The origin of excavator nesting behavior and its impact on the evolution of Neotropical parrots

Abstract

How the origin of novel behaviors can shape the evolutionary trajectory of organisms in response to environmental change remains poorly understood. Birds, especially those with big brains like parrots, are benchmarks for their behavioral innovation capacity in novel environments. Here, we assess whether and how the emergence of open areas in the Neotropics that started in the middle Miocene influenced the evolution of nesting behavior in parrots and how they triggered changes in other life-history traits. To address these questions, we use a phylogenetic-based analyses of trait evolution in the subfamily Arinae (Neotropical parrots), focusing on habitat, nesting behavior, morphology, and life-history traits (clutch size, incubation period and fledging period). Evolutionary reconstructions show that transitions to excavating behavior mostly happened when species colonized open areas, providing evidence that this behavior originated in open environments. Evolutionary models suggest that the new open areas and the excavator nesting behavior exerted new selective pressures on morphology and life-history traits, leading to evolutionary changes towards larger clutch sizes and shorter fledging periods in excavator parrots. Our study indicates that excavator nesting behavior in Neotropical parrots has likely played a key role in allowing them to exploit the ecological opportunities available in newly formed open biomes.