Metabolism correlates with variation in post‐natal growth rate among songbirds at three latitudes

Abstract

Summary Variation in post‐natal growth rates is substantial among organisms and especially strong among latitudes because tropical and south temperate species typically have slower growth than north temperate relatives. Metabolic rate is thought to be a critical mechanism underlying growth rates after accounting for allometric effects of body mass. However, comparative tests on a large spatial scale are lacking, and the importance of metabolism for growth rates remains unclear both within and particularly across latitudes. Songbirds exhibit strong interspecific variation in growth rates across geographic space, although within latitudes an association between metabolic rate and growth rate has not always been observed. Moreover, the hypothesis that differences in growth rates across latitudes reflect underlying differences in metabolism is untested. Here, we investigate these possibilities across north temperate, south temperate and tropical study sites. Phylogenetic analyses showed that, for a given body mass, metabolic rates of north temperate nestlings were higher than tropical and south temperate species. Metabolic rates controlled for body mass correlated with post‐natal growth rates both within and among latitudes. Offspring body mass explained substantial residual variation in growth rates as expected under classic allometric theory. Our results suggest that variation in metabolic rates has an important influence on broad patterns of avian growth rates at a global scale. We suggest further studies that address the ecological and physiological costs and consequences of variation in metabolism and growth rates.

Embryonic heart rate predicts prenatal development rate, but is not related to post‐natal growth rate or activity level in the zebra finch (Taeniopygia guttata)

“…Although more conventional methods for gathering data on metabolic rates could be used for both embryos and nestlings (e.g., respirometric measures, Lierz, Gooss, & Hafrez, ), such methods are rather intensive and difficult to achieve with large sample sizes. Assessing whether metabolic rates influence activity level within the same ontogenic stage, and whether metabolic rates persist across hatching, will allow us to clarify whether our results indicate that (a) metabolism is not related to activity levels in the zebra finch, or (b) metabolism is related to activity levels within the same ontogenic stage (as in other avian species, Ton & Martin, ). Addressing these limitations will not only enable us to better interpret the results of our study, but also help to more generally clarify the role of metabolic rate in maintaining consistent individual differences across an individual's life.…”

“…Interestingly, we also failed to detect any relationship between prenatal developmental rate and post‐natal growth rate. We are reasonably confident that embryonic heart rate is a good proxy for metabolic rate, because those individuals with a high heart rate developed at a faster rate during prenatal development than those with relatively low heart rates (an organisms metabolic rate limits the rate at which it processes energy, which in turn determines its development rate (McCarthy, ; Rosenfeld, Leeuwen, Richards, & Allen, ; Ton & Martin, ). Incubation temperature has a strong positive effect on embryonic heart rate and a strong negative effect on embryonic development time (Du et al ; Vedder et al, ).…”

Rediscovering and Reviving Old Observations and Explanations of Metabolic Scaling in Living Systems

“…By contrast, recent studies on birds report significant associations between rates of whole body growth and cell metabolism in tissue cultures [230,231]. In any case, interspecific associations between growth and metabolism are more likely to occur in growing juvenile animals, as observed in nestling songbirds at three different latitudes [232]. Empirical support for growth-based RD models at the interspecific level is presently weak for adult multicellular organisms.…”

Pace of life syndrome under warming and pollution: integrating life history, behavior, and physiology across latitudes

“…, Londono et al. , Ton and Martin ), this approach has rarely been explicitly used to study POLS patterns among populations (but see Wikelski et al. ).…”