Data from: The identification of concerted convergence in insect heads corroborates Palaeoptera

The relationships of the three major clades of winged insects - Ephemeroptera, Odonata and Neoptera - are still unclear. Many morphologists favor a clade Metapterygota (Odonata+Neoptera), but Chiastomyaria (Ephemeroptera+Neoptera) or Palaeoptera (Ephemeroptera+Odonata) have also been supported in some older and more recent studies.

A possible explanation for the difficulties in resolving these relationships is concerted convergence - the convergent evolution of entire character complexes under the same or similar selective pressures.

In this study we analyse possible instances of this phenomenon in the context of head structures of Ephemeroptera, Odonata and Neoptera. We apply a recently introduced formal approach to detect the occurrence of concerted convergence.

We found that characters of the tentorium and mandibles in particular, but also some other head structures, have apparently not evolved independently, and thus can cause artefacts in tree reconstruction. Our subsequent analyses, which exclude character sets that may be affected by concerted convergence, corroborate the Palaeoptera concept. We show that the analysis of homoplasy and its influence on tree inference can be formally improved with important consequences for the identification of incompatibilities between datasets. Our results suggest that modified weighting (or exclusion of characters) in cases of formally identified correlated cliques of characters may improve morphology based tree reconstruction.

有翅昆虫三大主要支系——蜉蝣目（Ephemeroptera）、蜻蜓目（Odonata）与新翅下纲（Neoptera）——之间的系统发育关系至今仍未明确。诸多形态学家支持将蜻蜓目与新翅下纲合并为后有翅类（Metapterygota）的支系假说，但在部分早期及近期研究中，也有学者分别支持交叉有翅类（Chiastomyaria，即蜉蝣目与新翅下纲合并）或古翅类（Palaeoptera，即蜉蝣目与蜻蜓目合并）的假说。

此类系统发育关系难以厘清的潜在解释之一是协同趋同演化：即在相同或相似选择压力下，整套性状复合体发生趋同演化。

本研究针对蜉蝣目、蜻蜓目及新翅下纲的头部结构，分析了这类演化现象的潜在案例。我们采用了新近提出的正式分析方法，以检测协同趋同演化的发生情况。

研究发现，尤其在幕骨（tentorium）与上颚（mandibles）的相关性状，以及部分其他头部结构中，演化过程并非独立进行，因此可能对系统发育树重建造成人为误差。后续分析中，我们剔除了可能受协同趋同演化影响的性状集合，结果支持古翅类（Palaeoptera）假说。本研究表明，对同塑性（homoplasy）及其对系统发育推断的影响进行分析，可通过正式方法加以优化，这对识别数据集间的不相容性具有重要意义。研究结果提示，在正式鉴定出的相关性状簇（correlated cliques of characters）案例中，采用调整性状加权（或剔除性状）的策略，可优化基于形态学数据的系统发育树重建工作。