Deviation by multiplication

Genetic mutation results in speciation

Published: Friday 31 May 2002

At times a species of animal splits into two without evolving in isolation for thousands of years. This phenomenon has nagged biologists since centuries. But now they have found an explanation for this intriguing occurrence in the curly shells of snails. Mats Bjorklund and Jonathan Stone from Sweden-based Uppsala University have discovered that genetic mutation in a gene of the mother snail can lead to the emergence of a new species.

Some snails have shells that coil in a right-handed or left-handed direction. "Righties" can't mate with "lefties" because their reproduction organs don't meet. The coil direction is controlled by a "maternal effect". A single gene in the mother codes for a protein that she deposits in her eggs, and this protein is responsible for the direction of the shells. According to the researchers, a rightly snail population generates a new lefty one when a rare mutation in a righty mother's egg switches the coiling gene to the left. However, the mother's egg protein still forces the embryo to coil to the right, resulting in a rightly daughter who can mate with other righties. But all her offspring are lefties who can mate with each other, thereby, producing a distinct species. The researchers opine that this theory could apply to other animals. For instance, an insect that normally mates in the morning could acquire a mutation that makes it mate only with its siblings in the afternoon.

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