A fascinating species of water flea exhibits a kind of flexibility that evolutionary biologists call adaptive plasticity.
(A)
That’s a clever trick, because producing spines and a helmet is costly, in terms of energy, and conserving energy is essential for an organism’s ability to survive and reproduce. The water flea only expends the energy needed to produce spines and a helmet when it needs to.
(B)
If the baby water flea is developing into an adult in water that includes the chemical signatures of creatures that prey on water fleas, it develops a helmet and spines to defend itself against predators. If the water around it doesn’t include the chemical signatures of predators, the water flea doesn’t develop these protective devices.
(C)
So it may well be that this plasticity is an adaptation: a trait that came to exist in a species because it contributed to reproductive fitness. There are many cases, across many species, of adaptive plasticity. Plasticity is conducive to fitness if there is sufficient variation in the environment.
* spine: 가시 돌기 ** conducive: 도움되는
