Host Energetics Explain Variation in Parasite Productivity across Hosts and Ecosystems

Estimating the magnitude and sensitivity of energy fluxes for stickleback hosts and Schistocephalus solidus parasites using the metabolic theory of ecology

“…Alternatively, since host organisms partition resources to different functions (e.g., growth, reproduction, activity), the worms could be siphoning resources that the stickleback would otherwise invest in growth or reserves without necessitating an increase in the metabolic rate of the fish (e.g., Barber, 2007 ). Furthermore, since hosts with lower metabolic rates have a greater fraction of their energy allocated to parasites (Grunberg & Anderson, 2022 ), retaining a lower metabolic rate even when infected may limit both host losses and parasite infrapopulation growth.…”

“…Mean energy flux of the population can then be estimated as the mean of individuals calculated from Equation (). Alternatively, energy flux at the population level can be calculated as the slope of the linear model $$$ {F}_{\mathrm{p}}\sim {\mathrm{slope}}^{\ast }{R}_{\mathrm{h}} $$$ (Grunberg & Anderson, 2022), where $$$ {F}_{\mathrm{p}} $$$ represents the energy flux of the parasite infrapopulation, and $$$ {R}_{\mathrm{h}} $$$ represents the whole host organism metabolic rate. We compare results from both the individual calculation and the population calculation.…”

“…Alternatively, using energy flux proxies (e.g., biomass) provides a coarse but easily measured estimate of the impact of parasites on ecosystems and hosts (Kuris et al., 2008 ; Mitchell, 2003 ; Paseka, 2017 ). However, there may be mismatches between biomass estimates and actual energy flux (Grunberg & Anderson, 2022 ). A third approach, which promises improved estimates, is to derive parasite energy flux from models of host and parasite energetic outcomes predicted by the metabolic theory of ecology (MTE; Table 1 ; e.g., Brown et al., 2004 ; Gillooly et al., 2001 ; Price et al., 2012 ).…”

Scaling species interactions: implications for community ecology and biological scaling theory

“…Some support for the latter assumption comes from studies documenting negative interspecific relationships between predation intensity and prey body mass [94,68,[150][151][152][153][154] and positive relationships between parasite biomass or intensity (number per host) and host body mass [155][156][157][158]. However, a recent energetic study suggests that eukaryotic parasites may extract a larger fraction of a host's energy budget in small versus large animal hosts [159]. In this section, I also speculate about the potential importance of other kinds of biotic interactions for biological scaling relationships, which I hope will stimulate further research.…”