It has long been thought that animals that ‘live slowly’, having a slow rate of metabolism, live longer than those that live their lives at a fast rate: having high metabolic rates. The notion is based on the assumption that animals with fast metabolic rates are more active, more exposed to predators, have higher rates of potentially harmful somatic mutations and produce more harmful metabolic by products such as free radicals. This tradeoff between metabolism and lifespan is commonly referred to as the ‘rate-of-living’ theory.
In a recent publication in the Journal Global Ecology and biogeography, we (Gavin Stark; Daniel Pincheira donoso and Shai Meiri) showed that the assumption under the “rate of living” theory which have been around for almost a century is unsupported by the results of our largest scale study (4,100 land vertebrate species: 2,214 endotherms & 1,886 ectotherms) to date of this theory. We could not find any connection between animal metabolic rate and longevity, either when we tested all land vertebrates (i.e. Mammals, Birds, Reptiles and Amphibians) or when we tested each group separately. In contrast, we did find other factor that did affect the lifespan of ectotherms (Reptiles and Amphibians), and it is ambient temperature. In colder regions around the world we expect species of reptiles and amphibians to live longer than other ectotherms living in warmer environments. The link between ectothermic (amphibians and reptiles) lifespan and ambient temperatures could mean that they are especially vulnerable to the unprecedented global warming that the planet is currently experiencing. Indeed, if increasing ambient temperatures reduces longevity, it may make ectothermic species more prone to go extinct as the climate warms. Our findings add a previously overlooked layer to the range of factors that are commonly thought to imperil species in the Anthropocene.
In a recent publication in the Journal Global Ecology and biogeography, we (Gavin Stark; Daniel Pincheira donoso and Shai Meiri) showed that the assumption under the “rate of living” theory which have been around for almost a century is unsupported by the results of our largest scale study (4,100 land vertebrate species: 2,214 endotherms & 1,886 ectotherms) to date of this theory. We could not find any connection between animal metabolic rate and longevity, either when we tested all land vertebrates (i.e. Mammals, Birds, Reptiles and Amphibians) or when we tested each group separately. In contrast, we did find other factor that did affect the lifespan of ectotherms (Reptiles and Amphibians), and it is ambient temperature. In colder regions around the world we expect species of reptiles and amphibians to live longer than other ectotherms living in warmer environments. The link between ectothermic (amphibians and reptiles) lifespan and ambient temperatures could mean that they are especially vulnerable to the unprecedented global warming that the planet is currently experiencing. Indeed, if increasing ambient temperatures reduces longevity, it may make ectothermic species more prone to go extinct as the climate warms. Our findings add a previously overlooked layer to the range of factors that are commonly thought to imperil species in the Anthropocene.
The relationship between longevity (y axis of all panels, log10 transformed) and (a–d) body mass (in g, log10 transformed) of amphibians (red circles), reptiles (black circles), birds (green triangles) and mammals (inverted blue triangles). (e–h) Mean annual temperature (regression lines only shown for amphibians and reptiles for which the relationship is significant), (i) basal metabolic rate (in ml O2/hr, log10 transformed), according to the color codes depicted in the top plots and (j) field metabolic rate (kJ/day, log10 transformed)
Author: Gavin Stark
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