Gonçalves Micael F M, Gomes Susana I L, Soares Amadeu M V M, Scott-Fordsmand Janeck J, Amorim Mónica J B
Department of Biology & CESAM, University of Aveiro, Aveiro, 3810-193, Portugal.
Department of Bioscience, Aarhus University, Vejlsovej 25, PO BOX 314, Silkeborg, DK-8600, Denmark.
Ecotoxicology. 2017 May;26(4):570-575. doi: 10.1007/s10646-017-1785-4. Epub 2017 Feb 23.
Organisms' density can influence physiological processes related with fitness. In the present study we assessed the influence of organisms' density on the life-history parameters in two consecutive generations in Enchytraeus crypticus (Oligochaeta), a standard model in soil ecotoxicology. The densities tested were 1 (N1) and 20 (N20) organisms per replicate and 10 vs. 20 g of soil (for the 2nd generation test only). Results showed that reproductive output was affected by density, with organisms in N1 producing three times more juveniles per adult than when at N20. Organisms' length was affected by both density and space, i.e., organisms were smaller when less space available. Further, the density of parental generation (F0) had no influence on the endpoints reproduction and length assessed in F1, hence there was no transference of effects. These findings have potential implications in the standard Enchytraeid Reproduction Test, i.e. early mortality of the adults during toxicant exposure can affect the number and size of the offspring and the final results will also reflect the density related changes in reproduction.
生物的密度会影响与适应性相关的生理过程。在本研究中，我们评估了生物密度对连续两代隐尾蚓（寡毛纲）生活史参数的影响，隐尾蚓是土壤生态毒理学中的标准模型。测试的密度为每个重复样本1个（N1）和20个（N20）生物，以及10克与20克土壤（仅用于第二代测试）。结果表明，繁殖产出受密度影响，N1中的生物每只成年个体产生的幼体数量是N20中的三倍。生物的体长受密度和空间两者影响，即空间越少生物越小。此外，亲代（F0）的密度对F1中评估的繁殖和体长终点指标没有影响，因此不存在效应转移。这些发现对标准的蚯蚓繁殖试验具有潜在影响，即毒物暴露期间成年个体的早期死亡会影响后代的数量和大小，最终结果也将反映繁殖中与密度相关的变化。
