砷污染环境生存下的螺形龟甲轮虫(Keratella cochlearis Gosse)对砷酸钠的适应进化

Adaptation Evolution of Sodium Arsenate in Keratella cochlearis Gosse Living in Arsenic Contaminated Environments

摘要: 砷是一种有毒的环境污染物，积累到一定浓度后不仅会对水中各种生物直接造成危害，还会通过食物链和食物网的传播间接影响水生生物。砷污染的研究大多集中在急性毒理学实验，但水生物种能否在砷污染湖泊中快速适应并进化以维持物种生存仍有待研究。实验选取了没有砷污染湖泊的螺形龟甲轮虫(Keratella cochlearis Gosse)作为实验生物，设置无砷组、低砷组、高砷组三个实验环境进行为期一年的种群选择，以验证在不同浓度的砷环境下三组实验种群是否对砷污染物产生了适应进化。结果表明，与在无砷污染下种群相比，无论是低砷组还是高砷组的螺形龟甲轮虫(Keratella cochlearis Gosse)种群，对有砷环境更加适应，能耐受更高的砷浓度。在砷环境选择进化的种群，其出生率比无砷种群高出10%~20%、死亡率低了5%~10%，有砷环境下的种群往往通过提高种群出生率和降低种群死亡率，来维持种群在有砷污染环境下的续存。

Abstract: Arsenic is a toxic environmental pollutant that accumulates to a certain concentration and not only causes direct harm to various organisms in water, but also affects aquatic organisms indirectly through the transmission of food chain and food web. Most studies on arsenic contamination have focused on acute toxicological experiments, but whether aquatic species can rapidly adapt and evolve to maintain species survival in arsenic-contaminated lakes remains to be studied. In the experiment, Keratella cochlearis Gosse from a lake without arsenic pollution was selected as the experimental organism. Three experimental environments were set up for population selection for one year, namely, the arsenic-free group, the low-arsenic group and the high-arsenic group, to verify whether the three experimental populations have evolved adaptation to arsenic pollutants under different concentrations of arsenic. The results showed that Keratella cochlearis Gosse population was more adaptable to arsenic environment and could tolerate higher arsenic concentration than the population without arsenic pollution, no matter in the low or high arsenic group. The birth rate of a population selected for evolution in an arsenic environment is 10%~20% higher and the death rate is 5%~10% lower than that of an arsenic-free population. Populations in an arsenic environment tend to maintain their survival in an arsenic polluted environment by increasing the birth rate and reducing the death rate.