DOI: 10.5061/dryad.k0p2ngfkz
title: Loss of paired weapons leads to larger testes and a lighter load for dispersal

description: Reproduction is often costly for males, as it may require the growth of
 structural traits that aid in dispersal to find females, competition over
 mating opportunities, and ejaculate production. The growth of such traits
 can be energetically demanding, and these demands often arise concurrently
 during development. As such, these traits may be especially prone to
 resource allocation trade‐offs. Yet, such traits are rarely studied in
 tandem. We designed a study to improve understanding of investment
 dynamics in flight muscle, a dispersal trait; a sexually selected weapon
 used in mate competition; and testes used for sperm production. We used
 the leaf‐footed cactus bug, Narnia femorata (Hemiptera: Coreidae), a
 species where males use their hindleg as weapons to compete for matings.
 Males can naturally drop their limbs, and when hindlegs are lost during
 development, adult males do not grow a weapon. Existing studies have
 revealed that testes growth increases when investment in weapons ceases.
 Yet, this work only examined responses to the loss of a single hindleg and
 limited the scope of traits to testes. Here, we examined weapon loss at
 two levels and investigated a third trait: dispersal. We found that testes
 size increased stepwise with limb loss; the loss of one hindleg weapon
 increased testes mass by around 9%, and two legs increased it by 20%. This
 intriguing pattern suggests a direct, quantity‐specific trade‐off in
 tissue development across traits. We also detected only a limited increase
 in dispersal investment when males did not grow weapons. Yet, dispersal
 may still be enhanced for those that drop hind legs; those without the
 substantial weight of hind limbs may have the potential to disperse
 farther.
description: # Loss of paired weapons leads to larger testes and a lighter load for
 dispersal **Data column descriptions; Manuscript_Data.csv:** * ID:
 Integer; Unique numerical identifier of each insect in the study * Fam:
 String; Identified the parental pair of each individual, for inclusion in
 linear mixed models as a random effect * MaleName: String; Unique string
 identifier of each insect in the study, including in order the project
 identifier (TMA), development order in clutch, Parental pair identifier,
 and alphabetical clutch identifier * Soft: Bool; Identifies whether the
 individual exhibited a phenotype of small, soft, and highly melanated
 cuticle during rearing * LookupName: String; Lookup value identifying the
 treatment of each individual. Individuals either "No Autotomy",
 "Single Autotomy", or "Double Autotomy" *
 PronotumWidth: Decimal; Pronotum width of each individual in millimeters *
 BodyMass: Decimal; Body mass of each individual in milligrams, does not
 include mass of testes, flight muscle, or any remaining weapons *
 RHindLegArea: Decimal; Area of the right hind leg in millimeters squared,
 #N/A for double autotomy individuals * DryTestesMass: Decimal; Mass of the
 both testes in milligrams, dried * DryMuscleMass: Decimal; Mass of the
 flight muscle in milligrams, dried * WeaponMass: Decimal; Mass of any
 remaining hind legs in milligrams, 0 for double autotomized individuals *
 SingleLegMass: Decimal; Mass of a single hind leg in milligrams, #N/A for
 double autotomized, found in no autotomy individuals by dividing
 WeaponMass by 2 Missing values exist where body parts were lost during the
 course of the experiment, where data values were unusable, or in the case
 of RHindLegArea and SingleLegMass, where both hind legs were removed, and
 there is no mass of the single hind leg. ##### **R script description;
 ManuscriptAnalysis.R:** Script containing all analyses conduced for this
 study. Script includes data transformations, model assumption tests,
 generalized linear mixed models, and path analysis, including model
 selection for path analysis. This script also includes code to generate
 all figures, except for the path figure (Figure 2), which was generated
 simply using Microsoft PowerPoint. ###### **Package versions:** R version:
 4.3.2 ggplot2 version: 3.5.1 dplyr version: 1.1.4 lmtest version: 0.9.40
 ggpubr version: 0.6.0 rstatix 3.5.10.7.2 tidyverse version: 2.0.0 emmeans
 version: 1.8.9 lme4 version: 1.1.35.1 lavaan version: 0.6.19 AICcmodavg
 version: 2.3.3