," "medium," and "long" hydroperiods (N = 4 in each category) in three seasons (fall, winter, and spring) over two full hydrological cycles (from 2012 to 2014). We assessed the role of spatial and environmental variables to metacommunity structure using distance‐based redundancy analysis and variation partitioning. Environmental and spatial variables explained macroinvertebrate metacommunity structure, although their relative influence markedly changed among seasons and hydroperiods. Environmental variables were important in fall and winter, whereas spatial variables predominated in spring. Different environmental variables influenced the metacommunity structure in each hydroperiod. Environmental variables influenced active‐dispersing macroinvertebrates, whereas the influence of environmental and spatial variables on passive‐dispersing taxa changed among seasons. We showed that the assembly mechanisms of macroinvertebrate metacommunities show a distinct temporal dynamic among wetlands with different hydroperiods. Our findings contribute to a more complete understanding of the metacommunity structure in temporary ecosystems. [ABSTRACT FROM AUTHOR]