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，来响应其生存环境的变化。近数十年来，随着农业与水产养殖业的集约化程度不断提升，学界对其给农业、水产养殖相关有害生物、寄生虫及病原体的生活史带来的演化影响愈发关注。本研究以鲑虱（Lepeophtheirus salmonis）为研究对象，探究现代化养殖可能对寄生虫的生活史演化产生的影响。研究人员将取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，取自养殖区域的鲑虱在首个产卵批次中会产出更多卵粒，后续产卵量则有所降低；它们在成年早期的感染强度更高，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选择出更倾向于早期繁殖投入的性状，但其代价是后期繁殖力与生存能力的下降。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。