Trophic differentiation and functional morphology of Niphargus (Amphipoda: Niphargus) ; Trofična diferenciacija in funkcionalna morfologija slepih postranic (Amphipoda: Niphargus)

The amphipod genus Niphargus is ecologically diverse, living in virtually all types of subterranean aquatic habitats. On a local scale, different Niphargus species regularly co-occur. The co-occurring species often differ in microhabitat preferences and morphology, suggesting that these species evolved different ecological niches. We focused on trophic niche differentiation of species occurring within the same community and aimed to identify possible links between selected morphological functional traits and trophic ecology. Previous studies suggested that Niphargus can feed on various food sources and use different feeding strategies, including detritivory, scavenging, and predation. Appendages involved into feeding, i.e. gnathopods, show a substantial between-species variation, suggesting that appendage morphology might correlate with feeding ecology. We sampled five caves and two interstitial sites, where at least two species of Niphargus co-occur. We measured carbon (C) and nitrogen (N) stable isotope ratios of animals and basal food resources, and estimated species’ trophic position. Besides that, we performed correlation analyses between morphological and isotopic data for cave species. The results imply that co-occurring species differ in their trophic ecology in all sampled communities. They differentiate either along δ15N, δ13C, or both, and occupy trophic positions ranging from 2.0 (detritivores) to 4.0 (secondary-level predators). In cave species, gnathopod size positively correlates with trophic position, while gnathopod shape negatively correlates with normalized δ13C values. Put together, our results suggest that trophic differentiation may operate as a mechanism mediating species coexistence within subterranean habitats, and that gnathopod size and shape are morphological functional traits which can be used to predict Niphargus’ trophic ecology. ; Slepe postranice iz rodu Niphargus so ekološko pestra skupina, ki naseljuje različne tipe podzemnih vodnih habitatov. Različne vrste slepih postranic na ...