DOI: 10.5061/dryad.8p502cr
title: Data from: The effects of male age, sperm age and mating history on ejaculate senescence

description: 1. In polyandrous species, a male's reproductive success depends on
 his ability to fertilize females which, in turn, depends on his mating
 ability and his ability to produce competitive ejaculates. In many
 species, sperm traits differ between old and young males in ways that are
 likely to decrease the sperm competitiveness and fertility of older males.
 This age-ejaculate quality relationship is attributed to male ageing (i.e.
 senescence). 2. In a natural setting, male age and mating history are
 usually confounded: older males have usually mated and replenished their
 sperm supplies more often, so they have made a greater lifetime
 reproductive effort. In principle, the costs of reproduction, independent
 of any causal effect of male age, could generate an age-related decline in
 ejaculate quality. 3. To date, only a handful of studies have determined
 how male age, reproductive effort, or their interaction affect ejaculate
 quality. Here, we experimentally manipulated the long-term mating history
 of 209 adult male mosquitofish (Gambusia holbrooki) over 14 weeks (N =
 1118 sperm samples). Males either had direct access to females and could
 mate freely; or had only visual and olfactory access to females. We
 documented the effect of mating history, adult male age (3, 9, and 14
 weeks post-maturation) and their interaction on sperm velocity, sperm
 reserves, and the rate of sperm replenishment. For sperm velocity we
 additionally examined the effects of sperm age, because when older males
 mate less (or more) often than younger males there will be a correlation
 between mean sperm age and male age. 4. Sexually active males produced
 fewer sperm, replenished their sperm at a lower rate, and their sperm had
 lower velocity than males prevented from mating. Though older males
 produced more sperm, the rate of replenishment and velocity of their sperm
 was lower than the sperm of younger males. We also tested for a difference
 in the velocity of recently replenished (&lt;24h) and older sperm
 (i.e. post-meiotic sperm senescence). There was no evidence that male age
 or mating history affect the extent of sperm senescence, but older sperm
 swam faster than recently produced sperm. Crucially, complex interactions
 are evident between male age and male mating history with respect to sperm
 number and the proportion of sperm that are replenished. 5. These results
 suggest that male age and mating history will interact to determine the
 reproductive success of a male under sperm competition. They reveal a
 complex relationship between a male’s age and his ejaculate quality. We
 suggest that both mating history and sperm age should be controlled for
 when measuring the intrinsic rate of senescence for male reproductive
 traits if the goal is to isolate effects that are solely attributable to a
 male’s chronological age.
description: Data for The effects of
 male age, sperm age and mating history on ejaculate
 senescenceThe first sheet provides
 data on body size measurements, the second sheet provides information on
 the labels for the body size measurements. The third sheet provides data
 on sperm traits used for the paper, the fourth sheet provides information
 on the labels for the sperm measurements.Vega Trejo et al 2019 Func Ecol
 Dryad.xls