Understanding how animals recycle nutrients is critically important, as animals take up, transform, release, and transport critical nutrients. Ecological stoichiometry (ES) is commonly used to evaluate animal-mediated nutrient recycling. However, empirical data on vertebrates rarely supports ES predictions, both because elemental demand and release do not appear tightly linked to body elemental content and because vertebrates often break the assumption of stoichiometric homeostasis (i.e. that body elemental content remains within bounds as environmental supply fluctuates). Bone, a phosphorus(P)-rich tissue, likely plays a significant role. We systematically reviewed zoological and medical literature to evaluate (1) how bone physiology impacts vertebrate elemental demand and release, (2) how bone causes stoichiometric flexibility, and (3) how bone density varies across both bone types and species. We found that not only does bone change body elemental content, but it also functions directly in mineral homeostasis, complicating how P content affects demand in vertebrates. Additionally, bone (1) can increase or decrease in density depending on environmental conditions, changing body P content, and (2) can substitute elements within its mineral structure, changing its stoichiometry. These two factors, along with bone’s unique role in female reproductive biology, make bone a key trait for understanding stoichiometry. We also found that bone is extremely variable both within and across species, further supporting its role in defining vertebrate P content and elemental flexibility. 

Primary Presenter: Emily May, University of Victoria (emilymay@uvic.ca)

Authors:

Emily May, University of Victoria  (emilymay@uvic.ca)

Rana El-Sabaawi, University of Victoria  (rana@uvic.ca)