Severe malformation in neonate Vipera ursinii rakosiensis
Many taxa are declining worldwide, and the cause of this decline has attracted massive concern (e.g. Caughley, 1994). One major contributor to endangerment has been habitat fragmentation, where a formerly wide-ranging taxon persists only as a series of small isolated populations (Knick and Rotenberry, 1995). Small isolated populations are not only more vulnerable to extinction through factors such as demographic and environmental stochasticity, but the loss of genetic variation may further increase the risk of extinction (e.g. Lande and Barrowclough, 1987; Madsen et al., 1999; Frankham et al., 2002). The Hungarian meadow viper (Vipera ursinii rakosiensis Méhely, 1893) is one of the most threatened snakes in Europe (e.g. Korsós, 1992; Ujvari et al., 2002). The former distribution of this taxon included the easternmost part of Austria, Hungary, Transylvania (Romania), and northern Bulgaria (Dely and Janisch, 1959). At present, however, small populations only exist in two regions of Hungary (in the Great Hungarian Plain between the rivers Danube and Tisza, and in the Hanság Nature Reserve, in north-western part of the country;Korsós, 1992). Since 1974 the meadow viper has received full legal protection in Hungary, with a present estimated nature conservation value of approximately 2000 EUR/specimen. Unfortunately, most of the few remaining wild populations are very small, fragmented and exhibit extremely low genetic diversity (Ujvari et al., 2002). In these population demographic and genetic factors have resulted in that the Hungarian meadow viper is suffering from severe inbreeding depression, resulting in chromosomal abnormalities, severe birth deformities, and low juvenile survival (Liptoi et al., 1999; Ujvari et al., 2000, 2002). The importance of maintaining large non-fragmented populations is further strengthened by the results from an Italian study where no such neonate abnormalities were documented from large, nonfragmented meadow viper populations (Filippi and Luiselli, 2004).