Unidad Ejecutora Lillo (CONICET-FML), Tucumán, Argentina.
Laboratorio de Genética Evolutiva, (IBS-CONICET), Misiones, Argentina.
PLoS One. 2019 Jun 27;14(6):e0218733. doi: 10.1371/journal.pone.0218733. eCollection 2019.
The study of early development in Neotropical Leiuperinae frogs (Anura, Leptodactylidae) has been addressed by several works in recent times. However, a comparative developmental approach under a phylogenetic context was not available. Herein we analyzed the morphological and ontogenetic diversity of embryos belonging to 22 species of the three largest genera in Leiuperinae. We find that in most cases, variations fit with the phylogeny at the inter- and intrageneric levels. Embryo kyphosis and whitish color are synapomorphies for the clade grouping Physalaemus and Engystomops. The presence of a third lower tooth row on the oral disc is plesiomorphic for Leiuperinae, only changing in derived clades. The configurations and developmental trajectories of the lower lip are exceptionally diverse. The developmental sequences optimized on the phylogenetic tree recover an early differentiated first lower tooth row a synapomorphy of Pseudopaludicola and Physalaemus, and an early differentiated second row as synapomorphy of Pleurodema. On the other hand, few features are highly conserved in the subfamily, such as the adhesive glands universally present in a type-C configuration. Our results also suggest that the morphology and ontogeny of embryos is in some cases associated to the environment where they develop. A large body size, poorly developed transient respiratory structures, large yolk provision and delayed development of the digestive tract occur convergently in embryos inhabiting cold, oxygenated environments. Embryos that develop in warmer water bodies in xeric environments show more complex and persistent transient respiratory structures and an early onset of hind limbs development. Our survey highlights that morphology and early development of anurans can be a valuable source of information for phylogenetic studies, and provide fundamental bases to explore and discuss how evolutionary changes can be shaped by environmental conditions.
近年来，已有多项研究关注新热带雨蛙科（蛙形目，细趾蟾科）的早期发育。然而，在系统发育背景下进行比较发育的方法尚未得到应用。在此，我们分析了 22 种雨蛙科三个最大属的胚胎的形态和个体发生多样性。我们发现，在大多数情况下，变异与种间和种内的系统发育一致。胚胎脊柱后凸和白色是 Physalaemus 和 Engystomops 分支的共形特征。口盘上第三排下齿是 Leiuperinae 的原始特征，仅在衍生支系中发生变化。下唇的形态和发育轨迹变化多样。在系统发育树上优化的发育序列恢复了第一排下齿的早期分化，这是 Pseudopaludicola 和 Physalaemus 的共形特征，而第二排的早期分化则是 Pleurodema 的共形特征。另一方面，该亚科的一些特征高度保守，例如普遍存在 C 型结构的粘性腺。我们的研究结果还表明，胚胎的形态和个体发生在某些情况下与它们发育的环境有关。体型较大、短暂呼吸结构发育不良、大量卵黄供应以及消化道发育延迟，这些特征在生活在寒冷、含氧环境中的胚胎中趋同出现。在干燥环境中温暖水体中发育的胚胎则具有更复杂和持久的短暂呼吸结构，以及后肢发育的早期开始。我们的研究表明，两栖动物的形态和早期发育可以为系统发育研究提供有价值的信息，并为探索和讨论进化变化如何受到环境条件的影响提供基础。
