image: Power doppler ultrasound image of a swamp wallaby embryo at day 15 of gestation. The yellow lines indicate blood flow in the uterus surrounding the early wallaby embryo (black disc) in the center of the image. view more
Credit: Image courtesy of Thomas B. Hildebrandt
Researchers report evidence suggesting an unusual mode of reproduction in swamp wallabies. In kangaroos and wallabies, young are born immature and complete development during an extended period of lactation. Females, which possess two uteri that are alternately used for conception, normally ovulate and mate after giving birth. Suckling of the newborn in the pouch triggers signals that arrest the development of the new embryo until the newborn leaves the pouch. Brandon Menzies and colleagues report an extraordinary form of reproduction in the swamp wallaby (Wallabia bicolor), which ovulates, mates, and conceives anew while still actively pregnant--a similar phenomenon was previously reported in the European brown hare. Mature female swamp wallabies were sourced from the wild in Victoria, Australia, and experiments on 10 individuals, some of which were scanned using high-resolution ultrasound through pregnancy, revealed that swamp wallabies ovulate and mate 1-2 days before giving birth and conceive a new embryo during active pregnancy. The finding indicates that gestation length in swamp wallabies exceeds the length of the oestrous cycle. Because they become pregnant before giving birth, swamp wallabies, the findings suggest, may be continuously pregnant throughout their reproductive lives, according to the authors.
###
Article #19-22678: "Unique reproductive strategy in the swamp wallaby," by Brandon R. Menzies, Thomas B. Hildebrandt, and Marilyn B. Renfree
MEDIA CONTACT: Brandon R. Menzies, University of Melbourne, Melbourne, AUSTRALIA; tel: +61402009860; e-mail: menziesb@unimelb.edu.au; Thomas Hildebrandt, Leibniz Institute of Zoo and Wildlife Research, Berlin, GERMANY; e-mail: hildebrandt@izw-berlin.de; Marilyn Renfree, University of Melbourne, Melbourne, AUSTRALIA; tel: +61383444376; e-mail: m.renfree@unimelb.edu.au
Journal
Proceedings of the National Academy of Sciences