生物谷報(bào)道：美國(guó)研究人員在英國(guó)《自然》（Nature）雜志上撰文說(shuō),，與許多生物學(xué)家的看法相反,，鳥(niǎo)類翅膀扇動(dòng)的幅度相對(duì)較小,，只有19度,。 利用4臺(tái)同步高速數(shù)碼攝像機(jī),，美國(guó)蒙大拿大學(xué)的科學(xué)家肯尼思·戴爾及同事記錄了北美洲的一種鳥(niǎo)——石雞的成長(zhǎng)過(guò)程,。他們每?jī)商鞂?duì)這些鳥(niǎo)記錄一次,，從它們孵出來(lái)開(kāi)始，直至成年,。 他們利用計(jì)算機(jī)技術(shù)分析石雞翅膀形狀和扇動(dòng)情況后驚訝地發(fā)現(xiàn),，石雞翅膀扇動(dòng)的角度相對(duì)于地面都在一個(gè)非常窄的幅度范圍內(nèi)。不管是跑動(dòng),、拍打翅膀或?qū)W習(xí)從幾乎垂直的斜面上起飛的雛鳥(niǎo),，還是能夠自由滑行和俯沖的成年鳥(niǎo)，都通過(guò)改變身體的姿勢(shì)完成飛行特技,，而鳥(niǎo)翅相對(duì)于地面的傾角基本相同,，翅膀扇動(dòng)幅度保持在19度。（生物谷援引新華網(wǎng)）
生物谷推薦英文原文：
Nature advance online publication 23 January 2008 | doi:10.1038/nature06517; Received 20 August 2007; Accepted 27 November 2007; Published online 23 January 2008
A fundamental avian wing-stroke provides a new perspective on the evolution of flight
Kenneth P. Dial1, Brandon E. Jackson1 & Paolo Segre1
Flight Laboratory, Division of Biological Sciences, University of Montana, 32 Campus Drive, Missoula, Montana 59812, USA
Correspondence to: Kenneth P. Dial1 Correspondence and requests for materials should be addressed to K.P.D. (Email: [email protected]).
Abstract
The evolution of avian flight remains one of biology's major controversies, with a long history of functional interpretations of fossil forms given as evidence for either an arboreal or cursorial origin of flight. Despite repeated emphasis on the 'wing-stroke' as a necessary avenue of investigation for addressing the evolution of flight1, 2, 3, 4, no empirical data exist on wing-stroke dynamics in an experimental evolutionary context. Here we present the first comparison of wing-stroke kinematics of the primary locomotor modes (descending flight and incline flap-running) that lead to level-flapping flight in juvenile ground birds throughout development (Fig. 1). We offer results that are contrary both to popular perception and inferences from other studies5, 6, 7. Starting shortly after hatching and continuing through adulthood, ground birds use a wing-stroke confined to a narrow range of less than 20°, when referenced to gravity, that directs aerodynamic forces about 40° above horizontal, permitting a 180° range in the direction of travel. Based on our results, we put forth an ontogenetic-transitional wing hypothesis that posits that the incremental adaptive stages leading to the evolution of avian flight correspond behaviourally and morphologically to transitional stages observed in ontogenetic forms.
FIGURE 1. Locomotor development during ontogeny in the chukar partridge from hatching to adulthood.
Our data suggest a default or basal wing-stroke is used by young and adults and may exist in all birds (Supplementary Videos). The fundamental wing-stroke described herein is used days after hatching and during all ages and over multiple behaviours (that is, flap-running, descending and level flight) and is the foundation of our new ontogenetic-transitional wing hypothesis. At hatching, chicks can ascend inclines as steep as 60° by crawling on all four limbs. From day 8 through adulthood, birds use a consistently orientated stroke-plane angle over all substrate inclines during wing-assisted incline running (red arcs) as well as during descending and level flight (blue arcs). Estimated force orientations from this conserved wing-stroke are limited to a narrow wedge (see Fig. 3b).
