每年冬天來(lái)臨的時(shí)候,，帝王蝴蝶就從加拿大和美國(guó)北部起飛，成千上萬(wàn)地聚集在一起，長(zhǎng)途遷徙到溫暖的墨西哥冷杉林中過(guò)冬,，然后再返回加拿大。而這趟旅行比我們之前所認(rèn)為的更加引人注意,。
加拿大圭爾夫大學(xué)一項(xiàng)最新的研究顯示,，一些產(chǎn)于美國(guó)北部的帝王蝴蝶直接向東飛，它們?cè)竭^(guò)阿巴拉契亞山脈,，并定居在東部海岸,。先前，科學(xué)家認(rèn)為大部分的帝王蝴蝶直接從美國(guó)海灣濱海地區(qū)向北方遷移,。
研究結(jié)果發(fā)布在最近一期的科學(xué)雜志Biology Letters上,。這是一項(xiàng)具有突破性的發(fā)現(xiàn)，該研究的負(fù)責(zé)人圭爾夫大學(xué)的Ryan Norris教授表示,。
東部海岸的蝴蝶容量與山脈另一邊的蝴蝶產(chǎn)量密切相關(guān),。帝王蝴蝶每年遷徙數(shù)千公里越冬，在這個(gè)過(guò)程中需要在不同的地域繁殖多代,。
先前就有生物學(xué)家猜測(cè),，帝王蝴蝶會(huì)從墨西哥自西向東飛，越過(guò)阿巴拉契亞山脈,。但是一直沒(méi)有證據(jù)支持這一論斷,。而這項(xiàng)研究則提供了第一個(gè)證據(jù)。
在2009年6月和7月,，研究人員從緬因州到弗吉尼亞州之間的17個(gè)區(qū)域收集了90個(gè)帝王蝴蝶的樣本,。同樣，在同年5月到7月,，他們采集了180個(gè)乳草屬植物的樣本,，在東部海岸的36個(gè)區(qū)域。
然后使用氫和碳的同位素測(cè)量確定帝王蝴蝶出生時(shí)間和地點(diǎn),。植物中的同位素值在縱向呈現(xiàn)不同變化,，也能在蝴蝶的翅膀中檢測(cè)到。
研究人員發(fā)現(xiàn)88%的帝王蝴蝶樣本源于中西部五大湖區(qū)域,。這就是說(shuō),，這些東部海岸的"移民"是在五大湖區(qū)域孵化,，然后向東遷移的。這項(xiàng)研究表明,，我們需要關(guān)注五大湖區(qū)域以保護(hù)東部海岸帝王蝴蝶的數(shù)量,。(生物谷Bioon.com)
生物谷推薦原文出處：
Biology Letters doi: 10.1098/rsbl.2010.0525
Monarch butterflies cross the Appalachians from the west to recolonize the east coast of North America
Nathan G. Miller1,*, Leonard I. Wassenaar2, Keith A. Hobson2 and D. Ryan Norris1
Each spring, millions of monarch butterflies (Danaus plexippus) migrate from overwintering sites in Mexico to recolonize eastern North America. However, few monarchs are found along the east coast of the USA until mid-summer. Brower (Brower, L. P. 1996 J. Exp. Biol. 199, 93–103.) proposed that east coast recolonization is accomplished by individuals migrating from the west over the Appalachians, but to date no evidence exists to support this hypothesis. We used hydrogen (δD) and carbon (δ13C) stable isotope measurements to estimate natal origins of 90 monarchs sampled from 17 sites along the eastern United States coast. We found the majority of monarchs (88%) originated in the mid-west and Great Lakes regions, providing, to our knowledge, the first direct evidence that second generation monarchs born in June complete a (trans-) longitudinal migration across the Appalachian mountains. The remaining individuals (12%) originated from parents that migrated directly from the Gulf coast during early spring. Our results provide evidence of a west to east longitudinal migration and provide additional rationale for conserving east coast populations by identifying breeding sources.
