Three-toed skink amazingly produces both eggs and live young

  Last updated April 10, 2019 at 12:00 pm

Topics:  

An Australian skink has amazed scientists by giving birth to both live young and eggs from the same pregnancy, making it the weirdest lizard in the world.


skink lizard australian

A three-toed skink, Saiphos equalis, in New South Wales. Credit: Auscape/UIG/Getty Images


Versatility, it is generally acknowledged, is a useful evolutionary trait, but an Australian lizard, the three-toed skink (Saiphos equalis), has been observed taking the idea to extremes.


The species is one of only a handful worldwide known to have a bimodal reproductive strategy. Some lay eggs, while others give birth to live young.


At least one resourceful three-toed skink, however, has been observed doing both – from the same pregnancy.


In a paper soon to be published in the journal Biology Letters, researchers led by Camilla Whittington from the University of Sydney detail the case of a lady lizard which, following impregnation, laid three eggs and then, three weeks later, gave birth to a live baby.


It is the only example known of any vertebrate producing both eggs and live young from a single pregnancy.


“We were studying the genetics of these skinks when we noticed one of the live-bearing females lay three eggs,” Whittington says.


“Several weeks later she gave birth to another baby. Seeing that baby was a very exciting moment!”


“Weirdest lizard in the world”


She notes that her team’s observation marks the skink as one of the “weirdest lizards in the world”, but also a key focus for studying the evolutionary transition from egg-laying to live birth.


Such transitions have arisen independently at least 150 times, she says, but the discovery that S. equalis can do both with equal facility makes it an ideal target for studying the evolution of pregnancy.


“It makes Australia one of the best places in the world to study the evolution of live birth, because we can watch evolution in action,” she explains.


“Put in the context of evolutionary biology, being able to switch between laying eggs and giving live birth could allow animals to hedge their bets according to environmental conditions.”


Related


This lizard evolved to lay eggs, twice


Lizard evolution highlights power of climate change


Why are bluetongue lizard tongues blue?


Educational Resource


Three-toed skink amazingly produces both eggs and live young




About the Author

Andrew Masterson
Andrew Masterson is editor of Cosmos.

Published By

Cosmos is a quarterly science magazine. We aim to inspire curiosity in ‘The Science of Everything’ and make the world of science accessible to everyone.


At Cosmos, we deliver the latest in science with beautiful pictures, clear explanations of the latest discoveries and breakthroughs and great writing.


Winner of 47 awards for high-quality journalism and design, Cosmos is a print magazine, online digital edition updated daily, a daily and weekly e-Newsletter and educational resource with custom, curriculum-mapped lessons for years 7 to 10.


Featured Videos

Placeholder
Fitting natural water treatment processes back into the landscape
Placeholder
Protecting the Great Barrier Reef at the National Sea Simulator