García-Huidobro M R, Varas O, George-Nascimento M, Pulgar J, Aldana M, Lardies M A, Lagos N A
Centro de Investigación e Innovación para el Cambio Climático (CiiCC), Facultad de Ciencias, Universidad Santo Tomás, Ejército 146, Santiago, Chile.
Programa de Doctorado en Conservación y Gestión de la Biodiversidad, Facultad de Ciencias, Universidad Santo Tomás, Ejército 146, Santiago, Chile.
Int J Parasitol Parasites Wildl. 2019 Mar 23;9:7-15. doi: 10.1016/j.ijppaw.2019.03.016. eCollection 2019 Aug.
Biological interactions and environmental constraints alter life-history traits, modifying organismal performances. Trematode parasites often impact their hosts by inducing parasitic castration, frequently correlated with increased body size in the host (i.e., gigantism hypothesis), which is postulated to reflect the re-allocation of energy released by the reduction in the reproductive process. In this study, we compared the effect of a trematode species on shell size and morphology in adult individuals of the intertidal mussels (>20 mm) collected from two local populations of contrasting environmental regimes experienced in central-southern Chile. Our field data indicates that in both study locations, parasitized mussels evidenced higher body sizes (shell length, total weight and volume) as compared with non-parasitized. In addition, parasitized mussels from the southern location evidenced thinner shells than non-parasitized ones and those collected from central Chile, suggesting geographical variation in shell carbonate precipitation across intertidal habitats of the Chilean coast. In laboratory conditions, mussels collected from a local population in central Chile were exposed to two temperature treatments (12 and 18 °C). Parasitized mussels showed higher growth rates than non-parasitized, regardless of the seawater temperature treatments. However, the metabolic rate was not influenced by the parasite condition or the temperature treatments. Our field and laboratory results support the parasite-induced gigantism hypothesis, and suggest that both the thermal environment and geographic location explain only a portion of the increased body size, while the parasitic condition is the most plausible factor modulating the outcome of this host-parasite interaction.
生物相互作用和环境限制会改变生活史特征，进而影响生物体的表现。吸虫寄生虫常常通过诱导寄生性阉割来影响其宿主，这通常与宿主身体尺寸的增加相关（即巨人症假说），据推测这反映了生殖过程减少所释放能量的重新分配。在本研究中，我们比较了一种吸虫物种对从智利中南部两个环境条件截然不同的当地种群采集的潮间带贻贝（>20毫米）成体的壳大小和形态的影响。我们的实地数据表明，在两个研究地点，与未受寄生的贻贝相比，受寄生的贻贝身体尺寸更大（壳长、总重量和体积）。此外，来自南部地点的受寄生贻贝的壳比未受寄生的以及从智利中部采集的贻贝壳更薄，这表明智利海岸潮间带栖息地的壳碳酸盐沉淀存在地理差异。在实验室条件下，从智利中部一个当地种群采集的贻贝接受了两种温度处理（12和18°C）。无论海水温度处理如何，受寄生的贻贝都比未受寄生的生长速度更快。然而，代谢率不受寄生虫状况或温度处理的影响。我们的实地和实验室结果支持寄生虫诱导的巨人症假说，并表明热环境和地理位置仅解释了身体尺寸增加的一部分原因，而寄生状况是调节这种宿主 - 寄生虫相互作用结果的最合理因素。
