Advanced paternal age has been repeatedly shown to modulate offspring quality via male- and/or female-driven processes, and there are theoretical reasons to expect that some of these effects can be sex-specific. For example, sex allocation theory predicts that, when mated with low-condition males, mothers should invest more in their daughters compared to their sons. This is because male fitness is generally more condition-dependent and more variable than female fitness, which makes it less risky to invest in female offspring. Here, we explore whether paternal age can affect the quality and quantity of offspring in a sex-specific way using Drosophila melanogaster as model organism. In order to understand the contribution of male-driven processes on paternal age effects, we also measured the seminal vesicle size of young and older males and explored its relationship with reproductive success and offspring quality. Older males had lower competitive reproductive success, as expected, but there was no difference between the offspring sex ratio of young and older males. However, we found that paternal age caused an increase in offspring quality (i.e., offspring weight), and that this increase was more marked in daughters than sons. We discuss different male- and female-driven processes that may explain such sex-specific paternal age effects.

Data for the manuscript accepted in Journal of Evolutionary Biology titled as: "Sex-specific paternal age effects on offspring quality in Drosophila melanogaster".

In the Paternal_age_LH.csv file the variables for life history traits are as follows: isoline (the code of the isoline), sex (offspring sex), timing (i.e., paternal age; early/young, late/older), offspring weight (mg), sv_size (the size of seminal vesicles, µm²), rs (reproductive success) and sv_size_dif (difference in the size of the seminal vesicles, late-early).

In the Paternal_age_SR.csv file variables are as follows: isoline (the code of the isoline), phenotype (eye phenotype of the offspring: sparkling poliert or wild-type/DGRP), timing (i.e., paternal age; early/young, late/older), sex_ratio (proportion of male offspring to total number of offspring) and productivity (calculated as the total number of offspring).

The Weight_raw.csv file contains the following variables: isoline (the code of the isoline), sex (offspring sex), timing (i.e., paternal age; early/young, late/older), replicate (per isoline) and offspring weight (mg).

Finally, the Offspring_raw.csv file contains the following variables: isoline (the code of the isoline), sex (offspring sex), timing (i.e., paternal age; early/young, late/older), phenotype (eye phenotype of the offspring: sparkling poliert or wild-type/DGRP), replicate (per isoline) and offspring (number of offspring).

The SV_examples.rar file consists of three representatives images of the seminal vesicle size of each paternal age (young and older males).