Predation drives stable coexistence ratios between red and green pea aphid morphs

Area of Science:

• Ecology
• Evolutionary Biology
• Animal Behavior

Background:

• Coexistence of different morphs is often influenced by predation.
• Pea aphids (Acyrthosiphon pisum) exhibit red and green color morphs with theoretical differences in predator susceptibility.

Purpose of the Study:

• To test if predation drives coexistence between red and green pea aphid morphs.
• To understand the role of predator-prey dynamics in maintaining specific morph ratios.

Main Methods:

• Field surveys on pea and alfalfa to observe morph ratios.
• Experimental manipulation of morph proportions and predator presence.
• Evaluation of predator efficiency on different morph ratios.

Main Results:

• A consistent 1:3 red to green aphid ratio was observed in the field.
• Red morphs exhibited higher fitness at a 1:3 ratio, especially with predators present.
• Red morphs are least vulnerable to predation when in a 1:3 ratio with green morphs.

Conclusions:

• The 1:3 red:green pea aphid ratio is maintained by a balance of predation and behavioral assorting by red morphs.
• Predation has significant ecological and evolutionary consequences on aphid morph proportions and survival.
• Behavioral strategies, like grouping, enhance red morph fitness and survival against predators.