Reproductive output of old males is limited by seminal fluid, not sperm number

Male reproductive senescence is typically characterised by a decline in the number of sperm produced and transferred by old males, a phenomenon that may be exacerbated in polygynous species where males mate-multiply. However, males also transfer seminal fluid to females, and little is known about its role in modulating male reproductive senescence. Here, we explore the contributions of sperm and seminal fluid towards male reproductive senescence in a series of sequential matings, using Drosophila melanogaster. As expected, old males produce fewer offspring than young males. However, this pattern is not driven by sperm limitation: old males have more sperm and transfer similar numbers to females, compared to young males. Instead, females storing fewer sperm of old males compared to that of young males, over a long-term, drives male reproductive senescence. We are able to mitigate the age-related decline in male reproductive output by supplementing females with the seminal fluid of a youn..., We conducted experiments and colelcted data directly through observations., , # Reproductive output of old males is limited by seminal fluid, not sperm number

Note: In the dataset, the labels for Experiment ID are contrasting the paper: in the dataset, Experiment B is actually experiment C from the paper, and experiment C in the dataset is experiment B in the paper.

[https://doi.org/10.5061/dryad.mpg4f4r99](https://doi.org/10.5061/dryad.mpg4f4r99)

## Description of the data and file structure

1\. BG.csv : csv data file for plotting batemans’s gradient in R code

2\. Stripping simple.rmd: R code needed to run all analysis (all data provided on OSF)

3\. Stripping: data from experiments A and C on reproductive output

4\. gfp_f.csv : data on sperm numbers inside females after dissection of females, to be used in R code. Also has data on the numbers of offspring produced by females over 24 hours of egg laying, in a male’s mating sequence, for experiment B.

5\. gfp_m.csv : data on sperm numbers inside male SV and size of male Accessory glands...