Winker Kevin
University of Alaska Museum, University of Alaska Fairbanks.
PeerJ. 2016 Aug 30;4:e2381. doi: 10.7717/peerj.2381. eCollection 2016.
The number of species recognized in Aulacorhynchus toucanets has varied tremendously over the past century. Revisors seem to disagree on whether head and bill coloration are useful indicators of species limits, especially in the A. "prasinus" complex. Using morphometrics, I tested the hypothesis that the major color-based subspecific groups of A. "prasinus" sensu lato are simply "cookie-cutter" (i.e., morphologically nearly identical) toucanets with different head and bill colorations. Univariate and multivariate analyses show that they are not simply morphological replicates of different colors: a complex array of morphometric similarities and dissimilarities occur between the major subspecific groups, and these variations differ between the sexes. Latitude and longitude had a small but significant association with female (but not male) PC1 and PC2. Hybridization and intergradation were also considered using plumage and bill characters as a surrogate to infer gene flow. Hybridization as indicated by phenotype appears to be substantial between A. "p." cyanolaemus and A. "p." atrogularis and nonexistent between other major groups, although from genetic evidence it is likely rare between A. "p." albivitta and A. "p." cyanolaemus. The congruence and complexities of the morphological and color changes occurring among these groups suggest that ecological adaptation (through natural selection) and social selection have co-occurred among these groups and that species limits are involved. Further, hybridization is not evident at key places, despite in many cases (hypothetical) opportunity for gene flow. Consequently, I recommend that this complex be recognized as comprising five biological species: A. wagleri, prasinus, caeruleogularis, albivitta, and atrogularis. Four of these also have valid subspecies within them, and additional work may eventually support elevation of some of these subspecies to full species. Species limits in South America especially need more study.
在过去的一个世纪里，被认可的绿巨嘴鸟种类数量变化极大。对于头部和喙的颜色是否是区分物种界限的有用指标，分类学家们似乎存在分歧，尤其是在 “prasinus” 复合体中。我运用形态测量学方法，检验了这样一个假设：广义的 “prasinus” 绿巨嘴鸟主要基于颜色的亚种群仅仅是头部和喙颜色不同的 “千篇一律”（即形态上几乎相同）的巨嘴鸟。单变量和多变量分析表明，它们并非仅仅是不同颜色的形态复制品：主要亚种群之间存在一系列复杂的形态测量相似性和差异性，而且这些差异在两性之间有所不同。纬度和经度与雌性（而非雄性）的主成分1和主成分2有小但显著的关联。还利用羽毛和喙的特征作为推断基因流动的替代指标来考虑杂交和渐渗现象。从表型来看，“p.” cyanolaemus 和 “p.” atrogularis 之间的杂交似乎很显著，而其他主要群体之间不存在杂交，不过从基因证据来看，“p.” albivitta 和 “p.” cyanolaemus 之间可能很少杂交。这些群体中形态和颜色变化的一致性和复杂性表明，生态适应（通过自然选择）和社会选择在这些群体中同时发生，并且涉及物种界限。此外，尽管在许多情况下（假设）存在基因流动的机会，但在关键区域杂交并不明显。因此，我建议将这个复合体认定为包含五个生物物种：wagleri、prasinus、caeruleogularis、albivitta 和 atrogularis。其中四个物种内部也有有效的亚种，进一步的研究可能最终支持将其中一些亚种提升为完整的物种。南美洲的物种界限尤其需要更多研究。
