Domesticated animals display suites of altered morphological, behavioral, and physiological traits compared to their wild ancestors, a phenomenon known as the domestication syndrome (DS). Because these alterations are observed to co‐occur across a wide range of present day domesticates, the traits within the DS are assumed to covary within species and a single developmental mechanism has been hypothesized to cause the observed co‐occurrence. However, due to the lack of formal testing it is currently not well‐resolved if the traits within DS actually covary. Here, we test the hypothesis that the presence of the classic morphological domestication traits white pigmentation, floppy ears, and curly tails predict the strength of behavioral correlations in support of the DS in 78 dog breeds. Contrary to the expectations of covariation among DS traits, we found that morphological traits did not covary among themselves, nor did they predict the strength of behavioral correlations among dog breeds. Further, the number of morphological traits in a breed did not predict the strength of behavioral correlations. Our results thus contrast with the hypothesis that the DS arises due to a shared underlying mechanism, but more importantly, questions if the morphological traits embedded in the DS are actual domestication traits or postdomestication improvement traits. For dogs, it seems highly likely that strong selection for breed specific morphological traits only happened recently and in relation to breed formation. Present day dogs therefore have limited bearing of the initial selection pressures applied during domestication and we should reevaluate our expectations of the DS accordingly.

中文翻译：

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形态学与犬驯化综合征的预测行为相关性不强

与野生祖先相比，驯养的动物表现出不同的形态，行为和生理特征，这是一种被称为驯化综合症（DS）的现象。由于观察到这些变化在当今的许多家畜中同时发生，因此假设DS内的性状在种内共存，并假设单个发育机制导致了所观察到的同时发生。但是，由于缺乏正式的测试，因此，如果DS中的特征确实存在，目前尚无法很好地解决。在这里，我们测试了以下假设：78个犬种中，经典的形态驯化性状白色色素沉着，松软的耳朵和卷曲的尾巴的存在预示着行为相关性支持DS的强度。与DS性状之间的协变期望相反，我们发现形态特征在它们之间并没有变迁，也没有预测狗品种之间行为相关的强度。此外，一个品种的形态特征数量不能预测行为相关性的强度。因此，我们的结果与假设DS是由于共同的潜在机制而产生的假设形成对比，但更重要的是，质疑DS中嵌入的形态特征是实际的驯化性还是驯化后的改良性。对于狗来说，对品种特定形态特征的强烈选择似乎只是在最近才发生的，并且与品种的形成有关。因此，当今的犬只对驯化过程中施加的初始选择压力的承受力有限，因此我们应重新评估我们对DS的期望。