When is size not everything?


Animals adapt to climate change using different methods

Scientists at the Senckenberg Biodiversity and Climate Research Center in Frankfurt, together with an international team, have investigated various adaptation strategies of mammals and birds to temperature changes. In doing so, they were able to refute the assumption, which has been valid for a good 60 years, that the size of the animals is the decisive factor for adaptation. The results in the recently published journal “Proceedings of the National Academy of Sciences” (PNAS)
published study help to understand the effects of climate change on wildlife.

The little Lapland tit (Poecile cinctus) feels at home in the cold regions of Scandinavia and Siberia, the African elephant populates the hot steppes of West Africa. “According to the Scholander-Irving model, that shouldn't exist at all,” explains Dr. Christian Hof from the Senckenberg Biodiversity and Climate Research Center in Frankfurt and continues: "That was the reason for us to take a closer look at this theory, which is over 60 years old." Based on the question of how mammals and birds can keep their body temperature almost constant, when the outside temperature changes - sometimes drastically - the biologists Laurence Irving and Per Scholander developed a model of thermoregulation in arctic mammals in the 1950s. Their theory is that warm-blooded mammals and birds compensate for the loss of heat to the environment through heat-generating metabolic processes. Both the rate of metabolic processes and the dissipation of heat to the outside are significantly influenced by body size. "According to the model that has been in place for 60 years, this would mean that large animals live in cold regions and small animals are restricted to hot parts of the world - but in reality it looks different," explains Hof and continues: "Small mammals, for example, kick in the most varied of habitats with temperatures from -35 degrees up to 45 degrees Celsius ".

Body size alone does not explain the adaptation to the different temperatures. The Frankfurt biologist: "We were able to identify thermal conductivity as a further factor for the adaptation." The thermal conductivity of an animal can be influenced, for example, by large ears, long legs or thick fur.

An international team of scientists led by Trevor Fristoe from the University of New Mexico examined 211 bird and 178 mammal species with regard to their body temperature and the temperature of their habitat. They come to the conclusion that the animals were able to adapt to the differently tempered habitats by adapting their metabolism as well as their thermal conductivity. "The Lapland tit was able to adapt to its icy habitat by increasing its body's own heat production or by reducing its thermal conductivity, for example through warm plumage, or a combination of both factors," explains Hof.

To understand the effects of climate change, it is important to know what possibilities animals have to adapt to different temperatures. “It was only because of the large amount of data available today that we were able to show that the Lapland tit and African elephant are no exception and refute the Scholander-Irving model,” adds Hof.

Fristoe, T. S .; Burger, J. R .; Balk, M. A .; Khaliq, I .; Hof, C. and Brown, J. H. (2015): Metabolic heat production and thermal conductance are mass-independent adaptations to thermal environment in
birds and mammals. PNAS 112 (52): 15 934 - 15 939. doi: 10.1073 / pnas.1521662112.


Senckenberg Society for Natural Research



♦ Also read the following articles from nature and landscape:

  • "Adaptive capacity of 50 species with a potentially high risk of extinction to climate change in Germany"by Kerth et al. in issue 1-2015;
  • "Natura 2000 and Climate Change - State of Knowledge"by Ellwanger et al. in issue 1-2011.

You can find further interesting specialist articles on the subject of climate change or other topics via the Article research. ♦