Trends in the sand: Directional evolution in the shell shape of recessing scallops (Bivalvia: Pectinidae)
Trends in the sand: Directional evolution in the shell shape of recessing scallops (Bivalvia: Pectinidae)
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沙子中的趋势：凹陷扇贝壳形状的定向演化（双壳纲：扇贝科）
DOI：
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
D. Adams
中科院分区：
文献类型：
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作者：
E. Sherratt;Alvin Alejandrino;Andrew C. Kraemer;J. Serb;D. Adams
定向进化是宏观进化中最引人注目的进化模式之一。然而，尽管其重要性，检测多变量数据中的这种趋势仍然是一个挑战。本研究采用几何形态计量学和系统发育比较的方法，对93种双壳扇贝壳形的多元进化进行了评价。Phylomorphospace可视化描述了该组形态多样化的历史，揭示了具有凹陷生活习性的类群在壳形上是最具特色的，并且似乎显示出方向性趋势。为了评估这一假设的经验，我们扩展了现有的方法，通过表征的平均方向演变的系统形态空间的凹进扇贝。然后，我们将这种模式与使用系统发育模拟的几种替代进化情景下的预期进行了比较。观察到的模式并不属于多变量布朗运动下获得的分布，使我们能够拒绝这种进化的情况。相比之下，观察到的模式更类似于，并落在，从模拟使用布朗运动结合方向趋势得到的分布。因此，所观察到的数据是一致的方向性进化的模式，这个谱系的凹进扇贝。我们讨论了这一假定的方向性进化趋势，在利用新的栖息地的潜在适应作用。
Directional evolution is one of the most compelling evolutionary patterns observed in macroevolution. Yet, despite its importance, detecting such trends in multivariate data remains a challenge. In this study, we evaluate multivariate evolution of shell shape in 93 bivalved scallop species, combining geometric morphometrics and phylogenetic comparative methods. Phylomorphospace visualization described the history of morphological diversification in the group; revealing that taxa with a recessing life habit were the most distinctive in shell shape, and appeared to display a directional trend. To evaluate this hypothesis empirically, we extended existing methods by characterizing the mean directional evolution in phylomorphospace for recessing scallops. We then compared this pattern to what was expected under several alternative evolutionary scenarios using phylogenetic simulations. The observed pattern did not fall within the distribution obtained under multivariate Brownian motion, enabling us to reject this evolutionary scenario. By contrast, the observed pattern was more similar to, and fell within, the distribution obtained from simulations using Brownian motion combined with a directional trend. Thus, the observed data are consistent with a pattern of directional evolution for this lineage of recessing scallops. We discuss this putative directional evolutionary trend in terms of its potential adaptive role in exploiting novel habitats.