FOUR OR MORE IS A CROWD: ASSESSING COMPETITION BETWEEN AUSTRALIAN DASYURIDS VIA DENTAL MICROWEAR TEXTURE ANALYSIS

Australia is home to many unique species, and understanding their ecology has become increasingly important as many species become threatened or go extinct. On mainland Australia, the tiger quoll (Dasyurus maculatus) is the largest mammalian carnivore present while both the eastern quoll (Dasyurus viverrinus) and the Tasmanian Devil (Sarcophilus harrisii) are absent. All three taxa co-occur on Tasmania, where foxes and dingos are noticeably absent. Here, we examined the dental microwear textures of the three mentioned dasyurids to infer their ecology on Tasmania—including carcass utilization relative to one another. Specifically, we examined the dental microwear textures on sheering facets on lower carnassial-like teeth in all three dasyurids via a 3D optical profiler and scale-sensitive fractal analysis. Complexity of dental microwear textures is significantly lower in the smallest quoll, Dasyurus viverrinus, than either Dasyurus maculatus or Sarcophilus harrisii. Further, Dasyurus maculatus and Sarcophilus harrisii are indistinguishable in all dental microwear attribute values here examined including anisotropy, complexity, and textural fill volume. These data confirm that Dasyurus maculatus engages in scavenging behavior similar to Sarcophilus harrisii. While these two species are known to compete, especially individuals of Dasyurus maculatus with sub-adults of Sarcophilus harrisii, dental microwear textures here document the consumption of hard foods by both taxa. The presence of foxes and dingos on mainland Australia may have increased competition between dasyurids on the mainland and/or between the native and non-native predators, resulting in the decline of native species. In short, the co-existence of four or more ecologically similar species may have led to increased competition for prey-resources including carcasses—leading to the local extirpation of Dasyurus viverrinus and Sarcophilus harrisii from mainland Australia.