成年雌性虎鲸可能引发它们母亲进入绝经期
Competition between older female orcas and their adult daughters when they can breed simultaneously may cause matriarch to enter menopause.
在年长雌性虎鲸和她们的成年雌性后代之间，当它们同时繁殖时产生的竞争可能导致年长母亲进入绝经期。
撰文/播音：卡伦·霍普金（Karen Hopkin）
翻译：郭鑫鹏
审校：丁可含
Menopause marks the end of a female’s babymaking era. And not just for humans. Female killer whales go through menopause, too. And a new study finds that they might get pushed into menopause by their up-and-coming daughters. Those findings are floated in the journal Current Biology. [Darren P. Croft et al., Reproductive Conflict and the Evolution of Menopause in Killer Whales]
绝经期标志着雌性生育期的完结。不仅仅是人类，雌性虎鲸也有绝经期。一项新的研究表明它们会因为它们充满精力的后代而被迫进入绝经期。这些发现发表在期刊《当代生物学》上。
Female orcas usually quit popping out calves between the ages of 30 and 40. Yet they can live to be more than 90 years old. One granny orca, who recently dropped from researchers’ radar and is (sadly) presumed to have passed, was thought to be 105.
雌性虎鲸通常在30到40岁间停止生育。但它们可以活到超过90岁。一个老年虎鲸最近在研究者们的观测中消失了，它被推测在105岁时死亡。
But why would a female whale stick around for so long after she’s done adding to the gene pool? One theory is that it pays to keep nanna around so she can help care for the younger members of her family group. Indeed, matriarchal orcas do spend a lot of time nurturing their descendants.
但是为什么一个雌性鲸鱼在它停止生育后还会存活这么长时间？一个理论指出它们存活是为了继续以监护人的身份帮助照顾家族中的年轻后代。的确如此，年长雌性虎鲸花费了大量时间养育它们的后代。
But that doesn’t explain why the old gals should stop having babies of their own. To dive deeper into that issue, researchers examined 43 years’ worth of demographic data on two populations of killer whales in the Pacific Northwest. The records tracked the ages and genealogical relationships of the resident orcas, including 525 calves.
但是这并不能解释为什么那些年长雌性虎鲸会停止生育。为了深入研究这个问题，研究者们检查了太平洋西北部两个虎鲸群体43年的数量统计数据，记录了这些虎鲸及其525个子女的年龄和家系关系。
Turns out that when mothers and daughters breed at the same time, the calves of the elder females-for reasons yet unclear-are almost twice as likely to die by the age of 15 than those of the younger moms. Which the researchers say could account for why the grande dames ultimately give up on reproduction and coast through their golden years doting on the gargantuan grandkids.
结果指出，当母亲和女儿同时进入生育期时，年长雌性的后代——因为一些未知的原因——比起年轻雌性虎鲸的后代，在15岁前死亡的可能性是两倍。研究者们指出这可以解释为什么这些年长雌性虎鲸放弃它们生育，而在它们的黄金年龄溺爱它们体型庞大的孙子。
-Karen Hopkin
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京ICP备11000850号-1
京公网安备11010502039775号 信息网络传播视听节目许可证0111611号
国家科技基础条件平台