title: Pouch brooding marsupial frogs transfer nutrients to developing embryos.
abstract: 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 a13C-fatty acid and a15N-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.
authors.affiliation: Department of Zoology, Southern Illinois University, 1125 Lincoln Drive, Carbondale, IL 62901-6501, USA rwarne@siu.edu.
authors.forename: Robin W
authors.identifier: 0000-0002-4900-418X
authors.initials: RW
authors.lastname: Warne
authors.affiliation: Department of Zoology, Southern Illinois University, 1125 Lincoln Drive, Carbondale, IL 62901-6501, USA.
authors.forename: Alessandro
authors.identifier: 0000-0002-3650-4783
authors.initials: A
authors.lastname: Catenazzi
mesh_terms: D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001001:Anura / Q000196:embryology / Q000502:physiology*; D004625:Embryo, Nonmammalian / Q000502:physiology; D047108:Embryonic Development; D005260:Female; D007313:Insecta; D010063:Ovum
keywords: amphibians; matrotrophy; reproductive mode; stable isotopes; tetrapod evolution; viviparity