The evolution of viviparity in squamates has been the focus of much scientific attention in previous years. In particular, the possibility of the transition from viviparity back to oviparity has been the subject of a vigorous debate. Some studies have suggested this reversal is more frequent than previously thought. However, none of them provide conclusive evidence. We investigated this problem by studying the phylogenetic relationships between oviparous and viviparous lineages of the reproductively bimodal lizard species Zootoca vivipara . Our results show that viviparous populations are not monophyletic, and that several evolutionary transitions in parity mode have occurred. The most parsimonious scenario involves a single origin of viviparity followed by a reversal back to oviparity. This is the first study with a strongly supported phylogenetic framework supporting a transition from viviparity to oviparity.

Despite many studies demonstrating the effect of acclimation on behavioural or physiological traits, considerable debate still exists about the evolutionary significance of this phenomenon. One of the unresolved issues is whether acclimation to warmer temperature is beneficial at treatment or at more extreme test temperatures. To answer this question, we assessed the effect of thermal acclimation on preferred body temperatures ( T p s), maximum swimming and running speed, and critical thermal maximum ( CT max ) in the Danube crested newt ( Triturus dobrogicus ). Adult newts were kept at 15 ° C (control) and 25 ° C (treatment) for 8 weeks prior to measurements. We measured T p s in an aquatic thermal gradient over 24 h, maximum speeds in a linear racetrack at six temperatures (5-33 ° C), and CT max in a continuously heated water bath. T p s were higher in newts kept at 15 ° C than in those kept at 25 ° C. The maximum swimming speed did not acclimate. The maximum running speed at 30-33 ° C was substantially higher in newts kept at 25 ° C than in those kept at 15 ° C. CT max increased with the treatment temperature. Hence, we conclude that the acclimation response to warm temperature is beneficial not at treatment but at more extreme temperatures in newts.

Introduced species are one of the most important anthropogenic impacts on freshwater ecosystems with many direct and indirect effects on native taxa. Among other invasive groups, such as plants, mussels and fish, several alien Decapoda species have also spread successfully in Europe in the last 110 years. In Hungary three native (Astacus astacus, Astacus leptodactylus, Austropotamobius torrentium) and three alien Decapoda species, namely Orconectes limosus, Pacifastacus leniusculus and Eriocheir sinensis are known to be present. O. limosus, which had been tried for use in crayfish farming in the 1950s, was the first to occur in the country's natural waters. Initially it was found in the Danube at river km 1,653 at Budapest in 1985. Since then, it has been spreading fast and populations have reached high abundances. By 1998, it was already in the Gemenc section of the river colonising five 50 km × 50 km UTM squares. In the early 2000s it was also found at Mohács (and further downstream in Croatia), in canals in the Great Hungarian Plain and in the River Ipoly, which added three new 50 km × 50 km UTM squares to its previously known distribution area in the Carpathian Basin. On the basis of the available records from the past 20 years, the downstream colonisation speed of this decapod was calculated to be more than 13 km yr -1 , but if its presence at Kopácsi rét/Kopacki rit in Croatia is also taken into consideration, it is over 16 km yr -1 . It is unknown, however, how much this process was helped by deliberate introductions, if at all. Besides the main watercourse of Hungary, O. limosus is also common in its lowland tributaries and spreading towards Lake Balaton along the Sió canal. However, it has not been recorded entering mountain streams in the Danube Bend, where A. torrentium lives, which is important for the conservation of that native species. If O. limosus spreads with the same speed and distribution pattern in the Carpathian Basin, it may colonise large rivers such as the River Tisza, their lowland tributaries and canals in the near future. Based on the present situation, O. limosus is likely to threaten A. astacus populations especially in the southern part of Transdanubia, perhaps leading to the elimination of some populations, but less likely to affect A. torrentium living in the mountains of the Danube Bend. Key