Living together but apart: spatial and trophic niche segregation of two termite species sharing the same nest

Resource differentiation and segregation is widely recognized as a key factor enabling species coexistence. However, patterns of niche segregation remain poorly understood in faunal assemblages confined by physical barriers, such as species cohabiting in the same nest. In termite–termite symbiosis where a species (inquiline) is hosted in the nest built by another species (host), resource partitioning within the nest appears critical for species coexistence. Here, we aim at disentangling the habitat and trophic niche segregation between Constrictotermes cavifrons and its inquiline, Inquilinitermes inquilinus. We assess how spatial segregation contributes to reducing competition by analyzing where the inquiline constructs its galleries within the host nest. Using an isotopic niche approach, we also examine whether I. inquilinus imposes costs on its host by depleting shared food resources or mitigates conflict through niche differentiation, by exploiting distinct dietary resources. Our findings suggest that the inquiline’s persistence within the nest is linked to spatial segregation, with the inquiline occupying zones rich in dark organic material, while the host inhabits clay-rich, friable galleries constructed by itself. Isotopic analyses further revealed dietary segregation between the two species, likely reducing competition and facilitating coexistence. The actual food used by the inquiline is most probably the dark mineral organic material found in the bottom of the host nest. These observations are in favor of a commensal symbiosis, wherein the inquiline would impose no alimentary or spatial cost upon the host.