Temperature and pathogen exposure act independently to drive host phenotypic trajectories

Area of Science:

• Ecology
• Evolutionary Biology
• Environmental Science

Background:

• Natural populations face increasing thermal stress and disease outbreaks.
• Understanding the interaction of these stressors is crucial for predicting population persistence.
• Generalizable predictions are challenging due to diverse traits affected by both stressors.

Purpose of the Study:

• To investigate the interactive effects of temperature and pathogen exposure on host phenotypes.
• To determine how these stressors shape multivariate host phenotypic trajectories in Daphnia magna.

Main Methods:

• Utilized Daphnia magna as the host model.
• Introduced the bacterial pathogen Pasteuria ramosa.
• Assessed phenotypic shifts under varying temperature and pathogen exposure conditions.

Main Results:

• Temperature and pathogen exposure acted largely independently on host phenotypes.
• Increased temperature favored early development and higher population growth rates.
• Pathogen exposure reduced lifetime fecundity, impacting reproductive potential.

Conclusions:

• Under mild thermal stress, temperature increases may not worsen pathogen impacts on host life-history traits.
• Conversely, pathogen exposure may not exacerbate thermal stress effects on host performance.
• These findings offer insights into host-stressor interactions in natural populations.