We’ve previously discussed how green anoles, Anolis carolinensis, are much more terrestrial in areas where A. sagrei doesn’t occur. Janson Jones, who has written on this previously, now adds a new twist–at one sagrei-less site in Georgia, they’re frolicking around in the water lilies and other aquatic vegetation. Read all about it here.
That got me thinking. Maybe this is how the famed “aquatic” anoles evolve? First you hang out on weeds in the water, next you’re jumping in for a dip?
And speaking of anoles, not only do they float, but they can swim, even those that rarely, if ever, enter the water. I’ve inadvertantly put A. sagrei into the ocean a number of times (think lizard noosing malfunction), and they just press their legs against their body and swim by undulating their tail, alligator-style. Green anoles do that, too, and I’ll bet all anoles innately can swim. I wonder what would happen if you put a crown giant in water. Anyone want to try that with their pet in the bathtub? I bet they can swim, too. So, anoles are pre-adapted (exapted, if you will) for becoming adding aquatic habitats to their repertoire.
And that leads me to one more thought in this ramble: Carl Gans published an obscure paper (Locomotor responses of Calotes to water (Agamidae: Sauria). J. Bombay Natural History Society, vol. 74:361-363, 1977) years ago about some Asian agamid lizards (Calotes) that he dropped into a swimming pool. At first they swam as described above, but then started flailing their legs ineffectually. Eventually, their head would drop below the water, they would breathe in some water, sink to the bottom and then start walking around, presumably until they would have drowned if not rescued. Doesn’t seem like they have much of a future in adapting to aquatic habitats. Similarly, if you dunk a baby duck under water (not that I’ve ever done that), they hold their breath, but baby chickens try to breathe, and things don’t go well. Take home lesson: basic motor patterns and behaviors are needed if a species is to have any hope of adapting to a new habitat. If it doesn’t have the necessary prerequisites to survive there, they have no chance of adapting. (This is, more or less, the theme of another Gans paper I stumbled across when looking for the one mentioned above).