Data from: Population genetic structure and reproductive strategy of the introduced grass Centotheca lappacea in tropical land-use systems in Sumatra

Intensive transformation of lowland rainforest into oil palm and rubber monocultures is the most common land-use practice in Sumatra (Indonesia), accompanied by invasion of weeds. In the Jambi province, Centotheca lappacea is one of the most abundant alien grass species in plantations and in jungle rubber (an extensively used agroforest), but largely missing in natural rainforests. Here, we investigated putative genetic differentiation and signatures for adaptation in the introduced area. We studied reproductive mode and ploidy level as putative factors for invasiveness of the species. We sampled 19 populations in oil palm and rubber monocultures and in jungle rubber in two regions (Bukit Duabelas and Harapan). Amplified fragment length polymorphisms (AFLP) revealed a high diversity of individual genotypes and only a weak differentiation among populations (FST = 0.173) and between the two regions (FST = 0.065). There was no significant genetic differentiation between the three land-use systems. The metapopulation of C. lappacea consists of five genetic partitions with high levels of admixture; all partitions appeared in both regions, but with different proportions. Within the Bukit Duabelas region we observed significant isolation-by-distance. Nine AFLP loci (5.3% of all loci) were under natural diversifying selection. All studied populations of C. lappacea were diploid, outcrossing and self-incompatible, without any hints of apomixis. The estimated residence time of c. 100 years coincides with the onset of rubber and oil palm planting in Sumatra. In the colonization process, the species is already in a phase of establishment, which may be enhanced by efficient selection acting on a highly diverse gene pool. In the land-use systems, seed dispersal might be enhanced by adhesive spikelets. At present, the abundance of established populations in intensively managed land-use systems might provide opportunities for rapid dispersal of C. lappacea across rural landscapes in Sumatra, while the invasion potential in rainforest ecosystems appears to be moderate as long as they remain undisturbed.

印度尼西亚苏门答腊地区，将低地雨林大规模转化为油棕与橡胶单一种植园是最主流的土地利用方式，该过程伴随杂草入侵。在占碑省，铺地黍（Centotheca lappacea）是种植园与橡胶林农园（一种广泛应用的农林业系统）中最为常见的外来禾草物种之一，但在天然雨林中几乎不见踪迹。本研究针对该物种在入侵区域的潜在遗传分化与适应信号展开探究，并将繁殖方式与倍性水平作为该物种入侵性的潜在影响因子进行分析。研究团队在两个区域（武吉杜亚贝拉斯（Bukit Duabelas）与哈潘（Harapan））的油棕单一种植园、橡胶单一种植园以及橡胶林农园中，共采集了19个种群样本。扩增片段长度多态性（Amplified fragment length polymorphisms, AFLP）分析结果显示，该物种的个体基因型多样性较高，但种群间的遗传分化系数（FST=0.173）以及两个区域间的遗传分化系数（FST=0.065）均处于较低水平。三种土地利用系统之间未检测到显著的遗传分化。铺地黍的集合种群包含5个遗传组分，且各组分间存在高度的基因混合；所有遗传组分在两个区域均有分布，但占比各不相同。在武吉杜亚贝拉斯区域内，研究人员观察到显著的距离隔离效应。9个AFLP位点（占总位点数的5.3%）处于自然歧化选择作用之下。所有供试的铺地黍种群均为二倍体，繁殖方式为异交且自交不亲和，未发现任何无融合生殖的迹象。该物种在苏门答腊的定殖时长估计约为100年，与当地橡胶与油棕种植的起始时间相吻合。在定殖过程中，该物种已处于种群建立阶段，而针对高度多样的基因库的高效选择作用可能进一步促进这一过程。在上述土地利用系统中，具粘性的小穗可能有助于提升该物种的种子传播效率。目前，在集约经营的土地利用系统中大量存在的定殖种群，为铺地黍在苏门答腊乡村景观中快速扩散提供了契机；而在未受干扰的雨林生态系统中，该物种的入侵潜力暂处于中等水平。