Abstract:
The study of interactions between copepods of the genus Acartia and toxic dinoflagellates of the genus Alexandrium has been an important topic during the last four decades. Feeding behavior and physiological responses of copepods have been studied in laboratory and field experiments, sometimes with contradictory results. More recently, an evolutionary adaptive mechanism leading to enhanced tolerance of Alexandrium toxins in a population of Acartia experiencing chronic exposure to these dinoflagellates has been reported. In the present work, we collected data from the existing studies on the effects of Alexandrium on feeding, reproduction and mortality of Acartia. With these data, we performed a systematic review consisting of a secondary analysis employing general or generalized linear models, weighting data from different studies by the reciprocal of their standard deviation. Our first aim was to overcome shortcomings of individual studies: limited ranges of the variables and overlooked variables (experiment length, population adaptation). These shortcomings could have led to inconsistent conclusions by missing heterogeneous patterns in copepod responses and in the interactions between variables. Our second aim was to test the enhanced physiological performance of chronically exposed relative to naïve copepod populations over a wide geographic range. We found that the feeding rate is enhanced by increased food biomass, irrespective of the food type. Toxins do not have a clear effect on egg production and have a bi-phasic effect on egg hatching success, which was negative above a specific threshold. Toxins also increased mortality. Experiment length had a positive effect on egg production and negative on egg hatching. Naïve copepod populations showed consistently lower ingestion of Alexandrium and egg hatching rates, thereby supporting the spread of the aforementioned mechanism across populations over a wide geographic range.
摘要:
在过去的四十年中,对Acartia属的co足类与亚历山大属的有毒鞭毛藻之间的相互作用的研究一直是一个重要课题。已经在实验室和田间试验中研究了co足类的摄食行为和生理反应。有时结果矛盾。最近,已经报道了一种进化适应性机制,该机制导致长期暴露于这些鞭毛藻的Acartia种群对Alexandrium毒素的耐受性增强。在目前的工作中,我们从现有的关于亚历山大对摄食的影响的研究中收集了数据,的繁殖和死亡率。有了这些数据,我们进行了系统综述,包括采用一般或广义线性模型的二次分析,根据不同研究的标准偏差的倒数对数据进行加权。我们的第一个目标是克服个别研究的缺点:变量的有限范围和被忽视的变量(实验长度,人口适应)。这些缺点可能会由于缺少co足类动物反应和变量之间相互作用的异质模式而导致结论不一致。我们的第二个目的是在广泛的地理范围内测试相对于原始co足类种群的长期暴露的生理性能增强。我们发现食物生物量的增加提高了摄食率,不管食物的种类。毒素对产卵没有明显的影响,对卵孵化成功具有双相作用,高于特定阈值为负。毒素也增加了死亡率。实验长度对产卵有积极影响,对卵孵化有消极影响。Naive足类动物种群表现出持续较低的Alexandrium摄取和卵孵化率,从而支持上述机制在广泛地理范围内的人群中的传播。