Elevated rates of positive selection drive the evolution of pestiferousness in the Colorado potato beetle ( Leptinotarsa decemlineata, Say)

In order to understand the evolution of pestiferousness, which we define as the accumulation of traits that contribute to an insect population’s success in an agroecosystem, we tested the importance of known genomic properties associated with rapid adaptation. Within the leaf beetle genus Leptinotarsa, only the Colorado potato beetle (CPB), Leptinotarsa decemlineata Say, and a few populations therein, has risen to pest status on cultivated nightshades, Solanum. Using whole genomes from ten closely related Leptinotarsa species native to the United States we reconstructed a high-quality species tree and used this phylogenetic framework to assess evolutionary patterns in four genomic features of rapid adaptation: standing genetic variation, gene family expansion and contraction, transposable element variation, and positive selection at protein coding genes. Throughout approximately 20 million years of history, Leptinotarsa species show little evidence of gene family turnover and transposab...