Data and code from: Inter- and intra-male variation in sperm length is associated with fertilization mode in marine fishes
Data files
Aug 06, 2026 version files 427.45 KB
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Body_information.csv
16.73 KB
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chimera.nwk
475 B
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README.md
5.85 KB
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Sperm_morphological_data.csv
151.46 KB
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Sperm_speed_data.csv
172.52 KB
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Sperm_variation_analyses_Dryad.R
53.11 KB
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Sperm_variation_analyses_loop_processing_Dryad.R
27.30 KB
Abstract
Sperm phenotypes are shaped by several evolutionary factors such as sperm competition and fertilisation mode (external and internal fertilisation). Comparative studies in several animal taxa have shown that sperm competition reduces variation in sperm morphology among and within males. However, little is known about the effects of different fertilisation modes on among- and within-male variations in sperm characteristics. In the present study, we compared the residual variance in sperm morphology and velocity among males and within males using 11 marine fish species with different fertilisation modes and sperm competition levels. Both among- and within-male variation of sperm length (total sperm and flagellar lengths) were significantly smaller in internally fertilising species than in externally fertilising species. No strong evidence was found that sperm competition affects variation in sperm length. When among- and within-male variation were compared across sperm components, the variation in sperm length was found to be significantly smaller than that in the others. Low among-male variation may have undergone stabilising selection that reduced variation, and low within-male variation may have resulted from the production of error-free sperm, along with the evolution of fertilisation modes in these fishes. Our study provides preliminary insights into how fertilisation mode (and potentially sperm competition) may influence sperm evolution across interspecific, intraspecific and ejaculation levels.
Dataset DOI: 10.5061/dryad.m0cfxppgt
Description of the data and file structure
This supplementary dataset accompanies the study investigating among- and within-male variation in sperm morphology and velocity. It includes all data and R scripts used for statistical analyses and figure generation.
- Body_information.csv: Contains biometric data for each individual, including total length, standard length, body weight, and testis mass.
- sperm_morphlogical_data.csv: Contains morphological measurements of sperm traits (e.g., total length, flagellum length, head length, head width) for each individual.
- Sperm_Speed_data.csv: Includes sperm velocity measurements for each male.
- Sperm_variation_analyses_Dryad.R: R script used for statistical analyses and figure generation related to sperm trait variation.
- Sperm_variation_analyses_loop_processing_Dryad.R: R script that performs loop-based statistical analyses and figure generation across multiple sperm traits (e.g., total length, flagellum length, head length, head width).
- chimera.nwk: Phylogenetic tree of 11 species constructed by combining two genome-scale phylogenetic trees (Rabosky et al., 2013; Betancur-R et al., 2017). The tree is provided in Newick format and was used for comparative analyses in this study.
Files and variables
File: Body_information.csv
Description:
Variables
- Group: Group of closely related species with contrasting fertilization modes.
- Scientific_name: Scientific name of the species.
- IndID: Unique identifier for each individual.
- RepSystem: Fertilization mode (1NonCop=External fertilization, 2Cop= Internal fertilization and internal gametic association).
- S.C.Level: Estimated level of sperm competition (0L = Low, 1M = Medium, 2H = High)..
- Sex: Biological sex of individual (All idividual are male).
- Total length: Total body length of the fish (mm).
- Standardlength: Standard body length (mm).
- Bodyweight: Total body mass (g).
- GutWeight: Mass of the digestive tract (g).
- Gonadweight: Mass of the testes (g).
- SomaW: Somatic body weight, calculated as Bodyweight − GutWeight − Gonadweight (g).
- LogSomaW: Natural log-transformed somatic body weight.
- LogGW: Natural log-transformed gonad weight.
- LogSL: Natural log-transformed standard length.
- RTM: Relative testis mass, calculated as the residual from the linear mixed model (LogGW = −1.7523 + 0.7367 × LogSomaW).
- Sperm.morph: Indicates whether sperm morphology was measured (Y = yes, N = no).
- Sperm.speed: Indicates whether sperm velocity was measured (Y = yes, N = no).
File: Sperm_morphological_data.csv
Description:
Variables
- No: Measurement number assigned to each sperm cell.
- PictureNo: Image file name (in Japanese romaji) from which the sperm was measured.
- SpermNo: Identifier for each sperm within a given image.
- Scientific_name: Scientific name of the species.
- RepSystem: Fertilization mode (1NonCop=External fertilization, 2Cop= Internal fertilization and internal gametic association).
- S.C.level: Estimated level of sperm competition (0L = Low, 1M = Medium, 2H = High).
- Group: Group of closely related species with contrasting fertilization modes.
- IndID: Individual ID from which the sperm was sampled.
- SpermLength: Total length of the sperm cell (µm).
- HeadLength: Length of the sperm head region (µm).
- HeadWidth: Width of the sperm head region (µm).
- MPLength: Length of the midpiece region (µm).
- MPWidth: Width of the midpiece region (µm).
- FlagellaLength: Length of the flagellum (µm).
- Missing data: NA
File: Sperm_speed_data.csv
Description:
Variables
- No.: Measurement number assigned to each sperm cell.
- PictureNo: Image file name (in Japanese romaji) used for sperm tracking.
- SpermNo: Identifier for each sperm within a given image.
- Scientific_name: Scientific name of the species.
- Group: Group of closely related species with contrasting fertilization modes.
- RepSystem: Fertilization mode (1NonCop=External fertilization, 2Cop= Internal fertilization and internal gametic association).
- S.C.level: Estimated level of sperm competition (0L = Low, 1M = Medium, 2H = High).
- IndID: Individual ID from which the sperm was sampled.
- Speed: Sperm velocity (µm/s).
File: Sperm_variation_analyses_Dryad.R
Description: This R script performs Bayesian phylogenetic mixed modeling using the MCMCglmm package to analyze variation in sperm traits within and among males. The script includes steps for model fitting, diagnostics, and figure generation used in the main analyses.
File: Sperm_variation_analyses_loop_processing_Dryad.R
Description: This R script extends the main analysis by implementing a loop-based procedure to systematically apply the MCMCglmm modeling framework to morphological sperm traits. It automates statistical model fitting and graphical output for comparative trait analysis.
File: chimera.nwk
Description: Phylogenetic tree of 11 species used in the Bayesian phylogenetic mixed model implemented in the R script.
Code/software
The data and analyses in this submission can be fully accessed and reproduced using free and open-source software, specifically the R statistical environment.
R (version 4.2.2 or higher recommended). Free software for statistical computing and graphics.
RStudio (optional but recommended). A free integrated development environment (IDExcel) for
Microsoft Excel- For handling .csv files.