Salamandrella Keyserlingii Research Articles

A comparative study of the hyobranchial apparatus in Hynobiidae (Amphibia: Urodela)

The morphology of the adult hyobranchial apparatus has played an important role in understanding the systematics and evolution of urodeles, but the hyobranchial apparatus of hynobiid salamanders has received little attention so far. In this study, the hyobranchial apparatus of eight hynobiid salamanders (Hynobius leechii, Onychodactylus zhangyapingi, Ranodon sibiricus, Batrachuperus pinchonii, Salamandrella keyserlingii, Liua shihi, Pachyhynobius shangchengensis and Pseudohynobius flavomaculatus) is described and compared based on the clearing and double-staining method. The basic elements of the hyobranchial apparatus of the eight species are similar, including one basibranchial, cornua, one pair of radial loops, one pair of ceratohyals, one pair of hypobranchials II, one pair of ceratobranchials II, one urohyal (absent in O. zhangyapingi), one pair of the complex of hypobranchial I and ceratobranchial I (separated in certain species). Although the hyobranchial apparatus is similar among hynobiid salamanders and shows a unique morphological pattern, there are also certain species-specific distinctions that may be used for specific or generic diagnosis. The results of an ancestral state reconstruction of five traits showed that the ossified basibranchial, the presence of a separated hypobranchial I and ceratobranchial I, the absence of a urohyal, the ossified hypobranchial I and the partially ossified ceratohyal are derived traits. The state shown by the traits of each species is consistent with the phylogenetic position of each species. Compared with other Urodela, the hyobranchial apparatus of this group shows certain distinctive features that may represent the diagnostic characters of the family Hynobiidae. The partially ossified ceratohyal is correlated with the habitat and represents an ecological adaptation.

Phylogeny and genetic history of the Siberian salamander (Salamandrella keyserlingii, Dybowski, 1870) inferred from complete mitochondrial genomes

We assessed phylogeny of the Siberian salamander (Salamandrella keyserlingii, Dybowski, 1870), the most northern ectothermic, terrestrial vertebrate in Eurasia, by sequence analysis of complete mitochondrial genomes in 26 specimens from different localities (China, Khabarovsk region, Sakhalin, Yakutia, Magadan region, Chukotka, Kamchatka, Ural, European part of Russia). In addition, a complete mitochondrial genome of the Schrenck salamander, Salamandrella schrenckii, was determined for the first time. Bayesian phylogenetic analysis of the entire mtDNA genomes of S. keyserlingii demonstrates that two haplotype clades, AB and C, radiated about 1.4millionyears ago (Mya). Bayesian skyline plots of population size change through time show an expansion around 250thousandyears ago (kya) and then a decline around the Last Glacial Maximum (25kya) with subsequent restoration of population size. Climatic changes during the Quaternary period have dramatically affected the population genetic structure of the Siberian salamanders. In addition, complete mtDNA sequence analysis allowed us to recognize that the vast area of Northern Eurasia was colonized only by the Siberian salamander clade C1b during the last 150kya. Meanwhile, we were unable to find evidence of molecular adaptation in this clade by analyzing the whole mitochondrial genomes of the Siberian salamanders.

Selective processes and adaptive evolution of the cytochrome b gene in salamanders of the genus Salamandrella

Sequence analysis of the cytochrome b gene fragment in the salamanders of the genus Salamandrella, Siberian salamander and Schrenk salamander was performed with the purpose to elucidate the effect of natural selection on the evolution of mitochondrial DNA (mtDNA) in these species. It was demonstrated that despite of notable influence of negative selection (expressed as very low dN/dS values), speciation and intraspecific divergence in salamanders was accompanied by the appearance of radical amino acid substitutions, caused by the influence of positive (directional) selection. To examine the evolutionary pattern of synonymous mtDNA sites, distribution of conservative and non-conservative substitutions was analyzed. The rates of conservative and non-conservative substitutions were nearly equal, pointing to neutrality of mutation process at synonymous mtDNA sites of salamanders. Analysis of conservative and non-conservative synonymous substitution distributions in different parts of phylogenetic trees showed that the differences between the synonymous groups compared were statistically significant only in one phylogenetic group of Siberian salamander (haplogroup C) (P = 0.02). In the group of single substitutions, located at terminal phylogenetic branches of Siberian salamanders from group C, increased rate of conservative substitutions was observed. Based on these findings, it was suggested that selective processes could have an influence on the formation of the synonymous substitution profile in the Siberian salamander mtDNA fragment examined.

Is the western boundary of the Siberian salamander (Salamandrella keyserlingii, Amphibia, Caudata, Hynobiidae) range determined by the specific features of its wintering?

Is the western boundary of the Siberian salamander (Salamandrella keyserlingii, Amphibia, Caudata, Hynobiidae) range determined by the specific features of its wintering?

Extremely Low Genetic Diversity Indicating the Endangered Status of Ranodon sibiricus (Amphibia: Caudata) and Implications for Phylogeography

BackgroundThe Siberian salamander (Ranodon sibiricus), distributed in geographically isolated areas of Central Asia, is an ideal alpine species for studies of conservation and phylogeography. However, there are few data regarding the genetic diversity in R. sibiricus populations.Methodology/Principal FindingsWe used two genetic markers (mtDNA and microsatellites) to survey all six populations of R. sibiricus in China. Both of the markers revealed extreme genetic uniformity among these populations. There were only three haplotypes in the mtDNA, and the overall nucleotide diversity in the mtDNA was 0.00064, ranging from 0.00000 to 0.00091 for the six populations. Although we recovered 70 sequences containing microsatellite repeats, there were only two loci that displayed polymorphism. We used the approximate Bayesian computation (ABC) method to study the demographic history of the populations. This analysis suggested that the extant populations diverged from the ancestral population approximately 120 years ago and that the historical population size was much larger than the present population size; i.e., R. sibiricus has experienced dramatic population declines.Conclusion/SignificanceOur findings suggest that the genetic diversity in the R. sibiricus populations is the lowest among all investigated amphibians. We conclude that the isolation of R. sibiricus populations occurred recently and was a result of recent human activity and/or climatic changes. The Pleistocene glaciation oscillations may have facilitated intraspecies genetic homogeneity rather than enhanced divergence. A low genomic evolutionary rate and elevated inbreeding frequency may have also contributed to the low genetic variation observed in this species. Our findings indicate the urgency of implementing a protection plan for this endangered species.

Polymorphism of the mitochondrial cytochrome b gene, phylogeography, and molecular adaptation of the Siberian salamander (Salamandrella keyserlingii, Amphibia, Caudata)

We performed an analysis of nucleotide variation of the mitochondrial DNA (mtDNA) cytochrome b gene in populations of the Siberian salamander (Salamandrella keyserlingii Dybowski, 1870) from Khabarovsk krai; the Jewish autonomous oblast; Amur, Sakhalin, and Magadan oblasts; Sakha; and other regions of northern Eurasia. Two major phylogenetic haplotype groups, AB and C, were found using phylogenetic analysis. The degree of intergroup divergence is 1.87%, which indicates that these groups diverged about 1.5 Ma ago. Siberian salamanders with the AB haplogroup and with four of the five subgroups of the C haplogroups are found only in the Far East, including Sakhalin; the rest of the geographical range is occupied by one of the haplogroups, C1. Analysis of the distribution of nonsynonymous and synonymous substitutions demonstrated that the cytochrome b gene variation of the Siberian salamander is neutral. However, nucleotide sequences of the AB and C groups differ significantly in the region corresponding to the cd-loop of the Q0 redox center of cytochrome b protein. In addition, the radical serine-to-leucine substitution in position 160 of the cd2-loop changes the physicochemical properties of the cd region of the C group sequences by increasing its hydrophobicity. The obtained results suggest that the changes in the sequence of the cytochrome b gene of the Siberian salamander group C are adaptive.

Reproduction of the Siberian salamander, Salamandrella keyserlingii (Amphibia, Caudata, Hynobiidae), in water bodies on permafrost in Northeastern Asia

The possibility for Siberian salamanders to reproduce in the permafrost zone of Eurasia is due to specific thermal conditions in small water bodies (pools) freezing to the bottom, rather than to the adaptive properties of the species. These conditions are as follows: (1) meltwater in freezing marshland pools appears relatively early; (2) the rate of water warming increases in the south-north direction due to the lengthening of the daylight period; (3) water temperature is higher than air temperature but does not reach the values critical for S. keyserlingii eggs and larvae; and (4) the thawed silt layer prevents water cooling by the underlying permafrost bed. Reproduction of Siberian salamanders in different parts of the species range begins under similar thermal conditions, which are formed 1.5–2 months earlier in the south (the Jewish Autonomous Region) than in the north (the Chaun Bay coast). In any region, the onset of spawning may vary by up to 30 days. The existence of Siberian salamanders in the tundra zone is facilitated by continuous daylight during the polar day, which provides for rapid water warming to relatively high temperatures and creates additional opportunities for larval feeding. These factors may account for the acceleration of amphibian ontogeny in the North, noted by Shvarts and Ishchenko (1971). The northern boundary of the Siberian salamander range in Eastern Siberia is defined by the sum of water temperatures over the warm season, which should be no less than 850–900°/day. This boundary in the tundras of Europe, Western Siberia, and the Chukchi Peninsula is shifted southward, with its location being apparently dependent on some other factors.

118. Siberian salamander Salamandrella keyserlingii as an object for study of cold resistance

118. Siberian salamander Salamandrella keyserlingii as an object for study of cold resistance

Phylogeography and molecular adaptation of Siberian salamander Salamandrella keyserlingii based on mitochondrial DNA variation

We assessed the phylogeographic pattern of Siberian salamander ( Salamandrella keyserlingii, Dybowski, 1870), which appear to be the most northern ectothermic, terrestrial vertebrate in Northern Eurasia, by sequence analysis of a 611-bp fragment of the mitochondrial cytochrome b gene in 159 specimens from different localities (Khabarovsk region, Sakhalin, Yakutia, Magadan region, Chukotka, Kamchatka and others). The data revealed that cytochrome b lineages of S. keyserlingii are divided into haplogroups A, B and C. Haplogroup A and B sequences are widespread in the Far East region, whereas haplogroup C consisting of several phylogenetic clusters (C1, C2, C3) is present in the all range of S. keyserlingii. Among them, cluster C3 appears to be specific for Sakhalin; most likely, it has arisen in situ in this island, with the entry time of the founder mtDNA estimated at about 0.4 MY. Analysis of cytochrome b gene variation by using different neutrality tests (including those based on K A/ K S-ratio) has shown that differences between haplogroups were statistically insignificant, thus suggesting selective neutrality. However, analysis of amino acid changes allowed us to detect a signature of molecular adaptation, which might have led to appearance of adaptive cytochrome b variants in haplogroup C, originating most likely at the end of Eopleistocene (about 0.64 MY based on the haplogroup C divergence level). It seems probable that this adaptive mechanism could promote subsequent populating of new regions.

Phylogeography of the Siberian newt Salamandrella keyserlingii by mitochondrial DNA sequence analysis

Differentiation of geographical populations of the Siberian newt Salamandrella keyserlingii throughout the species range was analyzed using a fragment of the cytochrome b gene. The population of the Primorye region (Russian Far East) is separated to the greatest extent; the Japanese and South Kuril populations are the next most separate. These populations are possibly subspecies. Geographical differentiation of populations in the Siberian part of the species range is lower, lacks a clinal variation, and is irregular. The molecular variation of S. keyserlingii supports the hypothesis that several primary vicarious refugia of pre-Pleistocene differentiation of a common ancestor of Salamandrella occurred in the southeastern part of its current distribution range and that northern and western regions were gradually colonized via repeated steps of expansion and retreat in the Siberian part of the modern species range.

Phylogenetic relationships of two Salamandrella species as revealed by mitochondrial DNA and allozyme variation (Amphibia: Caudata: Hynobiidae)

We conducted molecular phylogenetic analyses to confirm taxonomic relationships and to delimit distributional ranges of Siberian salamanders, Salamandrella keyserlingii and Salamandrella schrenckii, and to elucidate the origin of the isolated population of this species complex on Hokkaido, Japan. Phylogenetic trees constructed by MP, NJ, ML, and Bayesian methods, using complete sequences of mitochondrial cytochrome b genes, all indicated monophyly of Salamandrella and of each of the two species. Identical relationships were found on UPGMA, NJ, and CONTML trees derived from electrophoretic analysis of variation in 18 inferred allozyme loci. Populations from Hokkaido and northeastern China proved to be S. keyserlingii, while populations from Khabarovsk and Lazovsky are S. schrenckii. Genetic differentiations of S. keyserlingii within Sakhalin, and between Sakhalin and Hokkaido, are substantial. The Hokkaido population is hypothesized to have been isolated on the island since early Pleistocene, much earlier than isolation of sympatric anuran populations from their Sakhalin relatives. In contrast, the continental populations of S. keyserlingii are only slightly differentiated from some Sakhalin populations, and are thought to have expanded their ranges in the late Pleistocene.

Prolactin-based "Water-drive Theory" in Migratory Salamanders: Some Disprovable Data

ABSTRACT To reconsider a classic theory that prolactin induces water-drive behavior in migratory salamanders (i.e., prolactin-based water-drive theory), I showed, with a brief review of past references, some disprovable data on the basis of “migratory activity type” and “mucus secretion” in the hynobiid salamanders, Hynobius hidamontanus and Salamandrella keyserlingii. This theory could not explain fall immigrations toward terrestrial hibernacula unrelated to mating in S. keyserlingii. Likewise, literature review indicated that it also could not explain breeding immigrations toward dry pond basins in Ambystoma opacum and toward terrestrial nest-sites adjacent to the water in Tylototriton (Echinotriton) andersoni. Mucus that was secreted from dermal mucous glands, a target organ for prolactin, was absent on the skin of both fall-nonbreeding and spring-breeding immigrants of S. keyserlingii. In the context of existence of ecological and physiological examples against the prolactin-based water-drive theory, ...

Variation in number of trunk vertebrae and in count of costal grooves in salamanders of the family Hynobiidae

Ten species from five genera of the family Hynobiidae were studied. The number of trunk vertebrae varied between 14 and 21, and the count of costal grooves ranged from 10 to 15. Both the within-species variation and the within-population variation were recorded in some species. In both kinds the values of the coefficient of variation were quite low. In Salamandrella keyserlingii, the south-eastern samples markedly differed from remaining ones. Among the hynobiids, the genus Onychodactylus (both species) and Batrachuperus mustersi have higher number of vertebrae in the anterior part of trunk (5 and 4, respectively, versus 3), and, thus, demonstrated a distinct position. The relation between the number of trunk vertebrae and the count of costal grooves was studied. The variation in number of trunk vertebrae across urodelan families was discussed.

SKELETAL AND DENTAL ONTOGENY IN THE LONG-TAILED CLAWED SALAMANDER, Onychodactylus fischeri (URODELA: HYNOBIIDAE)

Skull, hyobranchial, and dental ontogeny of Onychodactylus fischeri (Hynobiidae) is described based on a developmental series ranging from early larvae to old postmetamorphic animals. If compared with other hynobiids ( Ranodon sibiricus and Salamandrella keyserlingii ), larvae of O. fischeri display the underdevelopment of certain larval specific features: e.g., the coronoid is edentate and occurs as a tiny bone only in the earliest larvae; the «Zahnfeld» on the vomer and palatine is absent, the palatine portion of the palatopterygoid is reduced. On the other hand, adult postmetamorphic O. fischeri specimens show the underdeveloped cranial and postcranial skeletal features in comparison with adult R. sibiricus and S. keyserlingii . Two phenomena seem to account for the abbreviation of the ontogenetic trajectory in O. fischeri . First, in O. fischeri which has the largest eggs among hynobiids, the initial larval development appears to have been shifted into the embryonic period (embryonalization which is accompanied in amphibians by the reduction or loss of certain larval specific features). Second, paedomorphosis caused by the retarded rate of somatic development in O. fischeri appears to have resulted in the loss or reduction of features that appear later in R. sibiricus and S. keyserlingii and, likely, in the ancestral ontogeny.

The bony skull of the Siberian Salamander Salamandrella keyserlingi (Amphibia: Urodela: Hynobiidae) and the role of thyroid hormones in its development.

The bony skull of the Siberian Salamander Salamandrella keyserlingi (Amphibia: Urodela: Hynobiidae) and the role of thyroid hormones in its development.