Aim

To investigate the role of traits in beetle community assembly and test for consistency in these effects among several bioclimatic regions. We asked (1) whether traits predicted species’ responses to environmental gradients (i.e., their niches), (2) whether these same traits could predict co-occurrence patterns, and (3) how consistent were niches and the role of traits among study regions.

Location

Boreal forests in Norway and Finland, temperate forests in Germany.

Methods

We complied capture records of 468 wood-living beetle species from the three regions, along with nine morphological and ecological traits. Eight climatic and forest covariates were also collected. We used Bayesian hierarchical joint species distribution models to estimate the influence of traits and phylogeny on species’ niches. We also tested for correlations between species associations and trait similarity. Finally, we compared species niches and the effects of traits among study regions.

Results

Traits explained some of the variability in species’ niches, but their effects differed among study regions. However, substantial phylogenetic signal in species niches implies that unmeasured but phylogenetically structured traits have a stronger effect. Degree of trait similarity was correlated with species associations but depended idiosyncratically on the trait and region. Species niches were much more consistent – widespread taxa often responded similarly to an environmental gradient among regions.

Main conclusions

The inconsistent effects of traits among regions limits their current use in understanding beetle community assembly. Phylogenetic signal in niches, however, implies that better predictive traits can eventually be identified. Consistency of species niches among regions means niches may remain relatively stable under future climate and land use changes; this lends credibility to predictive distribution models based on future climate projections but may imply that species’ scope for short-term adaptation is limited.

See manuscript and supplemental material for methods details.

Briefly:

Species detections - number of species captured in window traps at each site

Species traits - from references cited in manuscript (Hagge et al., Seibold et al., author knowledge)

Environmental covaraites - from multiple local and remote measurements

Thanks also to Sindre Ligaard for identifying the beetle species in Norway, to Petri Martikainen and Matti Koivula for contributing to data collection and identifying beetles in Finland, and to numerous field assistants who set and maintained traps.

No missing values; dataset contain readme files

Saved as two .csv files per country:

DATA_[country].csv has environmental covariates and species as columns, sites as rows

TRAITS_[country].csv has traits as columns, species as rows.

.txt readme files describe fields in each of these files; additional details available in manuscript.