Forging an alliance: Linking taxonomy, phylogeny and community ecology in terrestrial insects

Background/Question/Methods The increasing use of phylogenetic information in analyses of community structure and assembly means that ecologists require reliable phylogenetic and taxonomic information. This is not a problem with some well-studied groups of organisms, but can be a major obstacle in studies of lesser-known taxa. Terrestrial insect assemblages contain large numbers of species, many of which are undescribed or unidentifiable. They are also ecologically diverse and even closely-related species can  occupy different trophic groups. Phylogenetic relationships are unknown for many insects. Research in insect systematics and community ecology often proceeds in isolation, with little collaboration between the two disciplines, but the use of terrestrial arthropods in ecological studies will require closer collaboration between taxonomists and ecologists than either group may be used to. DNA barcoding is a useful and low-cost method of identifying species, but a single gene cannot necessarily resolve phylogenetic relationships. There is still a need for phylogenetic analyses and for species identification tools using other characters. Taxonomy provides a service to ecology but is not simply a service industry; both sides benefit from collaboration. Traditionally different ways of dealing with sampling design, common versus rare species, species identification, and vouchers may be perceived as obstacles to collaboration. However, these obstacles may not be real and they are certainly not insurmountable.

Results/Conclusions Our recent diversity studies on flies (Diptera) of temperate forests have provided material of value for both ecological and taxonomic studies. Undescribed species have been dominant in some of these studies and are ecologically distinct from well-known, closely-related species. Quantitative analyses require standardized, replicated sampling whereas taxonomists often use directed collecting to target prime microhabitats. However, we have found that random sampling yields large numbers of taxonomically valuable specimens, especially in poorly-studied fly families such as Tipulidae and Mycetophilidae. Abundant species generally drive diversity patterns in assemblages; rare species are often omitted in diversity analyses, but these are the species that are of most interest to taxonomists. Undescribed species are not always rare. High ecological and trophic diversity in some families, such as Chloropidae and Phoridae, necessitates identification to species (or morphospecies in difficult groups), otherwise ecological patterns may be obscured. Species-level characters in many of these groups are cryptic and require taxonomic expertise. Deposition of voucher specimens is critical for subsequent verifiability of specimens, especially morphospecies. Vouchers are a potential future source of taxonomic data and voucher deposition should be promoted in ecological studies.