Rogell Björn, Dowling Damian K, Husby Arild
Department of Zoology Stockholm University Svante Arrhenius väg 18 Stockholm Sweden.
Department of Aquatic Resources, Institute of Freshwater Research Swedish University of Agricultural Sciences Drottningholm 17893 Sweden.
Evol Lett. 2019 Dec 19;4(1):73-82. doi: 10.1002/evl3.151. eCollection 2020 Feb.
Many traits correlate with body size. Studies that seek to uncover the ecological factors that drive evolutionary responses in traits typically examine these responses relative to associated changes in body size using multiple regression analysis. However, it is not well appreciated that in the presence of strongly correlated variables, the partial (i.e., relative) regression coefficients often change sign compared to the original coefficients. Such sign reversals are difficult to interpret in a biologically meaningful way, and could lead to erroneous evolutionary inferences if the true mechanism underlying the sign reversal differed from the proposed mechanism. Here, we use simulations to demonstrate that sign reversal occurs over a wide range of parameter values common in the biological sciences. Further, as a case-in-point, we review the literature on brain size evolution; a field that explores how ecological traits relate to the evolution of relative brain size (brain size relative to body size). We find that most studies show sign reversals and thus that the inferences of many studies in this field may be inconclusive. Finally, we propose some approaches to mitigating this issue.
许多性状与体型相关。旨在揭示驱动性状进化响应的生态因素的研究通常使用多元回归分析，相对于体型的相关变化来检验这些响应。然而，人们并未充分认识到，在存在强相关变量的情况下，偏回归系数（即相对回归系数）往往与原始系数相比会改变符号。这种符号反转很难从生物学意义上进行解释，如果符号反转背后的真正机制与所提出的机制不同，可能会导致错误的进化推断。在这里，我们通过模拟证明，符号反转发生在生物科学中常见的广泛参数值范围内。此外，作为一个实例，我们回顾了关于脑容量进化的文献；该领域探讨了生态性状如何与相对脑容量（脑容量相对于体型）的进化相关。我们发现大多数研究都显示出符号反转，因此该领域许多研究的推断可能是不确定的。最后，我们提出了一些缓解这个问题的方法。
