Life history strategies often shape biological interactions by specifying the parameters for possible encounters, such as the timing, frequency or way of exposure to parasites. Consequentially alterations in life history strategies are closely intertwined with such interaction processes. Understanding the connection between life history alterations and host-parasite interactions can therefore be important to unveil potential links between adaptation to environmental change and changes in interaction processes. Here we studied how two different host-parasite interaction processes, oral and haemocoelic exposure to bacteria, affect various life histories of the Glanville fritillary butterfly Melitaea cinxia. We either fed or injected adult butterflies with the bacterium Micrococcus luteus and observed for differences in immune defenses, reproductive life histories and longevity, compared to control exposures. Our results indicate differences in how female butterflies adapt to the two exposure types. Orally infected females showed a reduction in clutch size and an earlier onset of reproduction, whereas, a reduction in egg weight was observed for haemocoelically exposed females. Both exposure types also led to shorter intervals between clutches and a reduced life span. These results indicate a relationship between host-parasite interactions and changes in life history strategies. This relationship could cast restrictions on the ability to adapt to new environments, and consequentially influence the population dynamics of a species in changing environmental conditions.

1a_OralExposure_GeneExpressionRaw gene expression values for oral exposure for the selected genes of interest and three reference genes.The file additionally contains measurements for male butterflies, which were not used in the publication.1b_OralExposure_EncapsulationCalculated grey values of the inserted nylon filaments for encapsulation measurements after oral exposure.1c_OralExposure_ReproductionMeasurements of life history traits after oral exposure.1d_OralExposure_LifespanSurvival after oral exposure.2a_HaemExposure_GeneExpressionRaw gene expression values for haemocoelic exposure for the selected genes of interest and three reference genes.The file additionally contains measurements for male butterflies, which were not used in the publication.2b_HaemExposure_EncapsulationCalculated grey values of the inserted nylon filaments for encapsulation measurements after haemocoelic exposure.2c_HaemExposure_ReproductionMeasurements of life history traits after haemocoelic exposure.2d_HaemExposure_LifespanSurvival after haemocoelic exposure.Analysis Script (R markdown)R markdown script for the data analysis. To run the script, the data files 1a-1d & 2a-2d need to be located in the same folder as this script.AnalysisV3.RmdAnalysis Script (rendered)Rendered output for the data analysis.AnalysisV3.html