Is Bergmann's Rule Valid for Mammals?

Ashton,; Tracy,; Queiroz, de

doi:10.2307/3079173

Cited by 147 publications

(222 citation statements)

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“…This prediction is generally supported by the examples of intraspecific variation in body size consistent with Bergmann's rule that have been documented in many, but by no means all, kinds of mammals and birds (10,11).…”

mentioning

confidence: 57%

Metabolic heat production and thermal conductance are mass-independent adaptations to thermal environment in birds and mammals

Fristoe

Burger

Balk

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

123

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The extent to which different kinds of organisms have adapted to environmental temperature regimes is central to understanding how they respond to climate change. The Scholander-Irving (S-I) model of heat transfer lays the foundation for explaining how endothermic birds and mammals maintain their high, relatively constant body temperatures in the face of wide variation in environmental temperature. The S-I model shows how body temperature is regulated by balancing the rates of heat production and heat loss. Both rates scale with body size, suggesting that larger animals should be better adapted to cold environments than smaller animals, and vice versa. However, the global distributions of ∼9,000 species of terrestrial birds and mammals show that the entire range of body sizes occurs in nearly all climatic regimes. Using physiological and environmental temperature data for 211 bird and 178 mammal species, we test for mass-independent adaptive changes in two key parameters of the S-I model: basal metabolic rate (BMR) and thermal conductance. We derive an axis of thermal adaptation that is independent of body size, extends the S-I model, and highlights interactions among physiological and morphological traits that allow endotherms to persist in a wide range of temperatures. Our macrophysiological and macroecological analyses support our predictions that shifts in BMR and thermal conductance confer important adaptations to environmental temperature in both birds and mammals.macrophysiology | Bergmann's rule | body size | metabolic rate | thermal conductance A fundamental problem in ecology and biogeography is to elucidate the physiological processes that determine the environmental tolerances and influence the distributions of species. Across their nearly worldwide distributions, endothermic birds and mammals maintain near-constant body temperatures in the face of extreme and fluctuating environmental temperatures. Elucidating the morphological and physiological adaptations that allow species to inhabit such a wide spectrum of thermal environments is important for understanding the distribution of biodiversity and for predicting responses of species to climate change (1, 2).In a seminal paper, Scholander et al. (3) showed how endotherms balance rates of heat production and heat loss so as to maintain a constant body temperature in the face of varying environmental temperatures. The essence of the Scholander-Irving (S-I) model is the equation:where T b is body temperature, T a is ambient temperature, B is the rate of metabolic heat production, and C is the rate of heat loss or thermal conductance (4). For a resting animal, which has minimized heat loss by maximizing insulation and optimizing body posture, C = minimum thermal conductance (C MIN ); B = basal metabolic rate (BMR); and T a = T lc , where T lc is the lower critical temperature or the lower limit of the thermal neutral zone (TNZ).The TNZ is ecologically important because it is the range of environmental temperatures where energy expenditure is minimal; out...

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mentioning

confidence: 57%

Metabolic heat production and thermal conductance are mass-independent adaptations to thermal environment in birds and mammals

Fristoe

Burger

Balk

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

123

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“…If we consider that evolutionary changes are a more likely explanation than fetal environment for skeletal differences between Neandertals and modern humans, climatic adaptation is the best-supported explanation for many aspects of Neandertal postcranial form because Neandertals have body proportions close to present-day humans with ancestry in cold climates (24,30,31), it appears that multiple generations are necessary for appreciable changes in body proportions (i.e., an evolutionary timescale is needed) (24,25), a wide variety of taxa exhibit similar ecological relationships (47)(48)(49), and laboratory experiments on human subjects demonstrate that body proportions influence heat loss (50) [see also Churchill (51)]. Recent research, however, has cast some doubt on this explanation.…”

Section: Discussionmentioning

confidence: 99%

Neonatal postcrania from Mezmaiskaya, Russia, and Le Moustier, France, and the development of Neandertal body form

Weaver

Coqueugniot

Golovanova³

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Neandertal and modern human adults differ in skeletal features of the cranium and postcranium, and it is clear that many of the cranial differences-although not all of them-are already present at the time of birth. We know less, however, about the developmental origins of the postcranial differences. Here, we address this deficiency with morphometric analyses of the postcrania of the two most complete Neandertal neonates-Mezmaiskaya 1 (from Russia) and Le Moustier 2 (from France)-and a recent human sample. We find that neonatal Neandertals already appear to possess the wide body, long pubis, and robust long bones of adult Neandertals. Taken together, current evidence indicates that skeletal differences between Neandertals and modern humans are largely established by the time of birth. body proportions | climatic adaptation | Homo neanderthalensis | infracranial | ontogeny

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“…Metabolic rates in endotherms are closely linked to body size, with larger bodies having higher absolute metabolic rates but lower rates per unit mass. As body size in endotherms tends to be greater at higher latitudes (Bergmann's rule), a counter gradient decrease in basal metabolic rate per unit mass with increased latitude is suggested (Ashton et al, 2000). But Gillman et al (2009) found that even when body size of mammals was accounted for, the rate of molecular evolution still increased towards the tropics.…”

Section: The Process Behind the Patternmentioning

confidence: 99%

Molecular evolution and the latitudinal biodiversity gradient

2013

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Species density is higher in the tropics (low latitude) than in temperate regions (high latitude) resulting in a latitudinal biodiversity gradient (LBG). The LBG must be generated by differential rates of speciation and/or extinction and/or immigration among regions, but the role of each of these processes is still unclear. Recent studies examining differences in rates of molecular evolution have inferred a direct link between rate of molecular evolution and rate of speciation, and postulated these as important drivers of the LBG. Here we review the molecular genetic evidence and examine the factors that might be responsible for differences in rates of molecular evolution. Critical to this is the directionality of the relationship between speciation rates and rates of molecular evolution.

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Is Bergmann's Rule Valid for Mammals?

Cited by 147 publications

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Metabolic heat production and thermal conductance are mass-independent adaptations to thermal environment in birds and mammals

Metabolic heat production and thermal conductance are mass-independent adaptations to thermal environment in birds and mammals

Neonatal postcrania from Mezmaiskaya, Russia, and Le Moustier, France, and the development of Neandertal body form

Molecular evolution and the latitudinal biodiversity gradient

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