Egg-Eating in Snakes
One feature of snakes, and a source of intrigue to many, is their ability to eat large, bulky prey items whole. In fact, this ability, in conjunction with the evolution of the venom apparatus, has been suggested as a key innovation in the radiation of modern snakes. Because dietary shifts are often associated with evolutionary diversification, this has been an area of frequent study in snakes. Snakes that eat solely eggs are extremely rare. Studies have suggested that because there are relatively few snakes that supplement their diets with bird eggs, the number of species to have shifted to specialize on eggs should be small. Only one group, the African snake genus Dasypeltis, has speciated to any substantial degree with 9 species found throughout sub-Saharan Africa. Several classic morphological studies have shown a suite of anatomical features presumed to assist in increasing egg-eating performance—yet none had been tested in an experimental framework. We examined mechanisms that could lead to the fixation of obligate egg-eating behavior and the fixation of certain morphological traits associated with egg eating by examining the relative performance of egg-eating ability in Dasypeltis, and a facultative egg-eater, the common kingsnake, Lampropeltis getula. Further, we examined the presence of selective regimes in southern Africa by exploring the number of birds that lay eggs of an ingestible size in regions occupied by either Dasypeltis, or Lampropletis.
Related Publications (click for PDF)
Gartner, G. E. A., and H. W. Greene. 2008. Adaptation in the African egg-eating snake:
A comparative approach to a classic study in evolutionary functional morphology. Journal of Zoology 275:368-374.