Parasitic Manipulations of the Host Phenotype: Effects in Internal and External Environments

Abstract

Parasites can influence their hosts in various ways. When a parasite changes the phenotype of its host to increase its own fitness, it is called parasitic manipulation of host phenotype. Perhaps, not all parasites are manipulators, but manipulations are undoubtedly a widespread natural phenomenon and well-established scientific concept. Parasites can manipulate the host phenotype to ensure their additional safety within the host body, create optimal conditions for their growth and development, and promote transmission from one host to another. Parasitic manipulative strategies are highly diverse and tightly connected with the parasite’s life cycle. The review gives insight into the most common types of manipulative strategies and discusses (i) the evolutionary advantages of these strategies, (ii) why some strategies are more common than others, and (iii) how manipulative strategies change in the course of parasite growth and development. Recently, it has become clear that parasitic manipulations can be an important factor influencing the relationships in both the parasitic infracommunity within the host and the ecosystem in general. The last two sections of the review describe the conflicts and cooperation within the parasitic infrapopulation and the role of parasitic manipulations in ecosystems. The review concludes with a short, imaginary journey into the future that discusses how climate change may influence the role of parasites and their manipulations in the ever-changing environment.