玩转3D打印的生物学家们

When the first rains arrive in the forests of northwest Costa Rica, yellow toads gather in the hundreds for an intense but short-lived breeding season.

当第一场雨洒落在哥斯达黎加西北的雨林里，黄色蟾蜍们就会成百地聚集在一起完成一场短暂而集中的繁殖季。

This year, however, they will be joined by a handful of intruders called “RoboToads.”

不过今年，它们当中会混进一些称为“机器蟾蜍”的不速之客。

These motorized amphibians—3D printed in a lab—could help uncover the secrets behind the real toads’ unusual mating ritual.

这些机动的两栖动物-—在实验室里3d打印出来—可以帮助揭开真实的蟾蜍不同寻常的交配仪式背后的秘密。

And that’s just one of many mysteries that 3D-printed animals are starting to reveal.

而这还只是利用3D打印动物来揭晓各种谜团的序幕。

“3D printing is really advancing the questions that we’re able to ask as field biologists,” says Daniel Mennill, who has been researching the toads for a decade alongside Stéphanie Doucet, both of whom are behavioral ecologists at the University of Windsor in Canada.

“3d打印真的帮助推进了我们野外生物学家一直好奇的问题，”丹尼尔.门尼尔说，他跟史蒂芬.杜塞特一起研究蟾蜍已经几十年了，他们都是加拿大温莎大学的行为生态学家。

Several years ago, the husband-and-wife duo discovered that during the breeding season—which lasts little more than a day—male toads change color from their normal dull brown to a striking lemon-yellow.

几年前，这对夫妻档发现在繁殖季时—通常持续一天多一点—雄蟾蜍会将平时暗褐色的体色转换为醒目的柠檬黄。

Using handmade clay models, they figured out why: The brief switch to yellow helps the males identify females, which remain brown.

利用手工制作的黏土模型，他们找到了原因：这种短期转变成黄色的策略可以帮助雄性识别出雌性，因为它们仍然是棕色的。

But now the team wants to figure out how the females choose among similarly colored males, a much harder task to do with crude clay models

不过现在这只团队想要找出雌性在颜色相近的雄性之间是如何择偶的，这个任务只用粗糙的黏土模型恐怕很难完成。

Enter the RoboToad.

于是机器蟾蜍闪亮登场啦。

Created by Mennill and Doucet’s graduate student Lincoln Savi, the toads were painstakingly sculpted into exactly the right shape and texture with computer software, after being scanned in from a handful of photos.

它们是由门尼尔和杜塞特的研究生林肯.赛维创建的，这些蟾蜍利用几张照片扫描的模板和电脑软件，煞费苦心地塑成了完全一样的形状和花纹。

Savi 3D printed several copies and painted them to look like males, some bright yellow and some a dull chartreuse.

赛维3D打印出了几个复印版，然后把它们涂成了雄性的样子，有一些是亮黄色，而有些是暗黄绿色。

Motors make the models move around randomly, giving the illusion of a living creature.

内部的机械让这些模型随机四处移动，营造出真实生物的假象。

With the RoboToad, the team no longer needs to sculpt individual clay models—or struggle to get them painted the precise shades they need for their research.

有了机械蟾蜍，这只团队再也不用手工雕塑黏土模型了—也不用费劲把它们涂成研究需要的精确色调。

When the rains begin, the team will set up arenas containing two 3D-printed male toads of different shades, and see which one a wild female chooses.

当雨季开始时，这支团队就会在求偶比赛中加入两只不同色调的3D打印的蟾蜍，然后看看野生的雌性会选谁。

The brief breeding window means that time is of the essence, and Mennill says the team is already out in Costa Rica, “sitting there staring up at the sky [and] waiting for the first rains to arrive.”

繁殖季的短暂意味着时间是很重要的，门尼尔说他们团队已经动身前往哥斯达黎加，“在那里坐着望着天空，等待第一场雨的降临。”

Back in Canada, biologist Grégory Bulté, of Carleton University in Ottawa, is using 3D printing to answer a question that’s been bugging him for more than a decade.

而在加拿大，渥太华的卡尔顿大学生物学家格利戈里.布尔特正用3D打印来解决一个困扰了他们几十年的问题。

Bulté studies northern map turtles, whose females can grow to twice the length of males.

布尔特研究的是北部地图龟，它们的雌雄可以长到雄性的两倍长。

He wondered whether males might be attracted to larger females, but the turtles’ skittish nature—and the fact that they mate on the floor of the lake—made observation tricky.

他想知道雄性是否会被更大的雌性吸引，不过这种龟多疑的天性—以及它们在湖底交配的事实—让观察变得尤为困难。

Bulté’s team printed two 3D models of female turtles, identical in every aspect except size, and placed them a meter apart on the lakebed, with cameras rigged up to record how wild males reacted.

布尔特的团队3D打印了两只雌龟，除了大小其他方面都一样，然把它们放在湖底相距一米远的地方，并接好了摄像机来记录野生雄性会如何作出反应。

As predicted, the males attempted to mate with the large model more often than the smaller one, the researchers report this month in Animal Behaviour.

正如预想的一样，比起小个的雌性，雄性更喜欢跟打个的雌性交配，这支研究团队本月在《动物行为学》杂志上发表了结果。

Using live animals in this sort of study would introduce a host of other variables that would be difficult to control, Bulté says.

假如在这种研究中采用活体动物，那么就会引入很多其他的很难控制的变量，布尔特说道。

For example, one of the animals could be related to the male, which could affect his choice.

例如，其中一只动物可能是与雄性认识，这样就会影响他的选择。

In contrast, 3D printing is “almost an ideal system.”

相比之下，3D打印“几乎是最理想的系统”。

And multiple copies can be printed relatively cheaply.

用很便宜的价格就可以打印出多个复制品。

That’s a far cry from past eras, when an artist or taxidermist needed to create each individual model.

这与过去的时代截然不同，当时艺术家或动物标本制作者需要制作出每一个个体模型。

3D printing is also allowing scientists to create models at a much finer scale, says ornithologist Mark Hauber at the University of Illinois in Urbana.

3D打印还可以让科学家们创造出更小型号的模型，伊利诺伊大学厄巴纳分校的鸟类学家马克.霍伯说。

Hauber studies a behavior known as brood parasitism, in which birds lay eggs in the nests of other species, leaving the unwitting foster parents to rear their chicks.

霍伯研究的是一种叫做寄生孵育的行为，指的是鸟类在别的品种的鸟的巢里面产卵，让被愚弄的养父母帮它抚养幼雏。

Previously, researchers studied host birds’ reactions by placing plaster and wood models of parasitic eggs in their nests.

之前，研究者们研究宿主鸟的行为时是把石膏或者木质的寄生鸟蛋放在它们的巢里面。

But using 3D printing, Hauber’s team created far more realistic looking cowbird eggs, which allowed his team to examine whether variations of just a few millimeters in size influenced robins’ decisions to throw the parasitic eggs out of their nests.

不过利用3D打印，霍伯的团队制作出了更为栩栩如生的燕八哥的蛋，这样他们团队就可以研究大小上仅仅几毫米的变动是否会影响知更鸟将寄生蛋扔出巢穴的决定。

Using these new models also means people can easily replicate experiments, Hauber says.

利用这种新模型也意味着人们更容易重复实验了，霍伯说。

He has made the digital models of his eggs freely available online, so anyone can print off their own copy and reproduce the research.

他已经将他的鸟蛋的数字模型免费发布到网上，这样任何人都可以打印他们自己的副本并复制研究。

But the number of groups using 3D printing is still small.

然而采用3D打印的团队的数量还是很少的。

That may be because beginners are intimidated, says Jocelyn Behm, an ecologist at Temple University in Philadelphia, Pennsylvania, who studies how predators respond to invasive lizards.

这可能是因为刚开始的时候人们总有点畏惧，乔瑟琳.贝姆说，她是宾夕法尼亚州费城的天普大学的生态学家，研究的是捕食者会对外来入侵的蜥蜴作何反应。

Rather than bringing a live exotic species into an ecosystem, she is using 3D-printed models.

不用在生态系统里真的引入外来物种，她用的是3D打印模型。

To help other researchers, Behm posted last month about her own experiences in a preprint on bioRxiv that also reviews recent papers using the technique.

为了帮助其他的研究者，贝姆上个月将她自己的实验连同近期采用这项技术的论文的综述的预印本发表在了生物学术论文储存及发表平台bioRxiv上。

“I really thought 3D printing was difficult … but then once I got into it, I realized it’s not that hard,” she says.

“我本来以为3D打印很复杂...不过一旦开始以后，我发现也没有那么难，”她说。

The key to using the technique, says Bulté, is collaboration.

利用这项技术的关键，布尔特说，在于合作。

“If people don’t talk to each other, then [they] might think it’s less accessible than it really is.”

“假如人们之间不交流的话，那么他们就会认为这很难，其实不然。”

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