一旦將這個(gè)環(huán)氧樹脂“花瓣”垂直放置,,蜜蜂便需要用其表面上的隆起保持平衡,。
(圖片提供:Beverley Glover)
為了喝到美味的花蜜,,一只大黃蜂不得不在搖擺的花瓣間保持身體的平衡。根據(jù)一項(xiàng)新的研究,,蜜蜂在采蜜的過(guò)程中得到了植物的幫助,。在80%的開花植物中發(fā)現(xiàn)的錐形細(xì)胞提供了一個(gè)堅(jiān)實(shí)的落腳點(diǎn),并且使授粉的機(jī)會(huì)大為增加,。
從上世紀(jì)70年代開始,,科學(xué)家便一直在爭(zhēng)論這些細(xì)胞,即所謂的錐形表皮細(xì)胞的功能。一些學(xué)者認(rèn)為,,通過(guò)改善花的顏色或是將植物的溫度升高一到兩攝氏度——這將有利于花蜜的形成,,錐形表皮細(xì)胞能夠讓花對(duì)蜜蜂產(chǎn)生更大的吸引力。然而英國(guó)劍橋大學(xué)的植物分子生物學(xué)家Beverley Glover卻提出了一個(gè)完全不同的假設(shè):這些細(xì)胞能夠?yàn)槊鄯涮峁└街Σ亮Α?/p>
Glover指出:“在野外,,一朵花絕對(duì)不是一個(gè)靜止的大餐盤,。”她說(shuō),盡管花會(huì)隨著風(fēng)擺動(dòng),,但這些細(xì)胞使得蜜蜂能夠站穩(wěn)腳跟,,從而大大增加了授粉的可能性,這或許是進(jìn)化的結(jié)果,。
為了排除錐形表皮細(xì)胞的顏色和氣味的功能,,Glover和同事制造了一個(gè)金魚草花瓣的白色、無(wú)味兒的環(huán)氧樹脂模型,。這個(gè)模型的表面不是平面就是模擬錐形表皮細(xì)胞的錐形隆起線紋,。而花瓣中的小管道里則填充了蔗糖。
當(dāng)這個(gè)模型水平放置時(shí),,平面和“崎嶇”的花瓣對(duì)蜜蜂具有同等的吸引力,。然而,一旦將這個(gè)模型按照一定的角度或垂直放置,,蜜蜂則更愿意選擇那些具有粗糙表面的花瓣,。研究人員在最近的《當(dāng)代生物學(xué)》雜志網(wǎng)絡(luò)版上報(bào)告了這一研究成果。用高速錄像機(jī)進(jìn)行的分析顯示,,當(dāng)蜜蜂在粗糙的花瓣模型上降落時(shí),,它們將所有的腳都插入花瓣表面,并停止拍打翅膀,,進(jìn)而從容地進(jìn)餐,。然而,當(dāng)蜜蜂試圖在平滑的花瓣上采蜜時(shí),,它們中間的腿會(huì)在花瓣表面胡亂地爬行,,同時(shí)猛烈地拍打翅膀。
美國(guó)加利福尼亞大學(xué)里弗賽德分校的退休進(jìn)化生態(tài)學(xué)家Nickolas Waser表示:“拍打翅膀使蜜蜂浪費(fèi)了大量的能量,。”Waser指出,,“動(dòng)物希望在盡可能短的時(shí)間里獲得盡可能多的能量,因此,,一個(gè)讓它們能夠在吃飯的時(shí)候保存更多能量的表面對(duì)蜜蜂而言具有重要的意義。”(生物谷Bioon.com)
生物谷推薦原始出處:
Current Biology, 14 May 2009 doi:10.1016/j.cub.2009.04.051
Conical Epidermal Cells Allow Bees to Grip Flowers and Increase Foraging Efficiency
Heather M. Whitney1,4,Lars Chittka2,Toby J.A. Bruce3andBeverley J. Glover1,,
1 Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
2 Research Centre for Psychology, School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, UK
3 Department of Biological Chemistry, Rothamsted Research, Harpenden AL5 2JQ, UK
4 Present Address: School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK
The plant surface is by default flat, and development away from this default is thought to have some function of evolutionary advantage. Although the functions of many plant epidermal cells have been described, the function of conical epidermal cells, a defining feature of petals in the majority of insect-pollinated flowers, has not [1,2]. The location and frequency of conical cells have led to speculation that they play a role in attracting animal pollinators [1,3,4]. Snapdragon (Antirrhinum) mutants lacking conical cells have been shown to be discriminated against by foraging bumblebees [4]. Here we investigated the extent to which a difference in petal surface structure influences pollinator behavior through touch-based discrimination. To isolate touch-based responses, we used both biomimetic replicas of petal surfaces and isogenic Antirrhinum lines differing only in petal epidermal cell shape. We show that foraging bumblebees are able to discriminate between different surfaces via tactile cues alone. We find that bumblebees use color cues to discriminate against flowers that lack conical cellsbut only when flower surfaces are presented at steep angles, making them difficult to manipulate. This facilitation of physical handling is a likely explanation for the prevalence of conical epidermal petal cells in most flowering plants.