Drivers of individual‐based, antagonistic interaction networks during plant range expansion

Abstract

Range expansion in plant populations, especially at the colonization front, can be either limited by disproportionately large effects of antagonistic interactions or facilitated by their release. How the strength of antagonistic interactions changes along successional gradients during range expansion is still poorly documented, especially when diverse assemblages of plant antagonists (rodents, invertebrates and birds) combine within interaction networks. We study the changes in individual‐based, predispersal seed–pulp predator networks along a colonization gradient in a rapidly expanding Juniperus phoenicea population in Doñana National Park (SW Spain). Additionally, we analysed the role of individual plant traits and neighbourhood attributes in network configuration by using Exponential Random Graph Models. Seven seed–pulp consumer animal species varied significantly in their frequency of interaction and prevalence. While invertebrate species were well‐established in old and intermediately mature stands, greenfinch Chloris chloris was dominant at the colonization front. Variable species roles and spread of interactions among individual plants generated changes in the configuration of interactions during plant expansion. Individual plant traits strongly determined the topology of these networks, although with differences between stands. Increasing individual crop size and seeds per cone increased the interaction odds of individual plants, while seed viability showed the opposite effect. The network topology at the colonization front appeared less driven by individual traits, possibly because of the short interaction history of this recently established area. The disproportionately large effect of C. chloris in these recently established stands, potentially resulted in large seed losses during range expansion. Synthesis. Turnover of antagonistic interactions, characterized the colonization front, resulting in more heterogeneous interaction strengths among individual plants. We found no evidence for a complete or sizeable antagonistic release of J. phoenicea at the colonization front promoting this rapid expansion. It becomes necessary to explore interactions with seed dispersers to understand how antagonistic and mutualistic plant–animal interactions balance during range expansion. Our study highlights the importance of an individual‐based approach in understanding how interactions are structured and driven in natural changing landscapes.

The turnover of plant–frugivore interactions along plant range expansion: consequences for natural colonization processes

“…Data accessibility. Data and code are available in Dryad repository with the DOI: https://doi.org/10.5061/dryad.h18931zq3 [65].…”

Animal‐mediated seed dispersal and the demo‐genetic configuration across plant colonization gradients

“…However, the implications of neighbourhood kinship are complex and pervasive down to small-scale contexts, affecting both plant-plant and plant-animal interactions, for example, interspecific competitive ability depending on whether intraspecific competition is with sibs versus non-sibs (Yamawo, 2015;Yamawo & Mukai, 2020). Next studies should amalgamate insights from plant-plant and plant-animal mutualistic and antagonistic interactions (Isla et al, 2022(Isla et al, , 2023Lloret et al, 2022)…”

“…Our objective is to investigate whether plant–frugivore seed dispersal interactions promote high levels of genetic diversity in expanding plant populations. We focus on a juniper expanding population within the Doñana Biological Reserve (SW Spain), a protected area where juniper woodland patches have flourished over the past five decades (García et al., 2014), attributed mainly to frugivore activity (Isla, Jácome‐Flores, Arroyo, et al., 2023) coupled with changes in land use management. Resident and migrant birds, as well as generalist mammals, forage on the fleshy cones (galbules) when other food resources are scarce in the area.…”

Using individual‐based trait frequency distributions to forecast plant‐pollinator network responses to environmental change

“…Dupont et al, 2014); (2) individual-species or resource, where there are two sets of nodes -one set representing individuals and another representing species or resources (e.g. Arroyo-Correa et al, 2023;Isla et al, 2022;Kuppler et al, 2016;Tur et al, 2014). This allows us to track the specific individual-level trait associated with using a given resource; and (3) niche-overlap networks, where nodes are individuals (of the same or different species), and links are the relative overlap in resource use between individuals (such as the unipartite projection in Arroyo-Correa et al, 2021;Gómez et al, 2011).…”