Environmentalists compared biodiversity on the mainland and on the Islands with frogs and lizards.

Analisada lizard, Costa Rica (photo Thomas Marent).

Island fauna and flora have been attracting increased attention of biologists. The first who expressed the keen interest in the island biodiversity, were notorious Charles Darwin and Alfred Russel Wallace, great explorers who reported large differences in species composition between the Islands and the mainland. Then, in the twentieth century, had the idea that biodiversity on Islands obviously exceeds the biodiversity on the continent. It was believed that the uniqueness of the species composition of the Islands of the greater and species of the more than on the island from the mainland. Theory of the superiority of island biodiversity, which has arisen due to the isolation and unique ecological and evolutionary processes, held until 2005, when a large group of ecologists compared the biodiversity of the Amazon basin and the jungles of Central Africa - and it turned out that these mainland area is quite can compete number and quirkiness species to the Islands.

In the new study, undertaken by ecologists from the University of Nottingham (UK), is another attempt to assess the diversity of island fauna and how it is different from the mainland. While scientists are not considered absolute number of species on the island, as compared different areas: so you could be more than adequate understanding of biodiversity. Environmentalists were interested in General regularities of development of island fauna, and for the study of these regularities they chose the group analisow lizards and frogs Terrarana. Both live in a New Light and wonderful wide variety of species.

For comparison were taken Caribbean and tropical areas in Central and South America. On the mainland have chosen territory, which was repeated in area of island and do not overlap each other. In addition, the researchers watched that and on the mainland and on the Islands at the disposal of amphibians and reptiles were the same resources. They wanted to know how many unique species of lizards and frogs were present in each territory. Naturally, taking into account the distance between the selected areas and potential environmental differences like height above sea level and frequency of rainfall.

It turned out that the Islands - with more or less equal conditions - indeed, there are more species than on the mainland. That is, and frogs, and lizards are more prone to speciation, being cut off from the mainland. Thus between the different Islands diversity varies weaker than that between the island and the mainland, but still stronger than between two mainland territories.

The research results are presented in the journal Proceedings of the Royal Society B.

On the one hand, it keeps within the evolutionary pattern: speciation pushed ecological and geographical separation of populations. That is, the researchers only found one environmental proof of this, although quite sophisticated. On the other hand, the authors admit that the data reflect only two groups of reptiles and amphibians and what you need confirmation from other animals. In addition, on the mainland there are areas with species of endemic, who for various reasons never leave their long-occupied area.

In the future, make sure to have confidence in the findings, the researchers were just going to compare the diversity of island species with mainland areas of endemic species.

Based on the materials ScienceNOW.