Antagonistic coevolution limits population persistence of a virus in a thermally deteriorating environment

Abstract

Understanding the conditions under which rapid evolutionary adaptation can prevent population extinction in deteriorating environments (i.e. evolutionary rescue) is a crucial aim in the face of global climate change. Despite a rapidly growing body of work in this area, little attention has been paid to the importance of interspecific coevolutionary interactions. Antagonistic coevolution commonly observed between hosts and parasites is likely to retard evolutionary rescue because it often reduces population sizes, and results in the evolution of costly host defence and parasite counter-defence. We used experimental populations of a bacterium Pseudomonas fluorescens SBW25 and a bacteriophage virus (SBW25Φ2), to study how host-parasite coevolution impacts viral population persistence in the face of gradually increasing temperature, an environmental stress for the virus but not the bacterium. The virus persisted much longer when it evolved in the presence of an evolutionarily constant host genotype (i.e. in the absence of coevolution) than when the bacterium and virus coevolved. Further experiments suggest that both a reduction in population size and costly infectivity strategies contributed to viral extinction as a result of coevolution. The results highlight the importance of interspecific evolutionary interactions for the evolutionary responses of populations to global climate change.

The probability of evolutionary rescue: towards a quantitative comparison between theory and evolution experiments

“…In general, qualitatively different stresses will be easier to compare by setting each stress level to obtain the same decay rate jr o j, so that the purely demographic impact of each stress is the same. This could be done, for example, with comparisons of multiple versus single antibiotics [41], or biotic versus abiotic stresses [15].…”

“…Usually, however, extinction has been considered as a nuisance in experimental evolution. Only recently, several studies have tackled the challenge of describing the probability of evolutionary rescue, using fastreproducing organisms in microcosms with various stresses causing decline, such as yeast adapting to saline conditions [13,14], virus adapting to high temperature [15], flour beetles adapting to a new host [16,17] or bacteria adapting to antibiotic stress [18]. The study of the emergence of resistance to chemotherapy in microbes also has a very long and fruitful history (reviewed in recent studies [3,19]), which relates directly to evolutionary rescue.…”

Eco-evolutionary feedbacks, adaptive dynamics and evolutionary rescue theory

“…Using experimental populations of a bacterium (Pseudomonas fluorescens) and a bacteriophage, Zhang & Buckling [85] studied how bacterium -virus coevolution impacts viral population persistence in the face of gradually increasing temperature. They garnered evidence that the virus persisted much longer when its infectivity evolved in the presence of an evolutionarily constant host genotype.…”

Experimental evolution can unravel the complex causes of natural selection in clinical infections

“…Similarly, P. fluorescens coevolving with lytic phage gained 10 times more non-synonymous substitutions than control populations evolving without phage and there was little overlap in the sets of mutations selected under these treatments (Scanlan et al, 2015). Indeed, coevolving appears to limit the capacity for abiotic adaptation in both the bacterium (Scanlan et al, 2015) and phage (Zhang & Buckling, 2011).…”