How should functional relationships be evaluated using phylogenetic comparative methods? A case study using metabolic rate and body temperature

Phylogenetic comparative methods are often used to test functional relationships between traits. However, million-year macroevolutionary observational datasets cannot definitively prove causal links between traits—correlation does not equal causation and experimental manipulation over such timescale...

Full description

Saved in:
Bibliographic Details
Published in:Evolution 2021-05, Vol.75 (5), p.1097-1105
Main Authors: Uyeda, Josef C., Bone, Nicholas, McHugh, Sean, Rolland, Jonathan, Pennell, Matthew W.
Format: Article
Language:English
Subjects:
Body temperature
BRIEF COMMUNICATION
Causation
Cenozoic
Evolution
Macroevolution
Metabolic rate
Metabolism
models/simulations
Paleontology
Phylogenetics
Phylogeny
physiology
Statistical methods
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Phylogenetic comparative methods are often used to test functional relationships between traits. However, million-year macroevolutionary observational datasets cannot definitively prove causal links between traits—correlation does not equal causation and experimental manipulation over such timescales is impossible. Although this caveat is widely understood, it is less appreciated that different phylogenetic approaches imply different causal assumptions about the functional relationships of traits. To make meaningful inferences, it is critical that our statistical methods make biologically reasonable assumptions. Here we illustrate the importance of causal reasoning in comparative biology by examining a recent study by Avaria-Llautureo et al (2019). that tested for the evolutionary coupling of metabolic rate and body temperature across endotherms and found that these traits were unlinked through evolutionary time and that body temperatures were, on average, higher in the early Cenozoic than they are today. We argue that the causal assumptions embedded into their models made it impossible for them to test the relevant functional and evolutionary hypotheses. We reanalyze their data using more biologically appropriate models and find support for the exact opposite conclusions, corroborating previous evidence from physiology and paleontology. We highlight the vital need for causal thinking, even when experiments are impossible.
ISSN:0014-3820
1558-5646
DOI:10.1111/evo.14213