A team of evolutionary biologists from the University of New South Wales and other institutes has analyzed the evolution of planing animals, animals that can be considered a middle ground between non-flying and flying animals.
These animals are equipped with “wings” that are used to glide jumping from great distances rather than flying.
The evolutionary path of these animals is very interesting and has been the subject of the study published in The American Naturalist.
The researchers confirm first of all the previous theories about these animals. Those we see today come, on an evolutionary level, from arboreal ancestors. The latter must have developed the planing system to escape predators in a period between 30 and 25 million years ago.
The advantage of being able to glide is clear: with such a technique one can literally exploit a new three-dimensional environment, for example by jumping from tree to tree, as Terry Ord, evolutionary ecologist at the UNSW and lead author of the study suggests: “From the point of view of an evolutionary biologist, it is assumed that these types of innovation that open up new opportunities promote even more appropriate diversification. Suddenly there are all these new microhabitats available that offer new resources and you have new species moving into those particular microhabitats where you would expect them to adapt even more”.
Unlike flying animals, however, which have developed anatomically more and more to take advantage of flight, in gliding animals there has not been a real radical change in the shape of the body or the size of its functions.
Gliding animals, unlike flying animals, have limited themselves to exploiting “soft landing”.
The researchers analyzed above all the Draco blanfordii (also “flying dragons”), a small lizard of the family of the agamas (Agamidae), reptiles widespread especially in south-east Asia, and the more known “flying squirrels”, rodents of the family of the sciurinae (Sciurinae).
In the case of African flying squirrels, for example, the body size and their characteristics are not so different from those of non-flying squirrels.
In the case of flying dragons there has been some structural change compared to the more similar but not flying species. These animals have developed larger bodies at the expense of gliding skills. To compensate for this these animals have developed a flattening of the body so that it almost “merges” with the bark of the trees. “So they are almost regressing from the gliding lifestyle. But in this case, the reason they are changing their body size is to outperform the competition with other lizards,” says Ord.