Biology subjects

Galiana, N.

Publications and source records attributed to Galiana, N..

4 recordsLinked to original sources

bioRxiv2025

Beyond biomass: how interactions shape species' importance for ecosystem functioning

Assessing the functional role of species in a changing world is critical for effectively preserving ecosystems. Intuitively, this role should relate to how the loss of a species ultimately impacts a function. We introduce the notion of a species dynamic contribution, which takes into account biotic interactions as they develop in the community. Contrary to the static contribution --a measure of what a species directly does-- the dynamic contribution captures what the presence of the species causes. Using both model simulations and empirical data from a ciliate microcosm experiment, we demonstrate that dynamic and static contributions of species are generically unrelated. Our novel characterization of species functional contributions reveals that, due to biotic interactions, rare species that do not possess unique functional traits are just as likely as any other species to play an important role for ecosystem functioning.

ecology↗

bioRxiv2023

Protected areas enhance avian food webs

Restoring and conserving habitat and the species they shelter has become a primary focus to mitigate the current extinction crisis. Setting aside land designated as protected areas (PAs) is an efficient way of achieving these aims. This strategy has been proven to enhance different aspects of species richness and abundance across ecosystems1-4. However, to truly understand the effects of global environmental change on biodiversity, and the efficiency of our mitigation measures, we must account for one of its fundamental dimensions: species interactions. Here we show that PAs enhance avian food webs across Europe by protecting key network and species traits. Using 376,556 observational records of 509 bird species from citizen science databases distributed across 45 networks of PAs, we found beneficial effects of protection on 10 out of 13 food web properties on an average of 25.9% of sites. PAs enhance food webs by harbouring large top predators, in turn increasing the length of biomass flow paths from basal to top species. Furthermore, we link these beneficial effects to environmental drivers and PA designations. PA benefits were augmented by specific protection goals such as European Directives for conservation. This study provides evidence for the effectiveness of PAs as a strategy to preserve fundamental aspects of biodiversity beyond species richness. We anticipate our study to be a starting point for the development of comprehensive frameworks to assess the critical role of PAs in safeguarding biodiversity worldwide. Improving the mapping of species occurrences and ecological interactions across the globe will is fundamental to develop optimal strategies for establishing networks of PAs aimed at protecting all aspects of ecosystem diversity.

ecology↗

bioRxiv2022

How collectively integrated are ecological communities?

Beyond abiotic conditions, do population dynamics mostly depend on the species direct predators, preys and conspecifics? Or can indirect feedbacks that ripple across the whole community be equally important? Here we show that the spectral radius of a communitys interaction matrix controls the length of indirect interaction pathways that actually contribute to community-level dynamical patterns, such as the depth of a perturbations reach, or the contribution of biotic processes to realized species niches. The spectral radius is a measure of collectivity that integrates existing approaches to complexity, interaction structure and indirect interactions, while also being accessible from imperfect knowledge of biotic interactions. Our work provides an original perspective on the question of to what degree communities are more than loose collections of species or simple interaction motifs; and explains when reductionist approaches focusing on particular species and small interaction motifs, ought to suffice or fail when applied to ecological communities.

ecology↗

bioRxiv2020

Can biomass distribution across trophic levels predict trophic cascades?

The biomass distribution across trophic levels (biomass pyramid), and cascading responses to perturbations (trophic cascades), are archetypal representatives of the interconnected set of static and dynamical properties of food chains. A vast literature has explored their respective ecological drivers, sometimes generating correlations between them. Here we instead reveal a fundamental connection: both pyramids and cascades reflect the dynamical sensitivity of the food chain to changes in species intrinsic rates. We deduce a direct relationship between cascades and pyramids, modulated by what we call trophic dissipation - a synthetic concept that encodes the contribution of top-down propagation of consumer losses in the biomass pyramid. Predictable across-ecosystem patterns emerge when systems are in similar regimes of trophic dissipation. Data from 31 aquatic mesocosm experiments demonstrate how our approach can reveal the causal mechanisms linking trophic cascades and biomass distributions, thus providing a road map to deduce reliable predictions from empirical patterns.

ecology↗