![]() In ecologically equivalent populations existing within a small, environmentally homogeneous area, an important role for environmentally neutral divergence is often found or inferred. Our study shows that adaptation to biotic aspects of the environment may play a more important role in allopatric speciation than previously suspected, even on a geographically very small scale.Ībstract = "AbstractGenetic divergence in geographically isolated populations is a prerequisite for allopatric speciation, one of the most common modes of speciation. We also found geographic differentiation in the behavior of the snails' invertebrate predator and evidence of an evolutionary interaction between aspects of shell shape and predator behavior. We found that a striking geographic divergence exists in shell morphology, which is partly associated with neutral genetic divergence. We used shell morphometrics, mitochondrial and nuclear DNA sequences, and marks of predation to study the factors involved in allopatric divergence. We studied a species complex of conspicuously shaped Opisthostoma land snails on scattered limestone outcrops within a small area of lowland rainforest in Borneo. But if the external skeleton cracked a little or a piece of it is broken, the snails can still be saved.AbstractGenetic divergence in geographically isolated populations is a prerequisite for allopatric speciation, one of the most common modes of speciation. Besides the fact that they are in danger from predators, they will not be able to move and will quickly lose moisture. The snails that were originally born with a shell cannot live without their “house”. Scientists believe that the shell of such creatures has atrophied during evolution: due to the spread of slugs in places with high humidity, but the lack of calcium, necessary for a strong shell. Shellfish without an external skeleton have scientific name “slugs”. Such mollusks are usually poisonous, so they are not edible. Moreover, the brighter the color, the more dangerous the creature is. Important! Decorative species of snails can have brightly colored shells. The popular small and big snails have grey shells correspondingly. ColorĮdible snails, used for the preparation of escargot, have brown color (it can vary from the light amber to dark brown). It can be observed in grape snails (Helix Pomatia). The ribbed surface of the shell retains moisture and also increases the strength of the external skeleton. Thus, the age of the individual can be determined by the number of spirals on the external skeleton. The substance is deposited in a circle and forms spirals. As they grow older, they absorb limestone from the water. Important! Young snails hatch with a shell, which is very soft and translucent. Thus, for example, the famous grape snail Jeremy has the mirrored internal organs, so the spirals on its shell are twisted in the opposite direction. However, there is a common characteristic: the spirals are twisted clockwise, with rare exceptions. The exterior of the shell determines the type of mollusk. In addition, the internal organs and muscles of the snail are also attached to the inner side of the shell. ![]() ![]() The mantle, the skin fold that holds the body together with the shell, is not considered part of the shell, but performs an important function. The inner layer is a mother-of-pearl shade. The outer layer, which consists of conhiolin, a special protein. The structure consists of the three layers: Therefore, it helps snails to move and holds parts of their body. Like other mollusks, the shell of the snail is an external skeleton. This fact is very interesting, because the shells of different snails differ by shape, structure and color. However, no one knows the real value of the shell. ![]() From the childhood we know that snails are the creatures that bring their house on the back.
0 Comments
Leave a Reply. |