Human impact on the functional diversity of Gerromorpha (Hemiptera: Heteroptera) and differential sexual dimorphism responses in Amazonian aquatic ecosystems

Abstract

Human activities impact the morphology and function of species, especially in aquatic ecosystems. However, little is known about how these effects influence intraspecific variation associated with sexual dimorphism. Therefore, it is essential to study organisms with conspicuous intersexual variations, such as semiaquatic bugs (Hemiptera: Heteroptera: Gerromorpha). This study aimed to assess the effect of land-use changes, conventional logging, reduced-impact logging, pasture, and mining activities on the taxonomic (alpha), functional (Fric and FEve) and beta functional (βF) diversity of semiaquatic bugs, with an emphasis on sexual dimorphism. We tested the following hypotheses: (i) habitat loss reduces the diversity; (ii) larger species are associated with forested streams, while species with slower locomotion are associated with low forest cover; (iii) male βF is driven by trait richness difference, while female βF is driven by trait replacement. We sampled 77 streams in the Capim river basin (Amazon, Brazil). CL and PST streams are associated with agricultural impact and high conductivity, whereas RIL streams were similar to forested sites environmentally and in composition. Environmental filters influenced only the taxonomic composition of males. In contrast, females had longer bodies and legs in forest environments and differed in βF, mainly due to traits loss/gain. Our results highlight the importance of forest conservation and the use of economic practices that cause less damage, as well as evaluating such effects under different biodiversity approaches and including intraspecific variation.