American Society of Naturalists

A membership society whose goal is to advance and to diffuse knowledge of organic evolution and other broad biological principles so as to enhance the conceptual unification of the biological sciences.

“Fecundity-longevity trade-off, vertical transmission, and evolution of virulence in sterilizing pathogens”

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Eva Janoušková and Luděk Berec (Jan 2020)

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We for the first time show that the fecundity-longevity trade-off is a relevant player in sterility virulence evolution


Sterilizing pathogens are common, yet studies focused on how such pathogens respond adaptively to fecundity reductions caused to their hosts are rare. Here we assume that the infected hosts, due to redistributing energy resources saved by reduced fecundity, have increased longevity and focus on exploring the consequences of such a fecundity-longevity trade-off on sterility virulence evolution in the pathogens. We find that the trade-off itself cannot prevent evolution of full sterilization. Therefore, we allow for vertical transmission and reveal that the fecundity-longevity trade-off strongly determines the threshold efficiency of vertical transmission above which partial host sterilization evolves. Partial sterilization may appear as an intermediate level of sterility virulence or as a stable dimorphism at which avirulent and highly virulent strains coexist. The fecundity-longevity trade-off significantly contributes to determining the actual outcome, in many cases countering predictions made in the absence of this trade-off. It is known that in well-mixed populations, partial sterilization may evolve in pathogens under a combination of horizontal and vertical transmission. Our study highlights that this is independent of the form of horizontal transmission and the type of density dependence in host demography, and that the fecundity-longevity trade-off is an important player in sterility virulence evolution.