A single plant with a large distribution: Phylogenetic relationships of South American populations of Pteridium esculentum (Dennstaedtiaceae)

The bracken fern (Pteridium, Dennstaedtiaceae) is a cosmopolitan fern genus, perhaps best known as weedy, disturbance colonizers. Bracken is also toxic to many livestock animals, and the control of this species is of agricultural interest. The taxonomy of Pteridium has been described in multiple schemes, ranging from one to four species with numerous subspecies and varieties. Recent work has focused on the world wide distribution and systematics of the bracken fern. South American species, however, have so far been poorly sampled in such work. Here, we present the first continent-wide sampling and analysis of Pteridum esculentum, a primarily southern hemisphere diploid species. Within South America, P. esculentum has several morphotypes, currently described as subspecies based on morphology alone. We use double digest restriction site-associated DNA sequencing (ddRADSeq) to assess the phylogenetic relationships of P. esculentum subspecies. The identification of patterns of morphological and molecular variability in P. esculentum will lay the foundations for studying variations in its behavior as a weed, as well as its impact on the production of agricultural livestock in South America.

蕨属（Pteridium，碗蕨科Dennstaedtiaceae）是一个广布全球的蕨类类群，其中多数类群以杂草性、干扰生境拓殖物种的身份为人熟知。同时，蕨属植物对多种家畜具有毒性，因此该物种的防控研究具有重要的农业应用价值。蕨属的分类系统存在多种划分方案，认可的物种数量从1到4种不等，同时伴随大量亚种与变种。近期相关研究聚焦于全球范围内蕨属植物的分布与系统分类，但截至目前，此类研究中针对南美物种的采样仍较为匮乏。本研究首次针对主要分布于南半球的二倍体物种食用蕨（Pteridium esculentum）开展全大陆范围的采样与系统分析。在南美区域内，食用蕨存在多个形态型，目前仅依据形态特征被划分为若干亚种。本研究采用双酶切限制性位点关联DNA测序（double digest restriction site-associated DNA sequencing, ddRADSeq）技术，解析食用蕨亚种间的系统发育关系。明确食用蕨的形态与分子变异模式，将为探究其杂草化行为变异及其对南美家畜养殖业的影响奠定重要的研究基础。