Institute of Biology, P.O. Box 9502, 2300 RA Leiden, The Netherlands.
Evolution. 2010 Jul;64(7):2159-65. doi: 10.1111/j.1558-5646.2010.00977.x. Epub 2010 Feb 19.
Individual symmetry is believed to be advantageous and reflecting developmental stability, but frequency-dependent selection can also maintain polymorphisms of asymmetric phenotypes. There are many examples of so-called antisymmetry, where mirror image morphs occur at equal frequencies. With very few exceptions, these are caused by nongenetic variation. One notable exception is handedness and mouth bending variation in the scale-eating cichlid Perissodus microlepis, which has been suggested to be an example of antisymmetry determined by a single genetic locus of large effect. Here, we report that this handedness and mouth bending asymmetry are not jointly and exclusively determined by a single major locus. We found no evidence of a major locus for asymmetry and some support for a major handedness locus. Also, asymmetry is plastic in this species: it can change in adults. We suggest that behavioral handedness in this system precedes and guides morphological asymmetry.
个体对称性被认为是有利的，反映了发育稳定性，但频率依赖选择也可以维持不对称表型的多态性。有许多所谓的反对称性的例子，其中镜像形态以相等的频率出现。极少数情况下，这是由非遗传变异引起的。一个值得注意的例外是食鳞鲷 Perissodus microlepis 的手性和口弯曲变异，有人认为这是由单个大效应遗传基因座决定的反对称性的一个例子。在这里，我们报告说，这种手性和口弯曲的不对称性不是由单个主要基因座共同和排他地决定的。我们没有发现不对称的主要基因座的证据，而对手性的主要基因座有一些支持。此外，这种物种的不对称性是可塑的：它可以在成体中改变。我们认为，这个系统中的行为手性先于并指导形态不对称。
