Leung Christelle, Breton Sophie, Angers Bernard
Department of Biological Sciences, Université de Montréal, Montréal, QC, Canada.
PeerJ. 2018 Nov 2;6:e5896. doi: 10.7717/peerj.5896. eCollection 2018.
Survival in temporally or spatially changing environments is a prerequisite for the perpetuation of a given species. In addition to genetic variation, the role of epigenetic processes is crucial in the persistence of organisms. For instance, mechanisms such as developmental flexibility enable the adjustment of the phenotype of a given individual to changing conditions throughout its development. However, the extent of factors other than genetic variability, like epigenetic processes, in the production of alternative phenotype and the consequences in realized ecological niches is still unclear.
In this study, we compared the extent of realized niches between asexual and sexual individuals from different environments. We used a trait-based ecology approach exploiting trophic and locomotive structures to infer the environment that each biotype actually used. More specifically, we compared the morphology of the all-female clonal and sperm-dependent fish to that of their sexual host species in common garden and natural conditions.
Transfer from natural to controlled conditions resulted in a similar shift in measured morphology for clonal and sexual individuals suggesting comparable level of flexibility in both kinds of organisms. However, clonal, but not sexual, individuals displayed a consistent phenotype when reared in uniform conditions indicating that in absence of genetic variation, one phenotype corresponds to one niche. This contrasted with results from natural conditions where clones were morphologically as variable as sexual individuals within a sampled site. In addition, similar phenotypic changes for both clonal and sexual individuals were observed among the majority of sampled sites, indicating that they responded similarly to the same environments.
Our results indicated that clones can efficiently use different niches and may evolve in a range of environmental conditions comparable to that of a sexual species, thus underlying the importance of factors other than genetic variability, like epigenetic processes, for coping with environmental heterogeneity.
在时间或空间变化的环境中生存是特定物种延续的前提条件。除了遗传变异外，表观遗传过程在生物体的存续中也起着关键作用。例如，发育灵活性等机制使特定个体在其整个发育过程中能够根据变化的条件调整表型。然而，除遗传变异性之外的其他因素，如表观遗传过程，在产生替代表型以及在实际生态位中的后果方面的程度仍不清楚。
在本研究中，我们比较了来自不同环境的无性和有性个体之间实际生态位的程度。我们采用基于性状的生态学方法，利用营养和运动结构来推断每种生物型实际利用的环境。更具体地说，我们在共同花园和自然条件下，比较了全雌克隆鱼和依赖精子的鱼类与其有性宿主物种的形态。
从自然条件转移到受控条件下，克隆个体和有性个体的测量形态发生了类似的变化，表明这两种生物体的灵活性水平相当。然而，克隆个体而非有性个体在统一条件下饲养时表现出一致的表型，这表明在没有遗传变异的情况下，一种表型对应一个生态位。这与自然条件下的结果形成对比，在自然条件下，克隆个体在采样地点内的形态与有性个体一样多变。此外，在大多数采样地点观察到克隆个体和有性个体有类似的表型变化，表明它们对相同环境的反应相似。
我们的结果表明，克隆体能够有效地利用不同的生态位，并且可能在与有性物种相当的一系列环境条件下进化，从而突显了除遗传变异性之外的其他因素，如表观遗传过程，对于应对环境异质性的重要性。
