The Allometry of Avian Basal Metabolic Rate: Good Predictions Need Good Data

Abstract

Basal metabolic rate (BMR) is often predicted by allometric interpolation, but such predictions are critically dependent on the quality of the data used to derive allometric equations relating BMR to body mass (Mb). An examination of the metabolic rates used to produce conventional and phylogenetically independent allometries for avian BMR in a recent analysis revealed that only 67 of 248 data unambiguously met the criteria for BMR and had sample sizes with n>/=3. The metabolic rates that represented BMR were significantly lower than those that did not meet the criteria for BMR or were measured under unspecified conditions. Moreover, our conventional allometric estimates of BMR (W; logBMR=-1.461+0.669logMb) using a more constrained data set that met the conditions that define BMR and had n>/=3 were 10%-12% lower than those obtained in the earlier analysis. The inclusion of data that do not represent BMR results in the overestimation of predicted BMR and can potentially lead to incorrect conclusions concerning metabolic adaptation. Our analyses using a data set that included only BMR with n>/=3 were consistent with the conclusion that BMR does not differ between passerine and nonpasserine birds after taking phylogeny into account. With an increased focus on data mining and synthetic analyses, our study suggests that a thorough knowledge of how data sets are generated and the underlying constraints on their interpretation is a necessary prerequisite for such exercises.

Group-foraging is not associated with longevity in North American birds

“…Future work could determine if increases in body mass allow non-passerine birds the opportunity to avoid predation to a greater extent or if physiological adaptations scaling with body size operate more forcefully in non-passerine birds. Interestingly, passerine and non-passerine birds do not differ in basic metabolic rate after controlling for phylogeny and body mass (McKechnie & Wolf 2004).…”

An Analysis of the Relationship Between Metabolism, Developmental Schedules, and Longevity Using Phylogenetic Independent Contrasts

“…Body mass and BMR pairs of values were obtained from published data sets compiled according to strict criteria (39)(40)(41)(42). Pairs of values for BMR and body mass were always obtained from the same source.…”

“…The reasons for exclusion are detailed elsewhere (39). Regarding birds, the data compilation by McKechnie and Wolf (41), which is based on earlier works (40,43), served as our benchmark. In contrast to McKechnie and Wolf, but in agreement with Reynolds and Lee (43), we included BMR estimates based on fewer than three animals, provided that the conditions for the measurement of BMR met the standards set by McKechnie and Wolf (41).…”

“…Regarding birds, the data compilation by McKechnie and Wolf (41), which is based on earlier works (40,43), served as our benchmark. In contrast to McKechnie and Wolf, but in agreement with Reynolds and Lee (43), we included BMR estimates based on fewer than three animals, provided that the conditions for the measurement of BMR met the standards set by McKechnie and Wolf (41). Several BMR estimates [including some of the data points from Bennett and Harvey (40)] that did not meet the standards set by McKechnie and Wolf (41), such as BMR values estimated in the active phase of the daily cycle, were not used in our analyses.…”

Giants on the landscape: modelling the abundance of megaherbivorous dinosaurs of the Morrison Formation (Late Jurassic, western USA)

“…circulatory and respiratory systems). However, although empirical analyses of metabolic scaling in vertebrates tend to show metabolic scaling exponents near 3/4, they generally do not support the conclusion that there is a common exponent relating metabolism to body mass (White and Seymour 2003McKechnie and Wolf 2004;Glazier 2005Glazier , 2010Clarke 2006;White et al 2006Downs et al 2008;Makarieva et al 2008;McNab 2008McNab , 2009aSieg et al 2009). In birds and mammals basal metabolic rate (BMR) or standard metabolic rate (SMR) as conventionally analysed scales to body mass to somewhere between 0.64 and 0.75 power, while the metabolic exponent for reptiles is greater, about 0.76-0.80 or even higher; the difference is observed whether non-phylogenetic or phylogenetically corrected analyses are employed.…”