Sparks John S, Dunlap Paul V, Smith W Leo
Department of Ichthyology, Division of Vertebrate Zoology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024, USA.
Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109-1048, USA.
Cladistics. 2005 Aug;21(4):305-327. doi: 10.1111/j.1096-0031.2005.00067.x.
A phylogeny was generated for Leiognathidae, an assemblage of bioluminescent, Indo-Pacific schooling fishes, using 6175 characters derived from seven mitochondrial genes (16S, COI, ND4, ND5, tRNA-His, tRNA-Ser, tRNA-Leu), two nuclear genes (28S, histone H3), and 15 morphological transformations corresponding to features of the fishes' sexually dimorphic light-organ system (LOS; e.g., circumesophageal light organ, lateral lining of the gas bladder, transparent flank and opercular patches). Leiognathidae comprises three genera, Gazza, Leiognathus, and Secutor. Our results demonstrate that Leiognathidae, Gazza, and Secutor are monophyletic, whereas Leiognathus is not. The recovered pattern of relationships reveals that a structurally complex, strongly sexually dimorphic and highly variable species-specific light organ is derived from a comparatively simple non-dimorphic structure, and that evolution of other sexually dimorphic internal and external features of the male LOS are closely linked with these light-organ modifications. Our results demonstrate the utility of LOS features, both for recovering phylogeny and resolving taxonomic issues in a clade whose members otherwise exhibit little morphological variation. We diagnose two new leiognathid genera, Photopectoralis and Photoplagios, on the basis of these apomorphic LOS features and also present derived features of the LOS to diagnose several additional leiognathid clades, including Gazza and Secutor. Furthermore, we show that five distinct and highly specialized morphologies for male-specific lateral luminescence signaling, which exhibit species-specific variation in structure, have evolved in these otherwise outwardly conservative fishes. Leiognathids inhabit turbid coastal waters with poor visibility and are often captured in mixed assemblages of several species. We hypothesize that the species-specific, sexually dimorphic internal and external modifications of the leiognathid LOS provide compelling evidence for an assortative mating scheme in which males use species-specific patterns of lateral luminescence signaling to attract mates, and that this system functions to maintain reproductive isolation in these turbid coastal environments.
利用从七个线粒体基因（16S、COI、ND4、ND5、tRNA - His、tRNA - Ser、tRNA - Leu）、两个核基因（28S、组蛋白H3）以及与鱼类两性异形发光器官系统（LOS；例如，围食管发光器官、鳔的侧衬、透明的体侧和鳃盖斑块）特征相对应的15个形态转变中获得的6175个字符，构建了发光鲾科（Leiognathidae）的系统发育树。发光鲾科包括三个属，即眶棘鲈属（Gazza）、发光鲾属（Leiognathus）和锯眶棘鲈属（Secutor）。我们的结果表明，发光鲾科、眶棘鲈属和锯眶棘鲈属是单系的，而发光鲾属不是。恢复的亲缘关系模式表明，结构复杂、两性异形强烈且高度可变的物种特异性发光器官源自相对简单的非两性异形结构，并且雄性LOS的其他两性异形内部和外部特征的进化与这些发光器官的变化密切相关。我们的结果证明了LOS特征在恢复系统发育和解决一个类群中的分类学问题方面的效用，该类群的成员在其他方面表现出很少的形态变异。基于这些近裔性状的LOS特征，我们诊断出两个新的发光鲾科属，即胸光鲾属（Photopectoralis）和光斜鲾属（Photoplagios），并还呈现了LOS的衍生特征以诊断几个其他的发光鲾科类群，包括眶棘鲈属和锯眶棘鲈属。此外，我们表明，在这些外观上较为保守的鱼类中，已经进化出了五种不同且高度特化的雄性特异性体侧发光信号形态，它们在结构上表现出物种特异性变异。发光鲾科鱼类栖息在能见度差的浑浊沿海水域，并且经常在几种物种的混合群体中被捕获。我们推测，发光鲾科LOS的物种特异性、两性异形内部和外部修饰为一种选型交配方案提供了有力证据，在这种方案中，雄性利用物种特异性的体侧发光信号模式来吸引配偶，并且这个系统在这些浑浊的沿海环境中起到维持生殖隔离的作用。
