Uni challenges long-held rule on the size of animals
A NEW study by the University of Reading is challenging a long-held belief about the link between temperature and the size of animals.
The research, published in last week’s edition of Nature Communications, has suggested that extinct species of animals do not follow previous assumptions about the effect of climate and animals’ sizes.
Bergmann’s Rule is a maxim in ecological academia which predicts that warm-blooded animals who live in colder climates in higher altitudes will be bigger than those below the equator.
Scientists used computer models to study the size of birds, and while they found no direct link between where the birds lived and their body size, they found that temperature did have an effect on modern birds.
Currently, birds have larger body sizes on average in colder climates, however analysis of fossils dinosaurs and extinct species of birds showed that this was not the case when compared with contemporary climate models.
Instead, it found that evidence that suggest that the modern relationship between temperature and body size is a recent phenomenon.
Scientists think this may mean that the difference is connected to recent climate change and its effect on the evolution of migratory birds.
The study was co-authored by Dr Jacob Gardner, who said: “Dinosaurs and mammals originated at the start of the Mesozoic Era more than 230 million years ago when global temperatures were much warmer.
“These two groups spread to every corner of the Earth, with dinosaurs diversifying into a wider range of sizes — from small flying birds to some of the largest terrestrial animals to exist.
“Our study shows that the size of dinosaurs and mammals didn’t just depend on where they lived. We found that Bergmann’s rule only works for some warm-blooded animals, like modern birds, and only when you look at temperature alone, ignoring other climate factors like rainfall or humidity.
“This suggests that Bergmann’s ‘rule’ is more of an exception than a rule.”