Host Developmental Stage Effects on Parasite Resistance and Tolerance

Area of Science:

• Ecology
• Evolutionary Biology
• Animal Physiology

Background:

• Hosts employ resistance and tolerance to combat parasites.
• Developmental stages can alter host defense strategies due to shifting resource allocation.
• Understanding these dynamics is crucial for host-parasite interaction research.

Purpose of the Study:

• To investigate how developmental stage influences resistance and tolerance in Atlantic salmon (Salmo salar).
• To examine the genetic basis of these defense mechanisms across different life stages.
• To assess the validity of tolerance estimates, particularly in relation to control groups.

Main Methods:

• Experimental exposure of 1-year-old Atlantic salmon (freshwater vs. marine transition stage) to the trematode Diplostomum pseudospathaceum.
• Utilizing 56 pedigreed families and multivariate animal models.
• Comparing tolerance slopes between infected and unexposed control groups based on additive genetic effects.

Main Results:

• Developmental transition in Atlantic salmon was linked to decreased resistance against parasites.
• Tolerance to parasite infection was not significantly affected by the developmental transition.
• Tolerance slopes, when compared with controls, indicated potential independence from infection, questioning their direct interpretation.

Conclusions:

• The relative importance of resistance and tolerance varies with host developmental stage.
• Developmental transitions in hosts can lead to stage-specific changes in defense strategies.
• The use of control treatments is essential for accurate assessment and interpretation of host tolerance.