SUBJECT: Some notes on the Mediterranean Island Herpetofauna

AUTHOR: Claudia Corti, Department of Animal Biology and Genetics "Leo Pardi" University of Florence, Italy

SUMMARY: The author looks at the human influence in the present distribution pattern of the Mediterranean Insular herpetofauna and the lacertid lizard fauna in particular .

KEYWORDS: Mediterranean Island herpetofauna, Lacertidae, distribution, conservation.

Thousands of islands and islets are located within the Mediterranean basin. For example, if one considers the Greek islands alone, there are 9838 whereas the number of the Sardinian satellite islands amounts to more than 160 units.

The terrestrial herpetofauna is considered to be one of the main indicators of island faunistic population dynamics and of the relations with the continental faunas. In the whole Mediterranean region, the rate of endemicity for herpetofauna is higher than for mammals (25%), corresponding to 56% of the amphibians and 62% of the reptiles.

If we look at the present terrestrial herpetofauna of the Mediterranean islands, we can still find several endemic elements, mainly represented by lacertid lizards.

Today the terrestrial herpetofauna of at least several of the Mediterranean islands displays a partially homogeneous composition of elements. It also consists of species that are more or less common to the present fauna of all the Mediterranean islands, and shows in part a generic continental origin influenced by the faunistic composition of the nearest mainland.

Strong and extended effect of human activity is one of the distinctive features of the present day Mediterranean faunas. As far as is presently known, this effect has acted since the beginning of the Neolithisation of the Mediterranean region, and starting in the Near East, involved geographical areas such as Cyprus, Crete and the Aegean islands in the course of the 8th-7th millennium BC, and extended westwards during the 6th millennium BC. Since those times many of the characteristic elements of the biogeography of the region have undergone a process of exploitation which has continued into historical times. The voluntary and/or involuntary introduction of continental taxa has gradually replaced the autochthonous faunal elements, represented on the islands mainly by endemic forms.

In the light of what is mentioned above, there are several effects produced by man that acted on the present distribution of lizards in particular:

- colonisation and exploitation of habitats like agriculture, shipping and in more recent times the building of touristic areas;
- direct and indirect effects of habitat pollution, including the diffusion of diseases;
- the introduction of predators and allochthonous competitors, including domestic animals such as feral cats, mainly carried out in recent historical times;
- in the case of small populations, trade and collecting by amateurs could be particularly injurious.

The Mediterranean region is an important biogeographical "crossroad" and islands represent very important biodiversity reserves that are particularly rich in numbers of endemic lizard species.

Despite their taxonomic subspecific status it is important to point out the importance of the eco-ecological features developed over thousands of years on several small islands and islets.

Focusing our attention on the eco-ethological features of single island populations is the only way to recognise the real conservation strategies that must be employed, taking into account also for instance the interaction between lizard populations and other vertebrate species under protection.

The survival of all of them must be the ultimate goal of any future conservation strategy.

References:
CORTI C., BöHME W., DELFINO M. & MASSETI M. (1999) - Man and Lacertids on the Mediterranean Islands: Conservation perspectives. Nat. Croat.Vol.8, 3: 287-300.
CORTI C., MASSETI M., DELFINO M. & PEREZ-MELLADO V.(1999) - Man and herpetofauna of the Mediterranean islands. Rev. Esp. Herp. 13: 83-100.