Dental microwear of sympatric rodent species sampled across habitats in southern Africa: Implications for environmental influence

Abstract

Dental microwear textures have proven to be a valuable tool for reconstructing the diets of a wide assortment of fossil vertebrates. Nevertheless, some studies have recently questioned the efficacy of this approach, suggesting that aspects of habitat unrelated to food preference, especially environmental grit load, might have a confounding effect on microwear patterning that obscures the diet signal. Here we evaluate this hypothesis by examining microwear textures of 3 extant sympatric rodent species that vary in diet breadth and are found in a variety of habitat types: Mastomys coucha, Micaelamys namaquensis and Rhabdomys pumilio. We sample each of these species from 3 distinct environmental settings in southern Africa that differ in rainfall and vegetative cover: Nama-Karoo shrublands (semi-desert) and Dry Highveld grasslands in the Free State Province of South Africa, and Afromontane (wet) grasslands in the highlands of Lesotho. While differences between habitat types are evident for some of the species, inconsistency in the pattern suggests that the microwear signal is driven by variation in foods eaten rather than grit-level per se. It is clear that, at least for species and habitats sampled in the current study, environmental grit load does not swamp diet-related microwear signatures.

Untangling the environmental from the dietary: dust does not matter

“…This would not be an issue when looking at niche partitioning among mammals from the same locality, as they would be uniformly affected by similar amounts of airborne dust. Similar results have been found on wild sympatric rodents inhabiting arid windblown environments in South Africa [43]. The issue could then arise when comparing different localities affected by different amounts of airborne dust.…”

Dental microwear texture analysis ofHomo sapienssapiens: Foragers, farmers, and pastoralists

“…In the end, their work determined that microwear could elucidate seasonal, microhabitat, and intergroup differences in diet. In fact, other researchers have determined that dental microwear analysis, be it scanning electron microscope (SEM)‐based, mesowear, or DMTA‐based, can successfully distinguished diets of living animals well beyond primates and hominins, including hyraxes, carnivorous mammals, peccaries, rodents, rabbits, ungulates, and fish (e.g., Burgman, Leichliter, Avenant, & Ungar, ; Calandra et al, ; Caporale & Ungar, ; DeSantis, Schubert, Scott, & Ungar, ; Hoffman et al, ; Merceron et al, ; Merceron, Schulz, Kordos, & Kaiser, ; Purnell & Darras, ; Schmidt, ; Schulz et al, ; Scott et al, ; Solounias & Semprebon, ; Stynder, Ungar, Scott, & Schubert, ; Walker, Hoeck, & Perez, ).…”

Canine and incisor microwear in pitheciids and Ateles reflects documented patterns of tooth use

“…Fieldwork examining primates in the wild has provided data on food preferences and on the fracture properties of masticated foods (e.g., Teaford et al, 2006;Lucas et al, 2008); this, combined with insights from studies of masticatory biomechanics (e.g., Hua et al, 2015), permits an understanding of molar microwear patterning. Indeed, molar microwear in primates and other mammals has been shown to reflect rather subtle variation in diet (Teaford, 1985(Teaford, , 1993Daegling and Grine, 1999;King et al, 1999), including seasonal and ecological zone differences within taxa (e.g., Teaford and Robinson, 1989;Teaford and Glander, 1996;Merceron et al, 2004;Nystrom et al, 2004;Estalrrich et al, 2015;Burgman et al, 2016). For example, Teaford and Walker (1984;Walker and Teaford, 1989) found that frugivorous anthropoids typically have more pitting on their Phase II facets than do folivorous taxa, which have more striations.…”

“…Recent analyses using scale-sensitive fractal analysis show that harder-object feeders typically exhibit more complex microwear surfaces and larger features on average than do soft-or tough-object feeders (e.g., Scott et al, 2006Scott et al, , 2012. Indeed, molar microwear in primates and other mammals has been shown to reflect rather subtle variation in diet (Teaford, 1985(Teaford, , 1993Daegling and Grine, 1999;King et al, 1999), including seasonal and ecological zone differences within taxa (e.g., Teaford and Robinson, 1989;Teaford and Glander, 1996;Merceron et al, 2004;Nystrom et al, 2004;Estalrrich et al, 2015;Burgman et al, 2016).…”