Presence of an alien turtle accelerates hatching of common frog (Rana temporaria) tadpoles

The presence of a predator affects prey populations either by direct predation or by modifying various parts of their life history. We investigated whether the hatching time, developmental stage, and body size at hatching of common frog (Rana temporaria) embryos would be altered in the presence of a red-eared slider (Trachemys scripta elegans) as a predator. The presence of a predator affected all factors examined. We found that in the absence of the slider, the embryos hatched in 12 days, while hatching was accelerated by two days when sliders were present. At the same time, the embryos hatched smaller and at a lower stage of development with the slider than without it. Our study extends the range of predators studied, including the effect on different phases of development of potential amphibian prey.

Phenetic peculiarities of biochorological groups of different scales in a common frog (Rana temporaria linnaeus)

На примере серий лягушки травяной из четырех биотопов, характеризующихся разной степенью пространственной изоляции, показана перспективность изучения биохорологической структуры данного вида с применением фенетического подхода. Наиболее детальную характеристику пространственно-генетической структуры можно получить при анализе пятнистости дорзальной поверхности тела. Так же для этих целей возможно использование вариаций таких элементов рисунка покровов тела, как форма межлопаточного пятна и число полос на бедре. The prospects of studying the biochorological structure of the selected species using a phenetic approach are shown in a series of common frogs from four biotopes characterized by varying degrees of spatial isolation. The most detailed characterization of the spatial-genetic structure can be obtained by analyzing the spotting of the dorsal surface of the body. Also, for these purposes, it is possible to use variations of such elements of the body covering pattern as the shape of the interscapular spot and the number of stripes on the thigh.

Recalculation of data from 1990 to 2010 on the effects of highly diluted thyroxine on the metamorphosis of highland amphibians

Experiments on amphibian metamorphosis can vary considerably in duration. The authors had set themselves the task of defining a generally applicable pooling method for metamorphosis experiments [1]. Normalization with respect to time was done on the assumption that differences in speed of metamorphosis attributable to treatment would override differences in duration between experiments. The problem of artificial differences in variability when comparing and pooling data from several experiments was approached by normalization with respect to time based on the development of both the test and the control animals. The range from 0% to 100% over which the fraction of four-legged animals progresses in the course of an experiment is divided into 10%-intervals and mapped onto a corresponding relative scale. Each measurement is then assigned to the point on the 10%-scale to which it is closest. In this way each reference point is assigned a value giving the number or percentage of four-legged animals at that point. These values are aggregated over all experiments within the test- and control-group. The results of experiments performed over the course of two decades (1990 - 2010) on highland Rana temporaria treated with a homeopathically prepared high dilution of thyroxine (“30x”) are presented in full detail based on this normalization method[1]. It was found that differences between treatment groups thus calculated were in line with those obtained with other pooling methods [2]. Thyroxine 30x does slow down metamorphosis in inert highland amphibians. This was observed by 5 researchers in 20 sub-experiments, and it seems to be the most reliable bio-assay found in amphibian research on homeopathy so far2. When experiments were performed with highland animals pretreated by hyperstimulation with molecular thyroxine, slowing down of metamorphosis was again observed (by 3 of 4 researchers) in most of 10 sub-experiments.

Highland amphibians - Recalculation of data from 1990 to 2010 on the effects of extremely diluted thyroxine

Experiments on amphibian metamorphosis can vary considerably in duration. The authors had set themselves the task of defining a generally applicable pooling method for metamorphosis experiments. The problem of artificial differences in variability when comparing and pooling data from several experiments was approached by normalization with respect to time based on the development of both test and the control animals. The range from 0% to 100% over which the fraction of four-legged animals progresses in the course of an experiment is divided into 10%-intervals and the 10% reference points are mapped on a corresponding scale. Each measurement is then assigned to the point on the time scale to which it is closest. In this way each reference point is assigned a value giving the number or percentage of four-legged animals at that point on the scale. Subsequent analysis was then based on the individual values for the test and control groups that corresponded to the joint 10% reference point. Normalization respect to time was done on the assumption that differences in metamorphosis speed attributable to treatment would override differences in duration between experiments. The results of experiments performed over the course of two decades (1990 - 2010) on highland Rana temporaria treated with a homeopathically prepared high dilution of thyroxine (“30x”) are presented in full detail based on this normalization method. Differences found between treatment groups thus calculated were in line with those obtained with other pooling methods. Thyroxine 30x does slow down metamorphosis in inert highland amphibians. This was observed by five researchers in 20 sub-experiments, and it seems to be the most reliable bio-assay found in amphibian research on homeopathy so far. When experiments were performed with highland animals pretreated by hyperstimulation with molecular thyroxine, slowing down of metamorphosis was again observed (by three out of four researchers) in most of 10 sub-experiments.

Lowland amphibians - recalculation of data on effects of diluted thyroxine

Our previous paper described methodological problems and a generally acceptable pooling method for metamorphosis experiments and application of that method to the results of multicentre experiments performed over the course of two decades (1990 - 2010) on highland amphibians (Rana temporaria) treated with a homeopathically prepared high dilution of thyroxine (“30x”). Differences between treatment groups thus calculated were in line with those obtained with other pooling methods: Thyroxine 30x does slow down metamorphosis in highland amphibians. This follow up paper provides a broader background on metamorphosis physiology and describes application of the pooling method to experiments with Rana temporaria from lowland biotopes both with a moderate dilution of thyroxine (“8x”) and with 30x. Analogously prepared water was used for control (water 8x or 30x). Development was, again as above, monitored by documenting the number of animals that had entered the 4-legged stage. Experiments were carried out between 1990 and 2000 by different researchers independently and in blind. As it is well known, metamorphosis can be speeded up by thyroxine 10-8 mol/l; interestingly, thyroxine 8x may produce a reverse, i.e. inhibiting effect (p < 0.01). In contrast to the inhibiting effect of thyroxine 30x on highland larvae (see above), 2-legged lowland larvae did not react to thyroxine 30x (p > 0.05). However, an inhibiting effect on lowland larvae was found when animals were treated from the spawn stage on (p < 0.01).

Assessing the performance of Alphitobius piceus (Oliver, 1792) as novel feeder insect species for small sized postmetamorphic frogs

One of the major difficulties of frog farming is providing adequate food in the first few weeks after the metamorphosis. This is a critical time frame, with rapid growth and high mortality. The established feeder insect species used throughout this delicate stage (cricket and mealworm larvae, adult fruit flies) are suitable from a trophic perspective, but present challenges and difficulties that influence the production costs. The aim of this study is to assess the performance of an alternative feeder species - Alphitobius piceus - with a simpler production technology and a lower production cost. Two species of feeder insect were used: the conventionally used Acheta domestica larvae as control species, and Alphitobius piceus larvae as experimental species. As model anuran we used the European common frog, Rana temporaria. The experimental insect species was easily accepted and produced a strong feeding response in the post-metamophic frogs. There were no significant differences between the control and experimental groups in terms of body condition index and mortality, however survival was better in the experimental group. This similarity indicates a high potential of Alphitobius piceus as feeder species for the newly metamorphosed frogs and also a good economic opportunity for frog farms.

Thermal conditions predict intraspecific variation in senescence rate in frogs and toads

Variation in temperature is known to influence mortality patterns in ectotherms. Even though a few experimental studies on model organisms have reported a positive relationship between temperature and actuarial senescence (i.e., the increase in mortality risk with age), how variation in climate influences the senescence rate across the range of a species is still poorly understood in free-ranging animals. We filled this knowledge gap by investigating the relationships linking senescence rate, adult lifespan, and climatic conditions using long-term capture–recapture data from multiple amphibian populations. We considered two pairs of related anuran species from the Ranidae (Rana luteiventris and Rana temporaria) and Bufonidae (Anaxyrus boreas and Bufo bufo) families, which diverged more than 100 Mya and are broadly distributed in North America and Europe. Senescence rates were positively associated with mean annual temperature in all species. In addition, lifespan was negatively correlated with mean annual temperature in all species except A. boreas. In both R. luteiventris and A. boreas, mean annual precipitation and human environmental footprint both had negligible effects on senescence rates or lifespans. Overall, our findings demonstrate the critical influence of thermal conditions on mortality patterns across anuran species from temperate regions. In the current context of further global temperature increases predicted by Intergovernmental Panel on Climate Change scenarios, a widespread acceleration of aging in amphibians is expected to occur in the decades to come, which might threaten even more seriously the viability of populations and exacerbate global decline.

The genome sequence of the common frog, Rana temporaria Linnaeus 1758

We present a genome assembly from an individual female Rana temporaria (the common frog; Chordata; Amphibia; Anura; Ranidae). The genome sequence is 4.11 gigabases in span. The majority of the assembly is scaffolded into 13 chromosomal pseudomolecules. Gene annotation of this assembly by the NCBI Eukaryotic Genome Annotation Pipeline has identified 23,707 protein coding genes.