Jiménez-Martín Iciar, Green Andy J, Szabó Nándor, Lukács Balázs András, Vincze Orsolya, Lovas-Kiss Ádám
Department of Conservation Biology and Global Change, Estación Biológica de Doñana (EBD), CSIC, Américo Vespucio 26, 41092 Sevilla, Spain.
MTA-HUN-REN-CER "Momentum" Dispersal Ecology Research Group, IAE, 4026 Debrecen Hungary.
Ann Bot. 2025 Aug 19. doi: 10.1093/aob/mcaf192.
Many plant species undergo long-distance dispersal through migratory waterbirds. However, there is little information about the effectiveness of this dispersal, especially regarding the chances of plant establishment, and the impact of gut passage or the faecal matrix on plant germination, growth, and reproductive investment in seeds.
In a greenhouse experiment, we addressed these questions using an annual mudflat species, Juncus bufonius (Juncaceae), and a perennial emergent aquatic species, Eleocharis palustris (Cyperaceae), whose seeds are dispersed by many waterbird species in Europe. We planted seeds directly in soil or within mallard faeces placed on soil, using both control seeds and seeds that survived gut passage through mallards. Over the following 11 weeks, we quantified germination and plant performance.
Gut passage reduced germination time of J. bufonius when there was no faecal matrix, and increased asymptotic height of E. palustris. Presence of the faecal matrix hindered germinability, plant growth and final biomass for both species, along with total seed production for J. bufonius. Presence of the faecal matrix slowed down germination in E. palustris, yet had the opposite effect for J. bufonius. It was also associated with greater relative investment in seeds in J. bufonius (more seeds per unit biomass), likely as a consequence of later germination. In both species, earlier germination increased final biomass (and seed production in J. bufonius).
Our results support the importance of waterbird endozoochory in plant dispersal, but suggest it may be more effective when faeces disintegrate, as when egested into water or disaggregated on land (e.g. by insects). Previous studies with other plants have recorded accelerated germination following waterbird gut passage, and our results show this can benefit plant fitness.
许多植物物种通过迁徙水鸟进行远距离传播。然而，关于这种传播的有效性的信息很少，特别是关于植物定植的机会，以及肠道通过或粪便基质对植物种子萌发、生长和繁殖投资的影响。
在一项温室实验中，我们使用一年生泥滩物种灯心草（灯心草科）和多年生挺水水生物种沼生荸荠（莎草科）来解决这些问题，这两种植物的种子在欧洲被多种水鸟传播。我们将种子直接种植在土壤中或放置在土壤上的绿头鸭粪便中，同时使用对照种子和经绿头鸭肠道通过后存活的种子。在接下来的11周内，我们对萌发和植物表现进行了量化。
在没有粪便基质的情况下，肠道通过缩短了灯心草的萌发时间，并增加了沼生荸荠的渐近高度。粪便基质的存在阻碍了这两个物种的发芽能力、植物生长和最终生物量，以及灯心草的种子总产量。粪便基质的存在减缓了沼生荸荠的萌发，但对灯心草有相反的影响。它还与灯心草在种子上的相对投资增加有关（每单位生物量的种子更多），这可能是后期萌发的结果。在这两个物种中，较早萌发增加了最终生物量（以及灯心草的种子产量）。
我们的结果支持水鸟内吞传播在植物传播中的重要性，但表明当粪便分解时可能更有效，例如当排入水中或在陆地上分解时（例如通过昆虫）。先前对其他植物的研究记录了水鸟肠道通过后萌发加速，我们的结果表明这可以有益于植物适合度。
