Astraptes fulgerator是一種中大型的蝴蝶，是一種棲居于南美至北阿根廷的常見(jiàn)蝴蝶,，普遍發(fā)現(xiàn)于都市庭院和熱帶雨林中,。人類對(duì)于這個(gè)種的認(rèn)知始于1775年，它們之前被認(rèn)為是同一種,。
在2004年10月1日的Proceedings of the National Academy of Sciences中,，Hebert等人報(bào)道說(shuō)，他們和賓州大學(xué)的Daniel Janzen等人合作,，Hebert等人分析了哥斯達(dá)黎加的480個(gè)弄蝶樣本,，但是藉由先進(jìn)的DNA編碼分析，發(fā)現(xiàn)這些種其實(shí)具有基因歧異性,，分屬10個(gè)不同的品種,，而且和它們選擇的食物息息相關(guān)。
由于多達(dá)六個(gè)種居住在同一塊土地上,，所以顯示這些蝴蝶中有生殖隔離的特性,。由于蝴蝶的外觀上十分相近,，之間的差別相當(dāng)輕微，所以只歸因于一般微小的歧異性,，這項(xiàng)發(fā)現(xiàn)對(duì)于生物多樣性的維持有更大的涵義,。
這項(xiàng)研究結(jié)果引起了一個(gè)有趣的問(wèn)題，有多少野生動(dòng)物也和者種蝴蝶一樣,，外觀相似,，但卻是有生殖隔離的不同品種？
我們也許會(huì)哀嘆植物或動(dòng)物在某個(gè)地方絕種,，但卻慶幸還好牠們?nèi)源嬖谟诘厍蛏系钠渌胤?，但事?shí)上，這些物種可能已經(jīng)真正消失了,，存在于他處的物種其實(shí)是不同的物種,。
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DNA Barcoders Nab New Species
Biologists dream of hand-held DNA scanners that could tell an ecologist in the field whether or not an organism is a new species. That dream is a long way from fruition, but two new tests of a molecular technique called DNA barcoding suggest that it will become a powerful tool for cataloging the diversity of life.
Hidden diversity.
Barcoding allows biologists to identify new butterfly species that have remarkably similar adult forms.
With species going extinct faster than they can be identified by traditional methods, a group of taxonomists has been developing DNA barcoding to speed up their work. The method focuses on DNA in the energy-generating mitochondria inside cells. Unlike DNA in the nucleus of cells, mitochondrial DNA evolves quickly. Unique changes will accumulate after two populations stop interbreeding, allowing biologists to tell whether two closely related organisms should be considered separate species.
Backers of this approach, including the authors of the new studies, have teamed up to form the Consortium for the Barcoding of Life. To standardize their efforts, they've agreed to use the 648 DNA letters of a mitochondrial gene called COI as the barcode marker. Their ultimate goal is to catalog the COI sequence of every species on Earth. But before that can happen, biologists have to make sure the technique is reliable.
The new work suggests that it is. A team led by Mark Stoeckle, a molecular ecologist at Rockefeller University in New York City, barcoded 260 bird species known to reproduce in the United States. Their results, published in the 28 September issue of the Public Library of Science, Biology, show that differences in the sequence of the COI gene are about 18 times greater between species than within species. Beyond demonstrating that DNA barcoding can distinguish known bird species, they found that four unknown bird species appear to be improperly lumped in with other species.
In a similar study, Daniel Janzen, an evolutionary biologist at the University of Pennsylvania in Philadelphia, and colleagues sequenced mitochondrial DNA from nearly 500 specimens of the tropical skipper butterfly preserved at the Smithsonian National Museum of Natural History in Washington, D.C. DNA barcoding of the specimens reveal 10 species within the tropical skipper group, a classification that had eluded naturalists because the adult forms of the butterflies are so similar, the team reports online this week in the Proceedings of the National Academy of Sciences.
Barcoding provides a relatively rapid tool in a field in which "time is an enormous enemy," says Daniel Brooks, an evolutionary biologist at the University of Toronto in Canada. But Brooks cautions that the traditional methods are needed to confirm the designations found by barcoding.
