Simultaneous inbreeding modifies inbreeding depression in a plant-herbivore interaction

Area of Science:

• Ecology
• Evolutionary Biology
• Plant-Herbivore Interactions

Background:

• Inbreeding is prevalent in natural plant and herbivore populations.
• Inbreeding and inbreeding depression can significantly alter plant-herbivore interactions and coevolutionary dynamics.
• Understanding these effects is crucial for predicting ecological and evolutionary outcomes.

Purpose of the Study:

• To investigate how inbreeding in both plants and their specialist herbivores influences their interactions.
• To determine if inbreeding depression in plant resistance is affected by the inbreeding level of the interacting herbivore.
• To explore the role of plant secondary compounds in mediating these effects.

Main Methods:

• A feeding assay was conducted using inbred and outbred lines of the perennial herb Vincetoxicum hirundinaria and its specialist herbivore Abrostola asclepiadis.
• Plant resistance and herbivore performance were measured under different inbreeding scenarios.
• Variation in plant secondary compounds was considered as a potential driver of population-specific effects.

Main Results:

• Plant inbreeding increased inbreeding depression in herbivore performance in some populations.
• The impact of inbreeding on plant resistance varied significantly across different plant and herbivore populations.
• Inbreeding depression in plant resistance was substantial with outbred herbivores but diminished with inbred herbivores.
• Variation in plant secondary compounds likely contributed to the observed among-population differences.

Conclusions:

• The expression of inbreeding depression in plant-herbivore interactions is dependent on the inbreeding levels of both interacting species.
• Inbred herbivores can reduce or eliminate inbreeding depression in plant resistance.
• Herbivore-induced selection against self-fertilization in plants may be diminished when herbivores are inbred.