Modeling the influence of invasive fish species Perccottus glenii (Dybowski, 1877) on the distribution of newts in Eastern Europe, exemplified by Lissotriton vulgaris (Linnaeus, 1758) and Triturus cristatus (Laurenti, 1768), using a GIS approach

Recently, there has been a decrease in the numbers of amphibians in Eastern Europe, their home ranges are shrinking and fragmented due to climate change, anthropogenic impact and the appearance of alien species. Representatives of Caudata are particularly affected. Thereby, in the south of the T. cristatus range, we have proposed to include this species to the Red Data Book of Ukraine. The next contender in this respect is L. vulgaris. One of the factors limiting their numbers is the appearance of alien fish species, which have recently actively spread in the region and occupied similar habitats, for instance P. glenii. We employed an ensemble distribution model approach to build stacked species distribution models (SSDMs), using a variety of modeling algorithms and multiple species. Results show that P. glenii in the future will have more, in terms to habitat suitability, expected areas to appear in. Under such circumstances T. cristatus can be especially affected, since P. glenii was found in the reservoirs where this newt would breed. Similarities were revealed between the SDMs of these species reaching an R² (coefficient of determination) of 60%. Similarity between L. vulgaris and P. glenii - 46%. But due to constant drought, especially in the south of the range, the number of reservoirs suitable for newts’ breeding has greatly decreased. Because of the long-lasting drought, particularly in the south, areas of breeding sites have been considerably reduced. Therefore, it is necessary to establish management plans for the protection of the two native urodelans’ species.