Experimental Evolution of Adaptive Phenotypic Plasticity in a Parasite

Abstract

Coinfection of parasite genotypes can select for various changes in parasite life history strategies relative to single genotype infections, with consequences for disease dynamics and severity. However, even where coinfection is common, a parasite genotype is also likely to regularly experience single genotype infections over relatively short periods of evolutionary time, due to chance, changes in local disease transmission, and parasite population structuring. Such alternating conditions between single genotype and coinfections will impose conflicting pressures on parasites, potentially selecting for facultative responses to coinfection. Although such adaptive phenotypic plasticity in response to social environment has been observed in protozoan parasites and viruses, here we show it evolving in real time in response to coinfection under conditions in which both single infections and coinfections are common. We experimentally evolved an obligate-killing virus under conditions of single virus infections (single lines) or a mix of single infections and coinfections (mixed lines) and found mixed lines to evolve a plastic lysis time: they killed host cells more rapidly when coinfecting than when infecting alone. This behavior resulted in high fitness under both infection conditions. Such plasticity has important consequences for the epidemiology of infectious diseases and the evolution of cooperation.

Evolution of Plastic Transmission Strategies in Avian Malaria

“…In spite of these costs, phenotypic plasticity is often viewed as an adaptation to variable environments [24], [25]. Many pathogens have indeed evolved an unparalleled level of phenotypic plasticity in their life history traits to cope with the temporal variability of their habitat [26]–[28]. In Plasmodium , plasticity has been shown to be a response to various stressful conditions such as drug treatment and the presence of competitors [29], [30].…”

Baculovirus infection triggers a positive phototactic response in caterpillars: a response to Dobson et al . (2015)

“…Virulence (which determines time to death) is a key parasite life-history trait, and its importance is extremely well documented (e.g. [20][21][22][23]). We do not expect this to be different in the context of parasite-mediated host manipulation, especially considering how well-timed the observed manipulation is (i.e.…”

Intensive aquaculture selects for increased virulence and interference competition in bacteria

“…The within-host competitive interactions have been traditionally linked to virulence via faster growth of more virulent parasite strains, which is expected to influence dynamics of disease epidemics [1,2,[9][10][11][12][13][14]. However, bacterial interactions towards each other are mainly negative [15].…”