Understanding the physiology of non-native species in Antarctica is key to elucidating their ability to colonise an area, and how they may respond to changes in climate. Eretmoptera murphyi is a chironomid midge introduced to Signy Island (Maritime Antarctic) from South Georgia (Sub-Antarctic) where it is endemic. Here, we explore the tolerance of this species’ egg masses to heat and desiccation stress encountered within two different oviposition microhabitats (ground surface vegetation and underlying soil layer). Our data show that, whilst oviposition takes place in both substrates, egg sacs laid individually in soil are at the greatest risk of failing to hatch, whilst those aggregated in the surface vegetation have the lowest risk. The two microhabitats are characterised by significantly different environmental conditions, with greater temperature fluctuations in the surface vegetation, but lower humidity (%RH) and available water content in the soil. Egg sacs were not desiccation resistant and lost water rapidly, with prolonged exposure to 75% RH affecting survival for eggs in singly oviposited egg sacs. In contrast, aggregated egg sacs (n = 10) experienced much lower desiccation rates and survival of eggs remained above 50% in all treatments. Eggs had high heat tolerance in the context of the current microhabitat conditions on Signy. We suggest that the atypical (for this family) use of egg sac aggregation in E. murphyi has developed as a response to environmental stress. Current temperature patterns and extremes on Signy Island are unlikely to affect egg survival, but changes in the frequency and duration of extreme events could be a greater challenge.

中文翻译：

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不是那么自由的范围吗？产卵微生境和卵聚集影响墨菲单翅目（双翅目：摇蚊科）繁殖成功

了解南极洲非本地物种的生理机能是阐明它们在一个地区定居的能力以及它们如何应对气候变化的关键。Eretmoptera murphyi 是一种摇蚊，从南乔治亚岛（亚南极洲）引入西尼岛（南极洲），在那里它是地方性的。在这里，我们探索了该物种的卵群对两种不同产卵微生境（地表植被和底层土壤层）中遇到的热和干燥胁迫的耐受性。我们的数据显示，虽然产卵发生在两种基质中，但单独放置在土壤中的卵囊无法孵化的风险最大，而聚集在表层植被中的卵囊风险最低。这两个微生境的特点是环境条件明显不同，表层植被的温度波动较大，但土壤中的湿度 (%RH) 和有效水含量较低。卵囊不耐干燥且失水迅速，长时间暴露于 75% RH 会影响单排卵囊中卵的存活率。相比之下，在所有处理中，聚集的卵囊（n = 10）的干燥率要低得多，并且卵的存活率保持在 50% 以上。在目前 Signy 的微生境条件下，鸡蛋具有很高的耐热性。我们认为 E. murphyi 中卵囊聚集的非典型（对于这个家庭）使用已经发展为对环境压力的反应。西尼岛上目前的温度模式和极端情况不太可能影响鸡蛋的存活率，但极端事件频率和持续时间的变化可能是一个更大的挑战。