Alberto Filipe, Gouveia Licínia, Arnaud-Haond Sophie, Pérez-Lloréns José L, Duarte Carlos M, Serrão Ester A
CCMAR, CIMAR-Laboratório Associado, University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
Mol Ecol. 2005 Aug;14(9):2669-81. doi: 10.1111/j.1365-294X.2005.02640.x.
Abstract The extent of clonality within populations strongly influences their spatial genetic structure (SGS), yet this is hardly ever thoroughly analysed. We employed spatial autocorrelation analysis to study effects of sexual and clonal reproduction on dispersal of the dioecious seagrass Cymodocea nodosa. Analyses were performed both at genet level (i.e. excluding clonal repeats) and at ramet level. Clonal structure was characterized by the clonal subrange, a spatial measure of the linear limits where clonality still affects SGS. We show that the clonal subrange is equivalent to the distance where the probability of clonal identity approaches zero. This combined approach was applied to two meadows with different levels of disturbance, Cadiz (stable) and Alfacs (disturbed). Genotypic richness, the proportion of the sample representing distinct genotypes, was moderate (0.38 Cadiz, 0.46 Alfacs) mostly due to dominance of a few clones. Expected heterozygosities were comparable to those found in other clonal plants. SGS analyses at the genet level revealed extremely restricted gene dispersal in Cadiz (Sp = 0.052, a statistic reflecting the decrease of pairwise kinship with distance), the strongest SGS found for seagrass species, comparable only to values for selfing herbaceous land plants. At Cadiz the clonal subrange extended across shorter distances (20-25 m) than in Alfacs (30-35 m). Comparisons of sexual and vegetative components of gene dispersal suggest that, as a dispersal vector within meadows, clonal spread is at least as important as sexual reproduction. The restricted dispersal and SGS pattern in both meadows indicates that the species follows a repeated seedling recruitment strategy.
摘要 种群内克隆性的程度对其空间遗传结构（SGS）有强烈影响，但这几乎从未得到过全面分析。我们采用空间自相关分析来研究有性繁殖和克隆繁殖对雌雄异株海草无茎草（Cymodocea nodosa）扩散的影响。分析分别在基株水平（即排除克隆重复）和分株水平上进行。克隆结构由克隆亚范围来表征，这是一个空间尺度，用于衡量克隆性仍影响SGS的线性界限。我们表明，克隆亚范围等同于克隆同一性概率接近零的距离。这种综合方法应用于两个受干扰程度不同的草甸，加的斯（稳定）和阿尔法克斯（受干扰）。基因型丰富度，即代表不同基因型的样本比例，适中（加的斯为0.38，阿尔法克斯为0.46），主要是由于少数克隆占主导地位。预期杂合度与其他克隆植物中的相当。在基株水平上的SGS分析显示，加的斯的基因扩散极其有限（Sp = 0.052，这一统计量反映了成对亲缘关系随距离的降低），这是海草物种中发现的最强SGS，仅与自花授粉草本陆生植物的值相当。在加的斯，克隆亚范围延伸的距离（20 - 25米）比在阿尔法克斯（30 - 35米）短。基因扩散的有性和营养成分的比较表明，作为草甸内的扩散载体，克隆传播至少与有性繁殖一样重要。两个草甸中有限的扩散和SGS模式表明该物种遵循重复的幼苗补充策略。
