Abstract
Chironomids are a useful group for investigating body size responses to warming due to their high local abundance and sensitivity to environmental change. We collected specimens of six species of chironomids every 2 weeks over a 2-year period (2017–2018) from mesocosm experiments using five ponds at ambient temperature and five ponds at 4°C higher than ambient temperature. We investigated (1) wing length responses to temperature within species and between sexes using a regression analysis, (2) interspecific body size responses to test whether the body size of species influences sensitivity to warming, and (3) the correlation between emergence date and wing length. We found a significantly shorter wing length with increasing temperature in both sexes of Procladius crassinervis and Tanytarsus nemorosus, in males of Polypedilum sordens, but no significant relationship in the other three species studied. The average body size of a species affects the magnitude of the temperature-size responses in both sexes, with larger species shrinking disproportionately more with increasing temperature. There was a significant decline in wing length with emergence date across most species studied (excluding Polypedilum nubeculosum and P. sordens), indicating that individuals emerging later in the season tend to be smaller.
Highlights
Since the 1990s, climate change as a consequence of anthropogenic activities has become an important issue in ecological, biodiversity and conservation research
The main characteristics of predicted global climate change are a change in precipitation patterns and intensity, stochastic temperature variability, and an increase in the average global mean temperature, that has increased at the rate of 0.08–0.14°C per decade since 1951 (Hansen et al, 2006; IPCC, 2014)
It is generally known that the developmental rate of early life stages in ectotherms depends on environmental temperature, known as the temperature-size rule (TSR) (Atkinson, 1994), which affects the final adult body size
Summary
Since the 1990s, climate change as a consequence of anthropogenic activities has become an important issue in ecological, biodiversity and conservation research. Changes in the final adult body size can affect individual fitness. In addition to individual fitness, increasing temperature can relay the effects of changes in body size to species interactions and community dynamics. A reduction in body size in species that are major food resources within a community can indirectly change food web structure and community dynamics by altering feeding rates and predator–prey interactions (Boukal et al, 2019). Understanding how warming affects the body sizes of animals toward the base of the food chain (e.g. chironomids) will allow us to better predict its potential cascading effects on ecological functioning in the future
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