New habitat makes lizards evolve faster

In 1971, biologists brought five pairs of adult Italian lizards from the home island of Pod Kopiste (south of the Adriatic Sea) to the neighboring island of Pod Mrcaru. Now, an international team of researchers has shown that putting lizards of green dorsal Podarcis sicula to new habitats has prompted them to evolve rapidly and extensively.

Duncan Irschick - Massachusetts Amherst biology professor - said: 'Impressive differences in head size and shape, increased power of bites with the development of new structures in the digestive system lizards have appeared in just 36 years - an extremely short period of time. Physical changes occur simultaneously with incredible changes in individual density as well as social structure '. The results of the study are published in the March 25 issue of the Proceedings of the National Academy of Sciences.

For three consecutive years, scientists returned to the island twice a year - in the spring and summer of 2004, 2005, and 2006. The captured lizards were taken to the laboratory. There scientists will measure their length from mouth to anus, head size as well as body weight. Tail samples were taken to conduct DNA analysis to make sure that the lizards on Pod Mrcaru had genomes similar to the original population on Pod Kopiste Island.

The observed changes in head shape stem from adaptations to new food sources. According to Irschick, the lizards living on the barren Pod Kopiste are very good at capturing mobile prey, their main food being insects. While living on Pod Mrcaru - where they have never been, there is a supply of food from plants, including bush leaves and stems. Through the peculiar characteristics of the lizards on Pod Island, Poduscaru shows that their diet has up to two-thirds of the plant depending on the season - a huge increase in populations on Pod Kopiste.

'As a result, individuals on Pod Mrcaru have a longer head, bigger and taller than the Pod Kopiste island lizards that lead to a large increase in the power of the bites . Because plants are high in fiber and tough, strong bite force helps lizards get small pieces of food, while helping them to break down the undigested plant cell walls, ' Irschick said.

Lizard on Pod Mrcaru island
(Photo: Anthony Herrel of the University of Antwerp)

Research on lizards' digestive system has revealed a more interesting thing: Eating more plants causes lizards to develop new structures called cecum valves with the effect of slowing blood flow by creating fermentation in the intestine. There bacteria can break down the hard to digest parts of plants. Caecal valves are present in both newly hatched, growing and mature children on Pod Mrcaru island. This part has never been discovered in lizards before, including the original population on Pod Kopiste Island.

Irschick said: "Less than 1% of scaly reptiles have this structure. Our data shows that the new evolutionary structure can happen only in a very short period of time. Progress The cystic valve has formed in parallel with the incredible relationship between lizards on Pod Mrcaru island with the tiny creature called parasitic nematode in the back intestine of the lizard that helps digest cellulose . "

Diet changes also affect the density of individuals as well as social structures in populations on Pod Mrcaru. Since plants are a major source of control and food, there are many more lizards in the same area on the island. The lizards just chew on the leaves without having to find a way to chase prey like before, so they have lost the habit of protecting their territory.

According to Irschick, 'the unique interesting thing in this finding is that rapid evolution not only affects the structure and function of a species, but also affects both natural and ecological history. behavior'.