Liendro-Bataglia Nahuel A, Martini Luca N, Pereyra-Civiello L Muriel, Ascune-Wachsmuth Zoe C, Lois-Milevicich Jimena, Gómez Raúl O
Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.
Departamento de Ecología, Genética y Evolución & IEGEBA - CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.
J Morphol. 2025 Oct;286(10):e70092. doi: 10.1002/jmor.70092.
New World Blackbirds (Icteridae) are a diverse group of Neotropical passerines and an important component of the continental radiation of nine-primaried songbirds (Emberizoidea). Icterids and other emberizoids are chiefly omnivorous, but with variable predilection for invertebrates, fruits, and seeds. The icterids also exhibit a peculiar "gaping" behavior, whereby they insert their beaks into soil, fruits or bark and then open them inside the substrate. Cowbirds (Molothrus) stand out among the icterids for not being gapers and, with the exception of the Giant Cowbird, for a marked tendency towards a granivorous diet. To explore the signal of trophic ecology in the lower jaw of icterids and other emberizoids, we applied three-dimensional geometric morphometrics on Microcomputed tomography data and phylogenetic comparative methods. Phylomorphospaces were constructed and possible correlates with diet, gaping, and evolutionary allometry were assessed through phylogenetic ANOVA. Convergence between seed-eater species was also estimated by recently developed measures (Ct1). Results show a significant signal of trophic ecology in the mandible, with seed-eater species occupying a narrow domain of morphospace, partially overwhelming the signal of evolutionary allometry. The cowbird Molothrus ater stands out for clearly diverging from most icterids, showing significant convergence with other seed-eater emberizoids. Mandibular morphology, often neglected in avian ecomorphological studies, is informative of the trophic ecology of these birds.
新大陆黑鹂（拟鹂科）是新热带界雀形目鸟类中的一个多样化群体，也是九种主要鸣禽（雀形亚目）大陆辐射的重要组成部分。拟鹂科鸟类和其他雀形亚目鸟类主要为杂食性，但对无脊椎动物、果实和种子的偏好各不相同。拟鹂科鸟类还表现出一种特殊的“张口”行为，即它们将喙插入土壤、果实或树皮中，然后在基质内部张开。牛鹂属（Molothrus）在拟鹂科中很突出，因为它们不会张口，并且除了大牛鹂外，明显倾向于以谷物为食。为了探究拟鹂科鸟类和其他雀形亚目鸟类下颌的营养生态学信号，我们对微型计算机断层扫描数据应用了三维几何形态测量学和系统发育比较方法。构建了系统发育形态空间，并通过系统发育方差分析评估了与饮食、张口行为和进化异速生长的可能相关性。食种子物种之间的趋同也通过最近开发的测量方法（Ct1）进行了估计。结果显示下颌存在显著的营养生态学信号，食种子物种占据了形态空间的一个狭窄区域，部分掩盖了进化异速生长的信号。牛鹂Molothrus ater明显与大多数拟鹂科鸟类不同，与其他食种子的雀形亚目鸟类表现出显著的趋同，这一点很突出。在鸟类生态形态学研究中常常被忽视的下颌形态，能够反映这些鸟类的营养生态学。
