Seed co‐occurrence caused by shared frugivores leaves a long‐lasting signal in the spatial co‐occurrence among plants

By dispersing seeds, frugivorous animals affect spatial co‐occurrence of plants, ultimately influencing plant community dynamics. Frugivorous animals are intrinsically involved in plant community dynamics, by dispersing seeds of fleshy‐fruited plants and influencing their spatial co‐occurrence. Particularly, generalist avian frugivores forage on them, co‐dispersing and co‐disseminating their seeds. This dispersal process often promotes spatial clumping and sets the initial spatial template on which subsequent ecological processes operate. Despite this mutualism is key at the early stages of fleshy‐fruited species, it remains unknown whether these co‐dispersed and co‐disseminated plant species maintain their initial pairwise seed co‐occurrence along their demographic cycle. If so, this would reflect a lasting signal of these early mutualistic interactions in the plant community assembly. We investigated whether plant species that share avian seed dispersers also co‐occur spatially across different life stages, from seed to adult individuals. We combined data on seed rain from nine fleshy‐fruited species, dispersed by a community of 21 bird species identified through DNA‐barcoding, with spatial co‐occurrence patterns among these plant species at the sapling and adult stages, using point pattern analyses. From this, we built matrices showing: 1) the number of frugivore species shared between each pair of plant species, and 2) their spatial co‐occurrence at different life stages: seeds (seed–seed), saplings (sapling–sapling and sapling–adult), and adults (adult–adult). We then used structural equation modelling to test whether the level of shared avian frugivores predicts the spatial co‐occurrence among adult plants, while also assessing the indirect effects of processes occurring at intermediate demographic stages. Our results revealed both direct and indirect effects of frugivore sharing during the fruit removal and seed dissemination stage on the spatial assembly of established adult species. Specifically, we found that higher levels of shared frugivores increased the co‐occurrence among plant species in seed rain (seed–seed), apparent facilitation (sapling–adult) and adult community (adult–adult), but not within the sapling bank (sapling–sapling). Frugivorous birds drive the co‐occurrence among fleshy‐fruited plant species, from seed to adult stages, although their influence decreases as the plant demographic cycle advances. However, the co‐occurrence at adult stages is exclusively achieved when adults apparently facilitate sapling establishment. This reinforces the key role of the plant–plant facilitation in Mediterranean systems, and the deterministic role of mutualistic avian frugivores as drivers of spatial assembly in plant communities.