Phenological uncoupling of seed dispersal interactions in a Mediterranean scrubland

Trabajo presentado en el XV Congreso Nacional de la Asociación Española de Ecología Terrestre (El valor de la Naturaleza para una sociedad global), celebrado en Plasencia del 18 al 21 de octubre de 2021.Biotic seed dispersal necessarily implies an overlap in the timing of life cycles of interacting organisms, i.e. their phenologies. A phenological uncoupling occurs when there is a mismatch between phenophases of potentially interacting partners, adding up to an important fraction of forbidden links in an interaction network. Despite the obvious connection between phenology and seed dispersal, we are completely ignorant of how future global-change scenarios will affect the prevalence of ecological interactions by means of disruptions of activity overlap (i.e., increased frequencies of forbidden links or interactions that are not established in nature irrespective of sampling effort). This study aims at analysing the prevalence of phenological uncoupling over short and long temporal scales, combining both empirical observations on seed dispersal by frugivorous birds and simulations under different climatic scenarios. Our empirical data come from a Mediterranean lowland scrubland in SW Spain (Hato Ratón, Doñana Natural Area). Bird censuses and phenological transects were performed to estimate the abundance of birds and fruits in 1981-1983 and repeated later in 2019-2020, also documenting the species interactions. We generated different models simulating phenological change, in which phenophases changed either in timing or duration. Results emphasize the role of phenological changes in the presence of forbidden links, with higher frequencies occurring when shifts were maintained over long temporal spans. Simulated scenarios presented a higher influence of phenological uncoupling when changes affected duration rather than timing. Our results signal the vulnerability of mutualistic interactions to phenological shifts induced by global change and the need of including phenology in biodiversity assessments.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement no. 798269Peer reviewe