Flower‐visitor communities of an arcto‐alpine plant—Global patterns in species richness, phylogenetic diversity and ecological functioning

Abstract

Pollination is an ecosystem function of global importance. Yet, who visits the flower of specific plants, how the composition of these visitors varies in space and time and how such variation translates into pollination services are hard to establish. The use of DNA barcodes allows us to address ecological patterns involving thousands of taxa that are difficult to identify. To clarify the regional variation in the visitor community of a widespread flower resource, we compared the composition of the arthropod community visiting species in the genus Dryas (mountain avens, family Rosaceae), throughout Arctic and high‐alpine areas. At each of 15 sites, we sampled Dryas visitors with 100 sticky flower mimics and identified specimens to Barcode Index Numbers ( BIN s) using a partial sequence of the mitochondrial COI gene. As a measure of ecosystem functioning, we quantified variation in the seed set of Dryas . To test for an association between phylogenetic and functional diversity, we characterized the structure of local visitor communities with both taxonomic and phylogenetic descriptors. In total, we detected 1,360 different BIN s, dominated by Diptera and Hymenoptera. The richness of visitors at each site appeared to be driven by local temperature and precipitation. Phylogeographic structure seemed reflective of geological history and mirrored trans‐Arctic patterns detected in plants. Seed set success varied widely among sites, with little variation attributable to pollinator species richness. This pattern suggests idiosyncratic associations, with function dominated by few and potentially different taxa at each site. Taken together, our findings illustrate the role of post‐glacial history in the assembly of flower‐visitor communities in the Arctic and offer insights for understanding how diversity translates into ecosystem functioning.

Introduction: Special issue on species interactions, ecological networks and community dynamics – Untangling the entangled bank using molecular techniques

“…Where Siegenthaler et al () use molecular techniques to identify what the shrimp feeds on, Tiusanen et al, () apply them to the opposite task of identifying which arthropods visit the flowers of several arctic Dryas species (all known as mountain avens). Targeting multiple sites around the Arctic, they too find an astonishing taxonomic range and richness, in this case of literally thousands of arthropod species sharing this common floral resource.…”

“…The current issue shows how molecular data can reveal processes shaping communities. Tiusanen et al () study flower‐visiting communities across the Arctic. By comparing patterns of phylogenetic diversity with those previously observed in plants, and by matching pairwise patterns of floristic and faunistic similarity across Arctic sites, they show that plants and arthropods have likely used similar expansion routes across the Arctic from shared refugia.…”

“…By comparing patterns of phylogenetic diversity with those previously observed in plants, and by matching pairwise patterns of floristic and faunistic similarity across Arctic sites, they show that plants and arthropods have likely used similar expansion routes across the Arctic from shared refugia. This reveals a strong imprint of geological history on current patterns of community structure, beyond imprints of current climate such as precipitation and temperature (Tiusanen et al, ).…”

“…In evidence of these claims, Doña, Proctor, et al () use high‐throughput sequencing (HTS) and DNA metabarcoding to determine gut contents from 1,833 individual mites of 18 species inhabiting 18 bird species, whereas Doña, Serrano, et al () report findings from 25,540 individual mites (representing 64 species) from 1,130 birds (representing 71 species). Tiusanen et al () sampled 31,345 arthropods, of which they individually sequenced 13,681 individuals, detecting 1,360 barcoding BINs in the process. Schröter et al () deal with root‐associated mycobiomes encompassing a total of 5,955 different operational taxonomic units across spatial scales of over 1,000 km in more than 100 temperate forest plots.…”

“…It is also the basis for grouping nodes into more and less similar blocks within webs, and for comparing the roles of such similar blocks among regions (e.g., “the role of blowflies in different ecosystems”). Mapping nodes (be they defined by any criteria, morphology or DNA) onto some concept of phylogeny will significantly increase our understanding of network/community structure (Tiusanen et al, ), and mapping them onto known taxonomy (most papers in this Special Issue) is perhaps the easiest way to go. For each of these endeavours, we need to maintain a link between molecular barcoding, MOTUs and some aspects of traditional taxonomy (Hebert, Cywinska, & Ball, ; Hebert & Gregory, ).…”