Recent colonization by a coastal plant of inland habitats at an ancient freshwater lake,Lake Biwa: multilocus sequencing and a demographic history of Lathyrus japonicus (Fabaceae)

Ancient lakes have been recognized as “long‐term isolated islands” in terrestrial ecosystems. Lake Biwa, one of the few ancient lakes that formed around 4 million years ago, harbors many coastal species that commonly inhabit seashores. The beach pea, Lathyrus japonicus, is a typical coastal species of this freshwater lake, where morphological, physiological, and genetic differentiations have been reported between Biwa and coastal populations. Whether Biwa populations were isolated for long periods throughout Pleistocene climatic oscillations and subsequent range shifts is unclear. We assessed population genetic structure and demography of beach pea in this ancient freshwater lake using the sequences of eight nuclear loci. The results of STRUCTURE analyses showed evidence of admixture between Biwa and coastal populations, reflecting recent gene flow. The estimated demographic parameters implemented by the isolation with migration model (IM model) revealed a recent divergence (postglacial period) of Biwa populations, with some gene flow from Biwa to coastal populations. In addition, Biwa populations were significantly smaller in size than the ancestral or coastal populations. Our study suggests that a Holocene thermal maximum, when transgression could allow seeds from coastal plants to access Lake Biwa, was involved in the origin of the Biwa populations and their genetic divergence. Thus, coastal populations might have migrated to Lake Biwa relatively recently. Our study concluded that ancestral migrants in Lake Biwa were derived from small founding populations and accelerated genetic isolation of Biwa populations during short‐term isolation.     

Long‐term isolation of the coastal plant Calystegia soldanella (Convolvulaceae) in ancient freshwater Lake Biwa,Japan

Lake Biwa is an ancient freshwater lake that was formed approximately 4 Mya and harbours many coastal plants that commonly inhabit the seashore. We used chloroplast DNA haplotype analysis using two spacer sequences and simple sequence repeat (SSR) analysis using eight nuclear microsatellite markers to detect genomic signatures indicating long‐term isolation of inland populations of Calystegia soldanella in Lake Biwa from coastal populations. We used 348 samples from 63 populations for haplotype analysis and 478 samples from 27 populations for SSR analysis covering the inland and coastal distribution of the species. We detected seven haplotypes, and the distribution pattern of these haplotypes was geographically highly structured between Lake Biwa and the coast. Nuclear SSR analysis also supported genetic differentiation between Lake Biwa and coastal populations (analyses of molecular variance, 43%), and the grouping of Lake Biwa and coastal populations by a Neighbour‐joining tree. In addition, genetic diversity of the inland populations (mean H_E = 0.153) was significantly lower than that of coastal populations (mean H_E = 0.328). These results suggested that inland populations at Lake Biwa have been isolated from coastal populations for a very long time. The inland populations most likely experienced a bottleneck effect, resulting in sufficient in situ genetic divergence to clearly distinguish them from coastal populations. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 51–66.     

Geographical differentiation inferred from flavonoid content between coastal and freshwater populations of the coastal plant Lathyrus japonicus (Fabaceae)

Lake Biwa, one of the few ancient lakes in the world, harbors many coastal species that commonly inhabit seashores. The beach pea (Lathyrus japonicus) is a typical coastal species of this freshwater lake, and morphological and genetic differentiation between inland and coastal populations of this species have been reported. Inland and coastal habitats inflict distinct environmental stresses to plants, the latter imposing salt stress and high-light intensity, which leads to physiological differentiation. These abiotic stresses affect phenolic compounds, which play an important role in the response of plants to the toxic by-products of stress metabolism. We investigated physiological differentiation of phenolic compounds of the beach pea between inland and coastal habitats using high-performance liquid chromatography (HPLC) analysis. Flavonoid composition analyses revealed that patterns of flavonoid composition of inland populations at Lake Biwa were differentiated from those of coastal populations. All Lake Biwa individuals were fixed in the same flavonols glycosylated at 3- and 7-positions. In contrast, most coastal individuals contained flavonols glycosylated at 3-position alone, and these populations exhibited higher variation in flavonoid composition compared to among/within inland populations. Variation was likely lower in inland populations because of a bottleneck during landlocked periods, which is consistent with previous phylogeographic studies. A qualitative HPLC survey of flavonoid content revealed substantial variation among individuals regardless of locality. These results suggest that changes in the habitat environment may have led to beach pea acclimation via alteration of the quantity and quality of flavonoids.     

Multiple colonizations of Lake Biwa by Sarcocheilichthys fishes and their population history

Rapid adaptation and speciation have not been well documented for organisms in Lake Biwa, Japan, the oldest ancient lake in East Asia. To examine these processes, we focused on the divergence of Sarcocheilichthys gudgeons and conducted phylogeographic and population genetic analyses using mitochondrial DNA sequences and microsatellite data. No remarkable genetic differentiation was found between two species, S. biwaensis and S. variegatus microoculus, both endemic to Lake Biwa, whereas this species group, including S. v. variegatus, was genetically divided into three major regional groups: the Lake Biwa, Ise Bay, and western groups. Divergent mtDNA haplotypes were included within the Lake Biwa and western groups, strongly suggesting secondary contacts among allopatrically isolated populations. Dating for mtDNA phylogeny using a geological constraint suggested the colonization of Lake Biwa by multiple Sarcocheilichthys lineages that diverged from each other in the early–middle Pleistocene. Coalescent-based population analyses indicated that the local populations colonized the rocky bottom habitat in Lake Biwa from other habitats after the Last Glacial Maximum, likely reflecting past environmental changes in the lake, including the disappearance of rocky areas during the glacial climate. Divergent morphological adaptation in Sarcocheilichthys associated with substrate type may have rapidly proceeded along with environmental changes.     

Hidden mitochondrial DNA divergence in the Lake Biwa endemic goby Gymnogobius isaza: implications for its evolutionary history

The gobiid Gymnogobius isaza is an endemic species that has adapted remarkably to the pelagic environment in Lake Biwa, Japan, a representative ancient lake in East Asia. To obtain clues that would reveal the origin and evolution of this species, we conducted phylogenetic and population genetic analyses based on partial sequences of the mitochondrial cytochrome b gene. Consistent with previous studies, our Bayesian phylogenetic analysis with a relaxed molecular clock model reconfirmed a sister relationship between G. isaza and Gymnogobius urotaenia?+?Gymnogobius petschiliensis, with a divergence time of about 2.9 million years (Myr), and provided an evolutionary rate of 3.0 %/Myr (pairwise) for their clade. Population genetic analysis revealed two distinct mtDNA groups in G. isaza, which were estimated to have diverged 0.66 million years ago (Mya) at the Lake Katata stage of Paleo-Lake Biwa, preceding the origin of the present Lake Biwa environment with its extensive deep pelagic area (0.3–0.4 Mya). A dumbbell-like haplotype network and bimodal mismatch distribution suggested that the population of G. isaza experienced secondary contact between two genetically differentiated populations. Demographic parameters from mismatch distribution analysis and Bayesian skyline plot analysis suggested that both of the mtDNA groups of G. isaza exhibited a signal of sudden population expansion at approximately the same time (80–90 thousand years ago) during the last glacial period after the development of the present Lake Biwa. These results imply the complex population history of G. isaza, including genetic isolation and secondary contact following differentiation from its relatives in the Pliocene.     

Geographic color variation of Phelotrupes auratus (Coleoptera,Geotrupidae) in the Kinki region,central Japan: A quantitative spectrophotometric analysis

We investigated geographic color variation of the beetle Phelotrupes auratus in the Kinki region of central Japan using a spectrophotometer. The reflectance spectrum of the dorsal surface of the elytron was measured for beetles collected from 23 sites. We focused on λmax(α), the wavelength at the peak (α peak) between 400 and 700 nm (human visual sensitivity range), for analyses of color variation. In populations distributed on the Kii Peninsula, in the southern part of the Kinki region, average λmax(α) values were lower (480–497 nm) than in populations distributed in the area west of Lake Biwa, the western part of the Kinki region (618–633 nm). For populations distributed in the areas south and southeast of Lake Biwa, a geographic cline of λmax(α) was observed approximately along an east–west transect, with average λmax values varying continuously from 624 to 557 nm. The easternmost populations along this cline had almost the same λmax(α) values as the populations distributed west of Lake Biwa. The coefficient of variation for λmax(α) tended to be larger in populations with intermediate averages than those with lower or higher average values.     

The recent spread of <Emphasis Type="Italic">Artemia parthenogenetica</Emphasis> in Western Australia

In Western Australia, populations of Artemia parthenogenetica in coastal salt lakes at Rottnest Island and Lake Hayward, and in salterns at Port Hedland and Shark Bay, are widely accepted to have been introduced by humans. Further, within the past 10 years, populations of A. parthenogenetica have been found in inland playa salt lakes in the wheatbelt of south-west Western Australia, where none had been recorded in previous salt lake studies. Here we hypothesise that birds act as transport vectors for Artemia cysts both within Australia and between the Asian and Australian continents. Allozyme analysis was used to identify clonal types (multi-locus genotypes), clonal frequencies, genotypic diversities and genotypic identity of six populations (three coastal, three inland). Overall, the inland populations displayed almost identical genotypic structure to the coastal population from Lake Hayward, indicating that Lake Hayward could be the major source for dispersal and colonisation of inland populations. Results support the hypothesis of dispersal inland by nomadic bird species. Furthermore, evidence suggests that the inland and Lake Hayward populations may be an example of a metapopulation. The greater variety of genotypes present in the Rottnest population indicates that this population has received a large number of small immigrations, or that it received one large introduction. The former may indicate a long period of suitable salinities, providing a greater time-span over which migration and succession of clonal types could occur in comparison to other populations. While we cannot rule out the possibility of human introduction of A. parthenogenetica to Rottnest, the hypothesis of cyst dispersal along the Austral-Asian flyway remains possible. Guest Editor: John M. Melack Saline Waters and their Biota     

Salinity effects on maturation, reproductive and life span characteristics of four Egyptian Artemia populations (International Study on Artemia. LXVIII)

Three parthenogenetic Artemia populations, i.e. two coastal from Borg El-Arab and El-Max saltworks and one from the inland Qarun Lake, and a bisexual strain (Artemia salina) from the inland carbonate lake of Wadi El-Natrun, all from upper Egypt were assayed for their response in 5 salinities (i.e. 35, 80, 120, 150 and 200 g l^?1). The experimental procedure was carried out under laboratory conditions, where the effects of salinity on maturation and ten reproductive and life span characteristics were investigated. The parthenogenetic Egyptian populations are more euryhaline compared to the bisexual one. The two coastal parthenogenetic populations appeared to be very similar in maturation rate and reproductive output at all salinities tested. The inland asexual strain showed a different reproductive response to the elevation of salinity from the two coastal populations. Discriminant function analysis has proven to be a useful tool in determining the differential response of closely related Artemia populations. The bisexual population showed significantly lower reproductive output compared to the parthenogenetic ones and performed best at 35 g l^?1; this is the first record of an A. salina population inhabiting a carbonate lake. These findings may provide valuable information on Artemia biodiversity in an area where very little is known. %     

Morphological and genetic divergence in Swedish postglacial stickleback (Pungitius pungitius) populations

Background

An important objective of evolutionary biology is to understand the processes that govern phenotypic variation in natural populations. We assessed patterns of morphological and genetic divergence among coastal and inland lake populations of nine-spined stickleback in northern Sweden. Coastal populations are either from the Baltic coast (n = 5) or from nearby coastal lakes (n = 3) that became isolated from the Baltic Sea (< 100 years before present, ybp). Inland populations are from freshwater lakes that became isolated from the Baltic approximately 10,000 ybp; either single species lakes without predators (n = 5), or lakes with a recent history of predation (n = 5) from stocking of salmonid predators (~50 ybp).

Results

Coastal populations showed little variation in 11 morphological traits and had longer spines per unit of body length than inland populations. Inland populations were larger, on average, and showed greater morphological variation than coastal populations. A principal component analysis (PCA) across all populations revealed two major morphological axes related to spine length (PC1, 47.7% variation) and body size (PC2, 32.9% variation). Analysis of PCA scores showed marked similarity in coastal (Baltic coast and coastal lake) populations. PCA scores indicate that inland populations with predators have higher within-group variance in spine length and lower within-group variance in body size than inland populations without predators. Estimates of within-group P _ST (a proxy for Q _ST) from PCA scores are similar to estimates of F _ST for coastal lake populations but P _ST > F _ST for Baltic coast populations. P _ST > F _ST for PC1 and PC2 for inland predator and inland no predator populations, with the exception that P _ST < F _ST for body size in inland populations lacking predators.

Conclusions

Baltic coast and coastal lake populations show little morphological and genetic variation within and between groups suggesting that these populations experience similar ecological conditions and that time since isolation of coastal lakes has been insufficient to demonstrate divergent morphology in coastal lake populations. Inland populations, on the other hand, showed much greater morphological and genetic variation characteristic of long periods of isolation. Inland populations from lakes without predators generally have larger body size, and smaller spine length relative to body size, suggesting systematic reduction in spine length. In contrast, inland populations with predators exhibit a wider range of spine lengths relative to body size suggesting that this trait is responding to local predation pressure differently among these populations. Taken together the results suggest that predation plays a role in shaping morphological variation among isolated inland populations. However, we cannot rule out that a causal relationship between predation versus other genetic and environmental influences on phenotypic variation not measured in this study exists, and this warrants further investigation.     

The origins of limnetic forms and cryptic divergence in Gnathopogon fishes (Cyprinidae) in Japan

The cyprinid species of the genus Gnathopogon, exhibiting flexible morphological and ecological variation, include limnetic life forms. We examined the origin of the limnetic forms and the population divergence of the Japanese Gnathopogon species, using molecular phylogenetic and phylogeographic analyses. A Bayesian phylogenetic inference approach based on mtDNA cytochrome b sequence data revealed three major lineages in G. elongatus. One of them formed a monophyletic group with the limnetic species G. caerulescens, which is endemic to an ancient lake, Lake Biwa. The divergence of the G. caerulescens lineage was estimated to date back to the early Pleistocene. This precedes the formation of the extensive pelagic environment in the present Lake Biwa. However, the recent genetic divergence of G. caerulescens was inferred to originate in the present Lake Biwa in the late Pleistocene. Another lacustrine population in the Mikata Lakes was shown to belong to a different lineage from G. caerulescens. The majority of the population possessed unique, but non-monophyletic, haplotypes, suggesting a short evolutionary history. One of the cryptic lineages of G. elongatus discovered in the Ina Valley, the lower area of Lake Suwa, might be related to the extinct lacustrine subspecies G. elongatus suwae, which has been replaced by introduced congeners. The previous and ongoing introductions of Gnathopogon fishes would have produced genetic disturbance to the indigenous populations.     

Phylogeny and historical demography of endemic fishes in Lake Biwa: the ancient lake as a promoter of evolution and diversification of freshwater fishes in western Japan

To elucidate the origins of the endemic fish of Lake Biwa, an ancient lake in Japan, and the role of the lake in the diversification of freshwater fish in western Japan, we established a molecular phylogenetic framework with an absolute time scale and inferred the historical demography of a large set of fish species in and around the lake. We used mtDNA sequences obtained from a total of 190 specimens, including 11 endemic species of Lake Biwa and their related species, for phylogenetic analyses with divergence time estimations and from a total of 2319 specimens of 42 species (including 14 endemics) occurring in the lake for population genetic analyses. Phylogenetic analysis suggested that some of the endemic species diverged from their closest relatives earlier (1.3–13.0 Ma) than the period in which the present environmental characteristics of the lake started to develop (ca. 0.4 Ma), whereas others diverged more recently (after 0.4 Ma). In contrast, historical demographic parameters suggested that almost all species, including endemic and nonendemic ones, expanded their populations after the development of the present lake environment. In phylogeographic analyses, common or very close haplotypes of some species were obtained from Lake Biwa and other regions of western Japan. The phylogenetic and historical demographic evidence suggests that there was a time lag between phylogenetic divergence and population establishment and that phenotypic adaptation of some endemic species to the limnetic environment occurred much later than the divergences of those endemic lineages. Population structure and phylogeographic patterns suggest that Lake Biwa has functioned not only as the center of adaptive evolution but also as a reservoir for fish diversity in western Japan.     

Development of microsatellites in Machilus thunbergii (Lauraceae), a warm-temperate coastal tree species in Japan

? Premise of the study: Microsatellite markers were developed and characterized in a typically coastal, widespread, and dominant tree species of the evergreen broadleaf forests, Machilus thunbergii, for comparison of the genetic diversity and structure of inland populations surrounding the ancient Lake Biwa and coastal populations in Japan. ? Methods and Results: Eighteen polymorphic microsatellites of this species were isolated using an improved technique for isolating codominant compound microsatellite markers. These isolated loci provided compound simple sequence repeat (SSR) markers with polymorphisms of three to 19 alleles per locus, with an average of 10.9. The expected and observed within-population heterozygosities ranged from 0.16 to 0.86 and from 0.13 to 0.72, respectively. ? Conclusions: These markers may be useful tools for further investigation of the population genetic structure and biogeographic history of M. thunbergii in the warm-temperate zone of East Asia.     

Nucleotide sequence variability of the Adh gene of the coastal plant Calystegia soldanella (Convolvulaceae) in Japan

Calystegia soldanella (Convolvulaceae) is a self-incompatible perennial herb distributed on sandy seashores throughout the temperate zone of the world. In Japan, the species occasionally grows on the sandy shores of Lake Biwa. To clarify the genetic differentiation among local populations, we investigated the nucleotide sequence variability of the Adh gene. In a 1625-bp sequence between exon 2 and the 3' noncoding region of the Adh gene, a total of 44 polymorphic sites were found among 91 individuals from 19 populations. The nucleotide diversity for the entire sample was 0.00212. Similar values were determined for geographical groups of populations. No genetic differentiation among the groups of populations was found. The complete lack of genetic differentiation between the sea coastal populations and the inland populations could not be attributed to gene flow. Although the inland populations are geographically isolated from the sea coastal populations, the time since separation might be insufficient to establish significant genetic differentiation.     

Population structure and gene flow of the syntopic turtles Emys and Mauremys from coastal and inland regions of Anatolia (Turkey): results from mitochondrial and microsatellite data

Revealing the genetic basis of the existence of different species living together in different geographic regions provides clarification of this phylogeographic differentiation. In this study, we investigated the population genetics and evaluated the level of genetic variation of inland and coastal populations of Mauremys and Emys in Turkey. Tissue samples of 196 terrapins were studied which were collected from syntopic coastal (Gölbent-Söke/Ayd?n; M. rivulata and E. orbicularis) and inland populations (Bahçesaray/Aksaray; M. caspica and E. orbicularis). DNA was isolated using the InnuPREP DNA Mini Kit. Mitochondrial DNA sequences and allelic variation at 13 microsatellite loci for Mauremys and 12 microsatellite loci for Emys were examined.  Three haplotypes were found for Emys orbicularis (Im, Ip and Iw) collected from the coastal region and two haplotypes for Emys orbicularis (Ig and Im) collected from inland. Two haplotypes were identified for M. caspica (Cmt8 and Cmt9) and three haplotypes were identified for M. rivulata (Rmt3, Rmt24 and Rmt26). Using microsatellites and the software STRUCTURE the most probable value for K was revealed as two 2 for both species. The F_ST value between M. rivulata and M. caspica was 0.39, and between the coastal and inland populations of E. orbicularis 0.09. It can be concluded that Emys populations tend to evolve by somehow preserving the allelic richness they have and Mauremys populations continue to differentiate so that new species emerge in the evolutionary process to reach the ideal allelic structure.

     

Isolation and characterisation of microsatellite loci in Calystegia soldanella (Convolvulaceae), an endangered coastal plant isolated in Lake Biwa,Japan

Eight microsatellite loci of Calystegia soldanella useful for comparisons of the genetic structure of isolated populations in the ancient Lake Biwa and coastal populations in Japan were isolated and characterised. The number of alleles ranged from 2 to 5. The expected (H _E) and observed (H _O) heterozygosities were 0.097–0.583 and 0.000–0.380, respectively, from 100 individuals from Lake Biwa and coastal populations. Seven of the eight loci exhibited significantly fewer heterozygotes than expected based on the Hardy–Weinberg equilibrium (P < 0.05). These primers amplifying microsatellites in C. soldanella may provide a population genetics tool useful in the establishment of a conservation strategy.     

An observation of the loss of genetic variability in prenant’s schizothoracin,Schizothorax prenanti,inhabiting a plateau lake

Prenant’s schizothoracin (Schizothorax prenanti) was found naturally distributed in a plateau lake (Lake Wuxu) in upper reaches of the River Jiulong. The genetic diversities of the populations from L. Wuxu and R. Jiulong were investigated according to analysis of mtDNA control region and compared against three other reported river populations. The L. Wuxu population showed lower haplotype (h = 0.74) and nucleotide (π = 0.001) diversities compared to the R. Jiulong population (h = 0.87; π = 0.012); the lake population had suffered from a bottleneck, which might contribute to its low genetic diversity; the lake population significantly differentiated from the river populations, and significant gene flow was hardly found between river populations and L. Wuxu population, suggesting that there is a strong population structure between the lake and river populations. The L. Wuxu population was ecologically isolated from the R. Jiulong population, while the relatively low genetic variability had not affected its viability.     

Mitochondrial DNA population structure of the white-spotted Charr (Salvelinus leucomaenis) in the Lake Biwa water system

A phylogeographic analysis of mitochondrial DNA sequences was performed in order to elucidate the origin, dispersal process, and genetic structure of white-spotted charr in the Lake Biwa water system. Two haplotypes were most common in the Lake Biwa water system, and were also common in the adjacent inlet rivers of the Sea of Japan. These results suggest that in the glacial periods of the Pleistocene, white-spotted charr dispersed into the northern inlet rivers of Lake Biwa from adjacent inlet rivers of the Sea of Japan by watershed exchanges, colonizing the whole of the Lake Biwa water system. Mitochondrial DNA diversity contrasted sharply between the western and eastern parts of the system, suggesting that the populations in the western part might be more reduced than those in the eastern part in relation to the smaller habitat size. The high overall FST estimate (0.50), together with pairwise comparisons of FST, indicated significant genetic divergence between populations due to isolation and small population size. Hierarchical analysis (AMOVA) also showed that genetic variation was more pronounced among regions (28.39%) and among populations within regions (47.24%) than within populations (24.37%). This suggests that each population in and around the Lake Biwa water system should be treated as a significant unit for conservation and management.     

Occurrence of the endangered species Nitellopsis obtusa (Charales,Charophyceae) in western Japan and the genetic differences within and among Japanese populations

Nitellopsis obtusa (Charales, Charophyceae) are widely distributed from Europe to Asia; however, this species has been recorded in only the five lakes in central Honshu in Japan. This species was thought to be extinct in Japan, but was rediscovered in limited areas of Lake Kawaguchi in central Honshu. More recently, we discovered more Japanese populations of N. obtusa in Lake Biwa in western Honshu, and it became clear that the species had a broader distribution in Japan than originally believed. In addition, although only male or female thalli have been collected at each lake, both male and female thalli were found from Lake Biwa. This is the first report of a potentially sexual population of N. obtusa in Japan. The DNA sequences of three chloroplast DNA markers, including both coding and non‐coding regions, were identical in all specimens from Lake Kawaguchi and Lake Nojiri (Central Honshu), and differed from those of Lake Biwa and German specimens. Although Japanese and German specimens were genetically similar, Japanese specimens displayed considerable genetic diversity according to locality.     

Morphological and Phylogenetic Characterizations of Freshwater Thioploca Species from Lake Biwa, Japan, and Lake Constance, Germany

Filamentous, gliding, sulfide-oxidizing bacteria of the genus Thioploca were found on sediments in profundal areas of Lake Biwa, a Japanese freshwater mesotrophic lake, and were characterized morphologically and phylogenetically. The Lake Biwa Thioploca resembled morphologically Thioploca ingrica, a brackish water species from a Danish fjord. The diameters of individual trichomes were 3 to 5.6 μm; the diameters of complete Thioploca filaments ranged from 18 to 75 μm. The cell lengths ranged from 1.2 to 3.8 μm. In transmission electron microscope specimens stained with uranyl acetate, dense intracellular particles were found, which did not show any positive signals for phosphorus and sulfur in an X-ray analysis. The 16S rRNA gene of the Thioploca from Lake Biwa was amplified by using newly designed Thioploca-specific primers (706-Thioploca, Biwa160F, and Biwa829R) in combination with general bacterial primers in order to avoid nonspecific amplification of contaminating bacterial DNA. Denaturing gradient gel electrophoresis (DGGE) analysis of the three overlapping PCR products resulted in single DGGE bands, indicating that a single 16S rRNA gene had been amplified. With the same method, the Thioploca from Lake Constance was examined. The 16S rRNA sequence was verified by performing fluorescence in situ hybridization targeted at specific motifs of the Lake Biwa Thioploca. Positive signals were obtained with the bacterial probe EUB-338, the γ-proteobacterial probe GAM42a, and probe Biwa829 targeting the Lake Biwa Thioploca. Based on the nearly complete 16S rRNA sequence and on morphological similarities, the Thioploca from Lake Biwa and the Thioploca from Lake Constance are closely related to T. ingrica and to each other.     

Coastal and freshwater pikeperch (Sander lucioperca) populations differ genetically in the Baltic Sea basin

Microsatellite DNA based analysis of the pattern of genetic diversity among three coastal and five freshwater populations of pikeperch Sander lucioperca in the northern part of the Baltic Sea drainage basin indicated marked genetic differentiation between the coastal and lake populations. The F(st) between these population groups was as high as 0.25 and R(st) =0.32. In general, the lake populations showed higher genetic diversity than the coastal ones. In terms of genetic distance, the three coastal populations (Vanhankaupunginlahti, V?stanfj?rd and Taivassalo) grouped tightly together. The freshwater samples formed a looser group, in which the northern Lake Kemij?rvi showed greater distance from the southern lakes than these did from each other. The two lake populations originally established through stockings (Lakes Painio and Averia) grouped near to their source population of Lake Lohjanj?rvi and their diversity level was nearly the same. Safeguarding the unique Baltic coastal populations of S. lucioperca against gene flow from increasing hatchery releases using freshwater S. lucioperca should be a high management priority.