Tag: Ecological interanctions

The future of hyperdiverse tropical ecosystems

The tropics contain the overwhelming majority of Earth’s biodiversity: their terrestrial, freshwater and marine ecosystems hold more than three-quarters of all species, including almost all shallow-water corals and over 90% of terrestrial birds. However, tropical ecosystems are also subject to pervasive and interacting stressors, such as deforestation, overfishing and climate change, and they are set within a socio-economic context that includes growing pressure from an increasingly globalized world, larger and more affluent tropical populations, and weak governance and response capacities. Concerted local, national and international actions are urgently required to prevent a collapse of tropical biodiversity.

 

The future of hyperdiverse tropical ecosystems
Jos Barlow, et al.
Nature volume 559, pages 517–526 (2018)

Source: www.nature.com

Effects of network modularity on the spread of perturbation impact in experimental metapopulations

The networks that form natural, social, and technological systems are vulnerable to the spreading impacts of perturbations. Theory predicts that networks with a clustered or modular structure—where nodes within a module interact more frequently than they do with nodes in other modules—might contain a perturbation, preventing it from spreading to the entire network. Gilarranz et al. conducted experiments with networked populations of springtail ( Folsomia candida ) microarthropods to show that modularity limits the impact of a local extinction on neighboring nodes (see the Perspective by Sales-Pardo). In networks with high modularity, the perturbation was contained within the targeted module, and its impact did not spread to nodes beyond it. However, simulations revealed that modularity is beneficial to the network only when perturbations are present; otherwise, it hinders population growth.

Science , this issue p. [199][1]; see also p. [128][2]

[1]: /lookup/doi/10.1126/science.aal4122
[2]: /lookup/doi/10.1126/science.aan8075

Source: science.sciencemag.org

Looplessness in networks is linked to trophic coherence

Complex systems such as cells, brains, or ecosystems are made up of many interconnected elements, each one acting on its neighbors, and sometimes influencing its own state via feedback loops. Certain biological networks have surprisingly few such loops. Although this may be advantageous in various ways, it is not known how feedback is suppressed. We show that trophic coherence, a structural property of ecosystems, is key to the extent of feedback in these as well as in many other systems, including networks related to genes, neurons, metabolites, words, computers, and trading nations. We derive mathematical expressions that provide a benchmark against which to examine empirical data, and conclude that “looplessness” in nature is probably a consequence of trophic coherenc

Source: www.pnas.org