Heiss Egon, Grell Julia
Institute of Zoology and Evolutionary Research, Friedrich-Schiller-University of Jena, Erbertstr. 1, 07743 Jena, Germany.
Zoological Lett. 2019 Jul 26;5:24. doi: 10.1186/s40851-019-0140-4. eCollection 2019.
Paedomorphosis describes the retention of larval characters in adult stages and is widespread amongst salamanders. Salamandrid newts exhibit facultative paedomorphosis, where paedomorphic and metamorphic adult forms coexist in the same population. Previous studies have shown that prey capture kinematics do not differ between paedomorphic and metamorphosed ambystomatid salamanders, despite diverging morphology and prey capture performance. It remained unclear, however, whether the stereotypy of prey capture kinematics across morphotypes is restricted to ambystomatids, or can be found in other salamander groups too. Here, we performed biplanar high-speed-recordings of the prey capture behavior in paedomorphic and metamorphic salamandrid newts and only found minor kinematic differences across morphotypes, suggesting that stereotypy across morphotypes is a more general feature within salamanders. We then compared anatomy of skull and hyobranchial skeleton, along with the physiological cross sectional area (PCSA) of the rectus cervicis muscle, the main muscle empowering suction feeding. Besides the overall morphological differences of the feeding apparatus, the PCSA of the rectus cervicis also differs significantly between morphotypes, being twice as large in paedomorphs. Accordingly, paedomorphs can exert more powerful suction strikes, which in turn may be one of the key factors why paedomorphs are more efficient in capturing elusive prey compared to metamorphs.
幼态延续描述了成体阶段保留幼体特征的现象，在蝾螈中很常见。蝾螈科蝾螈表现出兼性幼态延续，即幼态和成体变态形式在同一种群中共存。先前的研究表明，尽管形态和捕食性能不同，但幼态和变态的美西螈科蝾螈在捕食运动学上并无差异。然而，尚不清楚不同形态型之间捕食运动学的刻板性是否仅限于美西螈科，还是在其他蝾螈类群中也能发现。在这里，我们对幼态和变态的蝾螈科蝾螈的捕食行为进行了双平面高速记录，结果仅发现不同形态型之间存在微小的运动学差异，这表明不同形态型之间的刻板性是蝾螈类更普遍的特征。然后，我们比较了头骨和鳃骨骨骼的解剖结构，以及颈直肌的生理横截面积（PCSA），颈直肌是实现吸力摄食的主要肌肉。除了摄食器官的整体形态差异外，颈直肌的PCSA在不同形态型之间也存在显著差异，幼态的是成体变态的两倍。因此，幼态蝾螈可以施加更强大的吸力攻击，这反过来可能是幼态蝾螈在捕捉难以捉摸的猎物方面比成体变态蝾螈更高效的关键因素之一。
