Long-term coevolution between avian brood parasites and their hosts.

Area of Science:

• Evolutionary Biology
• Behavioral Ecology
• Coevolutionary Dynamics

Background:

• Brood parasitism involves hosts raising young of other species.
• Coevolutionary theory predicts cycles of defense and counter-defense between parasites and hosts.
• Previous models assumed costly host defenses would lead to abandonment and cycles.

Purpose of the Study:

• To investigate the frequency of different long-term outcomes in brood parasite-host coevolution.
• To examine coevolutionary cycles, lack of rejection, and successful resistance in 182 host species.
• To model the long-term evolutionary trajectories of host defenses against brood parasitism.

Main Methods:

• Exploratory comparative analysis of 182 host species.
• Review of existing literature on brood parasite-host interactions.
• Development of a model for coevolutionary trajectories focusing on egg rejection.

Main Results:

• Coevolutionary cycles are infrequent.
• Lack of rejection and successful resistance are common outcomes.
• Host defenses evolve dynamically, influenced by parasitism rates and costs.

Conclusions:

• Traditional coevolutionary cycle theory may not fully explain brood parasite-host dynamics.
• Successful host resistance is a frequent, stable outcome.
• Host acceptance is adaptive only at very low parasitism costs, not an evolutionary equilibrium.