Urbanization alters ecological and evolutionary interaction between Darwin's Finches and Tribulus cistoides on the Galápagos Islands

Emerging evidence has demonstrated that urbanization shapes the ecology and evolution of species interactions. Islands are particularly susceptible to urbanization due to the fragility of their ecosystems; however, few studies have examined the effects of urbanization on species interactions on islands. To address this gap, we studied the effects of urbanization on interactions between Darwin9s finches and its food source, Tribulus cistoides, on three towns in the Galapagos Islands. We assessed the effects of urbanization on seed and mericarp removal from T. cistoides mericarps, mericarp morphology, and finch community composition using natural population surveys, experimental manipulations, and finch observations. We found that both seed and fruit removal rates differed between urban and non-urban populations in the natural and experimental populations, and that urbanization modified selection on mericarp size and defense. We found that urban environments also supported smaller and less diverse ground finch communities than non-urban environments. Together, our results suggest that urbanization can dramatically alter ecological interactions between Darwin9s finches and T. cistoides, leading to modified selection on T. cistoides populations. This study demonstrates that urban development on islands can have profound effects on the ecology and evolution of trophic interactions.