Environmental factors prevail over dispersal constraints in determining the distribution and assembly of Trichoptera species in mountain lakes

Abstract

Aiming to elucidate whether large-scale dispersal factors or environmental species sorting prevail in determining patterns of Trichoptera species composition in mountain lakes, we analyzed the distribution and assembly of the most common Trichoptera (Plectrocnemia laetabilis, Polycentropus flavomaculatus, Drusus rectus, Annitella pyrenaea, and Mystacides azurea) in the mountain lakes of the Pyrenees (Spain, France, Andorra) based on a survey of 82 lakes covering the geographical and environmental extremes of the lake district. Spatial autocorrelation in species composition was determined using Moran’s eigenvector maps (MEM). Redundancy analysis (RDA) was applied to explore the influence of MEM variables and in-lake, and catchment environmental variables on Trichoptera assemblages. Variance partitioning analysis (partial RDA) revealed the fraction of species composition variation that could be attributed uniquely to either environmental variability or MEM variables. Finally, the distribution of individual species was analyzed in relation to specific environmental factors using binomial generalized linear models (GLM). Trichoptera assemblages showed spatial structure. However, the most relevant environmental variables in the RDA (i.e., temperature and woody vegetation in-lake catchments) were also related with spatial variables (i.e., altitude and longitude). Partial RDA revealed that the fraction of variation in species composition that was uniquely explained by environmental variability was larger than that uniquely explained by MEM variables. GLM results showed that the distribution of species with longitudinal bias is related to specific environmental factors with geographical trend. The environmental dependence found agrees with the particular traits of each species. We conclude that Trichoptera species distribution and composition in the lakes of the Pyrenees are governed predominantly by local environmental factors, rather than by dispersal constraints. For boreal lakes, with similar environmental conditions, a strong role of dispersal capacity has been suggested. Further investigation should address the role of spatial scaling, namely absolute geographical distances constraining dispersal and steepness of environmental gradients at short distances.

Metacommunity Structures of Macroinvertebrates and Diatoms in High Mountain Streams, Yunnan, China

“…Consequently, the influence of environmental filtering increases as more isolated communities are more strongly structured by local environmental factors (Brown and Swan, 2010;Cañedo-Argüelles et al, 2015). Studies focused on European high mountain lakes, which are more isolated than high mountain streams and rivers, have found that local environmental factors are more important in structuring macroinvertebrate communities than spatial factors (Kernan et al, 2009;de Mendoza and Catalan, 2010;de Mendoza et al, 2015). On the lake-connected aspect of the Cangshan Mountain, the interaction between dispersal and environmental filtering on river metacommunities has been altered compared to the river-connected aspect.…”

Predictability of stream insect distributions is dependent on niche position, but not on biological traits or taxonomic relatedness of species

“…niche position and niche breadth) have also formerly been found as significant correlates of the degree of site occupancy in stream insects (Heino , Siqueira et al , Verberk et al , Heino and Grönroos ). In particular, we tested 1) whether different species show independent responses to environmental, spatial and geographic variables at a regional scale (de Mendoza et al ); 2) whether ecological and biological traits explain variation in the accuracy of models predicting species distributions; and 3) whether species niche characteristics explain variation among species in model performance, because these variables are related to the degree of occupancy in stream insects (Heino ) and other groups of organisms (Slatyer et al ).…”

Nematode distributions as spatial null models for macroinvertebrate species richness across environmental gradients: A case from mountain lakes

“…4,000 individuals) were mounted on slides with glycerine, the preparations sealed with paraffin, and species determined under the microscope following mainly Abebe, Andrássy, and Traunspurger (). Taxonomic determination of oligochaetes was performed in a previous study (Collado & de Mendoza, ), as well as that of some insect groups such as Coleoptera (de Mendoza, Rico, & Catalan, ) and Trichoptera (de Mendoza, Ventura, & Catalan, ). Chironomids were determined as part of a separate manuscript in preparation (G. de Mendoza, M. Rieradevall and J. Catalan, unpublished manuscript ).…”