City Swans May Tolerate Humans Due to Gene Variant
基因决定天鹅是否惧怕人类

More members of an urban swan population that lets humans get near have a particular genetic variant than do a rural swan group that tends to take off when humans approach
郊外生活的的天鹅通常会回避人类，相比之下，城市中不害怕人类的天鹅更多，这种差异竟然是因为它们某种基因不同。

撰文 杰森·G·高曼
翻译 Meatle
审核 乔虹

Animals that live in the city are usually less wary of humans than their rural counterparts. Most people think the boldness comes from experience: since the majority of humans are rather harmless, the critters learn to go about their business without fear. But the truth turns out to be far more interesting, at least for Australian swans. Turns out the city birds are genetically different from their country counterparts.
 居住在城市的动物，相比它们的同类，更少地惧怕人类。大多数人认为这种胆识来自它们的经历：大多数人类对小动物并无恶意，这使它们学会了毫无畏惧的生活在人类周围。但真相却更为有趣，至少对于澳大利亚的天鹅而言。 结果表明，这些居住在城市的天鹅与它们居住在郊外的同类相比，有着基因上的差异。

Australian researchers looked at two groups of swans. One population lived on a pond in the center of Melbourne. The second hung out just 30 kilometers away in a more bucolic setting, surrounded by far fewer humans. The researchers measured what they call each bird’s “flight initiation distance”: basically, how close could a human get before the swan would fly away?
 澳大利亚的研究人员考察了两组天鹅。其中一组栖息在墨尔本城中心的一个池塘中，另一组生活在30公里外的乡间，这里人烟稀少。研究人员测量它们的“起飞反应距离”：简单地说，就是天鹅飞起来逃走时，人与天鹅之间的距离。

“We found that the flight initiation distance for the swans at the urban environment was only 13 meters, and on average at the non-urban environment it was 96 meters. So that’s like an 83 meter difference, a really big difference in how wary these swans are at the two habitats.” Victoria University ecologist Wouter van Dongen.
“我们发现，居住在城市的天鹅的起飞反应距离只有13米，而非城市的天鹅的平均距离则为96米。而这个83米的差异，真切地反映了这两种习性不同的天鹅在警惕性上的差异。”维多利亚大学的生态学家，沃特·范·东恩(Wouter van Dongen)说。

The researchers also took blood samples from some of the swans to analyze their DNA. And almost 90 percent of urban swans had the same variant of a gene for dopamine transport, while just 60 percent of rural birds had that version. And those swans were less wary of humans than were the swans with the rarer genotypes.
研究人员也获取了一些天鹅的血液样本以分析它们的基因。结果显示，几乎90%的城市天鹅持有一种掌管多巴胺传递的基因的变体，而只有60%的郊外天鹅持有这种基因。同时，相比于持有更稀有的基因型的天鹅，持有这种基因的天鹅更不惧怕人类。

Dopamine influences a lot of brain function, so the gene variation could be behind the difference in swan attitudes. The study is in the journal BMC Evolutionary Biology. [Wouter F. D. van Dongen et al, Variation at the DRD4 locus is associated with wariness and local site selection in urban black swans]
多巴胺会影响大脑的多种功能，因此这种基因差异可能是天鹅行为差异的成因。这项研究发表在《进化生物学》上。[Wouter F. D. van Dongen et al, Variation at the DRD4 locus is associated with wariness and local site selection in urban black swans]

Since swans can easily fly wherever they want, the researchers think that the bolder birds don’t mind setting up shop in the city, while the more timid swans prefer the quieter country life. And that’s something that wildlife managers should keep in mind.
由于天鹅能轻易地飞去任何地方，研究人员认为大胆的天鹅不介意定居于城市，而胆小的天鹅则喜欢更为宁静的乡村生活。而这正是野生动物管理人员需要注意的。

"With release programs, often you breed up a small population of whatever animal and then you release them into the wild…and so one potential application of our research is to select individuals that are better able to cope with human disturbance, those that are less wary of humans, and release them into those areas that are more likely to experience human disturbance."
“在放生项目中，我们经常需要饲养一小群各种各样的动物，然后把它们放归自然。而这项研究的其中一个应用就是选出更能适应人类干扰的个体。这些个体更不惧怕人类，因此可以把它们放生到一些更有可能受到人类干扰的区域。”