The three-toed skink, which evolutionary biologist Camilla Whittington affectionately calls "the weirdest lizard in the world," has long fascinated scientists as a case study on the evolution of reproductive strategies. The lizard, native to Australia, reproduce differently based on environment. Skinks in northern Australia give live births while skinks around Sydney lay eggs.
A new development has fascinated scientists and suggests a new transition for the species. Last year a skink gave live birth and laid eggs during the same pregnancy. The researchers, who published their findings in Molecular Ecology, suggest that this could be a form of 'bet-hedging' which could give the skink an advantage in unpredictable environments.
"For example, if it's cold or dry, it might be risky to lay eggs in an unprotected nest, and better for the mums to carry the babies until development is complete," Whittington wrote. "If there are a lot of predators around and pregnant mums find it harder to escape, it might be risky to carry babies to term. Mothers that are able to act flexibly could therefore have an advantage in an unpredictable environment."
This could mean that the skink is in a transitional point between the two methods of reproduction as well.
"At the moment, we can't rule out the possibility that the transitional animals could be descended from live-bearing ancestors -- which is why we are continuing to study these amazing lizards," she wrote.
"To complicate things, if the environment changes, the direction of selection could change too! In some environments, natural selection might favour laying eggs. In others, it might be more advantageous to give birth to live young."
Research will continue into these fascinating creatures and their patterns of reproduction, as it could give clues to the evolutionary patterns of life on the planet.