Diversification and adaptive radiations are tied to evolvability, which in turn is linked to morphological integration. Tightly integrated structures typically evolve in unison, whereas loosely integrated structures evolve separately. Highly integrated structures are therefore thought to constrain evolutionary change by limiting morphological disparity. Mounting evidence suggests that high integration may facilitate evolutionary change along a single trajectory. We used geometric morphometrics to compare cranial disparity and integration among phyllostomid bats—which exhibit the greatest dietary diversity of any mammalian family— and their sister taxa within the superfamily Noctilionoidea. Our results reveal that phyllostomids are more tightly integrated and have less disparity in cranial shape than their outgroups, despite exhibiting tenfold higher species richness and significantly increased rates of speciation. Phyllostomid cranial morphology appears to have diverged from that of other noctilionoids by evolving along a single axis of morphological variation that describes the relative length of the rostrum. We propose that phyllostomids were able to evolve to occupy a wide range of dietary niches by varying rostrum length, possibly along a line of least evolutionary resistance. This study provides a compelling empirical example of how increased integration can lead to adaptation, implying that both high and low integration can underlie diverse phenotypes in adaptive radiation.

中文翻译：

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高度多样化哺乳动物进化枝中高度整合下的形态多样化

多样化和适应性辐射与可进化性有关，而后者又与形态整合有关。紧密集成的结构通常是一致演化的，而松散集成的结构则分别演化。因此，高度整合的结构被认为通过限制形态差异来限制进化变化。越来越多的证据表明，高度整合可能会促进沿着单一轨迹的进化变化。我们使用几何形态计量学来比较叶口蝠科蝙蝠（它们表现出任何哺乳动物家族中最大的饮食多样性）及其在夜蛾总科中的姊妹类群之间的颅骨差异和整合。我们的研究结果表明，与它们的外群相比，叶口动物的整合更紧密，颅骨形状差异更小，尽管物种丰富度高出十倍，物种形成率显着增加。通过沿着描述讲台相对长度的形态变化的单个轴进化，叶口类动物的颅骨形态似乎与其他夜蛾的颅骨形态不同。我们提出，叶口纲动物能够通过不同的讲台长度进化来占据广泛的饮食生态位，可能沿着一条进化阻力最小的线。这项研究提供了一个令人信服的经验例子，说明增加的整合如何导致适应，这意味着高整合和低整合都可以成为适应辐射不同表型的基础。通过沿着描述讲台相对长度的形态变化的单个轴进化，叶口类动物的颅骨形态似乎与其他夜蛾的颅骨形态不同。我们提出，叶口纲动物能够通过不同的讲台长度进化来占据广泛的饮食生态位，可能沿着一条进化阻力最小的线。这项研究提供了一个令人信服的经验例子，说明增加的整合如何导致适应，这意味着高整合和低整合都可以成为适应辐射不同表型的基础。通过沿着描述讲台相对长度的形态变化的单个轴进化，叶口类动物的颅骨形态似乎与其他夜蛾的颅骨形态不同。我们提出，叶口纲动物能够通过不同的讲台长度进化来占据广泛的饮食生态位，可能沿着一条进化阻力最小的线。这项研究提供了一个令人信服的经验例子，说明增加的整合如何导致适应，这意味着高整合和低整合都可以成为适应辐射不同表型的基础。