Effects of developmental acclimation on adult salinity tolerance in the freshwater-invading copepod Eurytemora affinis
Effects of developmental acclimation on adult salinity tolerance in the freshwater-invading copepod Eurytemora affinis
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DOI：
10.1086/375433
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发表时间：
2003-05-01
影响因子：
1.6
通讯作者：
Petersen, CH
中科院分区：
文献类型：
--
作者：
Lee, CE;Petersen, CH
人们普遍认为入侵物种具有广泛的耐受性，使它们能够在新的栖息地定居，但这种假设很少得到检验。特别是，人们对驯化（可塑性）和适应对于入侵成功的相对重要性知之甚少。本研究探讨了短期和发育适应对桡足类Eurytemora affinis 成虫耐盐性的影响。这种微型甲壳类动物出现在河口和盐沼栖息地，但在上个世纪入侵了淡水栖息地。通过比较对急性和逐渐盐度变化到低盐度（淡水）的成虫存活率来确定短期适应的影响。发育适应对成虫耐受性的影响是通过对来自马萨诸塞州埃德加敦大池塘的一个咸水种群进行分巢 4 x 2 析因实验设计来确定的。将 20 个全同胞窝分开并在四种盐度（新鲜、5、10 和 27 实用盐度单位 [PSU]）下饲养。成年后，将来自三种盐度处理的窝（新鲜时没有存活者）分为低（新鲜）和高（40 PSU）盐度胁迫处理，并测量 24 小时的存活率。成虫的短期适应似乎不会对低盐度耐受性产生长期影响，因为相对于短期内（7 小时后）的急性转移，逐渐转移到淡水可提高存活率，但在 8 天的较长时期内则不会。发育适应对低盐度和高盐度耐受性具有截然不同的影响。也就是说，饲养盐度对高盐度（40 PSU）胁迫的耐受性有显着影响，但对低盐度（淡水）胁迫的耐受性没有显着影响。此外，在淡水条件下，离合对生存有显着影响，表明低盐度耐受性具有遗传成分，但对高盐度的反应没有显着的离合效应。虽然发育驯化可能会提高高盐度下的存活率，但驯化的最小影响和离合器对低盐度耐受性的显着影响表明自然选择在淡水入侵事件中的重要性。
Invasive species are commonly thought to have broad tolerances that enable them to colonize new habitats, but this assumption has rarely been tested. In particular, the relative importance of acclimation (plasticity) and adaptation for invasion success are poorly understood. This study examined effects of short-term and developmental acclimation on adult salinity tolerance in the copepod Eurytemora affinis. This microcrustacean occurs in estuarine and salt marsh habitats but has invaded freshwater habitats within the past century. Effects of short-term acclimation were determined by comparing adult survival in response to acute versus gradual salinity change to low salinity (fresh water). Effects of developmental acclimation on adult tolerance were determined using a split-brood 4 x 2 factorial experimental design for one brackish-water population from Edgartown Great Pond, Massachusetts. Twenty full-sib clutches were split and reared at four salinities (fresh, 5, 10, and 27 practical salinity units [PSU]). On reaching adulthood, clutches from three of the salinity treatments (no survivors at fresh) were split into low- (fresh) and high- (40 PSU) salinity stress treatments, at which survival was measured for 24 h. Short-term acclimation of adults did not appear to have a long-term affect on low- salinity tolerance, given that gradual transfers to fresh water enhanced survival relative to acute transfers in the short term (after 7 h) but not over a longer period of 8 d. Developmental acclimation had contrasting effects on low- versus high- salinity tolerance. Namely, rearing salinity had a significant effect on tolerance of high- salinity (40 PSU) stress but no significant effect on tolerance of low- salinity (freshwater) stress. In addition, there was a significant effect of clutch on survival under freshwater conditions, indicating a genetic component to low- salinity tolerance but no significant clutch effect in response to high salinity. While developmental acclimation might enhance survival at higher salinities, the minimal effect of acclimation and significant effect of clutch on low- salinity tolerance suggest the importance of natural selection during freshwater invasion events.