The spatio-temporal dimension of ecological networks
Ecological networks are dynamic, although most studies use static versions of them to identify structural properties. This hampers our ability to tease apart natural network variation through time and space, in comparison to variation caused by human-induced disturbances as habitat loss or climate change. One question to be addressed is whether these patterns hold through time and space.
Some studies on plant-pollination networks extending 2-4 years show that the overall ecological network structure seems constans and steady over time, but species and their connecting links show a high and strong turnover. We are investigating different kinds of temporal dynamics within different types of ecological networks, including host-parasitoid and classical food webs. We study seasonal dynamics and interannual variation over long time-scales. We are studying the largest temporal dataset of a species interaction network, that of vertebrates on the Pyrinees mountains (Spain), expanding over more than 40 years, in collaboration with Bernat Claramunt (CREAF).
I also study deep-time ecological netorks, In particular, I am interested on biodiversity recovery after mass extinctions. We have develop a simple model to explain the different types of recovery observed in the fossil record. Our model includes the importance of biotic interactions and speciation driven by increasing diversity for the different types of recovery patterns.
We are also interested on spatial and geographical changes in food web structure. We are looking for altitudinal gradients in food web structure in alpine ecosystems (mostly from the Pyrinees), and on a broader spatial scale, we are studying latitudinal gradients in host-parasitoid interaction networks, testing e.g. whether specialism, consumer overlap, compartmentalization, varies geographically. In collaboration with Bradford Hawkins and Ricard Solé, I'm exploring the variability of food web structure at large spatial scales, focusing on the influence of geographical variables. In particular, we are investigating whether a 'latitudinal' gradient in different aspects of food web structure exists. If this gradient does not exist, local dynamics might be governing food web structure independently of large-scale processes. If a gradient is observed, geographical processes might be necessary for understanding and predicting the structure or food webs and their implications to ecosystem stability and functioning. We are analyzing an extensive compilation of plant-herbivore-parasitoid food webs across different latitudes. The species represented in this type of food webs represent half of all known multicellular species. This analysis can help to elucidate to what extent large-scale processes are regulating the trophic structure of the local communities that dominate the biota, and whether biodiversity and food web structure can be regulated by similar mechanisms.