Abstract

The repeatability of findings is the key factor behind scientific reliability, and the failure to reproduce scientific findings has been termed the ‘replication crisis’. Geometric morphometrics is an established tool in evolutionary biology. However, different operators (and/or different methods) could act as large sources of variation in the data obtained. Here, we investigated inter-operator error in geometric morphometric protocols on complex shapes of Liolaemus lizards, as well as measurement error in three taxa varying in their difficulty of digitalization. We also examined the potential for these protocols to discriminate among complex shapes in closely related species. We found a wide range of inter-operator error, contributing between 19.5% and 60% to the total variation. Moreover, measurement error increased with the complexity of the quantified shape. All protocols were able to discriminate between species, but the use of more landmarks did not imply better performance. We present evidence that complex shapes reduce repeatability, highlighting the need to explore different sources of variation that could lead to such low repeatability. Lastly, we suggest some recommendations to improve the repeatability and reliability of geometric morphometrics results.

中文翻译：

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在复杂形状上使用几何形态计量学时，测试可重复性，测量误差和物种分化：以Liolaemus属的巴塔哥尼亚蜥蜴为例（鳞片：Liolaemini）

摘要

研究结果的可重复性是科学可靠性背后的关键因素，无法复制科学发现被称为“复制危机”。几何形态计量学是进化生物学中已建立的工具。但是，不同的运算符（和/或不同的方法）可以充当获得的数据中大量变化的来源。在这里，我们研究了Li鱼复杂形状的几何形态计量协议中的操作员间错误蜥蜴，以及三个分类单元的测量误差，其数字化难度各不相同。我们还检查了这些协议在区分密切相关物种的复杂形状中的潜力。我们发现操作员之间的误差范围很广，占总差异的19.5％至60％。而且，测量误差随着量化形状的复杂性而增加。所有协议都能够区分物种，但是使用更多地标并不意味着性能会更好。我们提供的证据表明，复杂的形状会降低可重复性，强调需要探索可能导致如此低的可重复性的不同变化来源。最后，我们提出一些建议，以提高几何形态计量学结果的可重复性和可靠性。