• Some plant traits may be legacies of coevolution with extinct megafauna. One example is the convergent evolution of ‘divaricate’ cage architectures in many New Zealand lineages, interpreted as a response to recently extinct flightless avian browsers whose ancestors arrived during the Paleogene period. Although experiments have confirmed that divaricate habit deters extant browsers, its abundance on frosty, droughty sites appears consistent with an earlier interpretation as a response to cold, dry Plio-Pleistocene climates.
• We used 45 protein-coding sequences from plastid genomes to reconstruct the evolutionary history of the divaricate habit in extant New Zealand lineages. Our dated phylogeny of 215 species included 91% of New Zealand eudicot divaricate species.
• We show that 86% of extant divaricate plants diverged from non-divaricate sisters within the last 5 Ma, implicating Plio-Pleistocene climates in the proliferation of cage architectures in New Zealand.
• Our results, combined with other recent findings, are consistent with the synthetic hypothesis that the browser-deterrent effect of cage architectures was strongly selected only when Plio-Pleistocene climatic constraints prevented woody plants from growing quickly out of reach of browsers. This is consistent with the abundance of cage architectures in other regions where plant growth is restricted by aridity or short frost-free periods.

中文翻译：

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过时的系统发育表明上更新世气候刺激了新西兰植物群中反浏览防御的进化

• 一些植物特征可能是与灭绝的巨型动物共同进化的遗产。一个例子是新西兰许多血统中“分叉”笼式结构的趋同进化，被解释为对最近灭绝的不会飞的鸟类浏览器的反应，这些浏览器的祖先是在古近纪时期到达的。尽管实验已经证实，分叉的习惯阻止了现存的浏览器，但它在寒冷、干旱的地点的丰富性似乎与早期的解释一致，即对寒冷、干燥的上更新世气候的反应。
• 我们使用来自质体基因组的 45 个蛋白质编码序列来重建现存新西兰谱系中分叉习惯的进化历史。我们过时的 215 个物种的系统发育包括 91% 的新西兰真双子叶植物。
• 我们表明，在过去的 5 Ma 内，86% 的现存二叉树植物从非二叉树姐妹中分化出来，这表明 Plio-Pleistocene 气候与新西兰网箱结构的扩散有关。
• 我们的结果与最近的其他发现相结合，与综合假设一致，即只有当 Plio-Pleistocene 气候限制阻止木本植物快速生长到浏览器无法触及时，才会强烈选择笼式结构的浏览器威慑效果。这与植物生长受干旱或短无霜期限制的其他地区大量的网箱结构是一致的。