Assessing five decades of change in a high Arctic parasitoid community

Abstract

Arctic ecosystems are fragile, and are particularly sensitive to the pressures of climate change. Both average temperature and precipitation have increased over the past five decades on Ellesmere Island, Nunavut, Canada in the high Arctic. Altered growth forms and increased biomass in dominant plant species on Ellesmere Island have been observed concurrent with the changing climate, but shifts in the diversity or rank abundance of plant and bird species have not been detected. Changes in diversity may take longer to appear, or may be assessed better using organisms with shorter generation times such as insects. We explored the ecological impacts of climate change on Ellesmere Island using historical and contemporary communities of ichneumonid wasps. We compared community diversity, functional composition, and body size of two common species using ichneumonid specimens collected in 1961–1965, 1980–1982, 1989–1992, and 2010. We found high compositional similarity between collections, overlapping estimates of species richness, no change in the proportion of idiobiont genera in the community, and no clear pattern in body size over time. The greatest amount of variation over time was detected in parasitoids of herbivores; proportionally fewer herbivore‐parasitizing genera were found in 2010 than in historical collections, and the two genera that were only found in one of the four collections were both parasitoids of herbivores. Our results point to the need to assess climate change effects in Arctic systems using a range of taxa, and responses to large‐scale environmental disturbances may be idiosyncratic and difficult to predict.

Establishing a community‐wideDNAbarcode library as a new tool for arctic research

“…; Timms et al . ). Here, new tools like the current DNA barcode library offer the potential to demonstrate how quick and widespread rates of change may be when assessed not for single guilds or taxa, but across entire communities.…”

“…In the current study, we detected a migratory moth new to the region through DNA barcoding of Malaise catches from 2014 (the diamond-back moth Plutella xylostella, BOLD: AAA1513; Appendix S4, Supporting information; Data set ZackGM). In terms of guild-wide change, a study by Fernandez-Triana et al (2011) reported substantial turnover of parasitoid wasp species at a subarctic site repeatedly sampled through time, whereas two other studies detected no clear changes in guilds of either parasitoid wasps or Diptera (Renaud et al 2012b;Timms et al 2013). Here, new tools like the current DNA barcode library offer the potential to demonstrate how quick and widespread rates of change may be when assessed not for single guilds or taxa, but across entire communities.…”

Declining diversity and abundance of High Arctic fly assemblages over two decades of rapid climate warming

“…A major decrease in the number of muscid flies caught annually across all habitats and in the wet fen in particular led to significant shifts in assemblage composition over the study period at Zackenberg, a result that could be detected mainly because of the repeated and standardized collection protocol. Some studies in which species abundance could not be considered due to differences in sampling protocols have failed to find any temporal shifts in Arctic insect biodiversity by comparing contemporary and historical data with presence–absence data (Renaud et al , Timms et al ). Our results show that abundance is a key aspect of biodiversity that needs to be measured and monitored in order to better document, understand and predict the effects of environmental changes on biodiversity in the Arctic.…”

Natural history collections as windows on evolutionary processes

“…Because invertebrates have short generation times and are generally abundant in NHCs, many other invertebrate studies have been able to utilize collections to examine evolutionary changes over time; phenotypic changes have been attributed to climate change (Anderson et al 2008;Babin-Fenske et al 2008;O _ zgo & Schilthuizen 2012;Timms et al 2013), habitat fragmentation (Norberg & Leimar 2002;Anderson et al 2008) and invasive species (Carroll & Boyd 1992), among other drivers. As more insect genomes are sequenced and annotated, insects will become a particularly suitable group in which the exploration of candidate genes could be combined with the unique temporal and highresolution spatial dimensions provided by NHCs.…”