Swillen Ine, Vanoverbeke Joost, De Meester Luc
Laboratory of Aquatic Ecology, Evolution and Conservation, University of Leuven Charles Deberiotstraat 32, 3000, Leuven, Belgium.
Ecol Evol. 2015 Jul;5(13):2712-21. doi: 10.1002/ece3.1545. Epub 2015 Jun 19.
Several studies have emphasized that inbreeding depression (ID) is enhanced under stressful conditions. Additionally, one might imagine a loss of adaptively plastic responses which may further contribute to a reduction in fitness under environmental stress. Here, we quantified ID in inbred families of the cyclical parthenogen Daphnia magna in the absence and presence of fish predation risk. We test whether predator stress affects the degree of ID and if inbred families have a reduced capacity to respond to predator stress by adaptive phenotypic plasticity. We obtained two inbred families through clonal selfing within clones isolated from a fish pond. After mild purging under standardized conditions, we compared life history traits and adaptive plasticity between inbred and outbred lineages (directly hatched from the natural dormant egg bank of the same pond). Initial purging of lineages under standardized conditions differed among inbred families and exceeded that in outbreds. The least purged inbred family exhibited strong ID for most life history traits. Predator-induced stress hardly affected the severity of ID, but the degree to which the capacity for adaptive phenotypic plasticity was retained varied strongly among the inbred families. The least purged family overall lacked the capacity for adaptive phenotypic plasticity, whereas the family that suffered only mild purging exhibited a potential for adaptive plasticity that was comparable to the outbred population. We thus found that inbred offspring may retain the capacity to respond to the presence of fish by adaptive phenotypic plasticity, but this strongly depends on the parental clone engaging in selfing.
多项研究强调，近亲繁殖衰退（ID）在压力条件下会增强。此外，人们可能会想象适应性可塑性反应的丧失，这可能会进一步导致在环境压力下适应性的降低。在这里，我们在有和没有鱼类捕食风险的情况下，对周期性孤雌生殖的大型溞的近亲繁殖家族中的近亲繁殖衰退进行了量化。我们测试捕食者压力是否会影响近亲繁殖衰退的程度，以及近亲繁殖家族通过适应性表型可塑性对捕食者压力做出反应的能力是否降低。我们通过从一个鱼塘分离出的克隆体内的克隆自交获得了两个近亲繁殖家族。在标准化条件下进行轻度清除后，我们比较了近亲繁殖和远亲繁殖谱系（直接从同一池塘的天然休眠卵库孵化）之间的生活史特征和适应性可塑性。在标准化条件下，不同近亲繁殖家族的谱系初始清除情况不同，且超过了远亲繁殖家族。清除最少的近亲繁殖家族在大多数生活史特征上表现出强烈的近亲繁殖衰退。捕食者诱导的压力几乎没有影响近亲繁殖衰退的严重程度，但近亲繁殖家族之间适应性表型可塑性能力保留的程度差异很大。清除最少的家族总体上缺乏适应性表型可塑性能力，而仅遭受轻度清除的家族表现出与远亲繁殖群体相当的适应性可塑性潜力。因此，我们发现近亲繁殖的后代可能通过适应性表型可塑性保留对鱼类存在做出反应的能力，但这在很大程度上取决于进行自交的亲本克隆。
