Aquatic insects in the order Trichoptera are extremely diverse in number of species and their trophic roles. However, their distribution and diversity patterns are poorly known in the Neotropics, including the species restricted to tropical mountain ecosystems. Recent studies in tropical mountains have shown high levels of endemism of aquatic insects and changes in the composition of communities over short distances. Still, the incidence of environmental filters that explain such patterns has not been addressed quantitatively. Given the relevance of understanding Trichoptera spatial diversity patterns to prioritize conservation areas for freshwaters, as well as to obtain baseline information to predict changes in aquatic communities facing global environmental changes, we assessed the species distribution and assemblages of caddisflies along an elevational gradient from 600 to 3,600 m a. s.l. on the equatorial Andes. In this area, we had long-term continuous climate data with hourly resolution. We collected adult caddisflies in seven localities along this gradient using light traps. We sampled each locality for two hours after sunset for three consecutive days. All specimens collected were identified to species or morphospecies. Our results showed an increase in species and genera numbers with decreasing altitude, albeit no significant. Minimum air temperature is the main environmental variable explaining Trichoptera community assemblages. β-diversity (taxon turnover among sites), as opposed to species richness, increased with altitude and showed a bimodal distribution along the elevation gradient for both genera and species assemblages, which resulted in a significant shift in community composition of species and genera at 2,000 m a.s.l. Our null-models confirm the observed patterns of B-diversity are non-random and suggest a strong environmental filtering of tropical caddisflies community assemblies and turnover. Geographic distance coupled with changes in environmental conditions along the elevation gradient explained a high percentage of community variance, as documented for other taxa (e.g., vascular plants), suggesting the importance of securing habitat connectivity along the altitudinal gradient to protect aquatic insect diversity effectively.
Bibliographical noteFunding Information:
This paper was developed thanks to the financial support of the EcoAndes Project conducted by CONDESAN and UN-Environment, funded by the Global Environmental Fund (GEF, http://www.thegef.org) (Grant number: 4750), The Swiss Agency for Development and Cooperation (SDC, http://www.eda.admin.ch/sdc) through the Andean Forest Program (Grant number 81028631). We also had the support of Universidad de Las Américas Research Grants: “Diversidad de Trichoptera en una Gradiente Altitudinal Neotropical” (AMB.BRT.18.01), "Mountain freshwater diversity, from taxonomy to functional genomics, and approximation from Trichoptera” (AMB.BRT.19.02" and Masphi Reserve. ERG was funded by a Peruvian government FONDECYT-CONCYTEC doctoral fellowship (grant contract number 277-2015-FONDECYT). ERG and RWH were also supported by University of Minnesota Agricultural Experiment Station projects MIN17-017 and 17-094. This support is gratefully acknowledged. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. We are grateful to Anderson Medina and Inty Arcos for their field assistance during this project. This work could not have been done without the generous help of the stewards and staff of the following private reserves: Bellavista Lodge (Richard Parson), Intillacta Reserve (Inty Arcos and Nina Duarte), Mashpi Reserve (Carolina Proaño, Mateo Roldán and Felipe Andrade), Mashpi-Shungo and Pambiliño Reserves and Chocolate Mashpi (Agustina Arcos, Alejandro Solano, and Oliver Torres), El Cedral Biological Reserve (Germán Toasa), and Verdecocha Reserve (María Elisa Visuete). We thank Raphael Ligeiro for the valuable reviews on early version of this manuscript.
© 2022 Ríos-Touma et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
PubMed: MeSH publication types
- Journal Article
- Research Support, Non-U.S. Gov't