Data from: Invest more and die faster: the life history of a parasite on intensive farms

Organisms are expected to respond to alterations in their survival by evolutionary changes in their life history traits. As agriculture and aquaculture have become increasingly intensive in the past decades, there has been growing interest in their evolutionary effects on the life histories of agri- and aquacultural pests, parasites and pathogens. In this study we used salmon lice (Lepeophtheirus salmonis) to explore how modern farming might have affected life history evolution in parasites. We infected salmon hosts with lice from either farmed or unfarmed locations, and monitored life history traits of those parasites in laboratory conditions. Our results show that compared to salmon lice from areas unaffected by salmon farming, those from farmed areas produced more eggs in their first clutch, and less eggs later on; they achieved higher infestation intensities in early adulthood, but suffered higher adult mortality. These results suggest that salmon lice on farms may have been selected for increased investment in early reproduction, at the expense of later fecundity and survival. This calls for further empirical studies of the extent to which farming practices may alter the virulence of agricultural parasites.

生物通常会通过生活史性状的演化改变，来应对生存环境的变化。近数十年来，随着农业与水产养殖业集约化程度不断提升，学界愈发关注其对农、水产有害生物、寄生虫及病原体生活史的演化影响。本研究以鲑虱（salmon lice, Lepeophtheirus salmonis）为研究对象，探究现代化养殖可能如何影响寄生虫的生活史演化。研究人员将来自养殖区域与非养殖区域的鲑虱分别感染鲑鱼宿主，并在实验室条件下监测这些寄生虫的生活史性状。研究结果显示，与未受鲑鱼养殖影响区域的鲑虱相比，来自养殖区域的鲑虱在首次产卵时产出的卵量更多，后续产卵量则更少；它们在成年早期的侵染强度更高，但成虫死亡率也更高。上述结果表明，养殖环境中的鲑虱可能已被自然选择青睐，使其在早期繁殖上投入更多资源，却以后期繁殖力与生存能力为代价。这一发现呼吁开展更多实证研究，以明确养殖实践对农业寄生虫毒力的改变程度。