Trade-offs between microhabitat selection and physiological plasticity in the Antarctic springtail, Cryptopygus antarcticus (Willem)

In the maritime Antarctic, terrestrial arthropods have recourse to two strategies to mitigate low summer temperatures: (1) physiological plasticity and (2) avoidance via microhabitat insulation. This study investigated the interaction between these strategies in the springtail, Cryptopygus antarcticus, established in situ within contrasting microcosms (buffered vs. exposed) and within two sets of habitat simulations (wet vs. dry) over diurnal scales through the Antarctic summer. Significant differences were found in the cold hardiness of springtails sampled simultaneously from each microcosm. Exposed animals showed greater plasticity in the "true" austral summer, but as field temperatures declined preceding the onset of winter, buffered animals showed greater resilience. Overall, water was found to inhibit the buffering effect of moss and there was a significantly greater discrimination between buffered and exposed microcosms in the dry treatment. Analysis of microhabitat temperatures indicate that it is thermal variability not lower temperature that is responsible for the greater plasticity of exposed animals.

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