内容来源：https://www.quantamagazine.org/genome-duplication-is-a-radical-evolutionary-gamble-20260902/

内容总结：

基因组加倍：一场激进的进化豪赌

在科学家眼中，生物体继承三套、四套甚至更多染色体（而非通常的两套）的现象被称为“多倍体”。对大多数物种而言，这往往是细胞分裂中的致命错误，仅有极少数全基因组加倍事件能在物种谱系中稳定下来。但一旦成功，其影响深远，堪比重棒球员的“本垒打”——尽管挥空次数多，但击中的那一刻足以改变全局。

长期以来，多倍体现象因测序技术限制而鲜为人知。随着全基因组测序的进步，科学家发现基因组加倍并非罕见事件：所有现存种子植物都经历过至少一次古老的基因组加倍，藤壶、昆虫、鳟鱼、蛛形纲动物乃至从盲鳗到人类的颌类脊椎动物，其基因组中都留有古老加倍事件的痕迹。

马里兰大学进化生物学家穆琳·尼曼研究的纽西兰亚历山大湖淡水螺，其基因组在不到一百万年前（进化尺度上极为“新近”）发生过加倍，携带三套或四套染色体。尼曼团队发现，这些螺已丢弃60%的多余基因拷贝，这一过程为观察多倍体如何“善后”提供了绝佳窗口。

基因组加倍是生物体在一代之内所能经历的最剧烈突变。细胞需要扩增细胞核、合成更多蛋白质，同时面临基因冗余的“筛选”——部分基因被保留、被修改、被关闭或被丢弃。环境剧变（如6600万年前的陨石撞击）似乎为多倍体存活提供了条件，因为剧烈的环境压力需要基因组“跳跃式进化”来应对。

然而，多倍体也是一场高风险赌博。大多数加倍基因组无法稳定，会逐渐丢失冗余基因，最终回到精简的二倍体状态。酵母研究中，额外的基因拷贝甚至削弱了生物对药物的适应能力。多倍体究竟是进化“死胡同”还是创新源泉，科学界仍在激烈争论。淡水螺的基因组记录着这场赌博的中间状态——它已挺过最初的冲击，正在为多出的遗传物质付出代价，也等待进化时间给出最终答案。

中文翻译：

基因组复制是一场激进的进化豪赌

艾达·泽君·沈为《Quanta Magazine》撰稿

波塔莫格里普斯螺（Potamopyrgus antipodarum）的体型不比火柴头大，看上去毫不起眼。到访新西兰亚历山德里娜湖的游客中，很少有人会注意到散落在湖岸上的这些微小腹足类动物。然而，这种螺的微小体型掩盖了一个巨大的秘密。在不久前的某个时刻，它的基因组发生了翻倍。与大多数动物拥有两套染色体、每个基因两个拷贝不同，它有三套或四套——遗传物质远超其应有之量。

“对于我们的螺或其他任何物种，我们实际上并不知道为什么这种现象会如此可靠地一而再、再而三地发生，”研究该物种的爱荷华大学进化生物学家莫琳·奈曼说道。

科学家推测，一个生物体继承三套、四套甚至更多染色体而非两套（这一状况称为多倍体），在大多数情况下是细胞分裂的致命错误。据认为，在所有全基因组复制事件中，只有极小一部分能在某个谱系中稳定下来。但那些成功稳定的复制事件可能产生重大影响。

巴特·泽尔斯特拉

“我们喜欢把它比作一个经常三振出局的棒球击球手，但一旦击中，就是全垒打，”佛罗里达自然史博物馆的植物进化遗传学家道格拉斯·索尔蒂斯说。“多倍体是这个星球上最重要却几乎无人了解的过程。”

全基因组测序的进步正在改变这一现状。横跨生命之树的研究发现，基因组复制并非罕见事件。在植物中，这几乎无法避免，爱荷华州立大学的进化生物学家乔纳森·温德尔说：今天现存的所有种子植物都至少经历过一次古老的全基因组复制，许多植物经历的次数更多。藤壶、昆虫、鳟鱼和蛛形纲动物的基因组中都带有古老复制事件的证据。生物学家们激烈争论，从盲鳗到人类的有颌脊椎动物所经历的重大进化变革，是否与数亿年前的古老基因复制事件存在关联。

如同基因倒位、易位或单核苷酸点突变一样，全基因组复制是一种推动进化变革的基因突变类型。事实上，基因组翻倍是一个生物体在一代之内所能经历的最激进的突变。研究人员正在分析不同物种的全基因组，以弄清生物体如何不仅能在这种潜在致命事件中存活下来，还能在此之后茁壮成长并适应环境。“所有这些不同的探究工具为我们打开了一个我们看不见、因此也不知道其存在的世界，”温德尔说。

这一过程如何展开的故事，正被书写在波塔莫螺的基因组中。奈曼的团队将该螺的基因组复制时间确定为不到一百万年前——在进化尺度上极为近期，但时间又长到足以让该物种开始适应其更沉重基因组负荷的漫长过程。这种近时性让奈曼得以近距离观察波塔莫螺是如何应对其多倍体生存的。

这是人们对多倍体认识不断深入过程中的最新证据，正改变着科学界对基因组复制进化重要性的理解。亚历山德里娜湖宁静的湖岸与拉斯维加斯大道相隔天涯，但这并未阻止波塔莫螺进行进化史上最大的一场豪赌。

遗传备份

在大规模DNA测序出现之前，多倍体在很大程度上仍然笼罩在神秘之中。科学家知道这种现象确实存在：任何习惯于在显微镜下数染色体的人都一目了然。但直到研究人员能够逐碱基对分析基因组时，他们才开始认识到全基因组复制的全部意义。

都柏林大学学院的进化生物学家肯尼斯·沃尔夫正是通过分析碱基对而对多倍体产生兴趣的。20世纪90年代初他建立自己的实验室时，利用了一项欧盟倡议——该倡议为每测序一个核苷酸向科学家支付2欧元，用于测序面包酵母（Saccharomyces cerevisiae）的基因组。（2022年，测序成本大约为每核苷酸0.000000006美元。）沃尔夫对酵母本身并不特别感兴趣，但他的实验室需要这笔经费。后来，当他与其他参加酵母基因组测序项目的研究人员开始共享结果时，他们注意到了一些有趣的现象。

“这些基因组中似乎有大量重复基因，”他回忆道。随着基因组计划接近完成，沃尔夫和他的团队发现酵母DNA中充满了重复区域。重复片段的同一性约为60%，而紧密相关的DNA区域之间隔着长得多的独特基因片段。“你真的可以看到过去发生了什么，”他说。“你可以追踪每个基因，看看它经历了什么。”

沃尔夫怀疑自己看到的是过去一次基因组复制事件的证据，同时也有迹象表明细胞正在修剪多余的DNA。沃尔夫1997年发表在《自然》杂志上关于这一主题的论文，帮助人们将越来越多的注意力转向多倍体及其逆过程——再二倍体化，即生物体保留部分翻倍基因、丢弃其余基因，最终使基因组恢复到精简的二倍体状态。

随着其他模式生物的完整基因组序列陆续问世，沃尔夫利用他的生物信息学专业知识在这些基因组中寻找复制迹象。秀丽隐杆线虫没有多倍体现象。果蝇也没有。沃尔夫暗自思忖，也许他在酵母中看到的现象只是偶然。随后在2000年，模式植物拟南芥的基因组发表了。

“那里有一个基因组复制事件在向我们大声呼喊，”他说。“而且不只是我的实验室——好几个实验室都发现了这个基因组复制事件。”

过去的生物学家曾就基因翻倍的进化益处提出过理论。1970年，日裔美国遗传学家大野乾发表了《基因复制驱动的进化》一书，提出单个基因的复制是一种被低估的进化创新来源。一次复制事件本身就可能导致新性状的产生。此外，有了每个基因的两个拷贝，进化可以修改其中一个版本，同时保留另一个作为备份；新功能可以在不失去基因原有用途的情况下出现。如果整个基因组翻倍，情况可能同样如此。在他的专著中，大野乾假设所有脊椎动物基因组中都含有古老基因组复制事件的证据。随后的基因组测序证实了这一点。

“你可能认为基因组——生命的蓝图——是稳定的东西，”不列颠哥伦比亚大学的进化生物学家莎拉·奥托说。“其实不然。它五花八门、变幻莫测。”

研究多倍体的生物学家面临的挑战在于，突然基因组翻倍带来的细胞冲击往往是致命的。即使存活下来的后代通常也不育，无法传递额外的DNA。要弄清多倍体事件如何能够存活下来，他们需要植物生物学家的帮助——后者有无数机会观察这一过程的发生。

激进变革

几十年前，在华盛顿州东部的干燥草原上，帕梅拉·索尔蒂斯和道格拉斯·索尔蒂斯开始追踪一次多倍体事件。他们几乎确切知道它发生的时间：20世纪20年代中期，几种名为“山羊胡”的植物从欧洲被引入美国。它们杂交后，不久便出现了两个新物种，拥有24条染色体——是原始物种的两倍。通过从种子培育这些植物并研究它们的基因组，索尔蒂斯夫妇可以看到基因组复制后细胞立即发生的变化。

他们发现的是混乱。几乎在山羊胡获得额外DNA的同时，这些植物就开始摆弄它们多余的基因——改变一些基因，丢弃另一些，保留少数几个，道格拉斯·索尔蒂斯说。“几乎立刻，在一代之內，它们就开始丢弃某些基因拷贝，某些基因的表达量不及其他基因。”

克尔斯滕·格蕾丝

数十亿年的进化已将许多真核细胞（包括植物和动物的细胞）优化为二倍体基因组——每个细胞携带每条染色体的两个拷贝（一个来自母亲，一个来自父亲）。当一个后代以翻倍基因组出生时，细胞会被所有这些额外的遗传物质所改变。

这是自然发生的最重大、最激进的突变，范德堡大学和康奈尔大学联合任命的进化生物学家凯尔·T·大卫说。“就像一代之内瞬间物种形成，”他说。

为了为如此多的额外DNA腾出空间，细胞核会变大。细胞从额外的基因序列中合成更多蛋白质。在某些情况下，合成这些蛋白质的过程似乎耗时更长。科学家不知道为什么某些物种似乎能很好地适应这些变化，而对其他物种来说，多倍体则是一条死胡同。

“很多时候会出问题，而且在许多不同物种中都会出问题，”奥托说。“据认为确实有多倍体人类产生，但他们会在早期自然流产。”

无论是人类还是山羊胡，细胞都会立即开始分诊处理。基因被保留、丢弃、关闭或修改。在数十年观察山羊胡在实验室中适应多倍体之后，索尔蒂斯夫妇甚至能预测哪些基因最可能被淘汰，哪些更可能留下来。

“令人惊叹的不仅是速度之快，而且这种过程是可重复的，”道格拉斯·索尔蒂斯说。“你可以看到进化在重复自己。”他推测基因组复制背后可能存在某些规律，尽管他承认他们仍在弄清楚这些规律究竟是什么。

大卫说，似乎能提高全基因组复制存活几率的因素是环境变化。而且不是微小的扰动：一些研究人员注意到一种模式——大规模灾难性事件，如6600万年前预示恐龙终结的小行星撞击，与基因组复制事件的密集发生大体同步。“面对剧烈的环境变化，你的基因组也需要类似的飞跃，”大卫说。“这增加了你获得那种极其罕见的重复基因家族组合的几率，这些家族能够获得新功能，并能在那些创伤性环境条件下发挥作用。”然而，一篇关于这一主题的2026年论文引发了争议；一份正式的驳斥文章声称该分析存在缺陷。

帕梅拉和道格拉斯·索尔蒂斯提供

随着研究人员开始在多倍体得以繁衍的罕见条件上取得进展，其他科学家则将注意力转向复制后的基因组如何适应突然冲击。

走向庞大

20世纪90年代末，奈曼作为本科生通过海外学习项目首次前往新西兰时，她万万没想到关于性进化的研究会最终把她带回去。亚历山德里娜湖是一座坐落于新西兰南岛崎岖山峰之间的高山湖泊，在湖岸边，大多数波塔莫格里普斯螺通过有性生殖繁衍——经典的精卵结合。然而，一些雌性通过克隆自身进行无性生殖。奈曼想知道为什么。

除了繁殖方式不同外，这两种螺几乎完全相同。奈曼推测它们之间一定存在某种遗传差异。当她的实验室开始拼凑30种不同有性生殖波塔莫螺物种的基因组时，他们偶然发现了一些奇怪的现象。他们测序的许多基因如预期那样有两个拷贝——一个来自母本，一个来自父本——但其他基因有三个，甚至有四个。

当几位博士生仔细梳理测序结果时，只有一个解释能说明为什么如此多的额外基因拷贝散落在波塔莫螺的整个基因组中。在最近约一百万年内的某个时刻，这种螺经历了一次全基因组复制。

“这些螺把自己的秘密藏在基因组里，”奈曼说。“没有人预料到这一点。”

她知道古老的多倍体事件。她也知道植物中更近期的例子。她发现的这个事件恰好处于科学上的“金发姑娘区”：足够近——螺还没有完成对其翻倍基因组的重组；又足够久远——这一过程已经进行得相当深入。

在相对短暂的进化时间里，这些螺已经丢失了60%的翻倍基因。“从一切翻倍的那一刻起，竞赛就开始了，因为突变无处不在，”温德尔说。“大量重复冗余的材料就这样被突变化并丢失。”奈曼于2025年11月在《基因组生物学与进化》杂志上发表了其团队的发现。

奈曼推测，多倍体与该螺不寻常的繁殖策略之间存在关联。无性生殖的雌性是三倍体或四倍体，这意味着它们每条染色体携带三到四个拷贝，而非通常的两个。她说，可能是雌性通过克隆繁殖更容易管理其额外DNA，而不是费力组织这些染色体来制造卵子。

波塔莫螺中的完全多倍体是短暂的，许多物种都是如此。代价高昂。大多数翻倍基因组从未稳定下来。那些稳定下来的则随着进化在冗余中筛选而开始脱落基因。“要么你找到新工作，要么你离开这个城市，”温德尔说。“大多数东西都在离开。”

翻倍基因组的长期不稳定性使一些研究人员质疑，多倍体在广泛进化意义上的重要性是否如其普遍性所暗示的那样大。例如，奥托的研究表明，在酵母中，每个基因都有额外拷贝会妨碍生物体适应常用抗真菌药物制霉菌素的能力。“大多数多倍体确实是死胡同，”她说。

波塔莫格里普斯螺正处在这种不稳定与创新之间的张力核心。这种螺在最初的冲击中幸存下来，现在正在应对写在其DNA中的这场豪赌的后果。只有进化时间才能告诉我们，它的谱系是否会大获全胜，利用其扩展的基因组找到一种新的生存方式。

英文来源：

Genome Duplication Is a Radical Evolutionary Gamble
Ada Zejun Shen for Quanta Magazine
No larger than the head of a match, Potamopyrgus antipodarum doesn’t look very impressive. Few people visiting New Zealand’s Lake Alexandrina even notice the tiny gastropods littering the shores. The snail’s diminutive size, however, conceals a massive secret. Sometime in the recent past, its genome doubled. Instead of having two sets of chromosomes and two copies of every gene, the way most animals do, it has three or four — significantly more genetic material than it ought to have.
“We actually don’t know, for our snails or any other species, why this happens so reliably, again and again and again,” said the evolutionary biologist Maurine Neiman, who studies the species at the University of Iowa.
Scientists suspect that an organism inheriting three, four, or more sets of chromosomes instead of two (a condition called polyploidy) is, in most cases, a fatal error of cell division. Only a tiny fraction of whole-genome duplication events are thought to stabilize in a lineage. But those that do can have significant consequences.
Bart Zijlstra
“We like to think of it as a baseball hitter that strikes out a lot, but when they do hit, it’s a home run,” said Douglas Soltis, a plant evolutionary geneticist at the Florida Museum of Natural History. “Polyploidy is the most important process on the planet that hardly anybody knows anything about.”
Advances in whole-genome sequencing are changing that. Studies across the tree of life are finding that genome duplication isn’t exactly an infrequent occurrence. Among plants, it’s hard to avoid, said Jonathan Wendel, an evolutionary biologist at Iowa State University: All seed plants living today have experienced at least one ancient whole-genome duplication, and many have undergone more. Barnacles, insects, trout, and arachnids carry evidence of ancient duplications in their genomes. Biologists hotly debate whether the significant evolutionary changes that led to jawed vertebrates, from hagfish to humans, are connected by ancient gene duplications hundreds of millions of years ago.
Like gene inversions and translocations or single-nucleotide point mutations, a whole-genome duplication is a type of genetic mutation that fuels evolutionary change. In fact, genome doubling is the single most radical mutation an organism can experience in a single generation. Researchers are analyzing the whole genomes of diverse species to find out how organisms manage not only to survive such a potentially lethal event, but also to thrive and adapt in its wake. “All these different interrogative tools have opened up this world to us that we could not see and hence did not know existed,” Wendel said.
A story of how this process unfolds is being written in potamo’s genome. Neiman’s team dated the snail’s genome duplication to less than a million years ago — incredibly recent in evolutionary terms, but long enough ago for the species to have begun the longer process of adjusting to its heavier genomic load. That recency is giving Neiman a close view of how potamo has managed its polyploid existence.
This is the latest evidence amid a growing awareness of polyploidy that is shifting science’s understanding of genome duplication’s evolutionary importance. The serene shores of Lake Alexandrina are about as far from the Las Vegas strip as you can get, but that didn’t stop potamos from taking one of evolution’s biggest gambles.
Genetic Backup
Until the advent of widespread DNA sequencing, polyploidy remained largely shrouded in mystery. Scientists knew that it happened: It was obvious to anyone in the habit of counting chromosomes under a microscope. But it wasn’t until researchers could analyze genomes, base pair by base pair, that they began to appreciate the full implications of whole-genome duplication.
Analyzing base pairs is how the evolutionary biologist Kenneth Wolfe at University College Dublin became interested in polyploidy. When he started his lab in the early 1990s, he took advantage of a European Union initiative that would pay scientists 2 euros per nucleotide to sequence the genome of baker’s yeast, Saccharomyces cerevisiae. (In 2022, sequencing cost roughly $0.000000006 per nucleotide in U.S. dollars.) Wolfe wasn’t especially interested in yeast, but his lab needed the money. Later, when he and other researchers with the Saccharomyces Genome Sequencing Project started sharing their results, they noticed something interesting.
“There just seemed to be an awful lot of duplicated genes in these genomes,” he recalled. As the genome project reached completion, Wolfe and his team found that yeast DNA was full of doubled regions. The duplicated segments were around 60% identical, and regions of closely related DNA were separated by far longer stretches of unique genes. “You could really see the history of what had happened,” he said. “You could track every gene and see what happened to it.”
Wolfe suspected that he was seeing evidence of a past genome duplication event alongside indications that the cells were in the process of pruning back excess DNA. Wolfe’s 1997 Nature paper on the subject helped turn increasing attention to both polyploidy and the inverse process, rediploidization, in which an organism retains some of its doubled genes and discards others, ultimately bringing the genome back to a streamlined diploid state.
As the complete genome sequences of other model organisms began trickling in, Wolfe used his bioinformatics expertise to look for genome duplications there. The roundworm Caenorhabditis elegans was devoid of polyploidy. So, too, was the fruit fly. Perhaps, Wolfe mused, what he saw in yeast was a fluke. Then, in 2000, the genome of the model plant Arabidopsis was published.
“There was a genome duplication in there screaming at us,” he said. “And it wasn’t just my lab — several labs discovered this genome duplication.”
Past biologists had theorized about the evolutionary benefit of doubled genes. In 1970, the Japanese American geneticist Susumu Ohno had published Evolution by Gene Duplication, which posited that the duplication of individual genes was an underappreciated source of evolutionary novelty. A doubling event on its own can result in novel traits. Plus, with two copies of each gene, evolution can tinker with one version while keeping the other as a backup; a new function could emerge without a gene losing its existing use. The same could potentially be true if the entire genome was doubled. In his treatise, Ohno hypothesized that all vertebrate genomes contained evidence of an ancient genome duplication event. Subsequent genome sequencing has shown this to be the case.
“You might think that the genome, the blueprint of life, would be a stable thing,” said Sarah Otto, an evolutionary biologist at the University of British Columbia. “It’s not. It’s all over the map.”
The challenge for biologists studying polyploidy was that the cellular shock of sudden genome doubling is often lethal. Even offspring that survive are usually sterile and have no way of passing on the extra DNA. To find out how a polyploidy event could be survivable, they would need input from plant biologists, who had myriad opportunities to watch it unfold.
Radical Change
Several decades ago, in the dry prairies of eastern Washington, Pamela Soltis and Douglas Soltis began tracking a polyploidy event. They knew almost exactly when it had happened: Several species of a plant known as goatsbeard were brought to the United States from Europe in the mid-1920s. They hybridized, and before long, two new species emerged with 24 chromosomes — twice as many as the original species. By growing the plants from seed and studying their genomes, the Soltises could see what happens to cells in the immediate aftermath of genome duplication.
What they found was chaos. Almost as soon as the goatsbeard acquired the extra DNA, the plants started to tinker with their surplus of genes — changing some genes, getting rid of others, keeping a few, Douglas Soltis said. “Immediately, in one generation, they’re already beginning to get rid of certain copies of genes [and] not expressing certain genes as much as other genes.”
Kristen Grace
Billions of years of evolution have optimized many eukaryotic cells, including those of plants and animals, for diploid genomes, where a cell carries two copies of each chromosome (one from the mother, one from the father). When an offspring is born with a duplicated genome, the cell is transformed by all the extra genetic material.
It’s the single biggest, most radical mutation that naturally occurs, according to the evolutionary biologist Kyle T. David, who has a joint appointment at Vanderbilt University and Cornell University. “It’s like instant speciation with one generation,” he said.
To create space for so much additional DNA, the nucleus enlarges. The cell synthesizes many more proteins from the additional gene sequences. And in some cases the process of synthesizing those proteins seems to take longer. Scientists don’t know why some species seem to adapt well to these changes, while for others polyploidy is a dead end.
“Things go wrong a lot of times, and it goes wrong in a lot of different species,” Otto said. “It is thought that there are polyploid humans produced, but they [spontaneously] abort early.”
Whether human or goatsbeard, the cell immediately begins performing triage. Genes are retained, tossed out, turned off, and modified. After their decades observing goatsbeard adapting to polyploidy in the lab, the Soltises can even predict which genes are most likely to get the boot and which are more likely to stick around.
“It’s amazing not only how fast it is, but that it’s repeatable,” Douglas Soltis said. “You can watch evolution repeat itself.” He speculates that there may be rules underlying genome doubling, though he admits they are still figuring out exactly what those rules might be.
What seems to stack the deck in favor of surviving whole-genome duplication, David said, is environmental shifts. And not small perturbations, either: Some researchers have noticed a pattern in which full-scale apocalyptic cataclysms, such as the asteroid collision that heralded the end of the dinosaurs 66 million years ago, occur around the same time as clusters of genome duplications. “With the severe environmental changes going on, you need a similar leap in your genome,” David said. “It just increases the chances that you’re going to get that really rare combination of duplicated gene families that can acquire new functions and can help under those traumatic environmental conditions.” However, a 2026 paper on the subject has proved controversial; a formal rebuttal claims that the analysis is flawed.
Courtesy of Pamela and Douglas Soltis
As researchers begin to make headway on understanding the rare conditions that allow polyploids to propagate, other scientists are turning their attention to how duplicated genomes adapt to the sudden shock.
Going Big
When Neiman first traveled to New Zealand as an undergraduate on a study abroad program in the late 1990s, she couldn’t have predicted that research on the evolution of sex would eventually bring her back. On the shores of Lake Alexandrina, an alpine lake nestled among the craggy peaks of New Zealand’s South Island, most Potamopyrgus antipodarum snails reproduce sexually — the classic egg-meets-sperm. Some females, however, reproduce asexually by making clones of themselves. Neiman wanted to know why.
Except for the way they reproduce, the two types of snails are almost identical. Neiman figured that there must be some genetic difference between them. When her lab began piecing together the genomes of 30 different sexually reproducing potamo species, they stumbled upon something odd. While many of the genes they sequenced had two copies, one maternal and one paternal, as expected, others had three, even four.
When several doctoral students combed through the sequencing results, there was only one way to explain why so many extra gene copies were scattered across the whole of the potamo genome. Sometime in the last million or so years, the snail had undergone a whole-genome duplication.
“The snails are hiding this secret in their genome,” Neiman said. “No one expected that.”
She knew about ancient polyploidy events. She also knew about more recent examples in plants. What she had found had occurred in a scientific Goldilocks zone: recent enough that the snail had yet to finish reorganizing its doubled genome, and long enough ago that the process was well underway.
In that relatively short amount of evolutionary time, the snails had already lost 60% of their doubled genes. “From the time everything’s doubled, the race is on, because mutation is happening everywhere,” Wendel said. “A lot of that duplicated, redundant material is just mutagenized [mutated] and lost.” Neiman published her team’s findings in November 2025 in Genome Biology and Evolution.
Neiman speculates that polyploidy and the snail’s unusual reproductive strategies are related. The females that reproduce asexually are triploid or tetraploid, meaning they carry three or four copies of every chromosome instead of the usual two. It could be that it’s easier for the females to manage their extra DNA by using clonal reproduction, she said, rather than trying to organize those chromosomes to make eggs.
Complete polyploidy in potamos is ephemeral, as it is in many species. It’s costly. Most duplicated genomes never stabilize. Those that do begin shedding genes as evolution sorts through the redundancy. “Either you get a new job, or you get out of town,” Wendel said. “Most things are getting out of town.”
The long-term instability of doubled genomes has led some researchers to question whether polyploidy is as important in broad evolutionary terms as its prevalence might suggest. For example, Otto’s research has shown that, in yeast, having extra copies of every gene hinders the organism’s ability to adapt to the common antifungal medication nystatin. “Most polyploids really are dead ends,” she said.
Potamopyrgus antipodarum sits at the heart of that tension between instability and innovation. The snail has survived the initial shock and is now negotiating the consequences of the gamble written into its DNA. Only evolutionary time will tell whether its lineage will win big and use its expanded genome to find a new way to live.