Reavey Catherine E, Warnock Neil D, Garbett Amy P, Cotter Sheena C
School of Biological Sciences Queen's University Belfast MBC 97 Lisburn Road Belfast BT9 7BL UK ; Lancaster Environment Centre Lancaster University Lancaster LA1 4YQ UK.
School of Biological Sciences Queen's University Belfast MBC 97 Lisburn Road Belfast BT9 7BL UK.
Ecol Evol. 2015 Sep 18;5(19):4365-75. doi: 10.1002/ece3.1668. eCollection 2015 Oct.
How much should an individual invest in immunity as it grows older? Immunity is costly and its value is likely to change across an organism's lifespan. A limited number of studies have focused on how personal immune investment changes with age in insects, but we do not know how social immunity, immune responses that protect kin, changes across lifespan, or how resources are divided between these two arms of the immune response. In this study, both personal and social immune functions are considered in the burying beetle, Nicrophorus vespilloides. We show that personal immune function declines (phenoloxidase levels) or is maintained (defensin expression) across lifespan in nonbreeding beetles but is maintained (phenoloxidase levels) or even upregulated (defensin expression) in breeding individuals. In contrast, social immunity increases in breeding burying beetles up to middle age, before decreasing in old age. Social immunity is not affected by a wounding challenge across lifespan, whereas personal immunity, through PO, is upregulated following wounding to a similar extent across lifespan. Personal immune function may be prioritized in younger individuals in order to ensure survival until reproductive maturity. If not breeding, this may then drop off in later life as state declines. As burying beetles are ephemeral breeders, breeding opportunities in later life may be rare. When allowed to breed, beetles may therefore invest heavily in "staying alive" in order to complete what could potentially be their final reproductive opportunity. As parental care is important for the survival and growth of offspring in this genus, staying alive to provide care behaviors will clearly have fitness payoffs. This study shows that all immune traits do not senesce at the same rate. In fact, the patterns observed depend upon the immune traits measured and the breeding status of the individual.
随着年龄增长，个体应该在免疫方面投入多少？免疫是有成本的，其价值可能会在生物体的整个生命周期中发生变化。有限的一些研究关注了昆虫个体的免疫投入如何随年龄变化，但我们不知道社会免疫（保护亲属的免疫反应）如何在整个生命周期中变化，也不知道资源如何在免疫反应的这两个方面之间分配。在这项研究中，我们在埋葬虫（Nicrophorus vespilloides）中考虑了个体免疫功能和社会免疫功能。我们发现，在非繁殖期的埋葬虫中，个体免疫功能在整个生命周期中会下降（酚氧化酶水平）或保持稳定（防御素表达），但在繁殖个体中会保持稳定（酚氧化酶水平）甚至上调（防御素表达）。相比之下，繁殖期埋葬虫的社会免疫在中年之前会增加，在老年时会下降。社会免疫在整个生命周期中不受伤口刺激的影响，而个体免疫通过酚氧化酶在受伤后会在整个生命周期中以类似程度上调。年轻个体可能会优先考虑个体免疫功能，以确保存活到生殖成熟。如果不繁殖，随着身体状况下降，这种功能在后期可能会下降。由于埋葬虫是临时性繁殖者，后期的繁殖机会可能很少。因此，当允许繁殖时，埋葬虫可能会在“维持生存”方面大量投入，以完成可能是它们最后的繁殖机会。由于亲代抚育对该属后代的生存和生长很重要，存活下来提供抚育行为显然会带来适应性回报。这项研究表明，并非所有免疫特征都会以相同的速度衰老。事实上，观察到的模式取决于所测量的免疫特征以及个体的繁殖状态。
