Hanish Carolyn J, Velez Sebastian, Moore Jon A, Devin Anderson Corey
Department of Biological Sciences, Florida Atlantic University, Boca Raton, FL, USA.
School of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln; Lincoln, NE, USA.
AoB Plants. 2020 Jun 19;12(4):plaa024. doi: 10.1093/aobpla/plaa024. eCollection 2020 Aug.
Some large-seeded plants lack effective seed dispersal agents when they are introduced as ornamental plants to new areas, but can rapidly colonize a landscape if seed dispersal functions are restored. We examined whether (Gopher Tortoise) facilitated the spread of (Cocoplum; Chrysobalanaceae) over a 14-year period in a suburban nature preserve (in Jupiter, FL, USA) by: (i) comparing germination patterns among gut-passed, hand-depulped and whole fruit treatments, and (ii) testing hypotheses about environmental predictors of the spatial distribution of , including information about movement pathways and burrow locations. While we did not find a significant difference in the total proportion of seeds that germinated in each treatment, time to event analysis revealed that seeds that were found in faeces germinated significantly earlier than seeds that were hand-depulped or that were planted as whole fruits, supporting a lone scarification effect. Point process modeling revealed that the density of bushes was higher near movement pathways and was lower inside (Saw Palmetto) patches, supporting a positive effect of tortoise movement patterns on plant distributions. The density of increased from west to east, consistent with westward dispersal from the four founder bushes on the east side of the study area. After removal of outliers, we also detected a negative association between spatial density and burrow density that was presumably explained by the fact that seeds defecated deep within burrows were unlikely to germinate and establish without secondary movement. The results suggest that contributed to the rapid dispersal of by scatter dispersal of seeds (via faeces) in areas where tortoises were active and that movement pathways provided suitable conditions for colonization. The spread of by over a relatively short period of time provides a valuable window into the earliest stages of the colonization process and further supports the role of Chelonians as effective seed dispersal agents for large-seeded plants.
一些大种子植物作为观赏植物被引入新区域时缺乏有效的种子传播媒介，但如果恢复种子传播功能，它们就能迅速在景观中定殖。我们研究了美国佛罗里达州朱庇特市一个郊区自然保护区内，地鼠龟是否在14年的时间里促进了可可李（Chrysobalanaceae科）的传播，方法如下：（i）比较经肠道排出、手工去皮和整果处理后的种子萌发模式，以及（ii）检验关于可可李空间分布的环境预测因子的假设，包括地鼠龟移动路径和洞穴位置的信息。虽然我们没有发现每种处理中可可李种子萌发的总比例有显著差异，但事件时间分析表明，在粪便中发现的种子比手工去皮或整果种植的种子发芽明显更早，这支持了单一的擦伤效应。点过程建模表明，可可李灌木丛的密度在龟移动路径附近较高，在锯齿棕（Saw Palmetto）斑块内较低，这支持了龟的移动模式对植物分布有积极影响。可可李的密度从西向东增加，这与研究区域东侧四株原始灌木丛向西扩散一致。去除异常值后，我们还检测到可可李空间密度与地鼠龟洞穴密度之间存在负相关，这可能是因为在洞穴深处排出的种子如果没有二次移动，不太可能发芽和定殖。结果表明，地鼠龟通过在其活跃区域以粪便形式散布种子，促进了可可李的快速传播，并且移动路径为定殖提供了适宜条件。地鼠龟在相对较短的时间内促进了可可李的传播，为定殖过程的早期阶段提供了一个有价值的窗口，并进一步支持了龟类作为大种子植物有效种子传播媒介的作用。
