  What determines biodiversity in nature is a prominent issue in ecology,
especially in biotic resource systems that are typically devoid of
cross-feeding. Here, we show that by incorporating pairwise encounters among
consumer individuals within the same species, a multitude of consumer species
can self-organize to coexist in a well-mixed system with one or a few biotic
resource species. The coexistence modes can manifest as either stable steady
states or self-organized oscillations. Importantly, all coexistence states are
robust to stochasticity, whether employing the stochastic simulation algorithm
or individual-based modeling. Our model quantitatively illustrates species
distribution patterns across a wide range of ecological communities and can be
broadly used to explain biodiversity in many biotic resource systems.
