Estimating the tolerance of species to the effects of global environmental change

Global environmental change is affecting species distribution and their interactions with other species. In particular, the main drivers of environmental change strongly affect the strength of interspecific interactions with considerable consequences to biodiversity. However, extrapolating the effects observed on pair-wise interactions to entire ecological networks is challenging. Here we propose a framework to estimate the tolerance to changes in the strength of mutualistic interaction that species in mutualistic networks can sustain before becoming extinct. We identify the scenarios where generalist species can be the least tolerant. We show that the least tolerant species across different scenarios do not appear to have uniquely common characteristics. Species tolerance is extremely sensitive to the direction of change in the strength of mutualistic interaction, as well as to the observed mutualistic trade-offs between the number of partners and the strength of the interactions.Comment: Nature Communications 4, Article number: 2350, (2013

Mutualistic networks

The mutually beneficial interactions between plants and their animal pollinators and seed dispersers form complex networks of species interdependence. Until very recently, the complexity of these networks precluded a community-wide approach to mutualism. However, recent studies using tools and concepts from physics and sociology have allowed the exploration of this complexity within a rational framework. Regardless of differ- ences across sites or species composition, networks of mutual benefit have a similar structure. Describing these network patterns is important for understanding both the generation of biodiversity and its responses to anthropogenic disturbances, such as habitat loss and species extinctions. This network approach is currently being applied to restoration ecology, biological invasions, and the conservation of endangered speciesPeer reviewe

How structurally stable are global socioeconomic systems?

The stability analysis of socioeconomic systems has been centered on answering whether small perturbations when a system is in a given quantitative state will push the system permanently to a different quantitative state. However, typically the quantitative state of socioeconomic systems is subject to constant change. Therefore, a key stability question that has been under-investigated is how strong the conditions of a system itself can change before the system moves to a qualitatively different behavior, i.e., how structurally stable the systems is. Here, we introduce a framework to investigate the structural stability of socioeconomic systems formed by the network of interactions among agents competing for resources. We measure the structural stability of the system as the range of conditions in the distribution and availability of resources compatible with the qualitative behavior in which all the constituent agents can be self-sustained across time. To illustrate our framework, we study an empirical representation of the global socioeconomic system formed by countries sharing and competing for multinational companies used as proxy for resources. We demonstrate that the structural stability of the system is inversely associated with the level of competition and the level of heterogeneity in the distribution of resources. Importantly, we show that the qualitative behavior of the observed global socioeconomic system is highly sensitive to changes in the distribution of resources. We believe this work provides a methodological basis to develop sustainable strategies for socioeconomic systems subject to constantly changing conditions

The role of asymmetric interactions on the effect of habitat destruction in mutualistic networks

Plant-pollinator mutualistic networks are asymmetric in their interactions: specialist plants are pollinated by generalist animals, while generalist plants are pollinated by a broad involving specialists and generalists. It has been suggested that this asymmetric ---or disassortative--- assemblage could play an important role in determining the equal susceptibility of specialist and generalist plants under habitat destruction. At the core of the argument lies the observation that specialist plants, otherwise candidates to extinction, could cope with the disruption thanks to their interaction with generalist pollinators. We present a theoretical framework that supports this thesis. We analyze a dynamical model of a system of mutualistic plants and pollinators, subject to the destruction of their habitat. We analyze and compare two families of interaction topologies, ranging from highly assortative to highly disassortative ones, as well as real pollination networks. We found that several features observed in natural systems are predicted by the mathematical model. First, there is a tendency to increase the asymmetry of the network as a result of the extinctions. Second, an entropy measure of the differential susceptibility to extinction of specialist and generalist species show that they tend to balance when the network is disassortative. Finally, the disappearance of links in the network, as a result of extinctions, shows that specialist plants preserve more connections than the corresponding plants in an assortative system, enabling them to resist the disruption.Comment: 14 pages, 7 figure

Nestedness in mutualistic networks

James et al. (2012) presented simulations that apparently falsify the analytical result by Bastolla et al. (2009), who showed that nested mutualistic interactions decrease interspecific competition and increase biodiversity in model ecosystems. This contradiction, however, mainly stems from the incorrect application of formulas derived for fully connected networks to empirical, sparse networks.Comment: 2 pages, 1 figur

Les papallones del camó d'Obiols. Un catàleg dels ropalòcers al municipi d'Avià

Aquest treball de recerca ha permés comptar les espècies diferents i elaborar un arxiu fotogràfic de més de 3000 fotografie

Molecular mechanisms of antibiotic resistance in Helicobacter pylori

Treballs Finals de Grau de Farmàcia, Facultat de Farmàcia i Ciències de l'Alimentació, Universitat de Barcelona, 2023. Tutor/a:Helicobacter pylori és un patogen que s’ha adaptat per sobreviure a l’estómac, un dels ambients més hostils de l’organisme. És l’agent etiològic de diverses patologies del sistema gastrointestinal, com la úlcera pèptica, la gastritis i dos tipus de càncer (adenocarcinoma gàstric i limfoma MALT), motiu pel qual es considera un carcinogen de classe I. Actualment, existeixen diferents combinacions terapèutiques per a tractar la infecció, però, malauradament, en els darrers anys, l’efectivitat d’aquestes s’ha vist significativament reduïda, fins al punt d’haver-se perdut totalment en alguns casos. La principal causa és la continua aparició de resistències a aquests fàrmacs. No obstant, els mecanismes que expliquen com H. pylori adquireix aquestes resistències no es coneixen del tot. En aquest projecte, a part d’un estudi bibliogràfic s’ha fet un estudi genètic de 52 soques procedents de l’Hospital Parc Taulí, de les quals s’han analitzat els principals gens relacionats amb les resistències als antibiòtics utilitzant les seqüències genòmiques obtingudes per la Unitat de Microbiologia de la Facultat de Farmàcia i Ciències de l’Alimentació de la Universitat de Barcelona. Els resultats van mostrar l’existència d’una gran varietat de mutacions en els diferents gens de resistència, algunes no descrites als estudis publicats fins ara, que podrien donar lloc a la resistència de les soques estudiades. Aquests resultats, juntament amb els obtinguts de la cerca bibliogràfica van demostrar que el desenvolupament de les resistències als antibiòtics en H. pylori és un procés multifactorial en el que una gran varietat de mecanismes actuen conjuntament per atorgar multiresistència a H. pylori. Paraules clau: Helicobacter pylori, mecanismes moleculars, resistència als antibiòtic