The Adaptiveness of Host Behavioural Manipulation Assessed Using Tinbergen's Four Questions.

Host organisms show altered phenotypic reactions when parasitised, some of which result from adaptive host manipulation, a phenomenon that has long been debated. Here, we provide an overview and discuss the rationale in distinguishing adaptive versus nonadaptive host behavioural manipulation. We discuss Poulin's criteria of adaptive host behavioural manipulation within the context of Tinbergen's four questions of ethology, while highlighting the importance of both the proximate and evolutionary explanations of such traits. We also provide guidelines for future studies exploring the adaptiveness of host behavioural manipulation. Through this article, we seek to encourage researchers to consider both the proximate and ultimate causes of host behavioural manipulation to infer on the adaptiveness of such traits. Host manipulation has evolved as a primary life history strategy in all major parasitic lineages, and its adaptive significance is well established. Although adaptiveness is an evolutionary concept, the complexity of analysing the evolutionary parameters of a manipulative trait has given rise to an ongoing debate on the criteria of adaptive host manipulation. The importance of both proximate and ultimate mechanisms for inferring the adaptiveness of host manipulation is discussed by reviewing Poulin's criteria considering Tinbergen's four questions of ethology. There are important parallels between Tinbergen's four questions and Poulin's criteria of adaptive host behavioural manipulation, from an ethological perspective. Their one-to-one analysis provides deeper insights into the importance of both proximate and ultimate mechanisms of adaptive host behavioural manipulation. [ABSTRACT FROM AUTHOR]