title: Geometry for a penguin-albatross rookery.
abstract: We introduce a simple ecological model describing the spatial organization of two interacting populations whose individuals are indifferent to conspecifics and avoid the proximity to heterospecifics. At small population densities Φ a nontrivial structure is observed where clusters of individuals arrange into a rhomboidal bipartite network with an average degree of 4. For Φ → 0 the length scale, order parameter, and susceptibility of the network exhibit power-law divergences compatible with hyperscaling, suggesting the existence of a zero-density nontrivial critical point. At larger densities a critical threshold Φ(c) is identified above which the evolution toward a partially ordered configuration is prevented and the system becomes jammed in a fully mixed state.
authors.affiliation: Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, Università degli Studi di Milano, Milano, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Giavazzi
authors.affiliation: Dipartimento di Fisica, Università degli Studi di Milano, I-20133 Milano, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Vailati
mesh_terms: D000818:Animals; D001717:Birds; D003198:Computer Simulation; D017753:Ecosystem; D008954:Models, Biological; D011156:Population Density; D011157:Population Dynamics; D046429:Spheniscidae