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The Mediterranean Basin is an ecologically diverse region, home to more than 450 species of reptiles and amphibians. Understanding the factors that shape this diversity is important not only for basic biogeographic interest, but also for applied management reasons. Humans have shaped reptile and amphibian communities across the Mediterranean through the modification of natural habitats, as well as through the introduction of species across the sea.
Together with Dr. D. Margomenou (Dept. of Classics, Univ. of Michigan) we investigate how, over the millennia, human activities have affected the distribution of reptiles and amphibians in the Mediterranean Basin. This work draws together molecular, morphological, ecological and historical lines of evidence to investigate whether species have been intentionally or accidentally introduced by humans.
Reptiles such as chameleons were likely transported unintentionally. Because chameleons can change color, they can readily travel hidden inside bundles of leaves or reeds used for animal feed. The African Chameleon (Chamaeleo africanus) occurs naturally in the Nile Valley in North Africa, though an isolated population was discovered recently in a single European location on the SW Peloponnese in Greece (see map). There it occurs in the immediate vicinity of a well-known harbor of ancient Pylos, suggesting that it was likely introduced by travelers from Egypt either during the Bronze Age or more likely in the early 19th century.
Other species may have been transported intentionally. Different kinds of snakes were associated with gods and mythical heroes and were part of religious practices, worship, and healing. The leopard snake (Zamenis situlus), for instance, is depicted in ancient Greek art and probably had symbolic significance – a Chalcidian black-figured hydria (ca. 550 BC) depicts Typhon, one of the most fearsome monsters of Greek mythology. Interestingly, it is depicted with two tails, representing the two known color morphs (striped vs. blotched) of Z. situlus. Molecular evidence suggests that the species was introduced to parts of Sicily, S. Italy and the Crimean Peninsula all of which happened to be ancient Greek colonies.
While the reptile communities on the southern margin of the Mediterranean are much richer than those in the north, many species have been able to expand northwards along the eastern rim of the Mediterranean Basin. In contrast in the west the Straits of Gibraltar have blocked many species from expanding northward.
African Chameleon and map of the main range in Egypt and the single isolated population on the Peloponnese.
Left: Natural range and reconstructed avenues of ancient introduction of the Leopard snake into S. Italy, Sicily and the Crimean Peninsula. Right: The two color morphs of the Leopard snake
Depiction of Typhon on an ancient Greek vase. Note the two different colored tails corresponding to the two color morphs of Z. situlus.
The Arkesilas Cup: the Cyrenian king Arkesilas watching over the bundling of trade goods for transport across the Mediterranean. Note the lizard in the background. Laconian black-figure cup, from Vulci, Etruria, 556–560 bc. [Cabinet des médailles, Bibliothèque Nationale de France in Paris.]
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