The role of spines in anthropogenic seed dispersal on the Galápagos islands

Dispersal has important ecological and evolutionary consequences for populations, but understanding the role of specific traits in dispersal can be difficult and requires careful experimentation. Moreover, understanding how humans alter dispersal is an important question, especially on oceanic islands where anthropogenic disturbance through species introductions can dramatically alter native ecosystems. In this study, we investigated the functional role of spines in seed dispersal of the plant caltrop (Tribulus cistoides L., Zygophyllaceae) by anthropogenic agents. We also tested whether anthropogenic or wildlife are more important seed dispersers of T. cistoides on the Galápagos. Tribulus cistoides is found on tropical mainland and oceanic island habitats. The dispersal structure of T. cistoides is called a mericarp, and they are typically protected by one pair of upper spines and a second pair of lower spines, but the presence and size of spines varies within and between popu...扩散对种群具有重要的生态与进化效应，但解析特定功能性状在扩散过程中的作用颇具挑战，需开展严谨的实验探究。此外，阐明人类活动如何改变生物扩散过程是一项关键科学问题，在海洋岛屿生态系统中尤为如此——此类区域因物种引入引发的人为干扰，会显著改变原生生态系统结构与功能。 本研究以蒺藜科（Zygophyllaceae）硬蒺藜（Tribulus cistoides L.）为研究对象，探究其棘刺在人为媒介介导的种子扩散（seed dispersal）过程中的功能作用；同时对比检验人为活动与野生动物，何者为加拉帕戈斯群岛（Galápagos）上硬蒺藜更重要的种子扩散者。 硬蒺藜自然分布于热带大陆及海洋岛屿生境中。其种子扩散结构称为分果瓣（mericarp），通常由一对上侧棘刺与一对下侧棘刺共同保护，但棘刺的有无及尺寸在种群内部与种群间均存在变异……