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Contributed Talk

Session: : Parasitism And Host-Parasite Interactions 2

COS 266-2 - Transgenerational Virulence: Maternal pathogen exposure reduced offspring fitness in a Daphnia-Microsporidian system

Thursday, August 10, 2023
10:15 AM – 10:30 AM PDT
Location: D137
Abstract: Virulence, the degree of damage caused by a pathogen, is a topic of intense research interest. However, despite ubiquitous evidence that effects of environmental factors can carry across generations, studies of virulence have been primarily focused within a single generation. We hypothesized that, given the abundant evidence of transgenerational effects of pathogens, parental exposure to a pathogen could result in reduced offspring fitness, which we refer to as transgenerational virulence. To test this, we collected and monitored offspring from unexposed and microsporidian-exposed mother Daphnia, using three different genotypes to give insights into the degree of genetic variation. This pathogen is of relatively low virulence in the mother generation. We found that maternal exposure to the pathogen significantly increased early mortality of unexposed offspring by over 300%. Maternal exposure also altered daughter fecundity; daughters of exposed mothers produced fewer offspring in the first 3 clutches (14.4) than daughters of unexposed mothers (23.2). These effects carried to the granddaughters, which were smaller if the grandmother had pathogen exposure. Notably, here we show impacts of pathogen exposure as mothers were exposed, not yet infected, at the time of gestation. Moreover, while there were some differences among genotypes, the overall pattern of transgenerational virulence was consistent. Thus, our work adds to evidence that virulence costs may start accumulating upon exposure and extends this to show those impacts can span generations. Given widespread prior evidence for transgenerational effects of predators, resources, and pathogens, we propose that transgenerational virulence may be common and has the potential to be ecologically important.