Data from: Sperm as a speciation phenotype in promiscuous songbirds
Data files
Oct 23, 2024 version files 472.27 KB
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20pairs.nex
4.48 KB
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40populations.nex
8.06 KB
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Data20pairs.txt
2.54 KB
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Passerinetree_Jetz.tre
278.64 KB
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RawData20pairs.xlsx
146.81 KB
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README.md
1.64 KB
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RelTestisSize_data.txt
11.28 KB
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RelTestisSize_EPY_66species.txt
2.73 KB
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SpermDivergence.R
14.29 KB
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SpermmeansSD.txt
1.80 KB
Oct 28, 2024 version files 472.53 KB
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20pairs.nex
4.48 KB
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40populations.nex
8.06 KB
-
Data20pairs.txt
2.54 KB
-
Passerinetree_Jetz.tre
278.64 KB
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RawData20pairs.xlsx
146.81 KB
-
README.md
1.84 KB
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RelTestisSize_data.txt
11.28 KB
-
RelTestisSize_EPY_66species.txt
2.73 KB
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SpermDivergence.R
14.34 KB
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SpermmeansSD.txt
1.80 KB
Abstract
The paper compares 20 population pairs of Passerida songbirds and shows that their rate of divergence in sperm length was positively associated with the level of female promiscuity (expressed by the proportion of offspring sired by extrapair males). The effect was largely caused by a reduced population variance in sperm length in more promiscuous species. The paper suggests that rapid sperm length divergence can promote postcopulatory prezygotic isolation and hence rapid speciation in promiscuous songbirds.
README: Data from: Sperm as a speciation phenotype in promiscuous songbirds
The data files and the associated .R script were used in the statistical tests and result presentations in the paper "Sperm as a speciation phenotype in promiscuous songbirds" and its Supplementary Material (Table S1 and Table S2).
Data files
RawData20pairs.xlsx: Raw data for each population with source information of the sperm length measurements, and the calculation of Hedges' g for each population pair.
20pairs.nex: Time-calibrated phylogeny for the 20 species pairs used in PGLS analyses. Can be visualized with the FigTree software (http://github.com/rambaut/figtree/).
40populations.nex: Time-calibrated phylogeny for the 40 populations with their within-pair divergence time. The phylogeny was visualized in Figure 2 (left panel) in the paper, using the FigTree software (http://github.com/rambaut/figtree/).
Passerinetree_Jetz.tre: Consensus tree of passerine birds derived from BirdTree.org (Jetz et al. 2012).
Data20pairs.txt: data used for the main analyses in the paper
SpermmeansSD.txt: data used to calculate the overlap coefficient for sperm length distributions of each population pair.
RelTestisSize_data.txt: data used to calculate the PGLS regression between testes mass and body mass for 160 passerine species.
RelTestisSize_EPY_66species.txt: data used to calculate a predicted EPY rate from relative testes mass for 3 species.
Analytical code
SpermDivergence.R: the R script used for data processing, statistical analyses and figure construction.
The script has undergone a slight revision regarding the code for the construction of the horizontal boxplot in Figure 2. The change was purely cosmetic and did not affect any data or analytical results.
Methods
Population pairs had estimates of total sperm length from minimum six males in each population, a published estimate of their divergence time using a molecular clock model, and an estimate of the proportion of extrapair young (EPY) for the actual populations or a population in the species complex. The two populations were either of the same taxonomic subspecies, different subspecies of the same species, or congeneric species with a known hybrid zone. Maximum divergence time was 2.41 million years since last common ancestor. For three population pairs, EPY was estimated from relative testes mass (no paternity studies known).
Sperm length data were extracted from raw data in published studies or from the database of the Avian Sperm Collection at the Natural History Museum, University of Oslo (Lifjeld 2019). In some cases, data from published studies were extended with additional unpublished data from the same study populations available in the museum’s database. As a standard, ten or more sperm cells were measured by light microscopy from formalin-fixed ejaculates to calculate the mean sperm length for each male (Grønstøl et al. 2023). Each mean value was log-transformed. From these log-means we calculated mean sperm length and the standard deviation for each population. Sperm length divergence was expressed in Hedges' g (Hedges 1981). We also calculated an overlap index for the sperm length distributions.
References:
Grønstøl, G., Danielsen, M., Cramer, E. R. A., Johannessen, L. E., Johnsen, A., Whittington, E., & Lifjeld, J. T. (2023). Effects of fixatives and storage duration on avian sperm morphology. Journal of Ornithology, 164(1), 171-181. doi:10.1007/s10336-022-02015-x
Hedges, L. V. (1981). Distribution theory for Glass's estimator of effect size and related estimators. Journal of Educational Statistics, 6(2), 107-128. doi:10.3102/10769986006002107
Jetz, W., Thomas, G. H., Joy, J. B., Hartmann, K., & Mooers, A. O. (2012). The global diversity of birds in space and time. Nature, 491(7424), 444-448. doi:10.1038/nature11631
Lifjeld, J. T. (2019). The avian sperm collection in the Natural History Museum, University of Oslo. Alauda, 87(3), 93–101.