Data from: Male sperm storage compromises sperm motility in guppies

Sperm senescence can have important evolutionary implications due to its
deleterious effects on sperm quality and offspring performance.
Consequently, it has been argued that polyandry (female multiple mating)
may facilitate the selection of younger, and therefore competitively
superior, sperm when ejaculates from multiple males compete for
fertilization. Surprisingly, however, unequivocal evidence that sperm
ageing influences traits that underlie sperm competitiveness is lacking.
Here, we used a paired experimental design that compares sperm quality
between ‘old’ and ‘young’ ejaculates from individual male guppies
(Poecilia reticulata). We show that older sperm exhibit significant
reductions in sperm velocity compared with younger sperm from the same
males. We found no evidence that the brightness of the male's orange
(carotenoid) spots, which are thought to signal resistance to oxidative
stress (and thus age-related declines in sperm fitness), signals a
male's ability to withstand the deleterious effects of sperm ageing.
Instead, polyandry may be a more effective strategy for females to
minimize the likelihood of being fertilized by aged sperm.