The unprecedented environmental change produced by human activities is not only reducing biodiversity in terms of a number of species, but also by the extinction of interactions among them. These ecological interactions (such as herbivory, parasitism, plant pollination by insects, seed dispersal by frugivores, or competition) are the wireframe that sustains the Web of Life, providing functional links and allowing species co-existence. Unfortunately, ecological interactions are also being lost at a very fast pace, sometimes preceding species extinctions, and this disappearance of interactions might trigger the collapse of communities, yet most recent efforts for biodiversity conservation focus on species. Thus, unveiling the complexity of ecological interactions is fundamental for biodiversity conservation in an era of global threats imposed by human impacts.
The main aim of the TEMPNET action was to provide a deep understanding of how phenological changes in interacting plants and animals affect their dynamics over seasonal and long-term time spans. TEMPNET has combined two temporal scales (frequent intra-annual censuses and long-term replication with 37 yrs of time span) for comparing fruit-frugivore networks from the Doñana National Park (Spain). Using state-of-the-art mathematical advances in multilayer network analysis, sound ecological theory, and field observation, temporal changes in interactions between fruits and birds have been shown. The results of this action point out that frugivorous birds in Doñana are relatively in worse conditions nowadays than when compared with 1981-1983: they had less fat content, migrant species are scarcer and they migrate earlier, which can lead to a mismatch with fruiting plant species. We generated different models simulating phenological change and evaluated the prevalence of forbidden links, i.e. interactions that do not take place, irrespective of sampling effort. 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. Our results signal the vulnerability of mutualistic interactions to phenological shifts induced by global change and the need of including phenology in biodiversity assessments. Results of TEMPNET action have exploitable applications for biodiversity conservation in a context of global change. Moreover, tools of network analyses employed have also applications for a range variety of fields, including transportation, banking, computing, or the study of contagion dynamics of infectious diseases.
