Meeting Abstract
Metabolic allometries typically take the form of power functions, and the Metabolic Theory of Ecology (MTE) asserts a “universal” three-quarter power for such scaling rules. Recent studies have differed over support for the three-quarter allometric coefficient required by the MTE. We have previously argued that such coefficients vary among mammalian clades and that 0.75 is not a universal scaling constant. Also as endotherms with a wealth of metabolic measurements on multiple clades, birds are a natural next step to observe clade-specific variation. Flight-related metabolic constraints may also affect birds’ metabolic allometries. In addition, existing literature examining the allometries of basal metabolic rates in birds has not considered the impacts of phylogeny beyond a binary passerine vs. non-passerine classification. Phylogenetic relatedness can account for variation, or lack thereof, in metabolic rate between closely related clades. It is also yet unclear as to whether the broad, “universal” three-quarter power allometries are composed of smaller sub-allometries that correspond with deeper classifications. We have amassed a database of 726 bird species from existing literature. After assigning each of them to one of 15 monophyletic clades we performed regressions using a variety of analytic techniques. For basal metabolic rate, both allometric slopes and intercepts (known as normalization constants) varied significantly among bird clades both between passerines and non-passerines. This parallels our previous findings among mammals.
