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To review:
The effect of evolutionary adaptation of snakes which is related to the jaw modification to eat right coiler snails more easily compare to the left coilers, on the evolution of snails in the areas where both species coexist.
Introduction:
Snails often considered as the model organism in study of developmental biology, as they show modifications in their development correlated to the environmental condition. The establishment of the body axes follows different modes, depending upon the species. In case of the snail, twisting or spiral characterstic is the fundamental property. Two types of coiling is present in the snail shell, sinistral and dextral. Dextral coiling is the opening to the right of snail shell and the sinistral coiling is the opening of the snail shell to left.
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Explanation of Solution
The snail clevage is controlled by the maternal regulation. The left or right orientation pattern of the clevage plane is regulated by the cytoplasmic factors present in the oocyte. Dextral coiling and sinistral coiling is also regulated by the clevage pattern. Under the normal condition the coiling pattern of a species is the same for all members, but the mutations creats the differences. The studies reveals that a single gene is responsible for the sinistral and dextral coiling in snails. Sinistral group is present in minority, compare to dextral snails, which are more common. Mating between these two groups is neary impossible, due to the difference in orientation.
The evolutionary adaptation of snakes to eat right coiler snails, can impact the evolution of snails because the left coiler snail has found the advantage to survive the predation from the snakes. This resistance to snake predation makes the left coiler more suitable for the natural selection of species. Here, the mutation which provides the resistance from predation becomes beneficial for the snail, thus it may persistent for a number of generation and leads to make a distinct species.
Thus it is concluded that the jaw modification of snakes to eat right coiler snails, gives advantage to the left coiler snails and makes them more suitable to evolved as a distinct species during natural selection.
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Chapter 8 Solutions
Developmental Biology
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