Stinging hairs on the Japanese nettle Urtica thunbergiana have a defensive function against mammalian but not insect herbivores
Stinging hairs on the Japanese nettle Urtica thunbergiana have a defensive function against mammalian but not insect herbivores
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日本荨麻 Urtica thunbergiana 上的刺毛对哺乳动物有防御功能，但对昆虫食草动物没有防御功能
DOI：
10.1007/s11284-014-1137-2
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发表时间：
2014
影响因子：
2
通讯作者：
Sato H
中科院分区：
文献类型：
--
作者：
Iwamoto M;Horikawa C;Shikata M;Wasaka N;Kato T;Sato H
植物的刺和毛发可以作为对食草动物的防御，尽管它们可能不是在食草动物的选择下进化的。日本奈良县奈良公园内的荨麻（Urtica thunbergiana）拥有 1200 年的梅花鹿保护历史，其刺毛比鹿少或无鹿地区的荨麻要多得多。先前的研究表明，这种毛茸茸的荨麻是在鹿强烈捕食的自然选择下进化而来的，因为带刺的毛发阻止了鹿捕食，而且种群间毛发密度的变化与鹿的数量有关。为了证实这一假设，我们通过实验室和现场实验，对奈良公园的有毛荨麻和其他地区的几乎无毛荨麻进行了实验，研究了（1）刺毛是否影响草食性昆虫的产卵和摄食偏好，以及（2）它们对鹿的威慑程度。一种专业蝴蝶——印度红海军上将，对有毛或无毛荨麻没有产卵或幼虫摄食偏好。两种变体之间的昆虫损害水平没有显着差异。相比之下，鹿吃无毛荨麻的次数多于有毛荨麻。然而，在毛荨麻中，鹿的啃食水平与刺毛密度不成正比，这可能是因为由于对刺毛的长期强烈定向选择，毛荨麻种群已经达到了抵抗力的平台期。这些结果证实了这样的假设：奈良公园的毛荨麻是在鹿的强烈啃食下通过自然选择进化而来的。
Thorns and hairs of plants can serve as defenses against herbivores, although they may not have evolved under selection by herbivory. Japanese nettles,Urtica thunbergiana, in Nara Park, Nara Prefecture, Japan, where sika deer have been protected for 1200 years, bear many more stinging hairs than those in areas with few or no deer. Previous studies suggested that such hairy nettles evolved under natural selection imposed by intense deer browsing, because stinging hairs deterred deer browsing and because among-population variation in hair density was associated with deer abundance. To confirm this hypothesis, we examined (1) whether stinging hairs affected oviposition and feeding preferences of herbivorous insects and (2) the degree to which they deterred deer via laboratory and field experiments with hairy nettles from Nara Park and with almost-hairless nettles from another area. A specialist butterfly, Indian red admiral, showed no oviposition or larval feeding preferences for either hairy or hairless nettles. Insect damage levels did not significantly differ between the two variants. In contrast, deer browsed hairless nettles more heavily than hairy ones. In hairy nettles, however, the level of deer browsing was not proportional to stinging-hair density, presumably because the hairy nettle population had reached a plateau for resistance as a result of long-term strong directional selection for stinging hairs. These results corroborate the hypothesis that hairy nettles in Nara Park evolved through natural selection under intense deer browsing.