Evans Suzanna M, Sinclair Elizabeth A, Poore Alistair G B, Bain Keryn F, Vergés Adriana
Centre for Marine Bio-Innovation, University of New South Wales, Sydney, New South Wales, Australia; Evolution & Ecology Research Centre, University of New South Wales, Sydney, New South Wales, Australia.
School of Plant Biology and Oceans Institute, University of Western Australia, Perth, Western Australia, Australia; Science Directorate, Botanic Gardens and Parks Authority, West Perth Western Australia, Australia.
PeerJ. 2016 Feb 18;4:e1633. doi: 10.7717/peerj.1633. eCollection 2016.
Declines in genetic diversity within a species can affect the stability and functioning of populations. The conservation of genetic diversity is thus a priority, especially for threatened or endangered species. The importance of genetic variation, however, is dependent on the degree to which it translates into phenotypic variation for traits that affect individual performance and ecological processes. This is especially important for predominantly clonal species, as no single clone is likely to maximise all aspects of performance. Here we show that intraspecific genotypic diversity as measured using microsatellites is a strong predictor of phenotypic variation in morphological traits and shoot productivity of the threatened, predominantly clonal seagrass Posidonia australis, on the east coast of Australia. Biomass and surface area variation was most strongly predicted by genotypic richness, while variation in leaf chemistry (phenolics and nitrogen) was unrelated to genotypic richness. Genotypic richness did not predict tissue loss to herbivores or epiphyte load, however we did find that increased herbivore damage was positively correlated with allelic richness. Although there was no clear relationship between higher primary productivity and genotypic richness, variation in shoot productivity within a meadow was significantly greater in more genotypically diverse meadows. The proportion of phenotypic variation explained by environmental conditions varied among different genotypes, and there was generally no variation in phenotypic traits among genotypes present in the same meadows. Our results show that genotypic richness as measured through the use of presumably neutral DNA markers does covary with phenotypic variation in functionally relevant traits such as leaf morphology and shoot productivity. The remarkably long lifespan of individual Posidonia plants suggests that plasticity within genotypes has played an important role in the longevity of the species. However, the strong link between genotypic and phenotypic variation suggests that a range of genotypes is still the best case scenario for adaptation to and recovery from predicted environmental change.
一个物种内遗传多样性的下降会影响种群的稳定性和功能。因此，保护遗传多样性是当务之急，尤其是对于受威胁或濒危物种。然而，遗传变异的重要性取决于它转化为影响个体表现和生态过程的性状表型变异的程度。这对于主要为克隆繁殖的物种尤为重要，因为没有一个单一的克隆体可能在所有表现方面都达到最优。在这里，我们表明，使用微卫星测量的种内基因型多样性是受威胁的、主要为克隆繁殖的澳大利亚东海岸海草南方波喜荡草形态性状和地上部生产力表型变异的有力预测指标。生物量和表面积变异最强烈地由基因型丰富度预测，而叶片化学物质（酚类和氮）的变异与基因型丰富度无关。基因型丰富度并不能预测食草动物造成的组织损失或附生植物负荷，然而我们确实发现食草动物造成的损害增加与等位基因丰富度呈正相关。虽然较高的初级生产力与基因型丰富度之间没有明确的关系，但在基因型更多样化的草甸中，草甸内地上部生产力的变异显著更大。环境条件解释的表型变异比例在不同基因型之间有所不同，并且在同一草甸中存在的基因型之间表型性状通常没有变异。我们的结果表明，通过使用大概为中性的DNA标记测量的基因型丰富度确实与叶形态和地上部生产力等功能相关性状的表型变异相关。南方波喜荡草个体极长的寿命表明基因型内的可塑性在该物种的长寿中发挥了重要作用。然而，基因型和表型变异之间的紧密联系表明，一系列基因型仍然是适应预测的环境变化并从中恢复的最佳情况。
