ARKHANGELSK, August 25. /TASS/. Scientists found out that climate has the greatest influence on high variability of shells of freshwater mollusk duck mussel (Anodonta anatina). Its shells can be so different that, before genetic studies, experts believed those were hundreds of different species, Director of the Laverov Federal Research Center for Integrated Arctic Studies (the Russian Academy of Sciences' Urals Branch, Arkhangelsk) Ivan Bolotov told TASS.

"Having used very extensive materials from almost all of Europe, Siberia and the Middle East, we have modeled factors affecting the morphological variability of the widespread species of mollusks, the duck mussel. We have managed to demonstrate that, on one hand, the shell shape is influenced by climatic factors, and on the other hand, by the mollusks' age. And the third factor is genetics. Noteworthy, the contribution of age and genetics is small, while the climate plays the key role," the scientist said.

The shells of duck mussels living in different bodies of water can vary greatly. In southern regions, they are rounded and mostly light; in northern regions, the shells are massive, dark and of a more elongated shape. Scientists from different countries and eras have believed they were describing 440 different species, while genetic studies have shown those are the same species having a very big range.

"It lives in the high Arctic, in our basins of the rivers Indiga, Pechora, Lena in Yakutia. At the same time, you may find it in the Orontes River basin, – in Syria, Lebanon, and Turkey. In the basins of North Africa's rivers, that is, Algeria, Tunisia. The species has a super range. This mollusk has very high adaptive abilities," he said.

Duck mussel most likely is the most numerous species of big freshwater bivalves. They are water bio filters, and they are very resistant to various pollutants. The total mass of these mollusks is a giant natural bio filter uniting millions of duck mussels.

The project to collect samples, conduct morphometric and genetics tests has continued for about 15 years. The final mathematical model shows that climate significantly affects the shell shape. In the fast Arctic rivers, they are massive and grow slowly; while in the south, shells grow quickly and they are much lighter. "Take a shell, for example, from some archaeological site, and you will be able to tell roughly by its shape where it comes from," the scientist said.