  Human perceptual and cognitive abilities are limited resources. Today, in the
age of cheap information --cheap to produce, to manipulate, to disseminate--,
this cognitive bottleneck translates into hypercompetition for visibility among
actors (individuals, institutions, etc). The same social communication
incentive --visibility-- pushes actors to mutualistically interact with
specific memes, seeking the virality of their messages. In turn, contents are
driven by selective pressure, i.e. the chances to persist and reach widely are
tightly subject to changes in the communication environment. In spite of all
this complexity, here we show that the underlying architecture of the
users-memes interaction in information ecosystems, apparently chaotic and
noisy, actually evolves towards emergent patterns, reminiscent of those found
in natural ecosystems. In particular we show, through the analysis of
empirical, large data streams, that communication networks are structurally
elastic, i.e. fluctuating from modular to nested architecture as a response to
environmental perturbations (e.g. extraordinary events). We then propose an
ecology-inspired modelling framework, bringing to light the precise mechanisms
causing the observed dynamical reorganisation. Finally, from numerical
simulations, the model predicts --and the data confirm-- that the users'
struggle for visibility induces a re-equilibration of the network towards a
very constrained organisation: the emergence of self-similar nested
arrangements.
