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Researchers at Penn State University and the University of Buffalo¹ have completed the most in depth bear DNA² study to date. The project has revealed a lot about genetic³ relationships between bears, and also the unlikely romances that pepper their history.
宾夕法尼亚州立大学和布法罗大学的的研究人员已经完成了迄今为止对熊的基因最为深入的研究。

From previous studies, we knew that polar and grizzly⁴ (or, brown) bears are “sister species.” That means that they share some DNA background; scientists believed they had split from one another fairly recently–about 600,000 years ago.
该项研究揭示了不同种类的熊之间的遗传关系，同时也揭露了熊之间的不太可能的关系，这种不可能性充斥着它们的历史。从之前的研究来看，我们知道北极熊和灰熊的关系是“姐妹品种”。

However, this latest DNA analysis suggests that they have, in fact, been two distinct species for the past four to five million years. Most grizzlies⁵ and polar bears out there these days share less than two percent of their DNA.
但是，这项最新的DNA分析却显示，事实上，在过去的四至五百万年，北极熊和灰熊一直是作为两个不同的物种存在的。如今现存的灰熊和北极熊拥有的相同基因少于百分之二。

Think of it this way: with polar bears sticking to the Arctic, and grizzlies hanging around farther south, it’s been pretty easy to maintain evolutionary–and genetic–separation: there simply haven’t been many chances for the two species to meet up!
让我们这样思考：北极熊一直在北极生活，而灰熊一直在地球上遥远的南面生活，所以它们各自不影响对方的进化和基因分离——它们甚至没有机会遇见对方！不过，其中还是会有一些特例。比如说，根据来自阿拉斯加亚历山大群岛的一群灰熊的基因显示，灰熊和北极熊还是有可能曾经在一起生活过。

There can be exceptions, though. For instance, the DNA from a group of grizzlies living in Alaska’s Alexander Archipelago indicates that, given the opportunity, grizzlies and polar bears certainly aren’t opposed to cuddling up. In fact, thanks to intermittent⁶ cross breeding over time, some of those Alaskan grizzlies share up to eleven percent of their DNA with polar bears!
事实上，由于历史上出现的断断续续的杂交，在这些来自于阿拉斯加的灰熊中，部分灰熊的基因和北极熊的相同竟达到了百分之十一！

This fact has far reaching implications for future bear genetics, especially now that climate change is shifting the geographical⁸ range of grizzly and polar bear populations. The potential for inter⁷ species “matchmaking” is on the rise, and in places where habitats now overlap⁹, researchers have already observed grizzly polar bear hybrids¹⁰ out roaming the landscape.
如今，气候改变影响着灰熊和北极熊的栖息范围，这一研究结果对未来熊的遗传学有着深远的启示作用。不同物种之间拥有“亲缘关系”的可能性正在增加，而且在一些栖息地重叠的地方，研究人员已经发现有灰色的北极杂交熊出没。