Assessing niche conservatism using a multiproxy approach: dietary ecology of extinct and extant spotted hyenas

Abstract

AbstractA central premise of bioclimatic envelope modeling is the assumption of niche conservatism. Whereas such assumptions are testable in modern populations, it is unclear whether niche conservatism holds over deeper time spans and over very large geographic ranges. Hyaenids occupied a diversity of ecological niches over time and space, and until the end-Pleistocene they occurred in Europe and most of Asia, with Asian populations ofCrocutasuggested as being genetically distinct from their closest living relatives. Further, little is known regarding whether and how the dietary ecology of extinct populations ofCrocutadiffered from those of their extant African counterparts. Here, we use a multiproxy approach to assess an assumption of conserved dietary ecology in late Pleistocene extant spotted hyenas via finite element analysis, dental microwear texture analysis, and a novel dental macrowear method (i.e., whether teeth are minimally, moderately, or extremely worn, as defined by degree of dentin exposure) proposed here. Results from finite element simulations of the masticatory apparatus of Chinese and AfricanCrocutademonstrate lower skull stiffness and higher stress in the orbital region of the former when biting with carnassial teeth, suggesting that ChineseCrocutacould not process prey with the same degree of efficiency as extantCrocuta crocuta. Dental microwear texture data further support this interpretation, as ChineseCrocutahave intermediate and indistinguishable complexity values (indicative of hard-object feeding) between the extant African lion (Panthera leo) and extant hyenas (C. crocuta,Hyaena hyaena, andParahyaena brunnea), being most similar to the omnivorousP. brunnea. The use of dental macrowear to infer dietary behavior may also be possible in extinct taxa, as evinced by dietary correlations between extant African feliforms and dental macrowear assignments. Collectively, this multiproxy analysis suggests that ChineseCrocutamay have exhibited dietary behavior distinct from that of livingC. crocuta, and assumptions of niche conservatism may mask significant dietary variation in species broadly distributed in time and space.