Over time, different animals have evolved to survive in different ways. Everything about a species — from its behaviors to its physical traits — has been developed to help the animal adapt to its natural habitat.
So when individual members of a species start to exhibit new behaviors, scientists definitely take note. One creature is changing so drastically that researchers believe they’re watching evolution in action… even though they have no idea why.
This strange-looking creature may look like a snake with silly tiny arms, but it is actually the yellow-bellied three-toed skink (or saiphos equalis), a species of reptile native to eastern Australia.
For most of its known history on Planet Earth, this type of skink has given birth by laying eggs, but recently scientists have noticed something unusual.
This means that this type of skink is evolving to a new method of reproduction right before our very eyes.
Throughout history, nearly 100 reptile lineages have transitioned from egg-laying to live births over time, and today roughly 20% of living snakes and lizards give birth to live young.
However, the yellow-bellied three-toed skink is the first time in history that scientists have caught a reptile transitioning from one behavior to the other.
James Stewart, a biologist at East Tennessee State University who’s researching the phenomenon, said, “By studying differences among populations that are in different stages of this process, you can begin to put together what looks like the transition from one [birth style] to the other.”
One question scientists hope to answer by studying the skink is how its live babies are getting nutrients with this new biological arrangement.
Baby mammals get nutrients from the placenta, and babies incubated inside eggs get their nutrients from the yolk and shell. Without either one of these protective casings, how live skink babies are surviving in vitro is currently a mystery.
Another thing to watch is whether the skinks will begin to favor one type of birth over the other, since both methods carry risks. Eggs are more vulnerable to external threats like weather and predators, but internal fetuses are more dangerous to the mother.
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