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Supporting data to: Evolution of realized Eltonian niches across Rajidae species

Cite this dataset

Shipley, Oliver et al. (2020). Supporting data to: Evolution of realized Eltonian niches across Rajidae species [Dataset]. Dryad.


The notion that closely related species resemble each other in ecological niche space (i.e., phylogenetic dependence) has been a longstanding, contentious paradigm in evolutionary biology, the incidence of which is important for predicting the ecosystem-level effects of species loss. Despite being examined across a multitude of terrestrial taxa, many aspects of niche conservatism have yet to be explored in marine species, especially for characteristics related to resource use and trophic behavior (Eltonian niche characteristics, ENCs). We combined ENCs derived from stable isotope ratios at assemblage- and species-levels with phylogenetic comparative methods to test the hypotheses that benthic marine fishes: 1) will exhibit similar assemblage-wide ENCs regardless of geographic location, and 2) will display phylogenetically dependent ENCs at the species-level. We used a 12-species sub-set of the monophyletic group Rajidae sampled from three independent assemblages (Central California, Gulf of Alaska, and Northwest Atlantic), which span two ocean basins. Assemblage-level ENCs implied low trophic diversity and high evenness, suggesting that Rajidae assemblages may exhibit a well-defined trophic role, a trend consistent regardless of geographic location. At the species-level we found evidence for phylogenetic dependence of ENCs relating to trophic diversity (i.e., isotopic niche width [SEAc]). Whether individuals can be considered functional equivalents across assemblages is hard to ascertain because we did not detect a significant phylogenetic signal for ENCs relating to trophic function (e.g., trophic position). Thus, additional, complimentary approaches are required to further examine the phylogenetic dependence of species functionality. Our approach illustrates the potential of stable isotope derived niche characteristics to provide insight on macroecological processes occurring across evolutionary time, which could help predict how assemblages may respond to the effects of species loss.