Matesanz Silvia, Rubio Teso María Luisa, García-Fernández Alfredo, Escudero Adrián
Área de Biodiversidad y Conservación, Departamento de Biología y Geología, Física y Química Inorgánica, Universidad Rey Juan CarlosMóstoles, Spain.
Front Plant Sci. 2017 May 26;8:843. doi: 10.3389/fpls.2017.00843. eCollection 2017.
Habitat fragmentation, i.e., fragment size and isolation, can differentially alter patterns of neutral and quantitative genetic variation, fitness and phenotypic plasticity of plant populations, but their effects have rarely been tested simultaneously. We assessed the combined effects of size and connectivity on these aspects of genetic and phenotypic variation in populations of , a narrow endemic gypsophile that previously showed performance differences associated with fragmentation. We grew 111 maternal families sampled from 10 populations that differed in their fragment size and connectivity in a common garden, and characterized quantitative genetic variation, phenotypic plasticity to drought for key functional traits, and plant survival, as a measure of population fitness. We also assessed neutral genetic variation within and among populations using eight microsatellite markers. Although is a narrow endemic gypsophile, we found substantial neutral genetic variation and quantitative variation for key functional traits. The partition of genetic variance indicated that a higher proportion of variation was found within populations, which is also consistent with low population differentiation in molecular markers, functional traits and their plasticity. This, combined with the generally small effect of habitat fragmentation suggests that gene flow among populations is not restricted, despite large differences in fragment size and isolation. Importantly, population's similarities in genetic variation and plasticity did not reflect the lower survival observed in isolated populations. Overall, our results indicate that, although the species consists of genetically variable populations able to express functional plasticity, such aspects of adaptive potential may not always reflect populations' survival. Given the differential effects of habitat connectivity on functional traits, genetic variation and fitness, our study highlights the need to shift the focus of fragmentation studies to the mechanisms that regulate connectivity effects, and call for caution on the use of genetic variation and plasticity to forecast population performance.
生境破碎化，即碎片大小和隔离程度，能够以不同方式改变植物种群中性和数量遗传变异、适合度以及表型可塑性的模式，但其影响很少同时得到检验。我们评估了大小和连通性对一种狭域特有喜钙植物种群遗传和表型变异这些方面的综合影响，该植物先前表现出与破碎化相关的性能差异。我们在一个共同园圃中种植了从10个种群采集的111个母系家系，这些种群在碎片大小和连通性方面存在差异，并对数量遗传变异、关键功能性状对干旱的表型可塑性以及作为种群适合度衡量指标的植物存活率进行了表征。我们还使用8个微卫星标记评估了种群内和种群间的中性遗传变异。尽管该植物是一种狭域特有喜钙植物，但我们发现关键功能性状存在大量中性遗传变异和数量变异。遗传方差的划分表明，在种群内发现了更高比例的变异，这也与分子标记、功能性状及其可塑性方面较低的种群分化相一致。这一点，再加上生境破碎化通常较小的影响，表明尽管碎片大小和隔离程度存在很大差异，但种群间的基因流动并未受到限制。重要的是，种群在遗传变异和可塑性方面的相似性并未反映出在隔离种群中观察到的较低存活率。总体而言，我们的结果表明，尽管该物种由能够表现出功能可塑性的遗传可变种群组成，但这种适应潜力的方面可能并不总是反映种群的存活率。鉴于生境连通性对功能性状、遗传变异和适合度的不同影响，我们的研究强调需要将破碎化研究的重点转移到调节连通性效应的机制上，并呼吁在使用遗传变异和可塑性来预测种群表现时要谨慎。
