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.

在印度尼西亚苏门答腊地区，将低地雨林大规模改造为油棕与橡胶单一种植园是最主流的土地利用模式，该过程伴随杂草入侵。在占碑省，长舌禾（Centotheca lappacea）是种植园与人工橡胶林（一种广泛应用的农林业系统）中优势度最高的外来草本物种之一，但在原生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性信号展开探究，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。研究人员在苏门答腊的两个区域——武吉杜亚贝拉斯（Bukit Duabelas）与哈拉潘（Harapan）——的油棕单一种植园、橡胶单一种植园以及人工橡胶林中，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（FST = 0.173）以及两个区域间（FST = 0.065）的遗传分化程度均较低。三种土地利用系统之间未出现显著的遗传分化。长舌禾的集合种群由5个遗传组分构成，且存在较高的遗传混合程度；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，研究人员观测到显著的距离衰减隔离效应。共有9个AFLP位点（占总位点数的5.3%）处于自然多样化选择作用之下。所有被研究的长舌禾种群均为二倍体、异交且自交不亲和，未发现无融合生殖的迹象。估算得到的该物种定居时长约为100年，与苏门答腊地区橡胶与油棕种植的起始时间相吻合。在定殖过程中，该物种已进入种群建立阶段，而高度多样的基因库所承受的高效选择压力可能进一步促进这一过程。在该土地利用系统中，带粘性的小穗可能有助于提升种子的传播效率。当前，集约管理的土地利用系统中已建立的种群数量众多，这为长舌禾在苏门答腊乡村景观中快速扩散提供了契机；而在未受干扰的原生雨林生态系统中，该物种的入侵潜力似乎较为有限。