Seed germination of a myrmecochorous plant endemic to the Brazilian semiarid region: the wolf is not so bad

ABSTRACT Studies about seed dispersal and germination are important to understand patterns of plant distribution and abundance, and help establish strategies for environmental conservation. We evaluated the role of two different dispersers, the ant Atta laevigata and the maned wolf Chrysocyon brachyurus, in the germination of Copaifera arenicola seeds, a characteristically myrmecochorous plant species. Germination was evaluated for seeds subjected to four treatments: (1) seeds manipulated by the ant, (2) seeds ingested by the maned wolf, (3) seeds that had the elaiosome removed manually, and (4) seeds with elaiosome (unmanipulated seeds). Seeds manipulated by the ant and seeds that had the elaiosome removed manually required less time to germinate and had higher germination percentages (98.6% and 95.8%, respectively) than the other treatments. However, seeds ingested by the maned wolf also had a high germination percentage (87.7%), above that of unmanipulated seeds (34.7%). Probably, elaiosomes of unmanipulated seeds and small remnants of this structure that resist digestion by maned wolf can decrease to some extent seed germination. We argue that dispersal of C. arenicola seeds by the ant and by the maned wolf result in different patterns of seed distribution in the environment and that they have complementary roles in structuring plant populations.

摘要 种子传播与萌发研究对于解析植物分布与种群多度格局至关重要，同时可为环境保护策略的制定提供科学依据。本研究评估了光滑切叶蚁（Atta laevigata）与鬃狼（Chrysocyon brachyurus）这两种不同传播者对沙地油楠（Copaifera arenicola，一种典型蚁媒传播（myrmecochorous）植物）种子萌发的作用。本研究对四组处理的种子开展萌发评估：(1) 经切叶蚁处理的种子；(2) 经鬃狼摄食消化的种子；(3) 人工去除油质体（elaiosome）的种子；(4) 保留完整油质体的未处理种子。结果显示，经切叶蚁处理的种子与人工去除油质体的种子，其萌发所需时长更短、萌发率亦更高，分别达98.6%与95.8%，显著高于其余两组处理。但经鬃狼摄食消化的种子萌发率亦达87.7%，同样高于未处理种子的34.7%。推测未处理种子的油质体以及难以被鬃狼消化的该结构少量残留，可在一定程度上抑制种子萌发。本研究认为，切叶蚁与鬃狼对沙地油楠（C. arenicola）种子的传播，会在环境中形成各异的种子分布格局，且二者在植物种群结构的塑造过程中发挥着互补作用。