Urbanization shapes phenotypic selection of fruit traits in a seed-dispersal mutualism

Abstract

Urbanization is currently one of the trademarks of the Anthropocene, accelerating evolutionary processes and reshaping ecological interactions over short time scales. Species interactions represent a fundamental pillar of diversity that is being altered globally by anthropogenic change. Urban environments, despite their potential impact, have seldom been studied in relation to how they shape natural selection of phenotypic traits in multispecies interactions. Using a seed-dispersal mutualism as a study system, we estimated the regime and magnitude of phenotypic selection exerted by frugivores on fruit and seed traits across three plant populations with different degrees of urbanization (urban, semiurban, and rural). Urbanization weakened phenotypic selection via an indirect positive impact on fruit production and fitness and, to a lesser extent, through a direct positive effect on species visitation rates. Our results show that urban ecosystems may affect multifarious selection of traits in the short term and highlight the role of humans in shaping eco-evolutionary dynamics of multispecies interactions.