Dispersal capacity as assessed by distance-decay relationships is lower for aquatic shredder insects than aquatic non-shredder insects in a Neotropical river network

By

García, Pavel
Hall Jr, Robert O.

Type

Article

Date of Publication

2024-6-28

Original Publication

Neotropical Biology and Conservation

Volume

19

Series / Issue

Issue: 2

Pages

235--252

Subjects

América Central , Bayesian linear models , Central America , dendritic network structure , Ensambles de insectos acuáticos , freshwater insect assemblages , Guatemala , Modelos lineares bayesianos , Redes dendríticas

Contributed by

Pensoft Publishers

Language

English

Published by

Brazil Universidade do Vale do Rio dos Sinos

Identifiers

DOI: https://doi.org/10.3897/neotropical.19.e113285

 

Abstract

Aquatic shredder insect diversity declines latitudinally toward the equator, contrary to the general latitudinal biodiversity gradient. Shredder diversity along tropical elevational gradients mimics this shredder latitudinal pattern. One of the hypotheses proposed to explain this pattern of diversity is that dispersal capacity drives variation in shredder assemblages given their low dispersal capacity in tropical streams. Additionally, tropical shredders probably have lower dispersal capacity than the rest of tropical aquatic insects, which have lower dispersal capacities than their counterparts in temperate areas. We tested this hypothesis in an elevational gradient of more than 2000 m in 16 reaches of streams distributed in the Usumacinta, Cahabon, and Polochic river watersheds. We quantitatively sampled aquatic insects and measured 12 environmental variables. We found a regional pool of 118 taxa, with 13 taxa classified as shredders, and 2 taxa of predator-shredders. Contrary to expectations, shredder rarefied richness decreased with increasing elevation, which suggests that dispersal capacity did not change with elevation. Assemblage similarity decreased with increasing distance between reaches due to low capacity to fly long distances. This relationship had a smaller slope when using the shortest spatial distances between pairs of reaches due to potential lateral scatter by flying adults. In sum, the results support the hypothesis that dispersal capacity drove aquatic shredder assemblage structure in these 16 tropical streams.