DOI: 10.5061/dryad.79cnp5j51
title: Data from: Stalk-eyed flies carrying a driving X chromosome compensate by increasing fight intensity

description: Exaggerated ornaments provide opportunities for understanding how
 selection can operate at different levels to shape the evolution of a
 trait. While these features aid their bearer in attracting mates or
 fending off competitors, they can also be costly and influenced by the
 environment and genetic variation. Eyestalks of the stalk-eyed fly,
 Teleopsis dalmanni, are of interest because eyestalk length is the target
 of both intra-and intersexual selection and is also reduced by loci on a
 highly-diverged sex ratio X chromosome (XSR), a meiotic driver accounting
 for up to 30% of wild X chromosomes. Male stalk-eyed flies fight to
 control access to females and over food using a combination of low
 intensity displays and high intensity physical fights. We staged, filmed
 and scored contests among eyespan-matched male pairs to evaluate whether X
 chromosome type impacts the behavior and outcome of aggressive
 interactions. While our results broadly match expectations from previous
 studies, we find that XSR males used more high intensity behaviors than
 males carrying a non-driving, standard X chromosome (XST), in particular
 when their eyestalks were of similar size or smaller than their opponents.
 Additionally, we find that when XSR males use high intensity behaviors
 they win more bouts than when they use low intensity behaviors. Taken
 together these results suggest that XSR impacts male aggressive behavior
 to compensate for the shorter eyestalks of XSR males, and may help to
 explain how this selfish chromosome is maintained.
description: Following previous studies of fighting in stalk-eyed flies
 (Panhuis and Wilkinson 1999; Egge et al. 2011; Bubak et al. 2014), we
 quantified male aggressive behavior in two sets of trials conducted either
 at SUNY Geneseo (outbred pair trials) or the University of Maryland,
 College Park (standardized opponent trials). We conducted trials with
 outbred and inbred flies as opponents to confirm that the results were
 robust to the opponents’ genetic background. Sexually mature males at
 least four weeks post-eclosion were anesthetized using carbon dioxide,
 eyespan and body length were measured from video-captured images to the
 nearest 0.01 mm using ImageJ. All trials were conducted in transparent
 plastic arenas (10 x 3.5 x 6 cm) lined with moist blotting paper and
 initially divided into three sections by opaque plastic barriers.  Each
 male was placed into an outer compartment of the arena and fasted 20-24
 h.  At the beginning of the trial, a piece of agar gel made with corn
 juice was placed into the center compartment as a food resource and the
 barriers were removed. Trials were video recorded for ten minutes. Scoring
 of each video was done blind to genotype. Occurrence of aggressive
 behaviors performed by each fly in each trial were scored from video
 recordings following a published ethogram. Within a trial, we defined
 fighting “bouts” to begin once either fly performed an aggressive behavior
 and end when the flies were more than a body length apart or not facing
 each other for 3 s without exhibiting any aggressive behavior. A male was
 scored as losing a bout if he moved away from his opponent at the end of a
 bout either slowly (away) or quickly (retreat) and his opponent did not. A
 mutual away or retreat was considered a tied bout. Most trials involved
 multiple bouts. Aggressive behaviors were categorized as either high
 intensity (HI) behaviors that involved physical contact (tussle,
 attack/lunge, jump attack) or low intensity (LI) behaviors that involved
 males mutually displaying their eyestalks in close proximity (approach,
 flex, and extend, line-up eyestalks). Escalations were tallied for each
 individual as a transition from a LI to a HI behavior with no other
 behaviors or the start or end of a bout separating them.  Similarly,
 de-escalations were defined as a transition from HI to LI behavior. Males
 were collected immediately after each trial for DNA extraction and
 genotyping for X chromosome type (X<sup>SR </sup>or
 X<sup>ST</sup>) using polymerase chain reaction (PCR) to
 amplify either of two markers (Table S1) that each predict drive phenotype
 in this population with 95% accuracy. 
description: # Dataset: Stalk-eyed flies carrying a driving X chromosome compensate by
 increasing fight intensity
 [https://doi.org/10.5061/dryad.79cnp5j51](https://doi.org/10.5061/dryad.79cnp5j51) ## Description of the data and file structure We staged, filmed and scored contests among eyespan-matched pairs of stalk-eyed fly males to evaluate whether X chromosome type impacts the behavior and outcome of aggressive interactions.  Males were genotyped for the presence of a meiotic drive X chromosome after scoring.  ### Files and variables #### File: Editorial\_1.XLSX **Description of the data table columns** | **Variable** | **Description** | | :-------------------- | :------------------------------------------------------------------------------------------------------------------------------------------------------ | | Trial type | Standardized opponent trials involved an outbred male fighting an inbred competitor; Outbred pair trials involved two outbred males fighting each other | | Focal Male | ID of first male | | Opponent Male | ID of opponent | | Any bout | Y if any aggressive interactions occurred, N if not | | Focal Eyespan | eyespan in mm (Focal) | | Focal Body | body length in mm (Focal) | | Focal Thorax | thorax width in mm (Focal) | | Opp Eyespan | eyespan in mm (Opponent) | | Opp Body Length | body length in mm (Opponent) | | Opp Thorax | thorax width in mm (Opponent) | | Focal X | X chromosome type, ST = XST, SR = XSR (Focal) | | Opp X | X chromosome type, ST = XST, SR = XSR (Opponent) | | Num Bouts | Number of aggressive contests within 10 minute trial, NA if none scored | | Total bout length (s) | Total duration of aggressive contests (s) | | First bout length (s) | Duration of the first aggressive contest (s) | | Last bout length (s) | Duration of the last aggressive contest (s) | | Focal Initiate | Number of times the  male initiated an aggressive contest (Focal) | | Focal Approach | Number of times the  male performed the approach behavior (Focal) | | Focal Line up | Number of times the  male performed the line-up  behavior (Focal) | | Focal Flex and Extend | Number of times the  male performed the flex and extend behavior (Focal) | | Focal Jump Attack | Number of times the  male performed the jump attack  behavior (Focal) | | Focal Attack/Lunge | Number of times the  male performed the  attack/lunge  behavior (Focal) | | Focal Tussle | Number of times the  male performed the tussle  behavior (Focal) | | Focal Away | Number of times the  male performed the away  behavior (Focal) | | Focal Pursue | Number of times the  male performed the pursue  behavior (Focal) | | Focal Retreat | Number of times the  male performed the retreat  behavior (Focal) | | Focal Escalation | Number of times the  male transitioned from low to high intensity behavior (Focal) | | Focal Descalation | Number of times the  male transitioned from high to low intensity behavior (Focal) | | Opp Initiate | Number of times the  male initiated an aggressive contest (Opponent) | | Opp Approach | Number of times the  male performed the approach behavior (Opponent) | | Opp Line up | Number of times the  male performed the line-up  behavior (Opponent) | | Opp Flex and Extend | Number of times the  male performed the flex and extend behavior (Opponent) | | Opp Jump Attack | Number of times the  male performed the jump attack  behavior (Opponent) | | Opp Attack/Lunge | Number of times the  male performed the  attack/lunge  behavior (Opponent) | | Opp Tussle | Number of times the  male performed the tussle  behavior (Opponent) | | Opp Away | Number of times the  male performed the away  behavior (Opponent) | | Opp Pursue | Number of times the  male performed the pursue  behavior (Opponent) | | Opp Retreat | Number of times the  male performed the retreat  behavior (Opponent) | | Opp Escalation | Number of times the  male transitioned from low to high intensity behavior (Opponent) | | Opp Descalation | Number of times the  male transitioned from high to low intensity behavior (Opponent) | | Focal Wins | Number of aggressive contests  won by the focal male | | Focal Loss | Number of aggressive contests lost by the focal male | | Draw | Number of aggressive contests drawn |