Paul Székely

Diversity and distribution of amphibians in Romania

Abstract Nineteen species of amphibians inhabit Romania, 9 of which reach their range limit on this territory. Based on published occurrence reports, museum collections and our own data we compiled a national database of amphibian occurrences. We georeferenced 26779 amphibian species occurrences, and performed an analysis of their spatial patterns, checking for hotspots and patterns of species richness. The results of spatial statistic analyses supported the idea of a biased sampling for Romania, with clear hotspots of increased sampling efforts. The sampling effort is biased towards species with high detectability, protected areas, and large cities. Future sampling efforts should be focused mostly on species with a high rarity score in order to accurately map their range. Our results are an important step in achieving the long-term goals of increasing the efficiency of conservation efforts and evaluating the species range shifts under climate change scenarios.

Diversity and distribution of reptiles in Romania

Abstract The reptile fauna of Romania comprises 23 species, out of which 12 species reach here the limit of their geographic range. We compiled and updated a national database of the reptile species occurrences from a variety of sources including our own field surveys, personal communication from specialists, museum collections and the scientific literature. The occurrence records were georeferenced and stored in a geodatabase for additional analysis of their spatial patterns. The spatial analysis revealed a biased sampling effort concentrated in various protected areas, and deficient in the vast agricultural areas of the southern part of Romania. The patterns of species richness showed a higher number of species in the warmer and drier regions, and a relatively low number of species in the rest of the country. Our database provides a starting point for further analyses, and represents a reliable tool for drafting conservation plans.

Effect of habitat drying on the development of the Eastern spadefoot toad ( Pelobates syriacus ) tadpoles

Amphibians exhibit plasticity in the timing of metamorphosis, and tadpoles of many species respond to pond drying by accelerating their development. In the present study we investigated the phenotypic plasticity of the developmental response to water volume reduction in tadpoles of Eastern spadefoot toad Pelobates syriacus. The response of tadpoles to the simulated drying conditions was evaluated by gradually reducing the water level in the experimental containers under controlled laboratory conditions. Four water level treatments were used: constant high, slow decrease, fast decrease and constant low level. We tested if (i) tadpoles can speed up their development in a drying aquatic habitat, and (ii) if the accelerated development causes a reduced body size at metamorphosis. Our results showed that P. syriacus tadpoles were able to respond to pond drying by speeding up their metamorphosis and that metamorphosis was not influenced by water level, but by water level decrease rate. The accelerated development caused by the decreasing water level resulted in smaller body size at metamorphosis. The smallest size at metamorphosis was in tadpoles raised in constant low water level treatments and was probably induced by the crowding effect. We compared our results to similar studies which show that the response of the Eastern spadefoot toad tadpoles to pond drying is less impressive, especially if compared to the response of the North American spadefoot toads inhabiting desert environments.

Age and Body Size in Populations of Two Syntopic Spadefoot Toads (Genus Pelobates) at the Limit of Their Ranges

Abstract Age and size at sexual maturity are major life-history traits that affect growth rate and reproductive output. The differences in these life-history traits can be better assessed in syntopic populations of related species, where environmental variability in time and space is removed. The Spadefoot Toads (Pelobates spp.) are highly specialized burrowing and nocturnal species with a narrow ecological niche. We tested if age-related parameters are responsible for sexual size dimorphism and size differences in two syntopic populations from the Danube Delta Biosphere Reserve (Romania). The two populations differed significantly in size and body mass, and showed distinct sexual dimorphism, with females significantly larger in P. fuscus, and males slightly larger in P. syriacus. We also found differences in age structure: P. fuscus was on average 5.0 yr old, whereas P. syriacus was on average 7.4 yr old. Both species reached sexual maturity at a similar age. Different growth rates before sexual maturity and differences in energy allocation between growth and reproduction after sexual maturity are responsible for the differences in adult size between these syntopic populations. Our results suggest that growth allocation between species and sexes cannot be explained solely on the basis of age-related parameters.

When Males Are Larger than Females in Ecthotherms: Reproductive Investment in the Eastern Spadefoot Toad Pelobates syriacus

The way animals allocate resources to growth and reproduction is of major importance in understanding life-history trade-offs. Because the investment in reproduction of the two sexes differs, comparing the costs and the reproductive strategies adopted offers an insight into the evolutionary forces that shaped them. In the Eastern Spadefoot Toad, Pelobates syriacus the males are larger than females in body length, but not in body mass. We studied the reproductive effort and output in a population of P. syriacus from the Danube Delta Biosphere Reserve (Romania), during two consecutive years (2010 and 2011). Body mass loss during mating and egg deposition in females averaged 27%, while in males it was 3.9%. Body mass loss in females was proportional with size, with larger females losing more weight than smaller ones. Initial body mass and body mass loss during reproduction were significantly correlated with clutch size, but egg size was not correlated to female size or body mass loss. Year had a significant effect on body size in both sexes, suggesting high plasticity and the effect of local environmental factors on growth and reproduction. Age of adults ranged between 2–12 years and did not differ significantly between sexes. A nonrandom, but not completely assortative, mating was observed, with the age and body size of paired animals slightly positively correlated, indicating an explosive breeder reproductive strategy.

SALINITY TOLERANCE IN PELOBATES FUSCUS (LAURENTI, 1768) TADPOLES (AMPHIBIA: PELOBATIDAE)

Abstract We investigated the effect of salinity on larval development and survival rate to metamorphosis in the common spadefoot toad Pelobates fuscus (Laurenti, 1768). Our hypothesis was that higher salinity would decrease tadpole survival rate and body size at metamorphosis, and delay metamorphosis. The response of the tadpoles was evaluated through an experimental design with three salinity treatments of 2, 4, and 8‰ compared to a control (deionized water). Survival varied across the treatments: neither of the tadpoles in 8‰ salinity treatment survived the experiment, nor achieved metamorphosis. Salinity levels of 2 and 4‰ had no significant influence on the mean time to metamorphosis, body mass and SVL at metamorphosis. Our results suggest that P. fuscus tadpoles have a tolerance threshold for brackish water up to 4‰, above which survival is impaired. Résumé Nous avons étudié l’effet de la salinité sur le développement larvaire et la survie à la métamorphose du Pélobate brun Pelobates fuscus (Laurenti, 1768). Notre hypothèse a été que en augmentant la salinité, le taux de survie des têtards et leurs dimensions à la métamorphose diminueraient et le temps nécessaire pour la métamorphose serait plus long. La réponse des têtards a été évaluée par un model expérimental avec trois traitements de salinité de 2, 4, et 8‰ par rapport à un témoin (eau déminéralisée). La survie des têtards a été différente à travers les traitements: aucun des têtards soumis au traitement de 8‰ de salinité n’a survit à l’expérience ou accompli sa métamorphose. Les niveaux de salinité de 2 et 4‰ n’ont pas influencé significativement le temps moyen à la métamorphose ou le poids corporel et les dimensions à la métamorphose. Nos résultats suggèrent que les têtards de P. fuscus ont un seuil de tolérance pour l’eau saumâtre jusqu’à 4‰, au dessus duquel la survie est compromise. REZUMAT În acest studiu am investigat efectul salinităţii asupra dezvoltării larvare şi a ratei de supravieţuire a larvelor până la metamorfoză la broasca de pământ brună Pelobates fuscus (Laurenti, 1768). Ipoteza testată a fost că, odată cu creşterea nivelului de salinitate, rata de supravieţuire a larvelor şi dimensiunile acestora la momentul metamorfozei vor descreşte, iar timpul necesar pentru metamorfoză va creşte. Reacţia mormolocilor a fost evaluată experimental în trei tratamente cu salinitate de 2, 4, şi 8 ‰ raportat la un control (apă deionizată). Supravieţuirea larvelor de P. fuscus a variat în cele trei tratamente faţă de control: nici unul dintre mormolocii din tratamentul de 8 ‰ nu a supravieţuit experimentului şi nici nu a ajuns la metamorfoză. Tratamentele de salinitate până la 4 ‰ nu au avut o influenţă semnificativă asupra timpului mediu până la metamorfoză, a greutăţii sau a dimensiunilor la momentul metamorfozei. Rezultatele noastre sugerează că larvele de P. fuscus tolerează ape salmastre cu salinitate de până la 4 ‰, neputând însă supravieţui dincolo de acest prag.

Out of the ground: two coexisting fossorial toad species differ in their emergence and movement patterns

Understanding the way species with similar niches can coexist is a challenge in ecology. The niche partitioning hypothesis has received much support, positing that species can exploit available resources in different ways. In the case of secretive species, behavioural mechanisms of partitioning are still poorly understood. This is especially true for fossorial frogs because individuals hide underground by day and are active only during the night. We investigated the nocturnal activity and tested the niche partitioning hypothesis in two syntopic fossorial spadefoot toads (Pelobates fuscus and Pelobates syriacus) by examining interspecific variation in emergence from the soil. We employed a night vision recording system combined with video tracking analyses in a replicated laboratory setting to quantify individual movement patterns, a procedure that has not been used until now to observe terrestrial amphibians. Most individuals appeared on the surface every night and returned to their original burrow (about 60% of the times), or dug a new one around morning. There was a large temporal overlap between the two species. However, P. syriacus was significantly more active than P. fuscus in terms of total distance covered and time spent moving, while P. fuscus individuals left their underground burrow more frequently than P. syriacus. Consequently, P. fuscus adopted more of a sit-and-wait behaviour compared to P. syriacus, and this could facilitate their coexistence. The use of night video tracking technologies offered the advantage of individually tracking these secretive organisms during their nocturnal activity period and getting fine-grained data to understand their movement patterns.

A new minute Pristimantis (Amphibia: Anura: Strabomantidae) from the Andes of southern Ecuador

We describe a new rainfrog species (Pristimantis), from the wetland complex Oña, Nabón, Saraguro and Yacuambi, in the Andes of southern Ecuador, at altitudes ranging between 3000–3400 m a.s.l. Pristimantis tiktik sp. nov. is a small frog, displaying sexual dimorphism (the males with dorsum of various shades of gray, brown, orange or green and a whitish or pinkish yellow venter; females with brownish gray or gray dorsum and a reticulated white and black venter), with SVL ranging between 19.7–20.4 mm in females (n = 3) and 16.1–18.4 mm in males (n = 6). The skin on dorsum is tuberculated, that on venter is coarsely areolate, dorsolateral folds are absent, tympanic membrane is absent but the tympanic annulus is evident, cranial crests are absent, discs on fingers just slightly expanded, heel is lacking enlarged tubercles, inner edge of tarsus is bearing a long fold, Toe V is slightly longer than Toe III and the iris coloration is bronze with fine black reticulations. The males have a large subgular vocal sac that extends onto the chest and vocal slits but lack nuptial pads. The unique advertisement call consists of long duration series of periodically repeated clicks: “tik”. Molecular analyses place the new species in the recently resurrected P. orestes group, as the sister species of the assemblage that contains P. bambu, P. mazar, P. simonbolivari and an undescribed species.

A new species of direct-developing frog of the genus Pristimantis (Anura: Terrarana: Craugastoridae) from Cordillera del Cóndor, Ecuador, with comments on threats to the anuran fauna of the region

A new frog in the genus Pristimantis is described from a cloud forest on the western flanks of the Cordillera del Cóndor and eastern Andean slopes in the province of Zamora Chinchipe, southeastern of Ecuador. We inferred its phylogenetic position using DNA sequences of mitochondrial and nuclear genes. The new species is strongly supported as part of a clade that includes P. ardalonychus, P. cajamarcensis, P. ceuthospilus, P. chalceus, P. minutulus, P. luteolateralis, P. parvillus, P. ockendeni, P. unistrigatus, and P. walkeri. It can be distinguished from all other species from Cordillera del Cóndor and congeneric species by the unique combination of the following characters: (1) iris light blue with black reticulations; (2) skin of dorsum finely shagreen with scattered pustular tubercles and absence of dorsal folds; (3) tympanic membrane and tympanic annulus visible; (4) snout rounded in dorsal and lateral view; (5) upper eyelid bearing two or three enlarged subconical tubercles; (6) cranial crest absent; (7) males lacking vocal sac and slits; and (8) venter uniformly bright red, light red, salmon or orange. The new species is most closely related to P. ardalonychus, P. cajamarcensis, P. ceuthospilus, P. ockendeni and P. unistrigatus. We consider the new species to be Endangered following IUCN criteria because it has been severely affected by large scale open-pit mining in some localities. Currently, the amphibian fauna of the Cordillera del Cóndor and nearby protected areas are threatened by large-scale copper and gold mining projects with devastating effects on ~20 species, including several undescribed ones.

The impact of salinity on early developmental stages in two sympatric spadefoot toads and implications for amphibian conservation in coastal areas

Salinity tolerance is critical during the early ontogeny of amphibians, shaping future population size, health and dispersal in a certain area. We focused our research on two related anurans with similar ecological niches—Pelobates fuscus and P. syriacus—inhabiting the western Black Sea coast, at the limits of their ranges. We hypothesize that their differences in salinity tolerance are shaping the actual range limits in coastal areas, within the sympatry zone. We quantified experimentally the impact of salinity (range 0–9‰) during early ontogeny to ask if salinity can modulate their coexistence, by affecting differently reproductive success and fitness. Exposure to salinity from egg to developmental stage Gosner 25 caused mild to severe malformations and affected survival and size in both species, but the impact was lower in P. syriacus compared to P. fuscus when exposed to salt concentrations of 6‰. Embryos of either species did not survive the 9‰ salinity concentration. We expect that increases in salinization up to 6‰ could severely reduce the range of P. fuscus, but not P. syriacus, in coastal areas. These results are highly relevant for the conservation of P. fuscus, which is already declining across Europe.