Saranathan Vinodkumar, Hamilton Deborah, Powell George V N, Kroodsma Donald E, Prum Richard O
Department of Ecology and Evolutionary Biology, and Peabody Museum of Natural History, Yale University, PO Box 208105, New Haven, CT 06250, USA.
Mol Ecol. 2007 Sep;16(17):3689-702. doi: 10.1111/j.1365-294X.2007.03415.x.
Vocal learning is thought to have evolved in three clades of birds (parrots, hummingbirds, and oscine passerines), and three clades of mammals (whales, bats, and primates). Behavioural data indicate that, unlike other suboscine passerines, the three-wattled bellbird Procnias tricarunculata (Cotingidae) is capable of vocal learning. Procnias tricarunculata shows conspicuous vocal ontogeny, striking geographical variation in song, and rapid temporal change in song within a population. Deprivation studies of vocal development in P. tricarunculata are impractical. Here, we report evidence from mitochondrial DNA sequences and nuclear microsatellite loci that genetic variation within and among the four allopatric breeding populations of P. tricarunculata is not congruent with variation in vocal behaviour. Sequences of the mitochondrial DNA control region document extensive haplotype sharing among localities and song types, and no phylogenetic resolution of geographical populations or behavioural groups. The vocally differentiated, allopatric breeding populations of P. tricarunculata are only weakly genetically differentiated populations, and are not distinct taxa. Mitochondrial DNA and microsatellite variation show small (2.9% and 13.5%, respectively) but significant correlation with geographical distance, but no significant residual variation by song type. Estimates of the strength of selection that would be needed to maintain the observed geographical pattern in vocal differentiation if songs were genetically based are unreasonably high, further discrediting the hypothesis of a genetic origin of vocal variation. These data support a fourth, phylogenetically independent origin of avian vocal learning in Procnias. Geographical variations in P. tricarunculata vocal behaviour are likely culturally evolved dialects.
人们认为发声学习在鸟类的三个分支（鹦鹉、蜂鸟和鸣禽雀形目）以及哺乳动物的三个分支（鲸鱼、蝙蝠和灵长类）中有所进化。行为数据表明，与其他亚鸣禽雀形目不同，三色钟雀（Procnias tricarunculata，伞鸟科）能够进行发声学习。三色钟雀表现出明显的发声个体发育过程、显著的鸣声地理变异以及种群内鸣声的快速时间变化。对三色钟雀发声发育进行剥夺研究并不实际。在此，我们报告来自线粒体DNA序列和核微卫星位点的证据，表明三色钟雀四个异域繁殖种群内部和之间的遗传变异与发声行为的变异并不一致。线粒体DNA控制区的序列记录了不同地点和鸣声类型之间广泛的单倍型共享，并且没有对地理种群或行为群体进行系统发育解析。三色钟雀在发声上有差异的异域繁殖种群只是遗传上微弱分化的种群，并非不同的分类单元。线粒体DNA和微卫星变异分别与地理距离呈现出小的（分别为2.9%和13.5%）但显著的相关性，但按鸣声类型没有显著的剩余变异。如果鸣声是基于遗传的，那么维持观察到的发声分化地理模式所需的选择强度估计过高，这进一步削弱了发声变异遗传起源的假说。这些数据支持了鸟类发声学习在三色钟雀中第四个系统发育上独立的起源。三色钟雀发声行为的地理变异可能是文化进化而来的方言。
