Do reptiles that live fast, die young?
Live fast, die young – does this apply to reptiles? More meat and more sex have been linked to decreased longevity in lepidosaurs, in a new comparative study by the University of Lincoln.
The Lepidosauria are a monophyletic subgroup of reptiles, which contains the Squamata and Rhychocephalia; snakes and lizards (Squamata), are the most speciose of the lepidosaurs. This study used data from 1014 species, collecting maximum age (longevity) information from the literature and from animals kept in zoological gardens. Other variables such as feeding habits, body size, age at first reproduction, brood frequency and size, activity time, type of reproduction and body temperature in the field were recorded from previous published studies. The species’ global distribution was mapped, and environmental variables calculated for each.
Reptiles eat a variety of foods; few are solely meat or veg eaters, tending to have a percentage of each in their diet. Many are carnivorous – the Mexican Beaded Lizard (Heloderma horridum horridum) eats other lizards, eggs, frogs, birds, rabbits and carrion, and will even climb trees to reach tastier morsels. In this study the lepidosaurs were classified as carnivorous, herbivorous or omnivorous depending on the relative proportion of greens they tend to consume.
It was hypothesized that larger species with a later first reproductive attempt should live longer since their ageing would be delayed, and that longevity would be negatively correlated to body temperature and mean annual temperature. Animals that had a greater intensity of reproduction, with larger clutch sizes and more broods per year, were predicted to have a decreased lifespan due to the life history trade-offs involved in reproduction.
As predicted, colder environmental conditions strongly boosted maximum age. Meat-eaters seemed to pay the price of their dietary habits: omnivorous lepidosaurs lived for 20% longer than carnivores, and herbivores for 20% longer than omnivores. It was suggested that poorer food consumption may lead to later maturation and longer life in herbivorous species. While mode of reproduction did not affect longevity, a greater reproductive effort reduced lifespan significantly.
The results of this study agree with established theories of life-history traits and ageing: ‘slow’ living in many reptiles may be the clue to a long life, while those that live ‘fast’ do indeed die young.
Scharf, I., Feldman, A., Novosolov, M., Pincheira-Donoso, D., Das, I., Böhm, M., Uetz, P., Torres-Carvajal, O., Bauer, A., Roll, U. and Meiri, S. (2014) Late bloomers and baby boomers: ecological drivers of longevity in squamates and the tuatara. Global Ecology and Biogeography DOI:10.1111/geb.12244
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