Journal of Comparative Physiology B

, Volume 171, Issue 2, pp 155–160

Placental nutrition in the Tasmanian skink, Niveoscincus ocellatus

Authors

  • M.B. Thompson
    • School of Biological Sciences and Wildlife Research Institute, Zoology Building (A08), University of Sydney, NSW 2006, Australia
  • B.K. Speake
    • Department of Biochemical Sciences, Scottish Agricultural College, Ayr, KA6 5HW, UK
  • J.R. Stewart
    • Department of Biological Sciences, Box 70703, East Tennessee State University, Johnson City, TN 37614, USA
  • K.J. Russell
    • School of Biological Sciences and Wildlife Research Institute, Zoology Building (A08), University of Sydney, NSW 2006, Australia
  • R.J. McCartney
    • Department of Biochemical Sciences, Scottish Agricultural College, Ayr, KA6 5HW, UK
Original Paper

DOI: 10.1007/s003600000166

Cite this article as:
Thompson, M., Speake, B., Stewart, J. et al. J Comp Physiol B (2001) 171: 155. doi:10.1007/s003600000166

Abstract.

Niveoscincus ocellatus is an important species in historical analyses of the evolution of viviparity because it is the species upon which the type II chorioallantoic placenta was based. Here we describe the net nutrient uptake across the placenta of N. ocellatus for comparison with other species of skinks with complex placentae. N. ocellatus is highly placentotrophic, with neonates being 1.68-times larger in dry matter than the fresh eggs. There is an increase of nitrogen from 6.3±0.2 mg to 9.2±0.6 mg, and ash from 3.8±0.3 mg to 6.7±0.6 mg. The increase in ash is made up by a more than two-fold increase in the amounts of calcium, potassium and sodium. There is no significant difference in lipids in the neonates compared to fresh eggs, so considerable lipid must have crossed the placenta to provide energy for embryonic development. N. ocellatus is significantly more placentotrophic than Niveoscincus metallicus, which also has a complex chorioallantoic placenta. Discovery of substantial placentotrophy in this genus confirms that two lineages of Australian lygosomine skinks (represented by the genera Pseudemoia and Niveoscincus) have evolved this pattern of embryonic nutrition and supports the hypothesis that the evolution of reptilian placentotrophy involves specialisations in addition to structural modifications of the chorioallantoic placenta.

Viviparity Lizard Lipid Embryo Yolk

Copyright information

© Springer-Verlag 2001