Data from: Pouch brooding marsupial frogs transfer nutrients to developing embryos

Marsupial frogs have a unique reproductive mode in which females carry eggs enclosed in a sealed dorsal brood pouch. While most anurans are considered to be oviparous with lecithotrophic eggs, the extensively vascularized membrane of the brood pouch in marsupial frogs suggests potential opportunities for nutrient transfer. We tested for matrotrophy in the live-bearing Gastrotheca excubitor (Hemiphractidae), through feeding insects labelled with a 13C-fatty acid and a 15N-amino acid to brooding marsupial frogs. We observed significant increases of δ13C and δ15N in both maternal pouch tissues and embryos, suggesting nutrient transfer. Embryo dry mass also increased with developmental stage, providing further direct evidence for matrotrophy. These results suggest that in addition to gas exchange, the vascularized brood pouch membrane of G. excubitor also enables maternal nutrient transfer. This finding revealed a suspected but untested trait in the evolution of parental care in marsupial frogs, in contrast to previous work on Gastrotheca species that release tadpoles, and suggests greater complexity in reproductive and provisioning modes than previously thought.囊蛙类具有独特的生殖模式：雌性个体将卵包裹于封闭的背部育幼袋内抚育。尽管绝大多数无尾两栖动物均为卵生，且其卵为卵黄营养型（营养完全依赖卵黄供给），但囊蛙类育幼袋的高度血管化膜结构，提示其存在营养传递的潜在可能。本研究针对胎生的艾氏囊蛙（Gastrotheca excubitor，盔蛙科Hemiphractidae）开展母体营养供给（matrotrophy）检测：向处于育幼期的囊蛙投喂经碳13标记脂肪酸与氮15标记氨基酸标记的昆虫。结果显示，母体育幼袋组织与胚胎内的δ¹³C与δ¹⁵N值均显著升高，表明存在营养传递现象。胚胎干重亦随发育阶段推进而增加，为母体营养供给提供了又一直接证据。上述结果表明，艾氏囊蛙的血管化育幼袋膜除可实现气体交换外，还可介导母体向胚胎的营养传递。与此前针对产蝌蚪的囊蛙属物种的研究不同，本发现揭示了囊蛙类亲本抚育演化中一个此前仅被推测但未得到验证的性状，同时表明囊蛙类的生殖与营养供给模式较此前认知更为复杂。