Great Lakes Institute for Environmental Research, University of Windsor, Windsor, ON, Canada.
Integr Comp Biol. 2011 Oct;51(4):623-33. doi: 10.1093/icb/icr103. Epub 2011 Aug 27.
The increased overexploitation of freshwater ecosystems and their extended watersheds often generates a cascade of anthropogenic stressors (e.g., acidification, eutrophication, metal contamination, Ca decline, changes in the physical environment, introduction of invasive species, over-harvesting of resources). The combined effect of these stressors is particularly difficult to study, requiring a coordinated multi-disciplinary effort and insights from various sub-disciplines of biology, including ecology, evolution, toxicology, and genetics. It also would benefit from a well-developed and broadly accepted model systems. The freshwater crustacean Daphnia is an excellent model organism for studying multiple stressors because it has been a chosen focus of study in all four of these fields. Daphnia is a widespread keystone species in most freshwater ecosystems, where it is routinely exposed to a multitude of anthropogenic and natural stressors. It has a fully sequenced genome, a well-understood life history and ecology, and a huge library of responses to toxicity. To make the case for its value as a model species, we consider the joint and separate effects of natural and three anthropogenic stressors-climatic change, calcium decline, and metal contaminants on daphniids. We propose that integrative approaches marrying various subfields of biology can advance our understanding of the combined effects of stressors. Such approaches can involve the measuring of multiple responses at several levels of biological organization from molecules to natural populations. For example, novel interdisciplinary approaches such as transcriptome profiling and mutation accumulation experiments can offer insights into how multiple stressors influence gene transcription and mutation rates across genomes, and, thus, help determine the causal mechanism between environmental stressors and population/community effects as well as long-term evolutionary patterns.
淡水生态系统及其延伸流域的过度开发常常会产生一连串人为压力源（例如酸化、富营养化、金属污染、钙下降、物理环境变化、入侵物种的引入、资源过度捕捞）。这些压力源的综合影响特别难以研究，需要协调多学科的努力，并从生物学的各个分支学科（包括生态学、进化、毒理学和遗传学）中获得见解。它还将受益于一个发达和广泛接受的模型系统。淡水甲壳类动物水蚤是研究多种压力源的理想模型生物，因为它已经成为这四个领域的研究重点。水蚤是大多数淡水生态系统中广泛存在的关键物种，在这些生态系统中，它经常暴露于多种人为和自然压力源下。它具有完全测序的基因组、充分理解的生活史和生态学，以及大量对毒性的反应库。为了证明它作为一种模式物种的价值，我们考虑了自然和三种人为压力源（气候变化、钙下降和金属污染物）对水蚤的联合和单独影响。我们提出，将生物学各个分支学科结合起来的综合方法可以促进我们对压力源综合影响的理解。这些方法可以涉及从分子到自然种群的多个层次的生物组织测量多种反应。例如，转录组分析和突变积累实验等新的跨学科方法可以深入了解多种压力源如何影响整个基因组的基因转录和突变率，从而有助于确定环境压力源与种群/群落效应以及长期进化模式之间的因果关系。
