DOI: 10.5061/dryad.tdz08kpxz
title: Data from: Host sex modulates the energetics of pathogen proliferation and its dependence on environmental resources

description: Sex differences in immunity are predicted to underlie much of the
 frequently observed sex differences in the prevalence or severity of
 infection. We propose the additional hypothesis that differences in the
 ability of males and females to acquire and use resources will also affect
 how readily a pathogen can convert host energy into transmission stages,
 thereby contributing to sex differences in infection dynamics. To test
 this we manipulated the resource environment of male and female Daphnia
 magna by altering the availability of food and then exposed hosts to a
 bacterial pathogen. We measured the production of transmission spores and
 virulence via the reduction in life span, together with feeding rates and
 changes in mass-independent metabolic rate, as a measure of the intake and
 expenditure of energy during infection. When raised in the presence of
 high resource levels, females more readily allowed for resources in the
 environment to be translated to pathogen exploitation, as represented by
 increased spore production, greater virulence, and higher energy use. In
 contrast, the traits of infected males were robust to changes in resource
 availability. High food availability thus exaggerated the degree of sexual
 dimorphism observed between the sexes. It also modiﬁed the relationship
 between host energy use, virulence, and pathogen spore production for each
 sex. These results suggest that a host’s resource environment can affect
 how a male or female is exploited by a pathogen and may thus be an
 additional factor driving sex-speciﬁc patterns of disease susceptibility
 or severity.
description: The resource acquisition of male and female <em>Daphnia
 magna</em> was manipulated by altering the availability of food, and
 then hosts were exposed to the bacterial pathogen Pasteuria ramosa. Via
 infection trials, traits related to pathogen fitness, such as the
 production of mature transmission spores and virulence, together with
 infection-induced changes in host metabolic rate as a measure of the way a
 host might use and processes energy during infection were measured. In a
 follow-up experiment, we quantiﬁed how differences in energy intake, as
 estimated via feeding trials, might help explain the observed patterns of
 pathogen spore production, virulence, and energy expenditure.
description: <strong>Pathogen proliferation and infection induced
 changes in host traits</strong> The influence of
 host sex and resource availability on: A) the production of transmission
 spores (Transmission_spores); B) virulence as estimated by the reduction
 in host lifespan caused by infection (Reduction_lifespan); and relative to
 controls, C) the change in host body size caused by infection
 (Change_bodysize); and, D) the increase in mass-independent metabolic rate
 of the host following infection (Rel_residual_mr).  
 infection-induced-changes-data-dryad.csv
 <strong>Response surface data</strong>
 Data describing how the standardised reduction in host lifespan
 caused by the pathogen (Zvirulence) and the standardised increase in
 mass-independent host metabolic rate following infection (Zrel_resid_mr)
 predict relative pathogen spore production (Wspores) for both males and
 females in high and low resource environments.  
 response-surface-data-dryad.csv
 <strong>Feeding rate data</strong>
 Data describing how the influence of host sex, infection
 treatment, and resource availability on feeding rates. 
 feeding-data-dryad.csv