Data from: Contrasting patterns of clonality and fine-scale genetic structure in two rare sedges with differing geographic distributions

For plants with mixed reproductive capabilities, asexual reproduction is more frequent in rare species and is considered a strategy for persistence when sexual recruitment is limited. We investigate whether asexual reproduction contributes to the persistence of two co-occurring, rare sedges that both experience irregular seed set and if their differing geographic distributions have a role in the relative contribution of clonality. Genotypic richness was high (R=0.889±0.02) across the clustered populations of Lepidosperma sp. Mt Caudan and, where detected, clonal patches were small, both in ramet numbers (less than or equal to3 ramets/genet) and physical size (1.3±0.1 m). In contrast, genotypic richness was lower in the isolated L. sp. Parker Range populations, albeit more variable (R=0.437±0.13), with genets as large as 17 ramets and up to 5.8 m in size. Aggregated clonal growth generated significant fine-scale genetic structure in both species but to a greater spatial extent and with additional genet-level structure in L. sp. Parker Range that is likely due to restricted seed dispersal. Despite both species being rare, asexual reproduction clearly has a more important role in the persistence of L. sp. Parker Range than L. sp. Mt Caudan. This is consistent with our prediction that limitations to sexual reproduction, via geographic isolation to effective gene exchange, can lead to greater contributions of asexual reproduction. These results demonstrate the role of population isolation in affecting the balance of alternate reproductive modes and the contextual nature of asexual reproduction in rare species.

对于兼具混合繁殖能力的植物而言，无性繁殖（asexual reproduction）在稀有种中更为普遍，被视为有性更新（sexual recruitment）受限时维持种群存续的适应性策略。本研究探究了无性繁殖是否有助于两种同域分布、均存在不规则结实现象的稀有莎草的种群存续，同时探讨二者不同的地理分布是否会对克隆生长（clonality）的相对贡献产生影响。在聚集分布的莱波斯佩尔马属（Lepidosperma）未定种Mt Caudan种群中，其基因型丰富度（genotypic richness）较高（R=0.889±0.02）；且在检测到克隆斑块的区域，克隆斑块均表现出较小的规模，无论是分株（ramet）数量（≤3株分株/基株（genet））还是物理尺寸（1.3±0.1 m）均如此。与之形成鲜明对比的是，孤立分布的莱波斯佩尔马属未定种Parker Range种群的基因型丰富度较低，尽管其变异程度更高（R=0.437±0.13），其基株最大可包含17株分株，空间尺寸可达5.8 m。聚集性的克隆生长模式在两个物种中均催生了显著的精细尺度遗传结构（fine-scale genetic structure），但在Parker Range种群中，该结构的空间尺度更大，且存在额外的基株水平结构，这一现象大概率由种子扩散（seed dispersal）受限所致。尽管两个物种均为稀有种，但无性繁殖在Parker Range种群的存续中所发挥的作用显然要大于Mt Caudan种群。该结果与我们的预测一致：通过地理隔离阻碍有效基因交流的有性繁殖限制，可导致无性繁殖的贡献显著提升。本研究结果揭示了种群隔离对两种交替繁殖模式平衡的调控作用，同时也阐明了无性繁殖在稀有种中的情境依赖性特征。