LETTERS TO THE EDITORS
To the Editors:
Several years ago I gave my granddaughter, Eden, a leopard gecko.
Then along comes Kellar Autumn's article on geckos' sticky feet
("How Geckos Toes Stick," March-April). I suggested to
Eden that we examine her gecko's feet with a hand lens, but she told
me that she had never seen her gecko climb any kind of wall. Sure
enough we did not see anything special about her gecko's feet.
I have combed through Dr. Autumn's article but cannot find any
reference to some geckos not having sticky feet. Is there an
explanation for this exception?
H. Stuart Whitney
Eden E. A. Whitney
Dr. Autumn responds:
Your granddaughter is correct: leopard geckos are not good climbers.
In my article, I failed to mention that while most of the 1,000 or
more gecko species have adhesive pads, some do not. Some geckos lack
pads because they never evolved them, while other species have
evolved them away. Leopard geckos lack adhesive pads because the
family they belong to (Eublepharidae) split from the gecko lineage
long before setae evolved. Euplepharids retain many ancestral lizard
characteristics such as eyelids and a terrestrial habitat.
Research by my colleague Anthony Russell at the University of
Calgary in Canada has shown that climbing and adhesive setae evolved
several times independently in geckos. Russell's work suggests that
the variations on a similar theme of gecko foot design are the
result of similar selective pressures on different lineages of
gecko. Thus, many of the differences we observe in gecko foot design
may represent different, but largely equivalent, evolutionary
solutions to the problem of how to climb smooth surfaces.