Inferring longevity from advanced rib remodelling in insular dwarf deer

Biological Journal of the Linnean Society, vol. 136, pp. 41–58

Abstract

Abstract Dwarfed insular mammals are of significant interest to evolutionary biology because of their morphological and physiological adaptations triggered by variables inherent to geographical isolation. One life history trait that is expected to be modified in relation to body size reduction is extended longevity facilitated by ecological parameters such as predator and competitor release and fluctuating resource availability. However, systematic examination of longevity in extreme cases of dwarfism is difficult as such cases are largely represented by fossils of extinct species. We studied seven rib fragments of the extraordinary endemic Pleistocene dwarf deer Candiacervus (size 2) to test whether its bone matrix shows evidence for extensive bone remodelling typically seen in large and long-living mammals. We found that all ribs had well-remodelled Haversian bone, implying several generations of resorption and re-deposition processes. Osteon density was high relative to small bone cross-section size, with examples of porosity similar to that seen in elderly animals. We report the first combined micro-morphological and micro-morphometric record of Candiacervus rib histology, agreeing with previous literature discussing the evolutionary biology of dwarf ruminants. Further experimental validation of osteon density in extant deer will confirm whether dwarfed Candiacervus indeed lived longer than expected for its body mass.

Authors 2

1. Justyna Jolanta Miszkiewicz corresponding

   The University of Queensland · Australian National University

   Affiliation as printed

   School of Archaeology and Anthropology, Australian National University, Canberra 2601, Australian Capital Territory, Australia

   School of Social Science, University of Queensland, St Lucia 4072, Queensland, Australia

2. Alexandra A. E. van der Geer corresponding Aachen Vertebrate Evolution Naturalis Biodiversity Center

   Naturalis Biodiversity Center

   Affiliation as printed

   Vertebrate Evolution, Development and Ecology, Naturalis Biodiversity Center, 2300 RA Leiden, The Netherlands