Host manipulation by parasitesDavid P.Hughes, JacquesBrodeur, and FrédéricThomas, eds Oxford University Press, UK

The book is a beautiful combination of expert thinking and knowledge on parasites exploiting multicellular host individuals, populations, societies and communities, as their ecosystem.The book comprises eleven chapters by expert behavioural ecologists as main authors, each one appended by an afterword from a nonbehavioural ecologist, a briefer reflection on the main authors' treatment.Reading this book can entertain any biologist's curiosity for the ubiquitous phenomenon of parasitism, and especially animal behaviour manipulation by microbial or animal parasites.I would recommend it or at least parts of it as reading to undergraduates taking introductory zoology, or as a main source for graduates in ecology, evolutionary biology, animal parasitology, medical and veterinary sciences, and biodiversity conservation.In the book foreword, Dawkins reminds us of his extended phenotype paradigm, which sets the host organism from the evolutionary viewpoint of the parasite: the parasitized host phenotype is 'bended to a direction hostile to the host's own genes'.But hostility varies widely across parasitic phenomena from negligible or benign, to stressful but tolerable (reduced growth and reproduction), and in extreme cases to host suppression either reproductively or completely (death) thus freeing the parasite into a dispersal stage.Parasitism is most intricate for multi-host parasites with complex cycles whose final (reproductively) host is a predator.The life style of Dawkins' Verticobacter seems to match that of Toxoplasma gondii in its parasitic relation to humans (see Chap 10, and below).As opposed to its lifestyle in primary host rodents, Toxoplasma in humans seems not to trouble with sex, its persistence being delegated to our viviparous reproduction ensuring direct continuity between mother and infant as successive hosts in the parasite's life.In Chapter 1, Moore tells us an informative story of how and when traditional parasitology recently became 'cool' or popular.Parasites at a node point of their cycle and making their host especially appealing to a predator were thought of as manipulators well before the 'cool age' (Moore cites Siebold 1853 on mode of transfer of Leuchochloridium to its next host).Like for other organisms, there is no goal or direction in parasite evolution.Thus, there is no support for benign parasites consistently emerging from brutal ancestors.A pattern with more sup-port is that relatively small parasites, which reproduce in the host, are selected more rapidly and evolve more often to sympatric speciation.Compilations by Moore indicate that parasites and their altered hosts became popular in the late 1900's, following the birth of many ecology journals.Moore reviews altered host behaviours that do not benefit parasites, such as vertebrate avoidance/defence against biting flies, self-medication and grooming, anorexia, sleep and 'depression' redirecting host resources to combat pathogens and ectotherms' behavioural fever with similar effects.Moore says we must thank behavioural ecologists for revealing the 'cool side' of parasites that make their hosts behave strangely.Part of Moore's expos e tells us of the many scientist women who have been leaders in parasitology, including 'cool' aspects such as induced host suicide as a key event in parasite transmission to predators, and the role of parasitism in sexual conflict (mate choice).Afterword author Alcock also praises the contribution of behavioural ecology to parasitology, pointing out the very productive and influential idea that female mate choice (in e.g.birds), may have evolved because of variable susceptibility to parasites among males.In reviewing evolutionary routes to manipulation in Chapter 2, Thomas, Rigaud and Brodeur consider two scenarios of parasitized host behaviour evolution, that is, parasite-driven (most studies) and host-driven, for example compensatory foraging or mating.As parasites first evolved from free-living ancestors, the second scenario seems more likely.Ancestral parasites were probably surviving and exploiting abundant resources in the digestive, aerial, or coelomic body cavities of accidental hosts.As pointed out, enhanced naturally iterative host behaviours such as sex and foraging can benefit fitness of both host and parasite, as demand-driven compensating behaviours.When even brief parasitism allows parasite survival and growth or reproduction, traits favouring parasitism durability and fixation, including host manipulative traits, are strongly selected.Interactive manipulation should persist as a 'cool' topic in parasitology, as parasitized hosts are relatively easy to observe, although they are in fact complex evolving units with intraspecific variability arising at multiple levels between genomes, species stages, sexes and morphs of the hosts and parasites.

Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.