DOI: 10.5061/dryad.dv41ns27n
title: Testing for age- and sex- specific mitonuclear epistasis in Drosophila

description: The need for efficient ATP production is predicted to result in the
 evolution of cooperation between the mitochondrial and nuclear encoded
 components of the electron transport system. Novel (i.e., mismatched)
 mitonuclear genotype combinations are therefore predicted to result in
 negative fitness consequences, which may become more prevalent with
 ageing. Such negative fitness effects are expected to be prominent in
 males, since maternal inheritance of mitochondria is predicted to lead to
 accumulation of male-harming mutations (the mother’s curse hypothesis). To
 test these predictions, we measured female and male fertility traits using
 a genetically diverse panel of 27 mitonuclear populations of Drosophila
 melanogaster with matched or experimentally mismatched mitonuclear genomes
 at different ages. We found no overall effect of mitonuclear mismatch. In
 females, we found no effect of mitonuclear epistasis. In males, we found
 limited evidence of mitonuclear epistasis affecting fitness in old age,
 however, not in the direction predicted. Experimentally mismatched males
 sired more offspring in one comparison. Sex-specific advantages of
 mismatched males might arise if novel nuclear alleles compensate for
 deleterious mitochondrial alleles that have accumulated. If such
 compensatory effects of novel mitonuclear combinations increasing fitness
 occur in nature, they could represent a possible counterforce to the
 mother’s curse.
description: # Testing for age- and sex- specific mitonuclear epistasis in Drosophila
 Dataset DOI: [10.5061/dryad.dv41ns27n](10.5061/dryad.dv41ns27n) ##
 Description of the data and file structure ### Files and variables ####
 File: dryad\_data.zip **Description:** File list - 7 .csv files, each
 labelled with the relevant data: #### File descriptions All
 files include variables: * **mito:** mitochondrial genotype levels (A/B/C)
 * **nuclear:** nuclear genotype levels (A/B/C) * **mtn (or similar):**
 combined mitonuclear genotype levels (AA/AB/AC/etc.) * **coevolved:**
 levels (matched/mismatched) * **mito_snp:** the mitochondrial haplotypes
 levels 1 to 9 * **LINE:** mitonuclear population ID for the 27 mitolines
 levels (AA1/AA2/AA3/etc.) * **age:** Male data includes "age"
 with levels (young/old) indicating male age (young = 5 days, old = 6
 weeks) Missing values are either blank cells or "NA" ##
 body\_data.csv Body size data. Wing length and landmark area for
 female and male flies. * **FlyID:** Individual fly identifier * **sex:**
 female = f; male = m * **fam:** unique identified for each vial in which
 flies laid by one female emerged * **Area:** wing area (mm2) *
 **scaled_area:** z-transformed wing area ##
 female\_fertility.csv Data on fecundity for mitoline females. *
 **ID:** unique female ID * **vial:** oviposition vial for each female (1
 to 7) * **progeny:** counts of adult progeny emerging from each vial *
 **OLRE:** observation level random effect ## male\_fertility.csv 
 Data on fecundity and hatching success for females mated with mitoline
 males. * **total_eggs:** counts of eggs laid by tester female *
 **total_offs:** counts of emerging larvae from total eggs *
 **total_fail:** counts of unhatched eggs (total eggs - total offs) *
 **fertilised:** calculated proportion of eggs that hatched * **OLRE:**
 observation level random effect ## sperm\_defence.csv Data for
 P1 * **ID:** unique male identifier * **Block:** experimental block  *
 **Day:** day of remating * **cop.dur:** copulation duration (mins) *
 **BW:** counts of brown eyed offspring, i.e., competitor male sire *
 **RED:** counts of red eyed offspring, i.e., focal male sire * **P1:**
 calculated proportion of offspring from the first (focal) male ##
 sperm\_met\_wrangled.csv Data on sperm metabolic rate * maleid:
 unique male identifier * **a1:** relative abundance of autofluorescence
 decay for free NAD(P)H molecules (t1) * **a2:** relative abundance of
 autofluorescence decay for protein-bound NAD(P)H molecules (t2) *
 **p.a2:** a2/100 ## sperm\_offence.csv Data for P2 * **ID:**
 unique male identifier * **Block:** experimental block  * **Day:** day of
 remating * **cop.dur:** copulation duration (mins) * **BW:** counts of
 brown eyed offspring, i.e., competitor male sire * **RED:** counts of red
 eyed offspring, i.e., focal male sire * **P2:** calculated proportion of
 offspring from the second (focal) male ## sperm\_viability\_wrangled.csv
 Data on sperm viability after live/dead staining in treatment or control *
 **male_ID:** unique male identifier * **days:** dissection day *
 **treatment:** control (c) or treatment (t) after sperm exposure to
 control or stress medium before measurement * **live:** counts of live
 sperm * **dead:** counts of dead sperm * **block:** experimental block  *
 **total sperm:** counts of total number of sperm * **viability:**
 calculated proportion of life sperm * **OLRE:** observation level random
 effect ## Code/software All code is available on *GitHub*:
 [https://martingarlovsky.github.io/mito_age_fert/](https://martingarlovsky.github.io/mito_age_fert/) and [https://github.com/suvoigt/mitonuclear_snp_analysis/](https://github.com/suvoigt/mitonuclear_snp_analysis/). ## Access information Other publicly accessible locations of the data: * Mitochondrial and nuclear sequencing data can be retrieved from NCBI using SRA accessions PRJNA532313 and PRJNA853138, respectively.