辣椒的辛辣阻止了不良的种子传播者

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为了弥补自身无法移动到其他地方的缺陷,许多植物会产生肉质的、带种子的果实,以引诱动物,然后这些动物会在不知不觉中为它们完成传播种子的工作。然而,许多水果含有脊椎动物认为难以下咽的化学物质。今天发表在《自然》杂志上的新研究表明,就小辣椒而言,这种明显的悖论实际上是一种理想的适应。

实验室研究表明,辣椒素是赋予辣椒辛辣味道的化学物质,对哺乳动物有毒,但对鸟类无毒。因此,当蒙大拿大学的约书亚·J·图克斯伯里和北亚利桑那大学的加里·P·纳布汉这两位研究作者观察亚利桑那州南部的一种野生小辣椒种群时,他们发现只有鸟类(主要是弯嘴嘲鸫)吃这种野生辣椒;当地的小型哺乳动物(仙人掌鼠和林鼠)会避开它们。

事实证明,这种选择性的阻止符合植物的最佳利益。使用一种与小辣椒非辛辣的近亲(哺乳动物拒绝吃辛辣的辣椒)进行的实验表明,仙人掌鼠和林鼠摄入的辣椒种子未能发芽。另一方面,嘲鸫的食用导致发芽率与直接从果实中播种的种子相当。(喂给嘲鸫的辛辣辣椒也产生了类似的积极结果。)


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图克斯伯里和纳布汉总结说,嘲鸫是更好的传播者,原因有几个。首先,与哺乳动物不同,它们排出完整的种子。但它们也经常将种子 deposit 在最佳地点:其他结果灌木和树木的保护性阴影下。作者写道,“因此,幼苗更容易建立,果实播前捕食率较低,种子传播范围更广。” 辣椒的火辣策略似乎产生了甜蜜的回报。

Kate Wong is an award-winning science writer and senior editor at 大众科学 focused on evolution, ecology, anthropology, archaeology, paleontology and animal behavior. She is fascinated by human origins, which she has covered for more than 25 years. Recently she has become obsessed with birds. Her reporting has taken her to caves in France and Croatia that Neandertals once called home, to the shores of Kenya's Lake Turkana in search of the oldest stone tools in the world, to Madagascar on an expedition to unearth ancient mammals and dinosaurs, to the icy waters of Antarctica, where humpback whales feast on krill, and on a "Big Day" race around the state of Connecticut to find as many bird species as possible in 24 hours. Kate is co-author, with Donald Johanson, of Lucy's Legacy: The Quest for Human Origins. She holds a bachelor of science degree in biological anthropology and zoology from the University of Michigan. Follow Wong on X (formerly Twitter) @katewong

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