Data from: Molecular identification of natural mangrove hybrids of Rhizophora in Peninsular Malaysia

Natural hybridization is common in plants. Very often, the identity of a putative hybrid is inferred based on the observation of morphological features intermediate between two possible parental species occurring in a specific location. However, due to plasticity of morphological features and the co-occurrence of more than two possible parental species, molecular markers would be most useful to establish the origin of a putative hybrid. In mangroves, three Rhizophora species (Rhizophora apiculata, Rhizophora mucronata, and Rhizophora stylosa) and two putative hybrids (Rhizophora × lamarckii and Rhizophora × annamalayana) are distributed in the Indo-West Pacific region. Leaf samples of Rhizophora were obtained from two locations in Peninsular Malaysia, namely, Bagan Lalang and Pulau Burung, where all three species grow in sympatry. We analyzed sequences of one chloroplast and six nuclear DNA regions. Our results confirmed earlier claims that the morphologically identified putative hybrids growing in Pulau Burung are R. × lamarckii, a cross between R. apiculata and R. stylosa. Our data also pointed to the possible discovery of a new Rhizophora hybrid—a cross between R. mucronata and R. stylosa—the identification of which would have been difficult based on morphological features alone. The directions and the stages of hybridization are also discussed.

自然杂交在植物界中极为常见。长期以来，研究者常通过观测特定分布区域内两个候选亲本物种间的中间形态特征，来推断推定杂种（putative hybrid）的分类身份。然而，由于形态特征具有表型可塑性，且同一区域可能共存不止两个候选亲本物种，因此分子标记（molecular marker）是确证推定杂种起源的可靠手段。
在红树林生态系统中，红树属（Rhizophora）共计3个物种：柱果红树（Rhizophora apiculata）、尖叶红树（Rhizophora mucronata）与红海榄（Rhizophora stylosa），另有两种推定杂种：拉马克红树（Rhizophora × lamarckii）及安纳马拉红树（Rhizophora × annamalayana），上述类群均分布于印度-西太平洋区域。
本研究从马来半岛的巴加兰兰（Bagan Lalang）与武隆岛（Pulau Burung）两个样点采集红树属植物的叶片样本，上述3个红树属物种在两处样点均呈同域分布状态。
我们对1个叶绿体（chloroplast）基因区域与6个核DNA区域开展了测序分析。
研究结果证实了此前的学术论断：武隆岛经形态学鉴定的推定杂种确为拉马克红树，其为柱果红树与红海榄的杂交后代。此外，本研究数据还提示发现了一个全新的红树属杂交种——尖叶红树与红海榄的杂交后代，该类群仅通过形态特征难以实现准确鉴定。
本研究同时对杂交事件的方向与阶段展开了探讨。