Vitt Simon, Mehlis-Rick Marion, Bakker Theo C M, Rick Ingolf P
Institute for Evolutionary Biology and Ecology, University of Bonn, An der Immenburg 1, 53121, Bonn, Germany.
Oecologia. 2019 Jun;190(2):355-366. doi: 10.1007/s00442-019-04422-z. Epub 2019 May 27.
Organisms inhabiting shallow aquatic habitats currently experience increasing levels of solar ultraviolet B radiation (UVB). UVB causes damage on cellular and molecular levels and can affect associated life-history traits either through direct exposure or indirectly through oxidative stress generation. We examined UVB effects on pre- and post-mating sexual traits in three-spined stickleback fish (Gasterosteus aculeatus). Adult, reproductively non-active males were assigned to two exposure treatments under semi-natural conditions in an outdoor experiment; one group received natural radiation (UVB) whilst the other group received additional UVB (UVB). After two months, colour metrics were used to quantify male breeding colouration as pre-mating trait. At the post-mating stage, sperm morphology, number and movement as well as testes mass were determined. Males did not significantly differ in sexual ornamentation between treatments, but UVB fish had smaller testes as well as fewer and shorter sperm than UVB fish. Sperm movement was not significantly different between treatments. However, in UVB males, linear and progressive movement of sperm was positively correlated with sperm morphology (head-to-tail length ratio), whereas in UVB males this relationship was negative (but not significant). Additionally, there was a significant treatment by body condition interaction concerning head-to-tail length ratio, i.e. head-to-tail length ratio increased with condition in UVB males whereas there was no relationship in UVB fish. Our findings reveal that increased UVB levels influence post-mating fitness-relevant traits in males whilst having no significant impact on pre-mating sexual traits, suggesting selective UVB-effects at the gamete level with consequences for reproductive performance.
栖息在浅水水生栖息地的生物目前正面临着太阳紫外线B辐射（UVB）水平的不断上升。UVB会在细胞和分子水平上造成损害，并可能通过直接照射或间接通过产生氧化应激来影响相关的生活史特征。我们研究了UVB对三刺鱼（Gasterosteus aculeatus）交配前和交配后性特征的影响。在一项户外实验中，将成年的、生殖上不活跃的雄性三刺鱼置于半自然条件下的两种照射处理中；一组接受自然辐射（UVB），而另一组接受额外的UVB（UVB）。两个月后，使用颜色指标来量化雄性的繁殖体色作为交配前的特征。在交配后阶段，测定精子的形态、数量和运动以及睾丸质量。不同处理间雄性的性装饰没有显著差异，但接受UVB照射的鱼的睾丸较小，精子数量较少且较短，相比接受自然辐射的鱼。不同处理间精子运动没有显著差异。然而，在接受UVB照射的雄性中，精子的直线运动和前进运动与精子形态（头尾长度比）呈正相关，而在接受自然辐射的雄性中这种关系呈负相关（但不显著）。此外，在头尾长度比方面存在显著的处理与身体状况的交互作用，即接受UVB照射的雄性的头尾长度比随身体状况增加，而接受自然辐射的鱼则没有这种关系。我们的研究结果表明，增加的UVB水平会影响雄性交配后的适合度相关特征，而对交配前的性特征没有显著影响，这表明在配子水平上存在选择性的UVB效应，对繁殖性能产生影响。
