Final Report Summary - FLOODPLAINEVOLUTION (An Evolutionary Approach to Biodiversity Conservation: Riverine Floodplains of the European Alps as a Model System) Project contextThis project used large-scale surveys of genetic variation in aquatic insect communities to measure species diversity and genetic relatedness in riverine flood plains. This method represents a technological advance over traditional survey methods that use morphological variation and employed state-of-the-art analytical models to analyse biodiversity patterns. Riverine flood plains are one of the most diverse ecosystems on earth and create a very high spatio-temporal heterogeneity. Unfortunately, the most diverse and abundant aquatic insects are poorly known at the species level, therefore research that has been carried out to link biodiversity and the spatiotemporal heterogeneity relies on estimates of diversity and lacks an evolutionary perspective. The project examined the role of habitat heterogeneity in the evolutionary processes of structuring biodiversity by sampling communities from different spatial components comprising a hierarchy system at microhabitat, habitats, reaches, section, and catchment levels.Project objectivesThe objectives of this project were:(1) to construct a 'DNA profile' of macroinvertebrate communities (specifically the "EPTC" taxa: Ephemeroptera (mayflies), Plecoptera (stoneflies), Trichoptera (caddisflies), and Chironomidae (non-biting midges)) along a semi-natural riverine corridor in the Alps, using DNA sequences and coalescent-based modelling to delineate species, rather than traditional morphological taxonomy;(2) determine the extent of local and regional endemism of flood-plain species;(3) reconstruct a phylogeny of all sampled species and calculate Phylogenetic Diversity (PD) of individual habitats, individual reaches of rivers, and whole river corridors; and(4) use the resulting tree topology to examine the degree of phylogenetic clustering and over-dispersion as a means to quantify the role of evolution in community assembly.Project tasksSeven tasks were performed during the project: fieldwork and sampling; laboratory sorting and DNA sequencing; sequence editing; fieldwork follow-up; phylogenetic and Generalized Mixed Yule-Coalescent (GMYC) analysis; additional analysis (statistical and simulation analyses); and writing for publication. All tasks have been 100 % completed except for writing for publication. Preparation of publications is approximately 80 % complete. Manuscripts are in preparation for broad-interest journals (Proceedings of the National Academy of Sciences, Ecology Letters) and for high-ranking freshwater journals (Freshwater Biology, Freshwater Sciences).Fieldwork and sampling were conducted on the Tagliamento River, Friuli, Italy. In summer 2009 and spring 2010, we collected qualitative samples of all target taxa (EPTC) from 20 reaches throughout the headwater and downstream river sections (4 to 1556 m in elevation). We employed a nested sampling design involving four levels of spatial hierarchy at section, reach, habitat, and microhabitat scales. Finally, a total of 450 samples of community assemblage were collected. Laboratory sorting took place in collaboration with taxonomic experts for each group. All laboratory steps required for DNA sequencing were performed using standard medium-throughput protocols. For all specimens, DNA sequence with 658-bp length of mitochondrial protein-coding cytochrome c oxidase subunit I (cox1) were obtained and edited using standard software. Following reconstruction of a phylogenetic tree using the DNA sequence data matrix, putative species were delineated using the GMYC method. Based on the outputs of GMYC species and the phylogenetic tree, we quantified the relative contribution of each of the smallest sampling unit (i.e. microhabitat) to the gamma-diversity, or total GMYC-species richness and phylogenetic diversity (PD, an index of evolutionary potential of community) at the catchment scale.Project resultsThe results indicated the very important ecological role of large woody debris (LWD) in sustaining species richness and the evolutionary potential (PD) of the Chironomidae community in the catchment. Percentages of contribution of LWD to the gamma-diversity at the catchment scale were more than 30 % both for species richness and evolutionary potential.We found 225 species of Chironomidae using the DNA approach. At first estimate, approximately 30 of these species are undescribed (i.e. 'new to science'). The diversity of other groups (Ephemeroptera, Plecoptera) was closer to that expected. The biodiversity partitioning analysis in the spatially hierarchal system showed an unexpected and extremely high contribution of large woody debris (LWD) to whole diversity at the catchment scale, both in species richness and the evolutionary potential of the chironomidae community. Percentages of contribution of LWD for the total diversity were more than 30 % both for species richness and phylogenetic diversity. This result suggests high conservation importance of wood supplied from terrestrial ecosystems in the catchment in sustaining biodiversity in the natural flood plain river in the Alps. This is a particularly important result in light of the current debate on management practice about whether or not to remove large woody debris from rivers.The overall level of species richness of Chironomidae uncovered by our methods was considerably higher than expected. This result will support the GMYC approach as a new tool to provide a powerful aid to standard morphological taxonomy of this highly diverse but difficult group. Results from other groups (mayflies, stoneflies, and caddisflies) were closer to the expected diversity. The result will also make great advances in understanding true biodiversity in the natural flood plain river, a biodiversity hot spot in Europe, giving a target image of biodiversity for river restoration projects in the Alps. Further, the high contribution of large woody debris to overall species richness and evolutionary potential in the catchment scale suggests conservation importance of these local ecological spaces for sustaining biodiversity of the flood plain rivers.
