Edited by Sebastian Steinfartz and Sylvain Ursenbacher
Matthieu Raemy and Sylvain Ursenbacher
Recent studies have demonstrated the potential of combining molecular technologies with environmental sampling to detect various vertebrate species in aquatic ecosystems. The European pond turtle (Emys orbicularis) is a threatened and elusive aquatic reptile with shy behaviour. We aimed to develop and evaluate a methodology to detect the presence of this secretive aquatic reptile in ponds from environmental water samples. First, we determined that reptilian DNA can be isolated and amplified from water samples in artificial and natural ponds with known turtle density. Then we compared the potential of two water sampling methods (through filtration or precipitation) and found no significant differences between these approaches. Finally, we demonstrated that the eDNA concentration detected is not correlated with the number of E. orbicularis individuals or biomass. Detection of eDNA was higher in artificial ponds with small volumes of water or in the shallow waters of natural ponds. The eDNA-based methodology aims to detect the presence of specific species, even at low density, with better accuracy than visual observation. However, our study indicates that this method of population monitoring should be applied with caution to aquatic reptiles.
Sylvain Ursenbacher, Philippe Christe and César Metzger
Despite the increase of animal and plant introductions worldwide and the strong augmentation of the reptile trade, few invasive snake populations have been studied. Dice snakes (Natrix tessellata) were introduced to the shores of Lake Geneva (Switzerland) in the early 1920s, and are now well established. This region of introduction was previously inhabited by Viperine snakes (N. maura). Ever since these two species have been under monitoring (which began in 1996) the Viperine snake population has shown drastic decline. We examine here the possibility of trophic competition by analysing diet composition, prey size and trophic niche overlap. Spatial distribution is also assessed in order to address the question of spatial competitive exclusion. We found very similar diets, and thus a high trophic niche overlap, indicating no partitioning of the trophic resource. No arguments in favour of spatial competitive exclusion were found. Our study suggests that trophic competition may occur between the two natricines and that it may give an explanation for the drastic decline of the Viperine snake in this area. Other pathways potentially playing a role in the exclusion of the Viperine snake are discussed.
Barbara Meister, Sylvain Ursenbacher and Bruno Baur
Males can enhance their reproductive success through mating with multiple females. For females, however, one mating is usually sufficient to inseminate all of their ova. Females may benefit from multiple mating by producing genetically more diverse offspring, and by having the opportunity to choose sperm of the genetically most compatible male. We used five microsatellite loci to investigate the occurrence and frequency of multiple paternity in 11 clutches of the grass snake (Natrix natrix) in Switzerland. Using a very conservative estimate (program GERUD), two or more fathers were found in 27% of the clutches. However, based on the maximum likelihood estimate (program COLONY), multiple paternity occurred in 91% of the clutches with 2-5 contributing males per female. This is the first investigation demonstrating multiple paternity in a European natricine, with a frequency similar to those found in new world natricines.
Sylvain Dubey, Luca Fumagalli, Sylvain Ursenbacher and Jérôme Pellet
The survival of threatened species as the European tree frog (Hyla arborea) is strongly dependent on the genetic variability within populations, as well as gene flow between them. In Switzerland, only two sectors in its western part still harbour metapopulations. The first is characterised by a very heterogeneous and urbanized landscape, while the second is characterised by a uninterrupted array of suitable habitats. In this study, six microsatellite loci were used to establish levels of genetic differentiation among the populations from the two different locations. The results show that the metapopulations have: (i) weak levels of genetic differentiation (FST within metapopulation ≈ 0.04), (ii) no difference in levels of genetic structuring between them, (iii) significant (p = 0.019) differences in terms of genetic diversity (Hs) and observed heterozygozity (Ho), the metapopulation located in a disturbed landscape showing lower values. Our results suggest that even if the dispersal of H. arborea among contiguous ponds seems to be efficient in areas of heterogeneous landscape, a loss of genetic diversity can occur.
Silvia Geser, Laura Kaiser, Valérie Zwahlen and Sylvain Ursenbacher
The Asp viper (Vipera aspis) is a highly endangered species in the Swiss Plateau and in the Jura Mountains of Switzerland. In the past, numerous populations disappeared due to human activities, but currently the trend is reversed and several locations seem favourable for this species. However, it is not known if the remaining populations are still genetically variable and viable. In this study, 12 new microsatellite loci markers were developed for Vipera aspis using Next Generation Sequencing (NGS) techniques (454 sequencing). All markers proved to be polymorphic with 2-9 alleles. When cross-tested with two Eurasian widespread viper species, 8 of the newly developed loci provided reliable amplification for V. berus and 3 loci for V. ammodytes.
Bayram Göçmen, Konrad Mebert, Mert Karış, Mehmet Anıl Oğuz and Sylvain Ursenbacher
We report on a new population of Vipera anatolica from the Geyik Mountain Range in eastern Antalya Province, Turkey. It represents only the second known location, and is situated in a valley about 200 km east from the terra typica at Kohu Dağ in western Antalya Province. We compare both populations and, based on marked differences in morphology, habitat, genetics, and its geographically isolated location, we describe the recently discovered population as a new subspecies. Aspects of ecology, threats, and conservation needs are discussed.
Jean-Claude Monney, Thierry Durand, Sylvain Ursenbacher, Marco Alberto Luca Zuffi, Philippe Golay, Alberto Conelli and Gilles Thiery
Following the opinion expressed by Kramer in 1971, it is commonly accepted that the V. aspis complex is composed of 5 subspecies: V. a. aspis (Linnaeus, 1758), V. a. atra Meisner, 1820, V. a. francisciredi Laurenti, 1768, V. a. hugyi Schinz, 1834 and V. a. zinnikeri Kramer, 1958. However, this point of view was recently challenged and a number of subspecies were elevated to species rank. We had the unique opportunity to study the sample employed by Kramer to revalidate the subspecies V. a. atra and V. a. francisciredi. Using Kramer's determinations, but another set of characters, we reanalysed his sample, by applying the same statistical methods (discriminant and canonical analyses), in order to determine whether observed differences among taxa were sufficiently distinctive to warrant recognition as subspecies. The preliminary results of our morphological study allow us to admit the validity of V. a. francisciredi Laurenti, 1768, but also to question the subspecific rank of V. a. atra Meisner, 1820. These conclusions agree perfectly with the results of our previous genetic study.