Oral Presentation- Symposium 12th International Mammalogical Congress

Forelimb adaptations to digging in the quenda (Isoodon obesulus fusciventer) (#451)

Meg L Lane 1 , Natalie M Warburton 1 , Kenny J Travouillon 2 , Trish A Fleming 1
  1. School of Veterinary and Life Science, Murdoch University, Murdoch, Western Australia, Australia
  2. Department of Terrestrial Zoology, Western Australian Museum, Welshpool, Western Australia, Australia

Many mammals dig, either during foraging to access sub-surface food resources, or for shelter. Digging requires large forces to be generated by muscles and transmitted to the soil via the skeletal system, and thus digging mammals tend to have characteristic adaptations that reflect their digging ability. Bandicoots (Marsupialia: Peramelidae) dig mainly for their food, searching for subterranean food items including invertebrates, seeds, and fungi (truffles). They have musculoskeletal adaptations to digging, including shortened, robust forelimb bones, large, powerful muscles, and enlarged muscle attachment areas. We investigated how these adaptations develop in the quenda (Isoodon obesulus fusciventer) by examining 29 males and females of a range of body size (260–1,840 g). We measured muscle mass, pennation angle, and fascicle lengths to calculate physiological cross-sectional area (PCSA), a functional estimate of maximum force, and made corresponding measures of bone architecture. Overall, we discovered total forelimb mass was significantly larger in males in absolute size, however only two individual muscles showed a significant different between the sexes. Positive allometry in muscle growth was seen in 20 of the 29 muscles, with only 9 of these having significant differences in growth rates between males and females. Muscles that were identified as digging muscles did not have significantly different growth rates compared to non-digging muscles, indicating their growth is influenced by body size rather than functionality.