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Statistical methods and data for: Absence of heterosis for hypoxia tolerance in F1 hybrids of Tigriopus californicus

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Nov 13, 2024 version files 133.86 KB

Abstract

This data set includes generalized structural equation models (SEM) for the parental populations and hybrid populations in Stata 18, code for figures in R and data in CSV format.  We used SEM over linear regression in order to also generate estimates of the errors and unexplained variance of the midpoint value of the parents.  First, we encoded sex, nuclear genome composition, collection cohort, days in lab after collection, and arena as variables in both models.  For the hybrid model, we also added terms for mitochondrial genome and interaction terms between sex and nuclear genome composition because we observed a different trend in sex differences for one population.  Separate SEM equations were necessary since parental populations were perfectly colinear with mitochondrial type, whereas F1 hybrids were not.  Since observations were grouped by arena and trial, we utilized a clustered standard error calculator when combining both models to allow for different variance between populations.  After, we tested the linear combinations of the means to determine if F1 hybrids performed significantly different from the midpoint value of the two parental populations. By using the estimates from the SEM, we were able to include the estimated error from the models into the equation as well.  Lastly, we tested the linear combinations of the means to determine if the reciprocal crosses of F1 hybrids performed significantly differently from each other.