来源：《新科学家》
原本刊登日期：2021年4月29日
本文时候英语二考生
On opposite sides of North America, house mice have strikingly similar adaptations to cold climates, and have independently evolved changes to genes that drive their similar behaviours and hardiness.
在北美的东西两边，家鼠对寒冷气候的适应惊人地相似，并且各自进化出了基因上的变化，这些变化推动了它们相似的行为和耐寒性。
House mice are native to Western Europe but have spread across the world thanks to their close association with humans. They arrived in the Americas more than 200 years ago and have since expanded into climates quite different from their original temperate home.
家鼠原产于西欧，但由于与人类的密切联系，家鼠已遍布世界各地。它们在200多年前到达美洲，并从那时起扩展到与他们最初的温带家园截然不同的气候地区。
To find out how these mice have adapted to new environmental conditions, Michael Nachman at the University of California, Berkeley, and his team collected 50 mice from locations in western North America ranging from Arizona in the US north to Alberta, Canada. The team analysed DNA from these wild mice and kept some to breed lab populations, comparing the western mice with those from a previous study on mice from eastern North America, ranging from Florida to New York.
为了弄清楚这些老鼠是如何适应新的环境条件的，加州大学伯克利分校的Nachman和他的团队从北美西部(从美国的亚利桑那往北到加拿大的阿尔伯塔)收集了50只老鼠。研究小组分析了这些野生小鼠的DNA，并保留了一些用于繁殖实验室种群，并将西部小鼠与之前对北美东部(从佛罗里达到纽约)小鼠进行的研究进行了比较。
The mice were most closely related to those that shared their side of the continent, suggesting that mice in western and eastern North America had moved north independently after an initial spreading along a southern route, says Nachman.
Nachman说，这些老鼠与那些在北美大陆同一侧的老鼠关系最密切，这表明北美西部和东部的老鼠在最初沿着南部路线传播后，是分别独立向北方移动的。
Yet the lab-reared mice from Alberta and New York were physically similar: both were bigger than southern mice and made larger nests, discouraging heat loss and providing insulation.
然而，来自阿尔伯塔和纽约的实验室饲养的老鼠在身体上是相似的：它们都比南方的老鼠大，巢穴也更大，阻止热量流失和提供隔热。
Nachman was surprised the nest style was so clearly genetically encoded after just a few hundred generations. “Even at room temperature in a comfy lab with plenty of water and constant temperature and plenty of food, the mice from Canada build a bigger nest than the mice from Arizona,” he says.
Nachman感到惊讶的是，仅仅几百代之后，巢穴的样式就被如此清晰的遗传编码了。他说：“即使在一个舒适的实验室里，在有充足的水、恒定的温度和充足的食物的条件下，来自加拿大的老鼠也会比来自亚利桑那州的老鼠建一个更大的窝。”
The western and eastern mice from cold climates shared changes in 16 genes, many involved with the regulation of body temperature. “This suggests that there’s some predictability to evolution, that some of the same genes have changed in parallel to give rise to similar traits,” says Nachman.
来自寒冷气候的西部和东部小鼠有16个共同的基因变化，其中许多与体温调节有关。Nachman说：“这表明进化有一定的可预测性，一些相同的基因同时发生了变化，产生了相似的特征。”
But the mice also showed regional adaptations – such as fur colour and changes to hydration regulation genes – which may be due to differences in soil colour and rainfall between west and east.
但这些老鼠也表现出区域适应性——比如皮毛颜色和水分调节基因的变化——这可能是由东西部土壤颜色和降雨量的差异造成的。
Going forward, Nachman wants to see if the same physical and genetic patterns occur in mice spanning the length of South America.
接下来，Nachman想看看在整个南美洲的老鼠身上是否也会出现同样的生理和基因模式。