Local adaptation: simultaneously considering herbivores and their host plants

Area of Science:

• Ecology
• Evolutionary Biology
• Plant-Insect Interactions

Background:

• Coevolutionary theory predicts reciprocal local adaptation between interacting species like plants and herbivores.
• Empirical testing of this reciprocal adaptation, particularly in natural settings, remains limited.

Purpose of the Study:

• To investigate the presence and variability of reciprocal local adaptation between an herbivorous insect and its host plant.
• To determine if adaptation patterns between the two species are interdependent.

Main Methods:

• Conducted two four-by-four cross-infestation experiments under controlled abiotic conditions.
• Laboratory experiments assessed individual herbivore performance.
• Common garden experiments evaluated herbivore population growth, plant seed production, and plant defenses (resistance and tolerance).

Main Results:

• Population differentiation patterns between the herbivore and plant were interdependent.
• Observed outcomes ranged from local adaptation to maladaptation.
• An association between plant resistance and herbivore performance was noted, but tolerance showed no clear pattern with herbivore local adaptation.
• Demonstrated reciprocal local adaptation, where adaptation in one species often corresponded with non-adaptation or maladaptation in the other.

Conclusions:

• Reciprocal local adaptation between this herbivore and host plant occurs, aligning with theoretical expectations.
• The magnitude and direction of local adaptation can vary significantly between interacting species.
• Plant resistance plays a role in herbivore adaptation, while tolerance's role is less clear.