10.5061/DRYAD.R3206
Vanthournout, Bram
Aarhus University
Busck, Mette Marie
Aarhus University
Bechsgaard, Jesper
Aarhus University
Hendrickx, Frederik
Royal Belgian Institute of Natural Sciences
Schramm, Andreas
Aarhus University
Bilde, Trine
Aarhus University
Data from: Male spiders control offspring sex ratio through greater
production of female-determining sperm
Dryad
dataset
2018
Stegodyphus dumicola
Social spider
Sperm
sex allocation
Stegodyphus mimosarum
Stegodyphus africanus
2018-02-27T15:27:14Z
2018-02-27T15:27:14Z
en
https://doi.org/10.1098/rspb.2017.2887
7428924 bytes
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CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Sex allocation theory predicts that when sons and daughters have different
reproductive values, parents should adjust offspring sex ratio towards the
sex with the higher fitness return. Haplo-diploid species directly control
offspring sex ratio, but species with chromosomal sex determination (CSD)
were presumed to be constrained by Mendelian segregation. There is now
increasing evidence that CSD species can adjust sex ratio strategically,
but the underlying mechanism is not well understood. One hypothesis states
that adaptive control is more likely to evolve in the heterogametic sex
through a bias in gamete production. We investigated this hypothesis in
males as the heterogametic sex in two social spider species that
consistently show adaptive female biased sex ratio and in one subsocial
species that is characterised by equal sex ratio. We quantified the
production of male (0) and female (X) determining sperm cells using flow
cytometry, and show that males of social species produce significantly
more X-carrying sperm than 0-sperm, on average 70%. This is consistent
with the production of more daughters. Males of the subsocial species
produced a significantly lower bias of 54% X-carrying sperm. We also
investigated whether inter-genomic conflict between hosts and their
endosymbionts may explain female bias. Next generation sequencing showed
that five common genera of bacterial endosymbionts known to affect sex
ratio are largely absent, ruling out that endosymbiont bacteria bias sex
ratio in social spiders. Our study provides evidence for paternal control
over sex allocation through biased gamete production as a mechanism by
which the heterogametic sex in CSD species adaptively adjust offspring sex
ratio.
Supplementary Information sperm scatter plotsThis supplementary excel file
presents the raw data of the flow cytometry analysis. Every worksheet
represents one sperm sample that is named according to sample names in
table S1. Within a worksheet the original and corrected scatterplots can
be found, together with the output of the normalmixEM function in R.