Department of Genetics, Maharshi Dayanand University, Rohtak 124001, India.
Biol Open. 2021 Jun 15;10(6). doi: 10.1242/bio.058527. Epub 2021 Jun 8.
Narrow distribution patterns of tropical Drosophila species are limited by lower resistance to cold or drought. In the invasive tropical Drosophila kikkawai, we tested whether developmental and adult acclimations at cooler temperatures could enhance its stress resistance level. Adult acclimation of winter collected body color morphs revealed a significant increase in the level of cold resistance. For light morph, its abundance during winter is not consistent with thermal-melanism hypothesis. However, higher cold acclimation capacity, as well as storage of energy metabolites could support its winter survival. In the wild-caught light and intermediate morphs, there is a lack of trade-off between cold and heat resistance but not in the case of dark morph. Developmental plasticity (15°C) resulted in the fivefold increase of cold survival at 0°C; and a twofold increase in desiccation resistance but a modest reduction (∼28-35%) in heat resistance as compared to morph strains reared at 25°C. Drought acclimation changes were significantly higher as compared with cold or heat pretreatment. We observed a trade-off between basal resistance and acclimation capacity for cold, heat, or drought resistance. For homeostatic energy balance, adult acclimation responses (cold versus drought; heat versus drought) caused compensatory plastic changes in the levels of proline or trehalose (shared patterns) but different patterns for total body lipids. In contrast, rapid cold or heat hardening-induced changes in energy metabolites were different as compared to acclimation. The ability of D. kikkawai to significantly increase stress tolerance through plasticity is likely to support its invasion potential.
热带果蝇的分布范围较窄，这是由于它们对寒冷或干旱的抵抗力较低。在入侵性的热带果蝇 D. kikkawai 中，我们测试了在较低温度下进行发育和成年适应是否可以提高其抗应激水平。对冬季收集的体色变体进行成年适应处理，发现其抗寒能力显著提高。对于浅色变体，其在冬季的丰度与热黑变假说不一致。然而，较高的冷适应能力以及能量代谢物的储存可以支持其在冬季的生存。在野外捕获的浅色和中间变体中，冷和热抗性之间没有权衡，但在深色变体中则存在这种权衡。发育可塑性（15°C）使在 0°C 下的冷存活率增加了五倍；在抗干燥能力方面增加了两倍，但在抗热能力方面略有降低（约 28-35%），与在 25°C 下饲养的变体相比。与冷或热预处理相比，干旱适应变化显著更高。我们观察到基础抗性和适应能力之间存在权衡，无论是对冷、热还是干旱抗性。对于体内能量平衡，成年适应反应（冷与干旱；热与干旱）导致脯氨酸或海藻糖水平的补偿性变化（共享模式），但总体脂的变化模式不同。相比之下，快速冷或热硬化诱导的能量代谢物变化与适应不同。D. kikkawai 通过可塑性显著提高抗应激能力的能力可能支持其入侵潜力。
