Cryptic male choice: experimental evidence of sperm sex ratio and seminal fluid adjustment in relation to coital rate
journal contribution
posted on 2023-05-19, 06:30authored byEdwards, AM, Elissa Cameron
The differential allocation hypothesis suggests that a mother should adjust the sex of offspring in relation to her mate’s attractiveness, thereby increasing future reproductive fitness when her sons inherit the attractive traits. More attractive males have been shown to sire more sons, but it is possible that the sex ratio skew could be a result of paternal rather than maternal manipulation, which would be a more parsimonious explanation. We manipulated coital rate (an indicator of attractiveness) in laboratory mice and showed that males that mate more often have higher levels of glucose in their semen despite lower blood glucose levels. Since peri-conceptual glucose levels in utero increase male conceptus survival, this could result in male-biased sex ratios. The males that mated most also had more remaining X-chromosome-bearing-spermatozoa, suggesting depletion of Y-chromosome-bearing-spermatozoa during mating. We hypothesise that males may alter both seminal fluids and X : Y ratios in an ejaculate to influence subsequent sex ratios. Our results further support a paternal role in sex allocation.
Funding
Australian Research Council
History
Publication title
Reproduction, Fertility and Development
Volume
29
Pagination
1401-1404
ISSN
1031-3613
Department/School
College Office - College of Sciences and Engineering
Publisher
CSIRO Publishing
Place of publication
150 Oxford St, Po Box 1139, Collingwood, Australia, Victoria, 3066