D. I. Berman

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.

Genetic structure of Schrenck newt Salamandrella schrenckii populations by mitochondrial cytochrome b variation

The nucleotide sequence variation of the mitochondrial cytochrome b gene was studied in Schrenck newt Salamandrella schrenckii (Strauch, 1870) from populations of Primorye and the Khabarovsk region. Phylogenetic analysis revealed two haplotype clusters, southern cluster 1 and northern cluster 2, with a divergence of 3%. Analysis of the mtDNA and cytochrome b amino acid sequence variations made it possible to assume that the modern range of Schrenck newt was colonized from south Primorye northwards. In contrast to the southern cluster, the northern one demonstrated all the signs of demographic expansion (a unimodal distribution of pairwise nucleotide differences, specific results of tests for selective neutrality of mtDNA variation, and a good correspondence of genetic parameters to those expected from demographic expansion models).

The Schrenck newt ( Salamandrella schrenckii , Amphibia, Caudata, Hynobiidae) is the second amphibian that withstands extremely low temperatures

In this connection, it seems promising to study the cold hardiness of another species of the same genus, the Schrenck newt (Salamandrella schrenckii Strauch 1870), whose geographic range in Russia is small com pared to the vast range of the Siberian newt (Fig. 1). The Schrenck newt mostly inhabits the Sikhote Alin, mountains of southwestern Primorsk territory, and adjacent lowlands [2]. The climate of these regions is characterized by considerably milder winters com pared to any other regions of Asian Russia (except for some islands). In contrast, the Siberian newt’s range encompasses almost the entire Siberia and a part of Europe, including Arctic regions. This species is believed to have colonized almost the entire northern Eurasia owing to its unique adaptation to low temper atures. Considering the comparative sizes of the ranges, one might assume that the Schrenck newt is less tolerant to low temperatures. The purpose of this study was to test this assumption.

Spread of the Earthworm Dendrobaena octaedra(Lumbricidae: Oligochaeta) from Europe to Northern Asia Is Restricted by Its Insufficient Frost Resistance

Although the eastern borders of the ranges of most Palearctic earthworm species that spread as far as 55 ° N [1] are varied, they share a common characteristic pattern: as one moves eastward, the borders of the range shift to the south, with the eastern border typically not reaching 40 ° –50 ° E, except for a few species that spread as far as 60 ° E. The factors that form species ranges are not only interesting from the general biological viewpoint, but may also be of practical importance in the case of key species of the ecosystems of areas with a high anthropogenic impact. The range of the cosmopolite earthworm Dendrobaena octaedra stands out because (1) it covers an almost entire European forest zone and European tundra, including the southern island of the Novaya Zemlya, (2) in western Siberia, it is spread farther than other earthworms, although its findings are few, and (3) it appears again farther east, on the Sea of Okhotsk coast near Magadan. The occurrence of D. octaedra in the tundra indicates that it is highly resistant to low temperatures in winter; however, the frost resistance of its northern populations has not been studied. Even approximate comparison of the northern and eastern borders of the D. octaedra range with winter air isotherms, which are known to be meridionally directed (Fig. 1a), suggests a relationship between the distribution of this species and lower limits of temperature in its habitats. To test this suggestion, we studied the frost resistance of D. octaedra and the temperature conditions of its wintering and constructed small-scale schemes of the minimum soil temperatures. The study was performed in 1997–1999. In the vicinity of Magadan, D. octaedra inhabits a narrow (10–15 m) flood plain of the Dukcha River grown with long-boled dwarf willows along several kilometers near the river mouth. In northeastern Asian continental regions, all attempts to find D. octaedra failed. The temperature regimen of the upper soil layers on the terrace of the Dukcha River was studied with the use of electron thermometers (loggers) and minimal meteorological thermometers for verification. The data obtained were normalized for multiyear average values based on regression equations of the soil and air temperatures. The summer microclimate of the Dukcha flood plain is more similar to that of European tundra, e.g., the Bol’shezemel’skaya Tundra and the tundras of the Chaunskaya Bay coast and the Amguema River valley [4–6], than to the microclimate of the forests and sparse-forest areas surrounding the Dukcha valley. In summer, the maximum temperature is 10.2°C in the upper 1-cm layer of the litter and only 6°C at a depth of 10 cm, with the sum of temperatures above zero (by the Celsius scale) throughout a year being 700 and 500 ° C, respectively. The temperatures are so low because of the almost completely closed upper layer of willow growth, large amounts of undecayed leaf debris, high ice content in the substrate, its periodic damping when the water level rises, etc. The average air temperature in January is –18°C . The absolute minimum temperature of the soil at a depth of 3–5 cm in the D. octaedra habitat in the flood plain varied from –9 to –10°C in our study. This temperature was recorded in the late December 1998, when there was little snow. According to our incomplete data, this temperature in the vicinity of Magadan varied from –27 to –2.0°C in different years.

Phylogeography of the earthworm Eisenia nordenskioldi nordenskioldi (Lumbricidae, Oligochaeta) in northeastern Eurasia

85 Eisenia nordenskioldi (Eisen, 1879) is the only spee cies of earthworms whose natural range is located in the tundra, forest, and forest–steppe zones, covering, within their limits, almost the entire Asian and part of eastern European Russia [1]. In the species E. nordenn skioldi, two subspecies are distinguished: E. n. nordenn skioldi (Eisen, 1879) and E. n. pallida Malevic 1956, which differ in distribution, pigmentation, and ploidy and belong to different morphoecological groups [2]. The nominative subspecies occupies the greater part of the range of the species, while E. n. pollida is confined mainly to the south of the forest zone and does not enter the permafrost region (except for river valleys). According to data of karyological studies, several races of ploidy are typical of E. n. nordenskioldi [3]. It is considered that these races formed as a result of parr thenogenesis and acquired the capacity for bisexual reproduction again further in evolution. Octaploid races in different regions have possibly appeared indee pendently of one another [4]. Molecular genetic studd ies have revealed a more complex picture: E. n. norr denskioldi has turned out to be a series of genetic linn eages strongly differing from one another [5, 6]. The number of paired substitutions between sequences of the mitochondrial gene cox1 of different lineages is 10–15%. Genetic diversity within each lineage is also considerable (up to 5% for some lineages). For comm parison, note that, for most animals, the range of intraspecific variation is less than 2%, and average diff ferences between species are about 11.3% [7]. The high level of differences between genetic lineages of E. n. nordenskioldi indicates that they diverged mill lions of years ago. Similar molecular genetic studies of E. n. nordenn skioldi did not cover northeastern Asia, the region with the most complex and interesting paleogeography determined by belonging to ancient Beringia. The above data raise the problem of studying the phylogeoo geography of E. n. nordenskioldi in this region, whose solution could contribute to understanding the origin and history of the species dispersal. In northeast Russia, the ninth genetic lineage of Eisenia n nordenskioldi, not identified previously, was found. The described eight lineages of the species from other regions do not spread here. Haplotypes belongg ing to the ninth lineage were found also in the vicinii ties of the cities of Yakutsk and Karpinsk (southeast of the Northern Urals), which indicates their wide …

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

97 It is considered that the Siberian salamander Sala mandrella keyserlingii Dybowski 1870 has colonized almost the entire Northern Asia, first and foremost, owing to its cold hardiness unique for a vertebrate animal: it is tolerant in a frozen state to a cooling to –35°C [1]. However, paradoxical as it may seem, this species is absent in milder climates in the major part of European Russia and Western Europe (Fig. 1). The western boundary of this species does not coincide with any geographic landmark.

Genetic polymorphism of Siberian newt (Salamandrella keyserlingii, Caudata, Amphibia) in its range and the cryptic species of the newt S. schrenckii from Primorie.

The Siberian newt ( Salamandrella keyserlingii Dybowski, 1870) occupies a vast range from tundras to steppes and from the Pacific Ocean to the northwestern borders of the European part of Russia. However, its morphological characters exhibit only a slight geographic variation, so the species is considered monotypical. Taxa of different levels have repeatedly been described in various parts of the range, but their validity is not recognized at present [1]. However, there is a general notion that the Siberian newts from Primorie (the southeastern region of continental Russia near the Sea of Japan) are morphologically and biologically distinct, with populations from other parts of the range insignificantly differing from one another [1–7], although this distinction is not reflected in the taxonomic status. Siberian newts from Primorie also differ from others with respect to genome size [8].

Ranges and cold hardiness of two earthworm subspecies (Eisenia nordenskioldi, Lumbricidae, Oligochaeta)

The ranges of two earthworm subspecies, Eisenia nordenskioldi nordenskioldi (Eisen 1879) and E. n. pallida Malevi 1956, differ in area and partially overlap. E. n. nordenskioldi populates the entire Asian Russia and eastern regions of the Russian Plain, from the lower reaches of the Volga and Don rivers to the Arctic Ocean coasts, while E. n. pallida has not expanded to the Asian permafrost zone and does not occur in European Russia and in the Urals. These subspecies “hold the record” in cold hardiness: the worms and cocoons of the nominotypical subspecies withstand temperatures down to −34 and −40°C, and those of E. n. pallida, to −28 and −23°C, respectively. Hence, their distribution is independent of subzero temperatures, and their ability to overwinter at any phase of the life cycle makes them also independent of heat supply during the summer period. Differences in geographic range may also be due to biological features of the subspecies. The nominotypical subspecies feeds belongs to the epiendogeic morphoecological type (feeding on the ground surface), whereas E. n. pallida is a true endogeic earthworm. Both subspecies have similar requirements for soil acidity; however, conditions in coarse-humus organomineral horizons of frozen soils appear to be unfavorable for E. n. pallida, which accounts for the absence of this subspecies in the permafrost zone.

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.

Centers of genetic diversity and origin of newts of the genus Salamandrella (Salamandrella keyserlingii and Salamandrella schrenckii, amphibia, caudata, hynobiidae)

448 Analysis of changes in the nucleotide sequences of the cytochrome b gene of mitochondrial DNA of Siberian newts from the population inhabited a con siderable part of northern Eurasia has shown two main phylogenic groups of haplotypes, AB and C. The rate of intergroup divergence is 1.87%, which indicates that the gene pool was subdivided about 1.5 Myr ago. Siberian newts of all haplogroups are found only in the Far East (including Sakhalin); one of the haplogroups (C1) occupies the rest of the species range. It colo nized northern Eurasia (no earlier than 125000 years ago), the middle Amur River basin (downstream of the Sungari river mouth), the northern Sikhote Alin, and Sakhalin. It may be considered to be the center of the Siberian newt genetic diversity and, probably, origin. According to the new data, the mitochondrial gene pool of Salamandrella schrenckii includes three phylo geographical groups, which began to diverge approxi mately 3 Myr ago, when a group inhabiting northeast ern China had separated.