Ecology of plant-animal interactions during plant population expansion processes

Plant-animal interactions are crucial for maintaining ecosystem functionality and biodiversity. Ecological research has shown that these interactions can be modified in different contexts, affecting natural dynamics. Currently, significant changes in the landscape, such as rural abandonment or the protection of natural areas, are creating a new ecological context for the formation and regeneration of new forested areas. Although the of the role of mutualistic and antagonistic interactions between plants and animals in ecosystems is acknowledge, we lack a comprehensive understanding of their role during the processes of colonization and expansion. Understanding the structure of ecological interactions and the role of the species involved along natural expansion gradients is key to comprehending the natural dynamics underlying expansion processes, as well as the mechanisms that may or may not facilitate the formation of new forests and biodiverse natural ecosystems. The aim of this PhD thesis is to document the structure and consequences of plant-animal interactions that are related to plant reproductive success along a natural expansion gradient. To achieve this, we analyze the interactions, both antagonistic and mutualistic, of predispersal seed predation and seed dispersal at the individual plant level and the resulting patterns such as seed rain and its maternal composition along the natural expansion gradient experienced by the Juniperus phoenicea subsp. turbinata population in the Doñana National Park since its protection five decades ago. We found that the interaction networks that shape individual plants, both with antagonistic (predispersal seed predators) and mutualistic (seed dispersers) species, were concordantly reconfigured along the population expansion gradient. The structuring at the individual level was influenced by the animals' preferences for certain phenotypic traits of the plants, as well as the neighborhood and maturity context in which they were found. Interactions with most animal species, including mutualists and antagonists, are well established in mature stands; however, at the colonization front, only certain species dominate the interaction networks. Both seed loss before dispersal and seed dispersal were accentuated in the expansion front stand due to the interaction with dominant species (Chloris chloris and Turdus philomelos). These results suggest a compensatory effect between opposite interactions that facilitates the contribution of propagules along the gradient, particularly at the colonization front, thereby driving population expansion. Furthermore, by characterizing the seed rain and its maternal genetic composition, we found that the frugivore assembly generates a seed rain that is equally dense and genetically diverse (in terms of source trees included) along the entire expansion gradient. This result highlights the potential of animal-mediated seed dispersal to mitigate the expected negative effects during rapid population expansion processes (founder effects) and promote colonization dynamics that guarantee the diversity of new forests. Both the combination of multiple sampling methods for ecological interactions together with the combination of field experiments and laboratory work for genetic analyses allowed an integrative study of dispersal dynamics. Taken together, our results suggest that ecological interactions between plants and animals are structured at an individual level, and that at a local scale, they are consistently reshaped along natural expansion gradients. Collectively, the chapters presented in this thesis represent a major step forward in our understanding of the ecology and implications of plant-animal interactions during the expansion of natural populations.

Author dc:creator

• Isla Escudero, Jorge

Advisors dc:contributor.advisor

• Jacome Flores, Miguel
• Jordano Barbudo, Pedro D.

Statement dc:rights

• Attribution-NonCommercial-NoDerivatives 4.0 Internacional

Licence dc:rights.uri

• http://creativecommons.org/licenses/by-nc-nd/4.0/

Language dc:language.iso

eng

Handle dc:identifier.uri

https://hdl.handle.net/11441/159167

OAI identifier oai:identifier

oai:idus.us.es:11441/159167