DOI: 10.5061/dryad.kr137
title: Data from: Sperm competition risk drives rapid ejaculate adjustments mediated by seminal fluid

description: In many species, males can make rapid adjustments to ejaculate performance
 in response to sperm competition risk; however, the mechanisms behind
 these changes are not understood. Here, we manipulate male social status
 in an externally fertilising fish, chinook salmon (Oncorhynchus
 tshawytscha), and find that in less than 48 hr, males can upregulate sperm
 velocity when faced with an increased risk of sperm competition. Using a
 series of in vitro sperm manipulation and competition experiments, we show
 that rapid changes in sperm velocity are mediated by seminal fluid and the
 effect of seminal fluid on sperm velocity directly impacts paternity share
 and therefore reproductive success. These combined findings, completely
 consistent with sperm competition theory, provide unequivocal evidence
 that sperm competition risk drives plastic adjustment of ejaculate
 quality, that seminal fluid harbours the mechanism for the rapid
 adjustment of sperm velocity and that fitness benefits accrue to males
 from such adjustment.
description: Comparing sperm velocity
 and sperm concentration in males of different social status at each stage
 of the experimentThis file contains data
 used to compare ejaculate parameters between dominant and subdominant
 males at the same stage of the experiment. Sperm concentration and
 velocity measurements for male chinook salmon taken at both stages of a
 two-stage social manipulation experiment. Social dominance was determined
 within each pair using video recordings of aggressive behavior. Sperm
 concentration was measured using a haemocytometer. Sperm velocity was
 measured using Computer Assisted Sperm Analysis.Assessing the change in
 sperm velocity and sperm concentration in the same males between stage 1
 and 2 of the experimentThis file contains data
 used to assess the change in ejaculate parameters from stage 1 to stage 2
 of the experiment within males of the same social status group. Sperm
 concentration and velocity measurements for male chinook salmon taken at
 both stages of a two-stage social manipulation experiment. Social
 dominance was determined within each pair using video recordings of
 aggressive behavior. Sperm concentration was measured using a
 haemocytometer. Sperm velocity was measured using Computer Assisted Sperm
 Analysis.Measuring change in
 sperm velocity for sperm incubated in their own seminal fluid vs rivals
 seminal fluidChinook salmon
 ejaculates were experimentally manipulated, separating sperm from seminal
 fluid and then recombining sperm with either seminal fluid from the same
 male or from a rival male. Ejaculates were collected from male chinook
 salmon taken at both stages of a two-stage social manipulation experiment.
 Social dominance was determined within each pair using video recordings of
 aggressive behavior. Sperm velocity was measured using Computer Assisted
 Sperm Analysis.Measuring change in VAP for
 sperm incubated in their own seminal fluid vs rivals seminal
 fluid.xlsxComparing fertilisation
 success for males of different social status and across seminal fluid
 treatmentsSperm competition trials
 were conducted, each trial using a single female and two male chinook
 salmon from a two-stage social manipulation experiment. Trials were also
 conducted using two seminal fluid treatments, (1) milt was unmanipulated,
 (2) seminal fluid was switched between the males in each trial. This data
 file contains sperm velocity measurements and paternity share data for
 each male. The paternity share of each male was determined using
 mircosatellite loci. Social dominance was determined within each pair
 using video recordings of aggressive behavior. Sperm concentration was
 measured using a haemocytometer. Sperm velocity was measured using
 Computer Assisted Sperm Analysis.