Data from: Winner-loser effects on life history traits
Data files
Mar 21, 2025 version files 93.90 KB
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counts.csv
2.11 KB
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mating_effort.csv
35.93 KB
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qpcr.csv
35.07 KB
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README.md
8.74 KB
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survival.csv
9.31 KB
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vcl_rep.csv
2.75 KB
Abstract
Ageing of adult males could be accelerated by both high mating/reproductive effort and fighting for mates. Testing the relative importance of these factors is challenging, however, because males that win fights also tend to have more mates. We used a 2 x 2 experimental design to test how a prolonged (9 week) period of either winning or losing fights, and either high or low reproductive effort (manipulating by varying access to females) interact to affect male ageing and future reproduction allocation in the mosquitofish, Gambusia holbrooki. We measured telomere length and several life-history traits, including mating effort and ejaculates (sperm count and velocity). After 9 weeks there were significant differences between winners and losers in their mating effort, but not in their ejaculates. Males with a higher past reproductive effort (i.e. access to females) had significantly lower current mating effort and grew more slowly. Males with a higher past reproductive effort also had slower swimming sperm, but only if they were smaller than average in body size. Surprisingly, neither males with a higher past reproductive effort nor males that repeatedly lost fights had shorter telomeres. Our findings show that past social dynamics affect how males allocate resources to reproduction and somatic maintenance.
https://doi.org/10.5061/dryad.rjdfn2zp3
Description of the data and file structure
There are 5 datasets (.csv files) used for analyses. The first dataset mating_effort is the main dataset used for analysis. Datasets 2-5 have been provided for transparency in our data collection. Dataset 2 qpcr is the raw output generated from qPCR used to generate data for telomere length determination. Dataset 3 counts is the dataset used to measure the repeatability of the 5 sperm count subsamples for each male. Dataset 4 vcl_rep is the data used to determine the repeatability of sperm velocity (vcl) for each male from two sperm samples. Dataset 5 survival is the dataset used to measure survival/mortality during the experimental period. All the missing data represented as NA.
Files and variables
File: data.xlsx
Description: complete datasheet containing all the datasets (5 in total) used for analyses and retaining their names as used in the provided R code (submitted to Zenodo)
Variables
Metadata (format - Column name: Description)
Dataset 1: mating_effort
This is the main dataset used for analyses (see provided code file Rcode.r)
Row_ID: Unique row identification
Male_ID: Unique male identification
Block_ID: Block number used as random effect in models
Date_Tagged: Date focal male was tagged with elastomer tag (see Methods)
Tag_Colour: Colour of tag - recorded to check for potential behavioural biases
Start_size_mm: Male standard length (SL) recorded when male was tagged using calipers
Experience: Contest experience treatment (Winner or Loser)
Treatment: Reproductive investment treatment (Contests Only or Contests + Reproduction)
Start_date_social: Start date for initial contests - week before reproductive investment treatment began
Start_date_treatment: Start date for reproductive investment treatment (week following contest treatment start - went for 8 weeks)
End_date_treatment: End date for experimental treatments - date of behavioural data recording in mating assay
End_size_mm : Male standard length recorded at the end of experimental period
Male_growth: Life history trait 1 - Calculated as end size - start size
Absolute_time_female_sec: Behavioural trait 1 - the total time male spent associating with female during mating assay
Mating_attempts: Behavioural trait 2 - the total number of mating attempts (see Methods) made during mating assay
Successful_attempts: Behavioural trait 3 - the total number of mating attempts that were successful (transfer spem) during mating assay
Female_size_mm: Female standard length recorded at the end of mating assay
Total_sperm: Ejaculate trait 1 - total number of sperm counted (average of 5 counts from 1 sample) from replenished sperm
Weighted_avg_VAP: Ejaculate trait 2 - weighted average sperm velocity VAP (average path velocity) (see methods) from replenished sperm
Weighted_avg_VCL: Ejaculate trait 3 - weighted average sperm velocity (curvilinear) VCL (see Methods) from replenished sperm
Weighted_avg_VSL: Ejaculate trait 4 - weighted average sperm velocity (straight line) VSL (see Methods) from replenished sperm
qPCR_Run_Number: Run number for qPCR
qPCR_Date: Date qPCR for male sample was run
Telomere_Cq1: Cq value from qPCR for telomeres - sample 1
MC1R_Cq1: Cq value from qPCR for MC1R reference gene - sample 1
Telomere_Cq2: Cq value from qPCR for telomeres - sample 2
MC1R_Cq2: Cq value from qPCR for MC1R reference gene - sample 2
Telomere_Cq3: Cq value from qPCR for telomeres - sample 2
MC1R_Cq3: Cq value from qPCR for MC1R reference gene - sample 2
rTL: Average relative telomere length averaged across the three samples for each male
rTL_1: relative telomere length calculated from sample 1
rTL_2: relative telomere length calculated from sample 2
rTL_3: relative telomere length calculated from sample 3
Dataset 2: qpcr
This is the dataset generated from qPCR output used to generate data for telomere length determination
Row_ID: Unique row identification
Male_ID: Unique male identification
qPCR_Run_Number: Run number for qPCR
qPCR_Date: Date qPCR for male sample was run
Well_1: Well number for 1st sample
Well_Position1: Plate position for 1st sample
Telomere_Cq1: Cq value from qPCR for telomeres - sample 1
MC1R_Cq1: Cq value from qPCR for MC1R reference gene - sample 1
Well_2 : Well number for 2nd sample
Well_Position2: Plate position for 2nd sample
Telomere_Cq2: Cq value from qPCR for telomeres - sample 2
MC1R_Cq2: Cq value from qPCR for MC1R reference gene - sample 2
Well_3: Well number for 3rd sample
Well_Position3: Plate position for 3rd sample
Telomere_Cq3: Cq value from qPCR for telomeres - sample 2
MC1R_Cq3: Cq value from qPCR for MC1R reference gene - sample 2
Tel_Interplate_ControlS1_1: Telomere control cq - golden sample used across plates - sample 1 run 1 (run in triplicate)
Tel_Interplate_ControlS1_2: Telomere control cq - golden sample used across plates - sample 1 run 2 (run in triplicate)
Tel_Interplate_ControlS1_3: Telomere control cq - golden sample used across plates - sample 1 run 3 (run in triplicate)
Tel_Interplate_ControlS2_1: Telomere control cq - golden sample used across plates - sample 2 run 1 (run in triplicate)
Tel_Interplate_ControlS2_2: Telomere control cq - golden sample used across plates - sample 2 run 2 (run in triplicate)
Tel_Interplate_ControlS2_3: Telomere control cq - golden sample used across plates - sample 2 run 3 (run in triplicate)
MC1R_Interplate_ControlS1_1: MC1R control cq - golden sample used across plates - sample 1 run 1 (run in triplicate)
MC1R_Interplate_ControlS1_2: MC1R control cq - golden sample used across plates - sample 1 run 2 (run in triplicate)
MC1R_Interplate_ControlS1_3: MC1R control cq - golden sample used across plates - sample 1 run 3 (run in triplicate)
MC1R_Interplate_ControlS2_1: MC1R control cq - golden sample used across plates - sample 2 run 1 (run in triplicate)
MC1R_Interplate_ControlS2_2: MC1R control cq - golden sample used across plates - sample 2 run 2 (run in triplicate)
MC1R_Interplate_ControlS2_3: MC1R control cq - golden sample used across plates - sample 2 run 3 (run in triplicate)
Amplification_Efficiency_Telomere: Amplification efficiency for telomere
Amplification_Efficiency_MC1R: Amplification efficiency for MC1R reference gene
rTL: Average relative telomere length averaged across the three samples for each male
AVG_TEL_CONTROL: Average Cq for the telomere controls (see Methods)
AVG_MC1R_CONTROL: Average Cq for the MC1R controls (see Methods)
rTL_1: relative telomere length calculated from sample 1
rTL_2: relative telomere length calculated from sample 2
rTL_3: relative telomere length calculated from sample 3
Dataset 3: counts
This is the dataset used to measure the repeatability of the 5 sperm count subsamples for each male
Male_ID: Unique male identification
total_C1: sperm count subsample 1
total_C2: sperm count subsample 2
total_C3: sperm count subsample 3
total_C4: sperm count subsample 4
total_C5: sperm count subsample 5
Dataset 4: vcl_rep
This is the data used to determine the repeatability of sperm velocity (vcl) for each male from two sperm samples. There are no raw videos associated with these data.
Male_ID: Unique male identification
mean_vcl_1: mean sperm velocity (vcl) from sample 1
mean_vcl_2: mean sperm velocity (vcl) from sample 2
Dataset 5: survival
This is the dataset used to measure survival/mortality during the experimental period
Male_ID: Unique male identification
Block_ID: Block number used as random effect in models
Start_date_social: Start date for initial contests - week before reproductive investment treatment began
Tag_Colour: Colour of tag - recorded to check for potential behavioural biases
Start_size_mm: Male standard length (SL) recorded when male was tagged using calipers
Experience: Contest experience treatment (Winner or Loser)
Treatment: Reproductive investment treatment (Contests Only or Contests + Reproduction)
Time: Days alive
Survival: Death = 1, Alive = 0
Data notes: Missing values recorded as NA
Code/software
For data analysis:
R (version 4.0.2)
Access information
Other publicly accessible locations of the data:
- Open Science Foundation study pre-registration (https://osf.io/saj46/)
Data was derived from the following sources:
- NA
Creating winners and losers
We randomly selected focal males to assign to experimental treatments and followed them individually throughout the study (n = 176). Focal males were anaesthetized briefly to measure their standard body length (SL) and then marked with a subcutaneous elastomer tag (NorthWest Marine Technology, WA, USA). After one week of isolation, focal males were randomly assigned to be winners or losers by being paired with either a smaller or larger rival. This method controls for intrinsic differences in fighting ability between males that might otherwise determine contest outcomes or affect investment into reproduction and somatic maintenance. Contests took place in 6 L aquaria that contained gravel, plastic plants for refugia, and had black plastic on three sides to minimize disturbance. Focal and rival males freely interacted for one week, after which a female was introduced to the tank to apply the reproductive treatment for another 8 weeks. In half the tanks, the two males could freely interact with the female and therefore the focal male could fully invest in reproduction (i.e. chase the female and mate). In the other half of the tanks there was also a female present, but she was kept behind a mesh barrier to prevent the males from mating with her. Equal numbers of winner and loser focal males therefore either had full access to a female (‘contests and mating’) or only interacted with a female through the barrier (‘contest only’) (NB: ‘contest’ refers to the fact that all males competed with a rival for the full 9 weeks). Rival males and stimulus females were rotated every 3-5 days so that focal males continued to fight to establish dominance, and to approach females
Male mating behaviour
After 9 weeks, each focal male was placed in a new 6 L aquaria with a random stock female. Each female was used once. Male mating behaviour was observed for 20 mins. We recorded: (a) time spent near the female (<5 cm and facing her); (b) the number of mating attempts; and (c) the number of successful attempts (i.e., those with the potential to transfer sperm).
Ejaculates
Immediately following the mating behaviour trials, focal males were anaesthetised in ice slurry to measure their body length (SL) and to strip their sperm. Males were then isolated for 5 days in 1 L aquaria to replenish their sperm reserves, after which we again stripped them. We had two ejaculate measures: total sperm count and sperm velocity.
For sperm counts, we vortexed the sample to disperse sperm then pipetted 3 µL onto a 20 µm capillary slide (Leja), and used a CEROS Sperm Tracker (Hamilton Thorne Research, Beverly, MA, USA) to count sperm under x100 magnification. We randomly counted five subsamples per sample. We estimated total sperm counts by adding the average sperm number per bundle to account for the six bundles removed for sperm velocity analyses.
To measure sperm velocity, we took two samples of three sperm bundles from each male’s ejaculate and pipetted the bundles into two separate PCR tubes containing 2 µL extender medium. We then pipetted each sample onto a cell of a 12-cell multi-test slide (MP Biomedicals, Aurora, OH, USA) coated with 1% polyvinyl alcohol solution (PVA). Sperm was ‘activated’ with 3 µL of solution (125 mM KCL and 2 mg/mL bovine serum albumin). We used a CEROS Sperm Tracker to record two measures of sperm velocity: VAP (average path velocity) and VCL (curvilinear velocity).
Relative telomere length
Relative telomere length (rTL) was measured using real-time quantitative PCR, determined as the ratio (T/S) of telomere repeat length (T) to a single-copy reference gene length (S). We used standard telomere primers Tel1b (5′-CGGTTTGTTTGGGTTTGGGTTTGGGTTTGGGTTTGGGTT-3′) and Tel2b (5′-GGCTTGCCTTACCCTTACCCTTACCCTTACCCTTACCCT-3′) and a Gambusia-specific region of the melanocortin 1 receptor (MC1R) as our control single-copy reference gene with the primers MC1R.F (5’-CCTGTAGGCGTAGATGAGCG-3’) and MC1R.R (5’-CACCAGTCCCTTCTGCAACT-3’).
We ran qPCRs for each sample in triplicate on 96-well plates. Telomere and MC1R amplifications were run concurrently on separate plates using QuantStudio3 (Thermo Fisher Scientific, Waltham, USA). Each plate had three negative controls (9 µL reagent mix and 1 µL MilliQ purified water), two inter-plate control samples (run in triplicate, the same two individuals across all plates), and a golden sample at five DNA concentrations (0.05, 0.2, 1, 5 and 20 ng/µL) to generate the standard curve and determine the amplification efficiency of each plate (telomere: 1.99-2.11; MC1R: 1.93-2.01).