The evolution of modular colonial animals such as reef corals and bryozoans is enigmatic because of the ability for modules to proliferate asexually as whole colonies reproduce sexually. This reproductive duality creates an evolutionary tension between modules and colonies because selection operates at both levels. To understand how this evolutionary conflict is resolved, we compared the evolutionary potential of module- and colony-level traits in two species of the bryozoan Stylopoma, grown and bred in a common garden experiment. We find quantitatively distinct differences in the evolutionary potential of modular and colony traits. Contrary to solitary organisms, individual traits are not heritable from mother to daughter modules, but colony traits are strongly heritable from parent to offspring colonies. Colony-level evolution therefore dominates because no evolutionary change can accumulate among its modules.

中文翻译：

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殖民地动物如何进化。

模块化珊瑚动物如礁珊瑚和苔藓动物的进化是难以捉摸的，因为随着整个殖民地有性繁殖，模块能够无性繁殖。由于选择在两个层面上都起作用，因此这种生殖二元性在模块和菌落之间产生了进化张力。为了了解这种进化冲突是如何解决的，我们比较了在常见的花园实验中生长和繁殖的两种苔藓苔藓植物茎突肉瘤的模块级和菌落级性状的进化潜力。我们发现在模块化和殖民地性状的进化潜力的数量上明显不同。与孤立生物相反，个体特征不能从母体遗传到子体遗传，但是菌落性状在母体到子代菌落中都是很强的遗传力。