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科学美国人60秒: 它一生都在怀孕

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Swamp Wallaby Reproduction Give Tribbles a Run

它一生都在怀孕

Picture a small kangaroo. You're basically seeing something very much like the Australian marsupial called the swamp wallaby. They're also known as black stinkers because of their distinctive odor.

想象一只小袋鼠。基本上你看到的是一种很像澳大利亚有袋动物的东西,叫做沼泽小袋鼠。也被称为黑臭鼬,因为它们有独特的气味。

"I can't really describe it except to say it's quite a pungent smell. It's not terribly pleasant."

“我无法描述,只能说它有一种刺鼻的气味。不是很舒服。”

University of Melbourne biologist Marilyn Renfree, who says that their unique scent isn't the only thing that sets swamp wallabies apart from their evolutionary relatives. She and her colleagues recently discovered that adult female swamp wallabies can carry two pregnancies—in different stages of development—at the same time. That's possible because—like other kangaroos and wallabies—they have not just one uterus but two. But unlike their close relatives, pregnant swamp wallabies mate again a day or two before they give birth.

墨尔本大学的生物学家玛丽琳·任福瑞说,沼泽小袋鼠独特的气味并不是使它们与进化亲戚分开的唯一原因。她和同事们最近发现,成年雌性沼泽小袋鼠可以同时携带两个处于不同发育阶段的孕期。这是可能因为像其他袋鼠一样,它们不只有一个子宫,而是拥有两子宫个。但与近亲不同的是,怀孕的沼泽小袋鼠会在分娩前一两天再次交配。

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"We only know that strategy in one other mammal, and that's the European hare. And the European hare does this mating while they're pregnant—a phenomenon known as superfetation. So they"—the wallabies—"have effectively a fetus at an advanced stage of pregnancy and a very, very early conceptus at the same time."

“我们只在另一种哺乳动物身上知道这种策略,那就是欧洲野兔。欧洲野兔在怀孕期间会进行这种交配,这种现象被称为“超孕”。因此,“小袋鼠”实际上是在怀孕的晚期同时孕育出了一个非常早的胎儿。

Renfree and her team confirmed the simultaneous pregnancies using high-resolution ultrasound.

任福瑞和团队使用高分辨率超声波确认了同时怀孕的情况。

"And so, for the first time we were able to actually prove that the swamp wallaby is pregnant its whole life. It's never not pregnant."

“因此,我们第一次能够证明沼泽小袋鼠一生都在怀孕。而不是从不怀孕。”

This revolving cycle of pregnancy means that after a female swamp wallaby gives birth to her first baby from one uterus, a second embryo lies dormant in her other uterus, while the first baby attaches to a teat within her pouch. After nine months, the first baby leaves the pouch, triggering the second embryo to start developing. And right before the second baby is born, the mother mates again, and a third embryo is implanted back in the first uterus.

这种怀孕循环意味着雌性沼泽小袋鼠在一个子宫里生下第一个宝宝后,第二个胚胎在另一个子宫里休眠,而第一个宝宝则附着在她育儿袋里的乳头上。九个月后,第一个婴儿离开育儿袋,促使第二个胚胎开始发育。在第二个孩子出生之前,母亲再次交配,第三个胚胎被植入第一个子宫。

What's more, while the second baby lives inside the mother's pouch, the first baby hops around outside, continuing to suckle from a teat in her pouch. But she's able to supply each of them with milk tailored to their specific developmental needs.

更重要的是,当第二个婴儿生活在母亲的育儿袋里时,第一个婴儿在外面跳来跳去,继续吮吸育儿袋里的乳头。但母体可以为每只幼崽提供适合特殊发育需要的奶。

"The little baby is drinking a milk of a totally different composition."

“这个小婴儿正在喝一种成分完全不同的奶。”

And once this second baby leaves the pouch, the third embryo starts to develop, and the cycle continues.

一旦第二个婴儿离开育儿袋,第三个胚胎开始发育,这个循环就会继续。

"So the swamp wallaby has it all. It has a continuous pregnancy and a continuous lactation for most of its life. Truly amazing animal."

“所以沼泽小袋鼠一直都在怀孕。它一生中大部分时间都在持续怀孕和哺乳,是真正神奇的动物。”

The study is in the Proceedings of the National Academy of Sciences. Whatever evolutionary benefit exists to the swamp wallaby's unusual reproductive strategy remains to be seen. After all, being pregnant all the time isn't exactly a hop in the park.

这项研究发表在《美国国家科学院院刊》上。沼泽小袋鼠不同寻常的繁殖策略在进化上有什么好处还有待观察。毕竟,一直怀孕并不是件容易的事。

Swamp Wallaby Reproduction Give Tribbles a Run

Picture a small kangaroo. You're basically seeing something very much like the Australian marsupial called the swamp wallaby. They're also known as black stinkers because of their distinctive odor.

"I can't really describe it except to say it's quite a pungent smell. It's not terribly pleasant."

University of Melbourne biologist Marilyn Renfree, who says that their unique scent isn't the only thing that sets swamp wallabies apart from their evolutionary relatives. She and her colleagues recently discovered that adult female swamp wallabies can carry two pregnancies—in different stages of development—at the same time. That's possible because—like other kangaroos and wallabies—they have not just one uterus but two. But unlike their close relatives, pregnant swamp wallabies mate again a day or two before they give birth.

"We only know that strategy in one other mammal, and that's the European hare. And the European hare does this mating while they're pregnant—a phenomenon known as superfetation. So they"—the wallabies—"have effectively a fetus at an advanced stage of pregnancy and a very, very early conceptus at the same time."

Renfree and her team confirmed the simultaneous pregnancies using high-resolution ultrasound.

"And so, for the first time we were able to actually prove that the swamp wallaby is pregnant its whole life. It's never not pregnant."

This revolving cycle of pregnancy means that after a female swamp wallaby gives birth to her first baby from one uterus, a second embryo lies dormant in her other uterus, while the first baby attaches to a teat within her pouch. After nine months, the first baby leaves the pouch, triggering the second embryo to start developing. And right before the second baby is born, the mother mates again, and a third embryo is implanted back in the first uterus.

What's more, while the second baby lives inside the mother's pouch, the first baby hops around outside, continuing to suckle from a teat in her pouch. But she's able to supply each of them with milk tailored to their specific developmental needs.

"The little baby is drinking a milk of a totally different composition."

And once this second baby leaves the pouch, the third embryo starts to develop, and the cycle continues.

"So the swamp wallaby has it all. It has a continuous pregnancy and a continuous lactation for most of its life. Truly amazing animal."

The study is in the Proceedings of the National Academy of Sciences. Whatever evolutionary benefit exists to the swamp wallaby's unusual reproductive strategy remains to be seen. After all, being pregnant all the time isn't exactly a hop in the park.


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