DOI: 10.5061/dryad.66t1g1k7m
title: Directional epistasis is common in morphological divergence

description: Epistasis is often portrayed as unimportant in evolution. While random
 patterns of epistasis may have limited effects on the response to
 selection, systematic directional epistasis can have substantial effects
 on evolutionary dynamics. Directional epistasis occurs when allelic
 substitutions that change a trait also modify the effects of allelic
 substitutions at other loci in a systematic direction. In this case, trait
 evolution may induce correlated changes in allelic effects and effective
 genetic variance (evolvability) that modify further evolution. Although
 theory thus suggests a potentially important role for directional
 epistasis in evolution, we still lack empirical evidence about its
 prevalence and magnitude. Using a new framework to estimate systematic
 patterns of epistasis from line-crosses experiments, we quantify its
 effects on 197 size-related traits from diverging natural populations in
 24 animal and 17 plant species. We show that directional epistasis is
 common and tends to become stronger with increasing morphological
 divergence. In animals, most traits displayed negative directionality
 toward larger size, suggesting that epistasis constraints reducing
 evolvability toward larger size may be common. Dominance was also common
 and did not systematically alter the effects of epistasis.
description: The data were collected through a literature search.
description: # Directional epistasis is common in morphological divergence
 [https://doi.org/10.5061/dryad.66t1g1k7m](https://doi.org/10.5061/dryad.66t1g1k7m) This folder contains four data files used for the paper "Directional epistasis is common in morphological divergence". ## Description of the data and file structure ### Dataset – epistasis.csv This dataset is the raw dataset used in the study "Directional epistasis is common in morphological divergence". The data in this file are not the product of any analysis, they are the results of our literature search. Each row corresponds to one trait. The naming of each derivate follows the diagram "Reciprocal line-cross explanation.pdf". Empty cells indicate the data could not be found. Study ID : identification name of the study used in our analysis ID trait : identification number of the trait used in our analysis Taxa : taxa involved in the line-cross experiment Cross.type : type of line-cross ; either inter-species or intra-species Character.category : type of trait; here only morphological trait Scale : scale of trait ; here only ratio-scale Measure : type of measure ; here only length (linear trait measurements) Character : the description of the trait measured Character_sex : fl (floral trait), no_fl (plant trait not related with the measurement of flowers), sex_related (sex trait in animals), non_sex_related (non sex related trait in animals) Error.term : type errors reported, here only standard errors (if the error term was reported as variance or standard deviation it has been converted in standard error) nP1 : number of P1 individuals measured nP2 : number of P2 individuals measured nF1_12 : number of F1_12  individuals measured nF1_21 : number of F1_21  individuals measured nF2_12 : number of F2_12 individuals measured nF2_11 : number of F2_11 individuals measured nF2_22 : number of F2_22 individuals measured nF2_21 : number of F2_21 individuals measured nB1_12 : number of B1_12 individuals measured nB1_11a : number of B1_11a individuals measured nB1_11b : number of B1_11b individuals measured nB1_21 : number of B1_21 individuals measured nB2_21 : number of B2_21 individuals measured nB2_22 : number of B2_22 individuals measured nB2_22b : number of B2_22b individuals measured nB2_12 : number of B2_12 individuals measured P1 : mean value of the trait measured on P1 individuals P1error : standard error associated to mean value of P1 individuals P2 : mean value of the trait measured on P2 individuals P2error : standard error associated to mean value of P2 individuals F1_12 : mean value of the trait measured on F1_12 individuals F1_12error : standard error associated to mean value of F1_12 individuals F1_21 : mean value of the trait measured on F1_21 individuals F1_21error : standard error associated to mean value of F1_21 individuals F2_12 : mean value of the trait measured on F2_12 individuals F2_12error : standard error associated to mean value of F2_12 individuals F2_11 : mean value of the trait measured on F2_11 individuals F2_11error : standard error associated to mean value of F2_11 individuals F2_22 : mean value of the trait measured on F2_22 individuals F2_22error : standard error associated to mean value of F2_22 individuals F2_21 : mean value of the trait measured on F2_21 individuals F2_21error : standard error associated to mean value of F2_21 individuals B1_12 : mean value of the trait measured on B1_12 individuals B1_12error : standard error associated to mean value of B1_12 individuals B1_11a : mean value of the trait measured on B1_11a individuals B1_11aerror : standard error associated to mean value of B1_11a individuals B1_11b : mean value of the trait measured on B1_11b individuals B1_11berror : standard error associated to mean value of B1_11b individuals B1_21 : mean value of the trait measured on B1_21 individuals B1_21error : standard error associated to mean value of B1_21 individuals B2_21 : mean value of the trait measured on B2_21 individuals B2_21error : standard error associated to mean value of B2_21 individuals B2_22 : mean value of the trait measured on B2_22 individuals B2_22error : standard error associated to mean value of B2_22 individuals B2_22b : mean value of the trait measured on B2_22b individuals B2_22berror : standard error associated to mean value of B2_22b individuals B2_12 : : mean value of the trait measured on B2_12 individuals B2_12error : standard error associated to mean value of B2_12 individuals ### Paperlist – epistasis.csv This list of studies contains all the papers we have included in our analysis. They were included because they fulfilled our list of requirements described in the supplementary information. Authors : First authors names of an included study Year : Year of publication of the study Study ID : identification name of the study used in our analysis Journal : Name of the journal where the study is published Title : Full title of the published study Sources : from what source this paper came to our knowledge Derivatives : the set of deritaves that we could use from the study Natural populations : origins of the parental populations Comments : relevant comments for the study Taxa : taxa involved in the line-cross experiment Species : species involved in the line-cross experiment ### Full list of studies – epistasis.csv This list of studies contains all the papers we have considered through our literature search. As described in Figure S1, 156 were discarded solely on the screening of their title and abstract, while for 886 of them, we assessed the whole manuscript. Authors : First authors names of a study considered Year : Year of publication of a study considered Title : Title of a study considered Comments : the reason why the paper is or is not included in our study ### AICs – epistasis.csv This file contains the AICs of the five models tested (additive, dominance, additive and dominance, additive and epistasis, additive dominance and epistasis), as presented in the figure S2. Each row corresponds to one trait. Study ID : identification name of the study used in our analysis ID trait : identification number of the trait used in our analysis Add.AIC : AIC from the additive model Dom.AIC : AIC from the dominance model Add_dom.AIC : AIC from the additive and dominance model Pure_epi.AIC : AIC from the additive and epistasis model Multi.AIC : AIC from the additive, dominance and epistasis model (full model)