DOI: 10.5061/dryad.dfn2z35cj
title: Sex-specific variation in thermal sensitivity has multiple negative effects on reproductive trait performance

description: Understanding how increasing temperatures influence ectotherm population
 growth rate is necessary for predicting population persistence. Population
 growth rate depends on the thermal performance of multiple life-history
 traits that have different thermal sensitivities. Reproductive traits are
 considered more thermally sensitive than other life-history traits, such
 as survival and development rate. Moreover, thermal sensitivity of
 reproductive traits can be sex-specific, which may differentially affect
 population growth. However, research concurrently assessing the
 sex-specific influence of heat stress on multiple reproductive traits is
 limited. We investigated the effect of heat stress on pupal survival and
 reproductive traits in both sexes to determine sex-specific thermal
 sensitivity and reproductive performance. Individuals of the butterfly
 Pieris napi were reared at either 22°C or 29°C throughout larval and pupal
 stages. The latter temperature reflects fastest development rate in this
 population, influencing generation time, a common population growth rate
 metric. We recorded pupal survival and adult body weight in both sexes.
 After eclosion, males and females from both treatments were allowed to
 interact, and mating success, copulation duration, egg production,
 fertility and male sterility recovery were measured. A subset of mated
 females was dissected to assess the number and length of fertilising
 eupyrene and non-fertilising apyrene sperm transferred by males of each
 treatment. While elevated temperatures reduced pupal survival and resulted
 in smaller body weights in both sexes, more substantial sex-specific
 effects on reproductive traits were observed. Mating success was reduced
 in heat-treated females but not males. In contrast, female egg production
 and fertility was unaffected by thermal treatment while heat-stressed
 males, despite having longer copulation durations, exhibited near-complete
 sterility. Male heat-induced sterility was mediated by a disruption to
 both eupyrene and apyrene sperm production or transfer. Male remating did
 not recover fertility, suggesting continued negative effects on sperm
 production. Our results highlight how increasing temperatures affect
 reproduction, illustrating that temperatures generating optimal
 performance for non-reproductive traits, like development rate, can
 negatively and differentially impact sex-specific reproductive fitness.
 These negative reproductive consequences may impact population
 persistence, highlighting the necessity to incorporate these findings into
 future advanced models predicting species’ responses to climate warming.
description: # Sex-specific variation in thermal sensitivity has multiple negative
 effects on reproductive trait performance
 [https://doi.org/10.5061/dryad.dfn2z35cj](https://doi.org/10.5061/dryad.dfn2z35cj) ## Results section 3.1  **Description:** The effect of temperature on pupal survival  ***dataset can be found in .Rmd file*** ## Results section 3.2 #### *File: weights.csv* **Description:** The effect of temperature on adult body weight across 2021 and 2022 ##### Variables * Treatment: Temperature (22°C or 29°C) * value: Weight (g) * Year: Experimental year (2021 or 2022)  * Sex: Male or female  ## Results section 3.3 #### *File: 50\_percent\_mate.csv* **Description:** The effect of temperature on mating success across 2021 and 2022 ##### Variables * Flight_cage: Flight cage ID * Mating_combo: Temperature treatment combination (female temperature written first) * Experiment: Experiment ID (1 = 2021, 2 = 2022) * Male_T: Male temperature (22°C or 29°C) * Female_T: Female temperature (22°C or 29°C) ## Results section 3.4 #### *File: copulation\_duration\_mate.csv* **Description:** The effect of temperature on copulation duration (of an initial mating) ##### Variables * Mating no. : Mating ID * Flight cage: Flight cage ID * Mating date: Date mating occurred  * Female: Female ID * Male: Male ID * Cop_start: Time copulation began * Cop_end: Time copulation ends * Cop_dur: Copulation duration (time) * Cop_dur_min: Copulation duration (minutes) * Bf_weight_Female: Female weight (g) * Bf_weight_Male: Male weight (g) * Treatment_Female: Female temperature (22°C or 29°C) * Treatment_Male: Male temperature (22°C or 29°C) Note: unavailable data ("NA") occured when the exact timing of copulation was missed, or an individual's ID was not recorded.  ## Results section 3.5 #### *File: egg\_larvae\_counts.csv* **Description:**  1. The effect of temperature on the number of eggs oviposited and the number of larvae hatched between days 1 - 3 following copulation across 2021 and 2022 2. The effect of temperature on the number of eggs oviposited and the number of larvae hatched between days 1 - 3 and days 4 - 6 following copulation in 2021 ##### Variables * Experiment: Experimental year (2021 or 2022) * Mating no. : Mating ID * Female: Female ID * Male: Male ID * Eggs_day_3: Number of eggs oviposited between days 1 - 3 * Larvae_day_3: Number of larvae hatched between days 1 - 3 * Bf_weight_Female: Female weight (g) * Bf_weight_Male: Male weight (g) * Treatment_Female: Female temperature (22°C or 29°C) * Treatment_Male: Male temperature (22°C or 29°C) * Eggs_6: Number of eggs oviposited between days 4 - 6 * Eggs_Tot: Total number of eggs oviposited between days 1 - 6 * Larv_6: Number of larvae hatched between days 4 - 6 * Larv_Tot: Total number of larvae hatched between days 1 - 6 ## Results section 3.6 #### *File: copulation\_duration\_remate.csv* **Description:** The effect of temperature on copulation duration during a male's second mating with a control female (and how this compares to the initial copulation duration during the first mating) ##### Variables * Mating_Ep: Mating episode (1 = initial mating, 2 = remating) * Flight.cage: Flight cage ID * Male: Male ID * Female: Female ID * Cop_dur_min: Copulation duration (minutes) * Female_2_w: Weight of second control female (g) * Bf_weight_Female: Weight of first female (g) * Bf_weight_Male: Weight of male (g) * Treatment_Female: Female temperature (22°C or 29°C) * Treatment_Male: Male temperature (22°C or 29°C) ## Results section 3.7 #### *File: remating\_recovery.csv* **Description:** The effect of male temperature on the number of eggs oviposited and the number of larvae hatched after remating with a control female (to investigate the capacity for male recovery following a remating) ##### Variables * Female: Female ID * Male: Male ID * Mate_Ep: Mating episode (1 = initial mating, 2 = remating) * Treatment_Female: Female temperature (22°C or 29°C) * Treatment_Male: Male temperature (22°C or 29°C) * Eggs: Number of eggs oviposited between days 1 - 3 * Larvae: Number of larvae hatched between days 1 - 3 * Bf_weight_Male: Male weight (g) * Female_weight_2: Weight of second control female (g) ## Results section 3.8 #### *File: sperm\_counts.csv* **Description:** The effect of temperature on the number of euyrene and apyrene sperm produced ##### Variables * Mating no.: Mating ID * Flight cage: Flight cage ID * Mating date: Date that mating occurred * Female: Female ID * Male: Male ID * Weight_F: Female weight (g) * Weight_M: Male weight (g) * Treatment: Temperature treatment combination (female temperature written first) * F_T: Female temperature (22°C or 29°C) * M_T: Male temperature (22°C or 29°C) * W_B: Weight of the vial before dissection (g) * W_A: Weight of the vial after adding sperm solution (g) * Weight: Weight of sperm solution (g) * Weight_ml: Weight of sperm solution (ml) * Eu: Eupyrene sperm number * Total_Eu: Total eupyrene sperm number (x256) * Par_1: Apyrene sperm count from first 10-μl aliquot * Par_2: Apyrene sperm count from second 10-μl aliquot * Par_3: Apyrene sperm count from third 10-μl aliquot * Par_4: Apyrene sperm count from fourth 10-μl aliquot * Par_5: Apyrene sperm count from fifth 10-μl aliquot * Par_6: Apyrene sperm count from sixth 10-μl aliquot * Total_Par: Total apyrene sperm count * Av_Par: Average apyrene sperm count (Total_Par / 6) * Full_Total: Total apyrene sperm count in the sperm solution #### *File: apyrene\_sperm\_length.csv* **Description:** The effect of temperature on apyrene sperm length  ##### Variables * Individual: Individual male ID * Number: Number of sperm measured for each male ID * Length: Apyrene sperm length (mm) * Average: Average sperm length for each male: Length (mm) / Number  * F_T: Female temperature (22°C or 29°C) * M_T: Male temperature (22°C or 29°C) * M_Weight: Male weight (g) * F_Weight: Female weight (g) For all datasets, missing values are described as "NA" ## Code/software All R code and packages are described in the .Rmd file