Controlling for body size leads to inferential biases in the biological sciences

Abstract 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...

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Main Authors: Björn Rogell, Damian K. Dowling, Arild Husby
Format: Article
Language:English
Published: Oxford University Press 2020-02-01
Series:Evolution Letters
Subjects:
Online Access:https://doi.org/10.1002/evl3.151
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author Björn Rogell
Damian K. Dowling
Arild Husby
author_facet Björn Rogell
Damian K. Dowling
Arild Husby
author_sort Björn Rogell
collection DOAJ
description Abstract 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.
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spelling doaj.art-d17137fef61e4a628c3b7c6187cd18552023-09-02T08:48:47ZengOxford University PressEvolution Letters2056-37442020-02-0141738210.1002/evl3.151Controlling for body size leads to inferential biases in the biological sciencesBjörn Rogell0Damian K. Dowling1Arild Husby2Department of Zoology Stockholm University Svante Arrhenius väg 18 Stockholm SwedenSchool of Biological Sciences Monash University Clayton Victoria 3800 AustraliaCentre for Biodiversity Dynamics Norwegian University of Science and Technology 7491 Trondheim NorwayAbstract 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.https://doi.org/10.1002/evl3.151Allometrybrain sizecollinearitycomparative methodssexual dimorphism
spellingShingle Björn Rogell
Damian K. Dowling
Arild Husby
Controlling for body size leads to inferential biases in the biological sciences
Evolution Letters
Allometry
brain size
collinearity
comparative methods
sexual dimorphism
title Controlling for body size leads to inferential biases in the biological sciences
title_full Controlling for body size leads to inferential biases in the biological sciences
title_fullStr Controlling for body size leads to inferential biases in the biological sciences
title_full_unstemmed Controlling for body size leads to inferential biases in the biological sciences
title_short Controlling for body size leads to inferential biases in the biological sciences
title_sort controlling for body size leads to inferential biases in the biological sciences
topic Allometry
brain size
collinearity
comparative methods
sexual dimorphism
url https://doi.org/10.1002/evl3.151
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