Transgenerational pathogen effects: Maternal pathogen exposure reduces offspring fitness

Area of Science:

• Ecology
• Evolutionary Biology
• Parasitology

Background:

• Pathogens can influence host phenotypes across generations.
• Transgenerational immune priming is a known phenomenon, but other transgenerational effects exist.
• Microsporidian parasites can impact host life history traits.

Purpose of the Study:

• To investigate the transgenerational impacts of maternal Ordospora pajunii infection on offspring fitness.
• To determine if transgenerational immune priming or tolerance occurs.
• To identify and characterize negative transgenerational effects, termed transgenerational virulence.

Main Methods:

• Experimental measurement of offspring fitness (mortality, growth, reproduction) following maternal exposure to Ordospora pajunii.
• Comparison of offspring from infected versus uninfected mothers, with and without parasite exposure.
• Development of mathematical models to assess population-level impacts of observed transgenerational effects.

Main Results:

• No evidence of transgenerational immune priming or tolerance was found; offspring infection rates and burden were similar between groups.
• Uninfected offspring of infected mothers exhibited significantly higher early-life mortality.
• Offspring of infected mothers showed reduced growth rates, fewer clutches, and lower overall reproductive output.

Conclusions:

• Maternal Ordosporapajunii infection leads to negative transgenerational impacts (transgenerational virulence) on offspring fitness, rather than immune priming.
• Transgenerational virulence reduces host population density, infection prevalence, and infected host density.
• Transgenerational virulence may be a common phenomenon with significant implications for host conservation and disease spillover, warranting further research.