Domínguez-Castanedo Omar, Gaspar-Navarro Jorge, Zúñiga-Vega J Jaime
Laboratorio de Ecología Evolutiva y Demografía Animal, Departamento de Ecología y Recursos Naturales, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City, Mexico.
Asociación Mexicana Para el Estudio y Conservación de Cyprinodontiformes, Mexico City, Mexico.
J Fish Dis. 2025 Feb;48(2):e14038. doi: 10.1111/jfd.14038. Epub 2024 Nov 17.
Life history theory predicts that a trade-off may occur when an increased investment in one fitness component causes a reduced investment in another. Parasites generate changes in the optimal life history traits of organisms, causing compromises for their hosts. The objective of this research was to determine whether trematodes Clinostomum sp. and Uvulifer sp. inflict measurable damage on the males of the viviparous fish Poeciliopsis infans, generating trade-offs between somatic condition and reproductive traits (gonad mass and gonopodium length). We found (i) a negative relationship of large encysted metacercariae and non-encysted metacercariae on somatic condition. Interestingly, individuals with a higher parasite load had a worse body condition, but bigger gonads and longer gonopodium; and, (ii) a bond between small encysted metacercariae and non-encysted metacercariae with smaller gonopodia, only in fish with poorer somatic condition. The strongest correlation was given by the non-encysted metacercariae, probably due to mechanical damage during migration through the body cavity. We did not find any trade-off effects of Uvulifer sp. We consider that the statistical effects found on somatic condition can be attributed to a greater reproductive investment, generating energetic costs that compromise their defences against infection, allowing a greater parasite load.
生活史理论预测，当对一个适合度成分的投资增加导致对另一个适合度成分的投资减少时，可能会出现权衡。寄生虫会引起生物体最优生活史特征的变化，给其宿主带来权衡。本研究的目的是确定吸虫Clinostomum sp.和Uvulifer sp.是否会对胎生鱼类Poeciliopsis infans的雄性造成可测量的损害，从而在身体状况和生殖特征（性腺质量和生殖足长度）之间产生权衡。我们发现：（i）大量包囊后尾蚴和未包囊后尾蚴与身体状况呈负相关。有趣的是，寄生虫负荷较高的个体身体状况较差，但性腺更大，生殖足更长；（ii）仅在身体状况较差的鱼类中，小的包囊后尾蚴和未包囊后尾蚴与较小的生殖足之间存在关联。未包囊后尾蚴的相关性最强，这可能是由于其在穿过体腔迁移过程中造成的机械损伤。我们未发现Uvulifer sp.有任何权衡效应。我们认为，在身体状况上发现的统计效应可归因于更大的生殖投资，产生了能量成本，损害了它们对感染的防御能力，从而允许更大的寄生虫负荷。
