Characterising functional strategies and trait space of freshwater macroinvertebrates

Abstract We examined the functional strategies and the trait space of 596 European taxa of freshwater macroinvertebrates characterized by 63 fuzzy coded traits belonging to 11 trait groups. Principal component analysis was used to reduce trait dimensionality, to explain ecological strategies, and to quantify the trait space occupied by taxa. Null models were used to compare observed occupancy with theoretical models, and randomization-based analyses were performed to test whether taxonomic relatedness, a proxy of phylogenetic signal, constrains the functional trait space of freshwater macroinvertebrates. We identified four major strategies along which functional traits of the taxa examined show trade-offs. In agreement with expectations and in contrast to existing evidence we found that life cycles and aquatic strategies are important in shaping functional structure of freshwater macroinvertebrates. Our results showed that the taxonomic groups examined fill remarkably different niches in the functional trait space. We found that the functional trait space of freshwater macroinvertebrates is reduced compared to the range of possibilities that would exist if traits varied independently. The observed decrease was between 23.44 and 44.61% depending on the formulation of the null expectations. We demonstrated also that taxonomic relatedness constrains the functional trait space of macroinvertebrates

Predicting beta diversity of terrestrial and aquatic beetles using ecogeographical variables:insights from the replacement and richness difference components

Abstract Aim: We examined the responses of the beta diversity of aquatic and terrestrial beetles to ecogeographical variables, including climate, land cover and land use, across Northern Europe. Location: Northern Europe (Denmark, Sweden, Norway and Finland). Methods: Information on the occurrence of ground beetles and diving beetles across Northern European biogeographical provinces was collated from literature sources. Beta diversity was examined using Jaccard dissimilarity coefficient as well as its replacement and richness difference components. Each of the three dissimilarity matrices (responses) was modelled using various ecogeographical variables (predictors) by generalized dissimilarity modelling (GDM). Results: The magnitude of total beta diversity was relatively similar between ground beetles and diving beetles, but the richness difference component contributed more than the replacement component to total beta diversity in ground beetles, whereas the opposite was true for diving beetles. The predictor variables most influential in GDM in accounting for spatial variation in beta diversity varied between the two beetle groups as well as between the replacement and richness difference components. In general, the richness difference component of ground beetles responded strongly to latitude and associated climatic variables, whereas the replacement component of diving beetles varied strongly along the same geographical gradient. Main conclusions: Our findings suggest that the study of the determinants of biodiversity patterns benefits from the partitioning of beta diversity into different components and from comparing terrestrial and aquatic groups. For example, our findings suggest that the strong climatic and land use‐related gradients in beta diversity have important implications for predicting and mitigating the effect of ongoing global change on the composition of regional biotas

A measure for assessing functional diversity in ecological communities

Functional diversity is regarded as a key in understanding the link between ecosystem function and biodiversity, but its measurement is rather problematic. The two widely used continuous measures are the dendrogram-based measure (DBM) and the functional attribute diversity (FAD). In contrast to DBM, FAD does not require the knowledge of the entire species pool before the analysis, and hence FAD is a more ideal tool for measuring functional diversity. However, the original form of FAD and its variants have several undesirable properties. Here, we suggest a modified FAD (denoted by MFAD), which-as illustrated by artificial and actual data sets-allows calculating functional diversity without violating the twinning and monotonicity criteria such that the number of species collected is compensated for. These requirements are met by replacing the original species by so-called functional species and then by dividing FAD by the number of functional units. Accordingly, MFAD measures the dispersion of species in the functional traits space so that MFAD values for different communities can directly be compared if the same set of functional traits is used. Finally, using data of two freshwater communities (caddisfly and riverine fish), we evaluate the change of species richness and functional diversity in relation to sampling effort (sample unit size). We found that functional diversity is a better and more reliable community descriptor than species richness in a sense that it converges to the maximum faster in the function of sampling effort

The global EPTO database:worldwide occurrences of aquatic insects

Abstract Motivation: Aquatic insects comprise 64% of freshwater animal diversity and are widely used as bioindicators to assess water quality impairment and freshwater ecosystem health, as well as to test ecological hypotheses. Despite their importance, a comprehensive, global database of aquatic insect occurrences for mapping freshwater biodiversity in macroecological studies and applied freshwater research is missing. We aim to fill this gap and present the Global EPTO Database, which includes worldwide geo-referenced aquatic insect occurrence records for four major taxa groups: Ephemeroptera, Plecoptera, Trichoptera and Odonata (EPTO). Main type of variables contained: A total of 8,368,467 occurrence records globally, of which 8,319,689 (99%) are publicly available. The records are attributed to the corresponding drainage basin and sub-catchment based on the Hydrography90m dataset and are accompanied by the elevation value, the freshwater ecoregion and the protection status of their location. Spatial location and grain: The database covers the global extent, with 86% of the observation records having coordinates with at least four decimal digits (11.1 m precision at the equator) in the World Geodetic System 1984 (WGS84) coordinate reference system. Time period and grain: Sampling years span from 1951 to 2021. Ninety-nine percent of the records have information on the year of the observation, 95% on the year and month, while 94% have a complete date. In the case of seven sub-datasets, exact dates can be retrieved upon communication with the data contributors. Major taxa and level of measurement: Ephemeroptera, Plecoptera, Trichoptera and Odonata, standardized at the genus taxonomic level. We provide species names for 7,727,980 (93%) records without further taxonomic verification. Software format: The entire tab-separated value (.csv) database can be downloaded and visualized at https://glowabio.org/project/epto_database/. Fifty individual datasets are also available at https://fred.igb-berlin.de, while six datasets have restricted access. For the latter, we share metadata and the contact details of the authors