534.19 KB
180The influence of dates of metamorphosis, size at metamorphosis, and number of emerged juveniles on the reproductive characteristics and female body size were studied by group-marking of postmetamorphic Rana arvalis individuals of three generations. The frogs under study emerged after metamorphosis from the breeding pond and their adults were recaptured in the same pond after 3–7 years. The maximum body size, egg size, and reproductive effort were revealed in the females born in 1991. This generation is characterized by the maximum size at metamorphosis and the minimum number of emerged juveniles. At the same time, similar variations in the mean annual values of body length, fecundity, and egg diameter were revealed in females of different generations. The differences between the generations of 1989 and 1990 are less pronounced, despite the similar size at metamorphosis and about the same initial number of juveniles. An increase in the female fecundity and egg diameter (but not in reproductive effort) with age was the general trend for each generation. Mature females originating from early juveniles were, on the average, significantly younger than late juveniles of the same generation. Most of females from the group of late small-sized animals reproduced for the first time after 4th wintering, i.e. one year later than other groups. The groups distinguished within generation differed in reproductive characteristics only slightly. In the early-large female group, a positive correlation between the size at metamorphosis and rates of growth and maturation was revealed.
The influence of dates of metamorphosis (early and late), size at metamorphosis (small-, medium- and large-sized) and number of emerged juveniles on the survivorship and other fitness characteristics of females were studied by counting and group-marking of postmetamorphic Rana arvalis individuals of three generations. The females under study emerged after metamorphosis from the breeding pond and were recaptured in the same pond after 3–7 years as adults. Within the generation born in 1989, the survivorship of the group of early juveniles till first and each successive reproduction was higher than in late ones, but within the generation of 1990 this survivorship of early juveniles was lower than in late ones. The survivorship of females of 1990 was higher in comparison not only with the generation of 1989, characterized by smaller sizes at metamorphosis, also with the generation of 1991, characterized by maximum size at metamorphosis. The total number of eggs produced by a given generation was determined by premetamorphic survivorship, and correspondingly by the number of emerged juveniles of a given generation. The net rate of reproduction (calculated on the basis of life-tables) was determined by premetamorphic survivorship to a greater extent than by size at metamorphosis and survivorship till maturity. Within each generation, the net rate of reproduction of a given group was affected rather by its survivorship till each successive breeding than by fecundity. Therefore, in the generation of 1989, the early group had higher net rate of reproduction than the late one. Within the generation of 1990, the relationship between these two groups was inverse. Large-sized (both early and late) groups of 1989 had maximal net rate of reproduction, but these differences were not revealed within the generation of 1990.
Based of the long-term studies of breeding Rana temporaria females, the components of intrapopulation variation of body size and reproductive characteristics were described, and the structure of relationship between them was estimated. The relegation of individuals to a certain generation was determined by skeletochronology. Within each generation female body length, fecundity, and egg size, but not reproductive effort and the relative clutch mass increased with aging. Both the increase and decrease of annual average values of body length, fecundity and egg size in females of different generations in the same years were revealed. Both body size and age of the frogs correlated positively and significantly with their fecundity and egg size. As shown by principal component analysis, each character (except for reproductive effort strongly influenced by fecundity) varied independently. Relationship between separate pairs of characters demonstrated the same relative independence. The weaker relationship of the relative clutch mass with age (compared to the other characters), intergeneration and annual variation is stipulated by the maximum investment of females in each reproduction, the latter characteristic correlating poorly with age and size of females.
The relative roles of natural selection and direct environmental induction, as well as of natural selection and genetic drift, in creating clinal latitudinal variation in quantitative traits have seldom been assessed in vertebrates. To address these issues, we compared molecular and quantitative genetic differentiation between six common frog (Rana temporaria) populations along an approximately 1600 km long latitudinal gradient across Scandinavia. The degree of population differentiation (QST 0.81) in three heritable quantitative traits (age and size at metamorphosis, growth rate) exceeded that in eight (neutral) microsatellite loci (FST = 0.24). Isolation by distance was clear for both neutral markers and quantitative traits, but considerably stronger for one of the three quantitative traits than for neutral markers. QST estimates obtained using animals subjected to different rearing conditions (temperature and food treatments) revealed some environmental dependency in patterns of population divergence in quantitative traits, but in general, these effects were weak in comparison to overall patterns. Pairwise comparisons of FST and QST estimates across populations and treatments revealed that the degree of quantitative trait differentiation was not generally predictable from knowledge of that in molecular markers. In fact, both positive and negative correlations were observed depending on conditions where the quantitative genetic variability had been measured. All in all, the results suggest a very high degree of genetic subdivision both in neutral marker genes and genes coding quantitative traits across a relatively recently (< 9000 years) colonized environmental gradient. In particular, they give evidence for natural selection being the primary agent behind the observed latitudinal differentiation in quantitative traits.
The highest altitude recorded for an amphibian in Europe (west of the Caucasus) is 2965 m. It refers to the "lacs de Cambalès" according to an old reference. However, these lakes are all situated below 2600 m, while the altitude corresponds exactly to that of the summit of the Pic de Cambalès. We undertook an almost complete survey of ponds in a 2.5 km radius from the Cambalès peak, and complemented these data by fieldwork in a larger portion of the Central Pyrenees. Based on our observations in a total of 325 lakes and ponds we conclude that no water bodies above 2800 m exist in the Cambalès area, and that no water bodies above 2600 m are populated by Rana temporaria. The highest amphibian record was that of a single R. temporaria specimen at 2569 m, while the highest reproducing population was found at 2516 m. Highest records of other amphibians were 2516 m (Alytes obstetricans), 2160 m (Bufo bufo), 2259 m (Euproctus asper), and 2142 m (Salamandra salamandra). The presence of ice-free water bodies during a sufficient amount of time for larval development is probably the limiting factor for elevational distribution of Pyrenean amphibians, and the adequate conditions are usually not met above 2500 m in this massif. In contrast, in the Alps, ponds at higher altitudes are often protected by much higher surrounding peaks, which leads to higher elevational occurrence of amphibians. The Italian Laghi di Tre Becchi (up to 2742 m) are therefore the highest locality of a reproducing anuran population in Europe west of the Caucasus.
Genetic differentiation of Rana temporaria from the Pyrenean and Cantabrian mountains in Spain was studied by means of allozyme electrophoresis. 24 loci were analysed in 104 specimens from 15 populations: nine populations from the Pyrenean massif, five populations from the area of the Cantabrian mountain chain (regions of Galicia, Asturias, and Basque Country), and one population from Germany. Three distinct clusters were distinguished by phenetic analysis: (a) the Pyrenean samples and the single population from the Basque Country, (b) the populations from Galicia and Asturias) and (c) the German population. Ordination (PCA) resulted in one principle component (PC1) that separated Cantabrian from Pyrenean populations, and in a second one (PC2) that separated the single German population from the Iberian ones. PC1 indicated introgression that was corroborated by west-east clines in several alleles along the Cantabrian chain. The rather clear separation of the Cantabrian and Pyrenean clusters (mean genetic distance 0.121) suggests that two genetically different subspecies of R. temporaria may be distinguished in Spain. The absence of fixed allelic differences between populations refutes recent hypotheses of the existence of syntopic sibling species within R. temporaria in Spain. Biogeographically, the Pyrenean and Cantabrian populations possibly originated in two separate colonisation events starting from different glacial refuges. The strong morphological differentiation of Pyrenean R. temporaria populations is not paralleled by genetic divergence, and may better be explained by ecological factors such as climate, altitude and vegetation.
Post-metamorphic dispersal in the common frog Rana temporaria (Amphibia, Anura) was studied with a combination of field (pit-fall traps) and laboratory (arena, artificial crossing) experiments. In the first studied population, the breeding place was surrounded by lines of fence-pitfall traps allowing capture of dispersing froglets. Dispersal was at random on the edge of the pond, but oriented in the most favorable terrestrial habitat at 10 m from the edge. Froglets of this population were then tested in orientation arena built on the University campus, where they also dispersed at random. The two other studied populations reproduced at each side (north and south) of a lake. Froglets from each population were tested in similar orientation arena, where they did not dispersed at random but to the north and south direction respectively. In the laboratory we crossed males and females originated from these two populations. Resulting crossed froglets exhibited variable dispersal patterns, which significantly differed from those observed with their respective parents. These results argued for an at least partly genetic control of emigration direction in these two frog populations, that we interpreted as the result of directional selection due to landscape change during the XXth century.
The aim of this study was to bring new information regarding the feeding of two amphibian species, Rana arvalis (moor frog) and Rana dalmatina (agile frog), in a forest habitat (Livada Plain, Romania). We have focused our attention upon the trophical spectrum variations that occur, depending on the species and the studying period. We noticed an increased diversity of prey taxa in the stomachal contents of the agil frog. The bugs, spiders and butterfly larvas are the most important prey for both species. There is an increased high mobility prey taxa amount (flying insects for instance) only in the agile frog's stomachal contents. We'd like to emphasize the fact that both species were hunting in terrestrial habitat.
A male Rana temporaria was observed in amplexus with a clutch for at least seven hours in April 2007, at a pond complex near Miercurea-Ciuc, Eastern Carpathians, Romania. This behavior is similar to the clutch-piracy described recently in a Pyrenean population of this species, and predicted to be widespread. This is the first record of this behavior outside the Pyrenees. Further studies are needed on the extent of this behavior in Romanian R. temporaria populations.
In general, amphibians are known to exhibit a higher degree of population subdivision than any other major animal taxa, but large-scale population genetic surveys of widely distributed species are still scarce, especially in the Eurasian continent. Using microsatellite markers and mitochondrial DNA sequences, we investigated the large-scale population genetic structure of the common frog (Rana temporaria) — one of the most widespread amphibians of the Palearctic region. Analyses of cytochrome b sequences revealed evidence for two distinct lineages inhabiting western and eastern parts of Europe. The separation of these lineages c. 700 000 years ago may have been induced by the onset of the Middle Pleistocene continental glaciations. Analyses of the variability of microsatellite loci within each of the clades revealed evidence for evolution of a high degree of population subdivision (FST ∼ 0.23) even in northern Fennoscandia, colonized less than 10 000 years ago. The high level of substructuring is puzzling in the face of an apparently high dispersal capacity, as evidenced by the rather rapid recolonization of northern Europe. This suggests that processes other than restricted dispersal capacity need to be explored as explanations for the high degree of population subdivision in amphibians. The colonization of northern Europe has been accompanied by loss of genetic variability as evidenced by decreasing levels of intrapopulational genetic variability in microsatellite loci from south to north across Europe.
