Adaptation fails

Global change will strike the oldest and most complex ecosystems of the world hardest, regardless of their past stability. This alarming finding is reported in a JRC-led article published in Nature Communications. The authors hypothesized that invasive species, the warming climate and environmental degradation have altered natural habitats so deeply that species adaptation to historical conditions may not be helpful under these new circumstances. Interestingly, the authors found independent support for this hypothesis from both computer simulations and real-world data. Starting from a single ancestor digital organism, the authors let artificial life communities evolve for hundreds of thousands of generations under different, stable environmental settings. These simulated communities included both free-living and 'parasite' digital organisms that helped researchers investigate how biodiversity and ecological networks develop over time, under different environmental conditions. Over several generations, both hosts and parasites diversified, and their interactions became more complex. The authors then investigated how these communities would respond to different scenarios of biodiversity loss. They found that when species become extinct in a sequence consistent with their degree of adaptation to the 'natural' environmental conditions within which they had evolved, their extinction has only a limited effect on the overall diversity of the community. Any deviation from this pattern however, may trigger extinction cascades, eventually leading to the collapse of the entire network. The tendency of consuming species to rely and specialise (develop in a way most suited to the environment) on dependable resources has enabled the evolution of complex systems. This basic mechanism may have doomed many species to extinction -- the authors demonstrate it by comparing the results of their artificial life simulations with several empirical host-parasite networks of different animal groups. Resources that had been largely available in the past are now becoming increasingly scarce, putting at risk the species that rely on them.