Overcoming problems with the use of ratios as continuous characters for phylogenetic analyses

The use of quantitative morphometric information for phylogenetic inference has been an intensely debated topic for most of the history of phylogenetic systematics. Despite several drawbacks, the most common strategy to include this sort of data into phylogenetic studies is the use of ratios, that i...

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Autores principales:	Soto, Ignacio M., Ramírez, Martín Javier
Publicado:	2015
Acceso en línea:	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_03003256_v44_n5_p463_MongiardinoKoch http://hdl.handle.net/20.500.12110/paper_03003256_v44_n5_p463_MongiardinoKoch
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

id	paper:paper_03003256_v44_n5_p463_MongiardinoKoch
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spelling	paper:paper_03003256_v44_n5_p463_MongiardinoKoch2025-07-30T18:05:04Z Overcoming problems with the use of ratios as continuous characters for phylogenetic analyses Soto, Ignacio M. Ramírez, Martín Javier The use of quantitative morphometric information for phylogenetic inference has been an intensely debated topic for most of the history of phylogenetic systematics. Despite several drawbacks, the most common strategy to include this sort of data into phylogenetic studies is the use of ratios, that is quotients between morphometric variables. Here, we discuss one particular problem associated with such methodology: the fact that the often arbitrary election of which variable serves as numerator and which as denominator affects the phylogenetic outcome of the analysis. We describe the cause for such an effect, and study its implications with the use of several published data matrices. Alternative coding schemes for ratio characters result in very different phylogenetic hypotheses, an effect that may even be strong enough to affect studies that combine continuous and discrete morphological information. Some of the resulting incongruence is produced by the differences in magnitude of the continuous characters involved, although different rescaling techniques are shown to decrease, but not eliminate, the confounding effect. To eliminate such problematic effect, ratios should be either log-transformed before their use or replaced by more effective ways to capture morphometric information. © 2015 Royal Swedish Academy of Sciences. Fil:Soto, I.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Ramírez, M.J. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2015 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_03003256_v44_n5_p463_MongiardinoKoch http://hdl.handle.net/20.500.12110/paper_03003256_v44_n5_p463_MongiardinoKoch
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
description	The use of quantitative morphometric information for phylogenetic inference has been an intensely debated topic for most of the history of phylogenetic systematics. Despite several drawbacks, the most common strategy to include this sort of data into phylogenetic studies is the use of ratios, that is quotients between morphometric variables. Here, we discuss one particular problem associated with such methodology: the fact that the often arbitrary election of which variable serves as numerator and which as denominator affects the phylogenetic outcome of the analysis. We describe the cause for such an effect, and study its implications with the use of several published data matrices. Alternative coding schemes for ratio characters result in very different phylogenetic hypotheses, an effect that may even be strong enough to affect studies that combine continuous and discrete morphological information. Some of the resulting incongruence is produced by the differences in magnitude of the continuous characters involved, although different rescaling techniques are shown to decrease, but not eliminate, the confounding effect. To eliminate such problematic effect, ratios should be either log-transformed before their use or replaced by more effective ways to capture morphometric information. © 2015 Royal Swedish Academy of Sciences.
author	Soto, Ignacio M. Ramírez, Martín Javier
spellingShingle	Soto, Ignacio M. Ramírez, Martín Javier Overcoming problems with the use of ratios as continuous characters for phylogenetic analyses
author_facet	Soto, Ignacio M. Ramírez, Martín Javier
author_sort	Soto, Ignacio M.
title	Overcoming problems with the use of ratios as continuous characters for phylogenetic analyses
title_short	Overcoming problems with the use of ratios as continuous characters for phylogenetic analyses
title_full	Overcoming problems with the use of ratios as continuous characters for phylogenetic analyses
title_fullStr	Overcoming problems with the use of ratios as continuous characters for phylogenetic analyses
title_full_unstemmed	Overcoming problems with the use of ratios as continuous characters for phylogenetic analyses
title_sort	overcoming problems with the use of ratios as continuous characters for phylogenetic analyses
publishDate	2015
url	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_03003256_v44_n5_p463_MongiardinoKoch http://hdl.handle.net/20.500.12110/paper_03003256_v44_n5_p463_MongiardinoKoch
work_keys_str_mv	AT sotoignaciom overcomingproblemswiththeuseofratiosascontinuouscharactersforphylogeneticanalyses AT ramirezmartinjavier overcomingproblemswiththeuseofratiosascontinuouscharactersforphylogeneticanalyses
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Overcoming problems with the use of ratios as continuous characters for phylogenetic analyses

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