BIOCHEMICAL EVOLUTION ASSOCIATED WITH ANTIPREDATOR ADAPTATION IN DAMSELFLIES.

Area of Science:

• Evolutionary biology
• Animal behavior
• Biochemistry

Background:

• Enallagma damselflies have shifted habitats from fish-predator lakes to dragonfly-predator ponds.
• These damselflies evolved enhanced swimming speeds to evade dragonfly predators.
• Previous research identified morphological adaptations for increased swimming speed.

Purpose of the Study:

• To investigate if biochemical adaptations for fueling swimming evolved alongside morphological changes.
• To assay enzyme activities in Enallagma damselflies to understand metabolic adaptations to predation.

Main Methods:

• Assayed mass-specific enzyme activities of pyruvate kinase, lactate dehydrogenase, and arginine kinase in 14 Enallagma species.
• Compared enzyme activities between species coexisting with dragonfly predators versus fish predators.
• Utilized evolutionary contrasts analyses to infer adaptive evolutionary changes.

Main Results:

• Species with dragonfly predators exhibited significantly higher mass-specific arginine kinase activities than those with fish predators.
• Evolutionary contrasts confirmed that increased arginine kinase activity is linked to habitat shifts to dragonfly lakes.
• Lactate dehydrogenase and pyruvate kinase showed evolutionary changes but not specifically linked to dragonfly predation adaptation.

Conclusions:

• Arginine kinase plays a crucial role in fueling the short, intense swimming bursts required to escape dragonfly predators.
• Biochemical adaptations in arginine kinase activity evolved in concert with morphological changes in response to new predation pressures.
• The rapid ATP regeneration by arginine kinase is favored for short-duration escape behaviors, unlike slower glycolytic pathways.