Short legs are good for climbing

When lizard habitats appear new carnivores, the natural selection process will play its role in two stages. At first, the advantage belonged to longer legs. But then, short-legged lizards have a better chance of survival.

The brown anolis lizard species ( Anolis sagrei ) lives mostly on the ground. When meeting a carnivorous lizard, the anolis run away by climbing up the tree. Over time, they move to live on trees to avoid being eaten.

Brown Anolis sagrei lizard (Photo: amazilia.net)

Anolis lizard's long legs help them to run very fast, providing an advantage in the underground environment, where balance is not so important. But will longer-legged anolis have an advantage in climbing life?

Jonathan Losos and Harvard biologists (USA) explore this problem with anolis lizards on 12 small islands in the Bahamas, where there are no any carnivorous lizards. They brought a variety of carnivorous lizards called Leiocephalus carinatus to six of them.

The first task of the expert team is to mark and count the number of lizards at the beginning of the study. 6 months later, they repeated this work a second time.

The results showed that after 6 months, anolis on 6 islands had carnivorous lizards reduced by at least half compared to the original. On closer examination, experts found that the surviving anolis had longer legs than those killed. They believe that long-legged lizards often run faster so they have a better chance of escaping the enemy.

A lizard Leiocephalus carinatus.
(Photo: nationalgeographic.com)

But the situation reversed after 6 months later, when the anolis were adapted to tree life. Scientists found that living anolis have shorter legs than those killed.

Meanwhile, the leg length of both the dead and alive anolis on the other six islands is not significantly different.

Experts believe that short legs are more suitable for orientation on narrow branches. Therefore, after a long time, surviving anolis lizards in 6 islands with carnivorous lizards will be shorter legs.

Viet Linh