McMillan W Owen, Weigt Lee A, Palumbi Stephen R
Departamento de Biología, Universidad de Puerto Rico, P.O. Box 23360, San Juan, Puerto Rico, 00931-3360.
Department of Zoology and Kewalo Marine Laboratory, University of Hawaii, Honolulu, Hawaii, 96822.
Evolution. 1999 Feb;53(1):247-260. doi: 10.1111/j.1558-5646.1999.tb05350.x.
In butterflyfishes (Chaetodontidae), color pattern evolves rapidly and is often the only morphological trait separating closely related species. Vivid coloration is frequently assumed to provide critical signals for mate recognition and mate choice, but few direct experimental tests are available. Here we analyze the relationship between color pattern change, mate choice, and genetic differentiation in a group of three very closely related allopatric butterflyfishes. We found that in only one member of this group, Chaetodon multicinctus, is color pattern evolution associated with mate preference and genetic divergence. For its two sister species, C. punctatofasciatus and C. pelewensis, color pattern change has not resulted in assortative mating (based on laboratory pairing experiments and field observations) or in significant mtDNA or allozyme differentiation. In a contact zone on reefs in the Solomon Islands and Papua New Guinea, hybridization between the two forms has nearly homogenized color pattern differences. Outside these areas, however, color pattern remains distinct. Genetic variation is homogeneous over a much larger geographic scale. Sequence variation in the tRNA-proline end of the mitochondrial control region and allozyme variation was distributed widely within C. punctatofasciatus and C. pelewensis, which suggests few constraints to mitochondrial or nuclear gene flow across the color pattern boundary. These contrasting patterns strongly suggest that selection is maintaining color pattern differences in allopatry in the face of potentially homogenizing levels of gene flow. The mating pattern data show that this selection is not operating on mate recognition in the strictest sense, but probably on some other aspect of the social system of these territorial fish. In this case, divergence in mating preference can follow color pattern evolution, but is not contemporaneous with it.
在蝴蝶鱼（蝴蝶鱼科）中，体色模式进化迅速，且常常是区分近缘物种的唯一形态特征。鲜艳的体色常被认为能为配偶识别和配偶选择提供关键信号，但相关的直接实验测试却很少。在此，我们分析了一组三种亲缘关系非常近的异域蝴蝶鱼的体色模式变化、配偶选择和遗传分化之间的关系。我们发现，在这一组中只有细纹蝴蝶鱼（Chaetodon multicinctus）的体色模式进化与配偶偏好和遗传分化有关。对于它的两个姐妹物种，即斑带蝴蝶鱼（C. punctatofasciatus）和贝氏蝴蝶鱼（C. pelewensis），体色模式的变化并未导致选型交配（基于实验室配对实验和野外观察），也未导致显著的线粒体DNA或等位酶分化。在所罗门群岛和巴布亚新几内亚珊瑚礁的一个接触区域，这两种形态之间的杂交几乎使体色模式差异同质化。然而，在这些区域之外，体色模式仍然明显不同。遗传变异在更大的地理尺度上是均匀的。线粒体控制区tRNA - 脯氨酸末端的序列变异和等位酶变异在斑带蝴蝶鱼和贝氏蝴蝶鱼中广泛分布，这表明跨越体色模式边界的线粒体或核基因流动几乎没有受到限制。这些截然不同的模式有力地表明，面对可能使基因流同质化的水平，选择正在异域环境中维持体色模式差异。交配模式数据表明，这种选择并非最严格意义上的基于配偶识别，而是可能作用于这些领域性鱼类社会系统的其他方面。在这种情况下，交配偏好的分化可以跟随体色模式的进化，但并非与之同步。
