The invisible niche: Weakly density-dependent mortality and the coexistence of species

Thilo Gross (1) , Andrew M. Edwards , Ulrike Feudel (2)

1 MPI-PKS - Max Planck Institute for the Physics of Complex Systems
2 OFFIS - Carl Von Ossietzky Universität Oldenburg = Carl von Ossietzky University of Oldenburg

Weakly density-dependent effects, characterized by fractional scaling exponents close to one, are rarely studied in the ecological literature. Here, we consider the effect of an additional weakly density-dependent term on a simple competition model. Our investigation reveals that weak density-dependence opens up an “invisible niche”. This niche does not constitute a new mechanism for coexistence, but is a previously unexplored consequence of known mechanisms. In the invisible niche a weaker competitor can survive at very low density. Coexistence thus requires large habitat size. Such niches, if found in nature, would have a direct impact on species-area laws and species-abundance curves and should therefore receive more attention.

Mots clés: Life Sciences

Thilo Gross, Andrew M. Edwards, Ulrike Feudel. The invisible niche: Weakly density-dependent mortality and the coexistence of species. Journal of Theoretical Biology, 2009, 258 (1), pp.148. ⟨10.1016/j.jtbi.2009.01.018⟩. ⟨hal-00554565⟩