Host manipulation in the face of environmental changes: Ecological consequences

Abstract

Several parasite species, particularly those having complex life-cycles, are known to induce phenotypic alterations in their hosts. Most often, such alterations appear to increase the fitness of the parasites at the expense of that of their hosts, a phenomenon known as “host manipulation”. Host manipulation can have important consequences, ranging from host population dynamics to ecosystem engineering. So far, the importance of environmental changes for host manipulation has received little attention. However, because manipulative parasites are embedded in complex systems, with many interacting components, changes in the environment are likely to affect those systems in various ways. Here, after reviewing the ecological importance of manipulative parasites, we consider potential causes and consequences of changes in host manipulation by parasites driven by environmental modifications. We show that such consequences can extend to trophic networks and population dynamics within communities, and alter the ecological role of manipulative parasites such as their ecosystem engineering. We suggest that taking them into account could improve the accuracy of predictions regarding the effects of global change. We also propose several directions for future studies.

Thermal Change and the Dynamics of Multi-Host Parasite Life Cycles in Aquatic Ecosystems

“…Thermal regimes can also interact with the behavior of host organisms to generate infection phenotypes that influence the dynamics of parasite life cycles ( Labaude et al 2015 ). For example, in some instances, infected hosts are known to select thermal regimes that negatively impact the development of their parasites (e.g., behavioral fevers/behavioral chills; Moore 2002 ; Moore and Freehling 2002 ), and/or aid recovery from parasitic infections.…”

“…More generally, altered thermal environments that affect the developmental rates of manipulative parasites (section “Development of parasites in intermediate hosts”) have considerable potential to influence the patterns of parasite-induced behavior change that are observed, and where these behaviors influence transmission between successive hosts, life cycle dynamics will inevitably be affected ( Labaude et al 2015 ). Developing a better understanding of how changing environments—including altered thermal regimes—impact the behavioral interactions of hosts should be an important goal of future studies.…”

Magnitude and direction of parasite‐induced phenotypic alterations: a meta‐analysis in acanthocephalans

“…Whether host manipulation is studied from the point of view of its evolutionary routes (Thomas, Rigaud, & Brodeur, 2012), its underlying mechanisms (Perrot‐Minnot & Cezilly, ) or its ecological consequences (Lafferty & Kuris, ; Labaude, Rigaud, & Cézilly, ), an important question is what causes variation at different levels in the magnitude of phenotypic alterations coincidental with infection by manipulative parasites. Variation in the extent of such phenotypic alterations exists both within and among infected individuals in a single host population, as well as among host populations (Thomas et al ., ; Fayard, Cezilly, & Perrot‐Minnot, ) or among host species infected with the same parasite (Gotelli & Moore, ; Bauer et al ., ; Tain, Perrot‐Minnot, & Cezilly, ).…”

Additive effects of temperature and infection with an acanthocephalan parasite on the shredding activity of Gammarus fossarum (Crustacea: Amphipoda): the importance of aggregative behavior

“…In addition, parasites are themselves highly affected by changes in temperature (Marcogliese, 2001;Morley & Lewis, 2014). Although parasites and global warming are likely to have cumulative effects on the role of key species within ecosystems (Lafferty & Kuris, 1999;Labaude et al, 2015a), it is not clear whether such effects would be additive or interactive.…”