Gansu Key Laboratory of Biomonitoring and Bioremediation for Environmental Pollution, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.
Gansu Key Laboratory of Biomonitoring and Bioremediation for Environmental Pollution, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.
Sci Total Environ. 2021 Oct 10;790:148109. doi: 10.1016/j.scitotenv.2021.148109. Epub 2021 May 29.
Environmental stress can affect sperm traits whose changes have been reported to be associated with extra-pair fertilization (EPF) level in natural animal populations. However, little is known regarding how exposure to environmental heavy metals influences sperm traits and EPF level in free-living bird populations. In a previous study, we found that a tree sparrow (Passer montanus) population that has been exposed to heavy metal pollution over 60 years (Baiyin, BY) exhibits increased sperm quality compared with a population from a relatively unpolluted area (Liujiaxia, LJX). The high sperm quality could be related to extra-pair mating rates. Therefore, the present study investigated EPF level (the ratio of extra-pair offspring) in tree sparrow populations from BY and LJX, and analyzed the relationship between sperm traits (morphology, velocity and quantity) and EPF success. EPF success of tree sparrows was significantly correlated with their sperm velocity (p = 0.048) and total sperm length (p = 0.045), indicating that these sperm traits were important for EPF success. Tree sparrows from the BY population produced longer sperm with lower head/flagellum ratio and faster swimming sperm and showed a significantly higher EPF level than conspecifics from LJX. Thus, adaptive variation of sperm characteristics was related to the high EPF level in tree sparrows under long-term environmental heavy metal pollution. The findings are of scientific significance for exploring the evolution of mating tactics in wild bird populations under environmental stress.
环境压力会影响精子特征，已有研究报道称这些变化与自然种群中的种间交配（EPF）水平有关。然而，对于暴露于环境重金属如何影响自由生活鸟类种群的精子特征和 EPF 水平，人们知之甚少。在之前的一项研究中，我们发现，一个暴露在重金属污染下超过 60 年的树麻雀（Passer montanus）种群（Baiyin，BY）与来自相对未受污染地区的种群（Liujiasha，LJX）相比，精子质量有所提高。高质量的精子可能与种间交配率有关。因此，本研究调查了来自 BY 和 LJX 的树麻雀种群的 EPF 水平（种间后代的比例），并分析了精子特征（形态、速度和数量）与 EPF 成功之间的关系。树麻雀的 EPF 成功率与精子速度（p = 0.048）和总精子长度（p = 0.045）呈显著相关，表明这些精子特征对 EPF 成功很重要。来自 BY 种群的树麻雀产生的精子更长，头部/鞭毛比例更低，游动速度更快，EPF 水平明显高于来自 LJX 的同种鸟类。因此，在长期的环境重金属污染下，精子特征的适应性变化与树麻雀的高 EPF 水平有关。这些发现对于探索环境压力下野生鸟类种群交配策略的进化具有科学意义。
