Keogh Carolyn L, Sanderson Martha E, Byers James E
Odum School of Ecology, University of Georgia, Athens, GA, 30602, USA.
Shoals Marine Laboratory, Appledore Island, ME, USA.
Oecologia. 2016 Jan;180(1):137-47. doi: 10.1007/s00442-015-3461-9. Epub 2015 Oct 6.
Local adaptation may optimize an organism's investment in defenses in response to the risk of infection by spatially heterogeneous parasites and other natural enemies. However, local adaptation may be constrained if recruitment is decoupled from selective pressure experienced by the parent generation. We predicted that the ability of three intertidal littorinid snail species to defend against trematode parasites would depend on prior levels of population exposure to parasites and on larval dispersal mode, a proxy for population openness. In a common garden experiment, for two snail species with direct development and localized recruitment (Littorina obtusata and Littorina saxatilis), hosts from sites with high trematode infection risk were less susceptible to infection than hosts from low-risk sites. However, this relationship was not apparent for a third host species with broadcast larvae (Littorina littorea), suggesting that broad larval dispersal can impede local adaptation; alternatively, the lack of response in this species could owe to other factors that limited experimental infection in this host. Our findings support that locally recruiting hosts can adapt their defenses to scale with localized infection risk.
局部适应性可能会优化生物体在应对空间异质寄生虫和其他天敌感染风险时在防御方面的投入。然而，如果补充过程与亲代所经历的选择压力脱钩，局部适应性可能会受到限制。我们预测，三种潮间带滨螺科蜗牛物种抵御吸虫寄生虫的能力将取决于种群先前接触寄生虫的水平以及幼虫扩散模式（种群开放性的一个指标）。在一项共同花园实验中，对于两种具有直接发育和局部补充的蜗牛物种（钝拟滨螺和岩滨螺），来自吸虫感染风险高的地点的宿主比来自低风险地点的宿主更不易感染。然而，对于第三种具有浮游幼虫的宿主物种（欧洲滨螺），这种关系并不明显，这表明广泛的幼虫扩散会阻碍局部适应性；或者，该物种缺乏反应可能归因于限制该宿主实验感染的其他因素。我们的研究结果支持，局部补充的宿主可以调整其防御以适应局部感染风险。
