School of the Environment, University of Queensland, Brisbane, Queensland, Australia.
Institute of the Environment and Sustainability, University of California Los Angeles, Los Angeles, California, USA.
Ecology. 2024 Oct;105(10):e4409. doi: 10.1002/ecy.4409. Epub 2024 Aug 27.
Animals disperse seeds in various ways that affect seed deposition sites and seed survival, ultimately shaping plant species distribution, community composition, and ecosystem structure. Some animal species can disperse seeds through multiple pathways (e.g., defecation, regurgitation, epizoochory), each likely producing distinct seed dispersal outcomes. We studied how seed traits (size and toughness) interact with disperser species to influence seed dispersal pathway and how this ultimately shapes the proportion of seeds deposited in various habitat types. We focused on three frugivorous species of duikers (African forest antelopes) in the Dja Faunal Reserve, a tropical rainforest in southern Cameroon. Duikers can both defecate and regurgitate seeds, the latter predominantly occurring during rumination at their bedding sites (or "nests"). We located duiker nests and dungs along 18 linear 1-km-transects to assess: (1) how seed traits affect the likelihood of dispersal via defecation versus regurgitation, (2) if defecated versus regurgitated seeds are deposited at different rates in different forest types (assessed by indigenous Baka), microhabitats, and forest structural attributes (measured by drone lidar), and (3) if these differ between three duiker species that vary in size and diel activity patterns. We found that duikers predominantly defecated small seeds (<3 mm length) and regurgitated larger and tougher seeds (>10 mm length), the latter including 25 different plant species. The three duiker species varied in their nesting habits, with nocturnal bay duikers (Cephalophus dorsalis) nesting in dense understory vegetation at proportions 3-4 times higher than Peter's and yellow-backed duikers (Cephalophus callipygus and Cephalophus silvicultor). As a result, bay duikers deposited larger regurgitated seeds at a higher rate in habitats with denser understory where lianas and palms predominate and near fallen trees. This directed regurgitation seed deposition likely plays an important and unique role in forest succession and structure. This study highlights the importance of ungulate seed dispersal by regurgitation, a vastly understudied process that could impact many ecosystems given the prevalence of ruminating ungulates worldwide.
动物以各种方式传播种子，这些方式影响种子的沉积地点和种子的存活，最终塑造了植物物种的分布、群落组成和生态系统结构。一些动物物种可以通过多种途径（例如，排泄、反刍、体外被毛传播）来传播种子，每种途径可能产生不同的种子传播结果。我们研究了种子特性（大小和坚韧度）如何与散布者物种相互作用，从而影响种子传播途径，以及这如何最终影响种子在各种生境类型中的沉积比例。我们专注于喀麦隆南部热带雨林的 DJA 动物保护区的三种杜氏赤麂（非洲森林羚羊），它们是食果动物。杜氏赤麂既可以排泄种子，也可以反刍种子，后者主要发生在它们的栖息地（或“巢穴”）中反刍时。我们在 18 条 1 公里长的线性样带上定位了杜氏赤麂的巢穴和粪便，以评估：（1）种子特性如何影响通过排泄或反刍传播的可能性，（2）在不同的森林类型（由当地的巴卡人评估）、微生境和森林结构属性（由无人机激光雷达测量）中，排泄和反刍的种子的沉积速度是否不同，以及（3）这在大小和昼夜活动模式不同的三种杜氏赤麂物种之间是否存在差异。我们发现，杜氏赤麂主要排泄小种子（<3 毫米长），反刍大而坚韧的种子（>10 毫米长），其中包括 25 种不同的植物物种。三种杜氏赤麂在筑巢习惯上有所不同，夜间活动的巴氏赤麂（Cephalophus dorsalis）在茂密的林下植被中筑巢的比例比彼得赤麂（Cephalophus callipygus）和黄背赤麂（Cephalophus silvicultor）高出 3-4 倍。因此，巴氏赤麂在林下植被密度较高、藤本植物和棕榈树较多且靠近倒下的树木的栖息地中，以更高的速度沉积更大的反刍种子。这种定向反刍种子沉积可能在森林演替和结构中发挥重要而独特的作用。本研究强调了反刍动物传播种子的重要性，反刍动物传播是一个被严重低估的过程，考虑到世界范围内反刍动物的普遍存在，它可能会影响许多生态系统。
