Xie Lingtian, Klerks Paul L
Department of Biology, University of Louisiana at Lafayette, PO Box 42451, Lafayette, Louisiana 70504, USA.
Environ Toxicol Chem. 2003 Feb;22(2):313-20.
An artificial selection experiment was conducted for six generations to investigate the responses to selection for cadmium resistance in the least killifish, Heterandria formosa. There was a rapid response to selection. After only one generation of selection, two of the three selection lines had an increased resistance to cadmium, while all three selection lines had an elevated resistance by the next generation. After six generations of selection, fish from the selection lines survived about three times as long as control line fish when exposed to cadmium. Realized heritability for cadmium resistance was estimated to be 0.50. Cross-resistance to copper was studied in the F2, F3, and F6 generations; fish from the cadmium-resistant lines had a longer survival time than those from the control lines. Resistance to heat was investigated in the F2, F3, and F5 generations; the cadmium-resistant lines had a significantly shorter survival time than the control lines. Our results showed that evolution of resistance to cadmium was rapid, that cross-resistance to copper occurred, and that the evolution of resistance to cadmium was accompanied by a trade-off (fitness costs) as evidenced by the reduced heat tolerance.
进行了六代人工选择实验，以研究细纹鳉（Heterandria formosa）对镉抗性选择的反应。对选择有快速反应。仅经过一代选择，三个选择系中的两个对镉的抗性就有所增加，而到下一代时，所有三个选择系的抗性都有所提高。经过六代选择后，当暴露于镉时，选择系的鱼存活时间约为对照系鱼的三倍。镉抗性的实现遗传力估计为0.50。在F2、F3和F6代研究了对铜的交叉抗性；抗镉系的鱼比对照系的鱼存活时间更长。在F2、F3和F5代研究了对热的抗性；抗镉系的存活时间明显短于对照系。我们的结果表明，对镉抗性的进化很快，出现了对铜的交叉抗性，并且对镉抗性的进化伴随着权衡（适应性代价），耐热性降低就是证明。
