Late ontogeny growth acceleration and size form transformations in Transbaikalian Arctic charr, <Emphasis Type="Italic">Salvelinus alpinus</Emphasis> complex: evidence from fin ray cross section growth layers

In some polymorphic populations of Arctic charr in Transbaikalia, an individual can transform from a smaller to larger size form during their lifetime as a result of accelerated growth that follows a period of slow growth and reproduction as a small size form. Alternating periods of slow and fast growth are reflected in growth layer patterns visible in fin ray cross sections. Stained microtome fin ray cross sections were used to reveal the incidence of transformations from one form to another. Data were collected from 14 northern Transbaikalian lakes containing two or three sympatric Arctic charr forms (‘dwarf’, ‘small’, and ‘large’) exhibiting varying levels of morphological separation. Individuals recruited from the dwarf or small form were found in varying proportions among the small and/or large form in 12 lakes. Small or large form charr that grew without noticeable acceleration to the adult size typical of the form or experienced accelerated growth as juveniles prior to maturation were also observed. There were no transformations between sympatric forms that differed in the length and number of gill rakers and in some other meristic characters. Results indicate that in the region under study, transformations of sympatric Arctic charr size forms are a widespread, but not a ubiquitous, phenomenon. Such transformations reflect the plasticity of the developmental channels of the forms. In the course of intra-lacustrine form divergence and genetic differentiation, the frequency of the observed transformations decreases to zero.     

Effects of Partially Anadromous Arctic Charr (Salvelinus alpinus) Populations on Ecology of Coastal Arctic Lakes

Little research has been conducted on effects of iteroparous anadromous fishes on Arctic lakes. We investigated trophic ecology, fish growth, and food web structure in six lakes located in Nunavut, Canada; three lakes contained anadromous Arctic charr (Salvelinus alpinus) whereas three lakes did not contain Arctic charr. All lakes contained forage fishes and lake trout (Salvelinus namaycush; top predator). Isotope ratios (δ¹³C, δ¹⁵N) of fishes and invertebrates did not differ between lakes with and without anadromous Arctic charr; if anadromous Arctic charr deliver marine-derived nutrients and/or organic matter to freshwater lakes, these inputs could not be detected with δ¹³C and/or δ¹⁵N. Lake trout carbon (C):nitrogen (N) and condition were significantly higher in lakes with Arctic charr (C:N = 3.42, K = 1.1) than in lakes without Arctic charr (C:N = 3.17, K = 0.99), however, and ninespine stickleback (Pungitius pungitius) condition was significantly lower in lakes with Arctic charr (K = 0.58) than in lakes without Arctic charr (K = 0.64). Isotope data indicated that pre-smolt and resident Arctic charr may be prey for lake trout and compete with ninespine stickleback. Linear distance metrics applied to isotope data showed that food webs were more compact and isotopically redundant in lakes where Arctic charr were present. Despite this, lake trout populations in lakes with Arctic charr occupied a larger isotope space and showed greater inter-individual isotope differences. Anadromous Arctic charr appear to affect ecology and feeding of sympatric freshwater species, but effects are more subtle than those seen for semelparous anadromous species.     

Parallel divergence of sympatric genetic and body size forms of Arctic charr,Salvelinus alpinus,from two Scottish lakes

F _ST and R_ST estimates for Arctic charr from six microsatelite markers collected from two neighbouring Scottish lakes, Loch Maree and Loch Stack, confirm the presence of two distinct genetic groupings representing separate populations within each lake. In both lakes, there was also a clear body size dimorphism, with large and small body size forms that segregated according to genetic grouping. There was evidence of only subtle foraging ecology differences between morphs, with the small body size morph in both lakes being more generalist in its foraging in the summer (consuming mostly plankton but also some macrobenthos) than the large body size morph, which specialized on planktonic prey. Trophic morphology (head and mouth shape) did not differ significantly between morphs (although the small sample size for Maree makes this a preliminary finding). Cluster analysis of the microsatelite data and the presence of private alleles showed that morphologically similar forms in different lakes were not genetically similar, as would be expected under a multiple invasion hypothesis. Thus, the data do not support a hypothesis of a dual invasion of both lakes by two common ancestors but instead suggest an independent origin of the two forms in each lake. Thus parallel sympatric divergence as a result of common selection pressures in both lakes is the most parsimonious explanation of the evolutionary origin of these polymorphisms. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 748–757.     

Diversification, Sympatric Speciation, and Trophic Polymorphism of Arctic Charr, Salvelinus Alpinus Complex, in Transbaikalia

In northern Transbaikalia, independently evolving landlocked populations of Arctic charr are found in mountain lakes. To assess the diversity of charr in this region, speciation modes involved in the evolution of charr forms, and the role of trophic polymorphism in their divergence, we studied the morphology and feeding of dwarf, small, and large forms of Arctic charr from a number of Transbaikalian lakes. Meristic data on charr from five lakes support the earlier conclusion that the three forms do not represent separate lineages but have independently diverged in sympatry in each of the lakes. In 10 lakes, the dwarf form showed varying degrees of differentiation from normal (small and large) charr in meristic characters (up to morphologically distinct and presumably reproductively isolated groupings), which is viewed as various levels of sympatric divergence. Indexes of gill raker length in fish from 20 lakes vary among populations of both dwarf and normal charr, with forms having short and long rakers being sympatric in some of these lakes. However, the index can be used only for comparing charr of different forms up to about 32cm fork length (FL) because it is strongly negatively correlated with size in larger fish. The study of charr diets in 21 lakes indicates that large charr are piscivorous whereas dwarf and small charr feed on a wide range of invertebrates, partitioning these resources in different ways. Planktivores, including very specialized ones, and non-planktivores (benthic feeders, insectivores) can be identified within the small and dwarf forms. The proportion of plankton in the diets of dwarf and small charr is positively correlated with the number and length of gill rakers while the proportion of benthos is negatively correlated. Allopatric planktivorous and non-planktivorous small charr differ in body proportions; parallel emergence of such morphotypes in different parts of the range is a characteristic feature of the Salvelinus alpinus complex.     

Landlocked Arctic charr (Salvelinus alpinus) population structure and lake morphometry in Greenland – is there a connection?

Landlocked Arctic charr (Salvelinus alpinus) populations in sub-Arctic and Arctic Greenland lakes were sampled with multi-mesh-sized survey gillnets. The study covered a range of small shallow lakes (0.01 km², maximum depth <3.3 m) to large deep lakes (43 km², maximum depth >200 m). Arctic charr were found in one to three different forms in lakes with maximum depths >3 m. A dwarf form occurred in all lakes inhabited by Arctic charr and was the only form in lakes with maximum depths <8 m. In deeper lakes with maximum depths >20 m and a surface area <0.5 km², larger charr were found, although in low numbers, the length-frequency distribution being unimodal with a tail towards large sizes. In lakes with a maximum depth >20 m, large-sized charr were more abundant, and the length-frequency distribution of the population was bimodal, with a first mode around 10–12 cm and a second mode around 26–37 cm. In a single large and deep lake, a distinct medium-sized pelagic zooplankton-eating charr form occurred. Maximum size of individual charr was significantly positively correlated with lake maximum depth and volume, and the mean size of large-sized charr was significantly positively correlated with lake volume. Our study indicates that the charr population structure became more complex with increasing lake size. Moreover, the population structure seemed to be influenced by lake-water transparency and the presence or absence of three-spined stickleback (Gasterosteus aculeatus). Accepted: 31 January 2000     

A morphometric method for estimation of total lipid level in live Arctic charr: a case study of its application on wild fish

Linear body measurements were made on wild Arctic charr Salvelinus alpinus parr (100–200 mm L_F) from two populations in northern Norway during spring (May), summer (June and July) and autumn (October). To reduce handling stress, a method was developed were dorsal and ventral body measurements could subsequently be taken easily from a single picture of the anaesthetized fish. Multiple regression analyses investigated the possible correlation between the body measurements and both total and percentage lipid content of the fish. For both populations and during all seasons, the regression equations gave better estimates for total lipid than for percentage lipid. The regression equations for total lipid accounted for between 67·7 and 89·5% of the variance in lipid content for the different seasons within the lakes. The pooled data within each lake accounted for 62·9 and 81·0% of the variance in total lipid, while the pooled data for both lakes accounted for 67·7% of the variance. In general, the condition factor alone did not give a satisfactory estimate of lipid content of the Arctic charr (r² = 0·003–0·521). Shrinkage on validation values was high (0·20–0·52). Employing a ridge regression method resulted in models with lower r² values and lower shrinkage values (indicating more stable models). Published equations used for hatchery‐reared Arctic charr could not be used on wild fish from the same population. The close correlations between actual and predicted lipid levels found in this study show that morphometric measurements can predict total lipid levels in wild Arctic charr with reasonable accuracy. The most accurate results were obtained when equations were derived from each data set. Therefore, the method has the potential within a single study to estimate lipid levels in live fish as long as some fish can be sacrificed to develop a unique regression equation for each population or experiment.     

Arctic charr in sympatry with burbot: ecological and evolutionary consequences

The trophic niche and parasite infection of Arctic charr (Salvelinus alpinus) were explored in two lakes with sympatric burbot (Lota lota) and two lakes without burbot in subarctic Norway. The CPUE of burbot and charr were similar in one lake, but burbot had a low population density in the other. Burbot were benthivorous in both lakes. Other co-occurring species like brown trout (Salmo trutta), Atlantic salmon parr (Salmo salar), grayling (Thymallus thymallus) and minnow (Phoxinus phoxinus) were also benthivores. At high densities, benthivorous burbot forced the whole Arctic charr population to utilise mainly the limnetic trophic niche. In contrast, at low burbot density or without burbot present, Arctic charr were primarily benthivorous in the littoral zone. Thus, a clear interactive segregation in diet was observed between Arctic charr and burbot at high burbot densities. There was also a high predation pressure from burbot on young Arctic charr along the benthic zones. The extensive use of zooplankton as prey caused a high parasite infection pressure of copepod transmitted Diphyllobothrium spp. larvae, with the potential for high negative impact on the Arctic charr population. As the benthivore trophic niche was occupied by burbot, the ecological opportunities for polymorphism with benthivorous ecotypes or morphs of Arctic charr were probably prevented. Therefore, the sympatry with burbot seems to have large ecological and evolutionary consequences for this Arctic charr population compared with neighbouring lakes where burbot is absent.     

Determination of the population genetic structure of the invasive weed <Emphasis Type="Italic">Ageratina adenophora</Emphasis> using ISSR-PCR markers

A genetic analysis of nuclear DNA was performed by inter-simple sequence repeat-polymerase chain reaction (ISSR-PCR) technique on 32 populations of Ageratina adenophora, an invasive triploid weed in China. Among the 100 ISSR markers detected, 12 showed genetic variation both within and among the populations. Among the 446 amplified bands, 93.5% were found polymorphic. Most individuals (99%) displayed a unique ISSR fingerprint pattern, which yielded a high level of polymorphism (P _o = 93.5%) and genetic diversity (Nei’s H _T = 0.2354). The estimates of population variation, based on ISSR-PCR, were high, as measured by the analysis of molecular variance (AMOVA, F _ST = 0.3140), the Wright’s F-statistics (G _ST = 0.3453), and the Shannon’s information index (H _sp = 0.3716). AMOVA revealed 68.6% genetic variation within the populations and 91.2% within the provinces. The Mantel test showed that genetic distance was significantly correlated with geographic distance. Published in Russian in Fiziologiya Rastenii, 2009, Vol. 56, No. 3, pp. 453–459. This text was submitted by the authors in English.     

Reproduction and development in the dwarf form of Arctic charr Salvelinus alpinus from Lake Davatchan, Transbaikalia

Biological characteristics in the deepwater dwarf form of Arctic charr Salvelinus alpinus from Lake Davatchan, Transbaikalia, are described. In nine from fifteen attempts of artificial insemination of eggs from a female by sperm from a male, developing eggs are obtained. Embryonic and larval development is described at the initial temperature 1.6–3.6°C and subsequent (from early gastrulation to the transition of larvae to exogenous feeding) average temperature 4.4 and 8.6°C. To take into account the data obtained previously (Pavlov et al., 1990, 1993b), the comparison of early ontogeny is conducted between the dwarf and small forms of charr from Lake Davatchan and the charr from Lake Leprindokan (two lakes are separated by the ridge 8 km in width). A substantial similarity in early ontogeny between the dwarf and small forms of charr from Lake Davatchan suggests that genes controlling development of the embryos and prelarvae until the transition of the young to exogenous feeding have not been subjected to natural selection determining a considerable differentiation between two forms and their reproductive isolation. Published in Voprosy Ikhtiologii, 2008, Vol. 48, No. 1, pp. 102–119. The article was translated by the author.     

Food habit divergence between white-spotted charr and masu salmon in Japanese mountain streams: circumstantial evidence for competition

 The diet and foraging microhabitat of white-spotted charr, Salvelinus leucomaenis, were compared between mountain stream reaches where it occurs with (sympatric) and without (allopatric) masu salmon, Oncorhynchus masou masou, a potential competitor, to examine the evidence for interspecific competition between these fish, which commonly co-occur in Japanese mountain streams. In three streams examined, the similarity between the diets of allopatric charr and salmon was much greater than that between the diets of sympatric charr and salmon. Both allopatric charr and sympatric salmon intensively utilized terrestrial invertebrates among stream drifts (52%–65% of the diet), whereas this prey category made up only an intermediate portion of sympatric charr diets (11%–29%). Examination of available prey composition in stream drifts showed that the consumption of terrestrial invertebrates by allopatric charr and sympatric salmon was approximately twice as much as that by sympatric charr. The presence of salmon, a potential competitor, may alter the diet of charr in the sympatric reaches. Charr holding focal points closer to the streambed were considered less efficient than sympatric salmon in their utilization of terrestrial invertebrates drifting primarily on the stream surface, although the foraging microhabitat of the charr was not influenced by the salmon. The mechanisms responsible for the dietary divergence between sympatric charr and salmon are probably the consequence of scramble competition over terrestrial invertebrates drifting on the stream surface. Received: January 21, 2002 / Accepted: November 19, 2002 Acknowledgments We thank Y. Tokuda, T. Takasu, Y. Kaneda, H. Jyoya, and H. Aoe for their assistance. This work was partly supported by funding through the Takara Harmonist Fund by the Takara Syuzo Co. Ltd. and the Japan Ministry of Education, Science, Sport and Culture (grants 09NP1501 and 11440224). Correspondence to:H. Miyasaka     

Development of a species-specific fractionation equation for Arctic charr (<Emphasis Type="Italic">Salvelinus alpinus</Emphasis> (L.)): an experimental approach

A species-specific fractionation equation for Arctic charr (Salvelinus alpinus (L.)) was developed experimentally for use in ecological studies of temperature-driven phenologies for the species. Juvenile Arctic charr were reared in controlled conditions at different temperatures (2–14°C), with three replicates of each temperature. Otoliths from the fish and water samples from the chambers were analysed for oxygen isotope composition and used to estimate temperature-dependent fractionation equations relating the isotopic ratio to rearing temperature. A linear and a second order polynomial relationship were estimated and validated using comparable Arctic charr data from another study. Temperatures predicted using the polynomial equation were not significantly different from recorded experimental temperatures, whereas with the linear equation there were significant differences between the predicted and measured temperatures. The polynomial equation also showed the least bias as measured by mean predictive error. Statistical comparisons of the polynomial fractionation equation to a similarly estimated equation for brook charr (Salvelinus fontinalis (Mitchill)) indicated significant differences. Results imply the need for species-specific fractionation equations, even for closely related fish. Results further suggest the polynomial form of the fractionation equation will facilitate more accurate characterisation of water temperatures suitable for use in ecological studies of temperature-driven phenologies of Arctic charr.     

Selection on Arctic charr generated by competition from brown trout

We experimentally explored population‐ and individual‐level effects on Arctic charr (Salvelinus alpinus) resulting from resource competition with its common European competitor, the brown trout (Salmo trutta). At the population level, we compared performance of the two species in their natural sympatric state with that of Arctic charr in allopatry. At the individual level, we established selection gradients for morphological traits of Arctic charr in allopatric and in sympatric conditions. We found evidence for interspecific competition likely by interference at the population level when comparing differences in average performance between treatments. The growth and feeding rates did not differ significantly between allopatric and sympatric Arctic charr despite lower charr densities (substitutive design) in sympatric enclosures indicating that inter‐ and intraspecific competition are of similar strength. The two species showed distinct niche segregation in sympatry, and brown trout grew faster than Arctic charr. Arctic charr did not expand their niche in allopatry, indicating that the two species compete to a limited degree for the same resources and that interference may suppress the growth of charr in sympatric enclosures. At the individual level, however, we found directional selection in sympatric enclosures against individual Arctic charr with large head and long fins and against individuals feeding on zoobenthos rather than zooplankton indicating competition for common resources (possibly exploitative) between trout and these charr individuals. In allopatric enclosures these relations were not significant. Diets were correlated to the morphology supporting selection against the benthic‐feeding type, i.e. individuals with morphology and feeding behaviour most similar to their competitor, the benthic feeding brown trout. Thus, this study lends support to the hypothesis that Arctic charr have evolved in competition with brown trout, and through ecological character displacement adapted to their present niche.     

Extant and extinct forms of arctic charr Salvelinus alpinus (L.) complex from the Leprindo lake system (Transbaikalia): Differentiation in life history, morphology, and genetics

Interconnected lakes Bol’shoe Leprindo and Maloe Leprindo in Transbaikalia hosted large (extinct) and dwarf charr forms. Rarely “small” individuals intermediate in size between these forms are caught. In order to assess morphological, ecological, and genetic differentiation of sympatric charr forms and parapatric charr populations we studied their meristic and morphometric characters, feeding, breeding, and growth; we also investigated variation at 8 microsatellite loci using DNA isolated both from contemporary and historic samples. Profound differences were found between large and dwarf charr in growth rate, feeding (piscivores and highly specialized zooplanktivores, respectively), spawning time, and morphology. Dwarf charr from the two lakes demonstrate minor differences in morphology and growth rate. “Small” individuals are morphologically similar with dwarf charr and spawn together with them, they are recruited from dwarf form in late ontogeny as the result of transition to piscivorous feeding and growth acceleration. Microsatellite analysis showed that: (1) large and dwarf charr forms display high degree of genetic differentiation and reproductive isolation; (2) dwarf charr from interconnected lakes belong to different isolted populations; (3) “small charr” are genetically identical with dwarfs. The degree of ecomorphological and genetic differentiation between large and dwarf forms places charr from Leprindo Lakes among the most strongly differentiated Arctic charr forms’ flocks known at the vast range of S. alpinus complex.     

Comparative population structure of Chinese sumac aphid <Emphasis Type="Italic">Schlechtendalia chinensis</Emphasis> and its primary host-plant <Emphasis Type="Italic">Rhus chinensis</Emphasis>

Most of our current understanding of comparative population structure has been come from studies of parasite–host systems, whereas the genetic comparison of gallnut-aphids and their host-plants remain poorly documented. Here, we examined the population genetic structure of the Chinese sumac aphid Schlechtendalia chinensis and its unique primary host-plant Rhus chinensis in a mountainous province in western China using inter-simple sequence repeat (ISSR) markers. Despite being sampled from a mountainous geographic range, analysis of molecular variance (AMOVA) showed that the majority of genetic variation occurred among individuals within populations of both the aphid and its host. The aphid populations were found to be structured similarly to their primary host populations (F _ST values were 0.239 for the aphid and 0.209 for its host), suggesting that there are similar patterns of gene flow between the populations of the aphid and between populations of its host-plant. The genetic distances (F _ST/1 − F _ST) between the aphid populations and between its host-plant populations were uncorrelated, indicating that sites with genetically similar host-plant populations may not always have genetically similar aphid populations. The lack of relationships between genetic and geographical distance matrices suggested that isolation by distance (IBD) played a negligible role at this level. This may be mainly attributed to the founder effect, genetic drift and the relative small spatial scale between populations. Zhumei Ren and Bin Zhu contributed equally to this work.     

Characterizing neutral and adaptive genomic differentiation in a changing climate: The most northerly freshwater fish as a model

Arctic freshwater ecosystems have been profoundly affected by climate change. Given that the Arctic charr (Salvelinus alpinus) is often the only fish species inhabiting these ecosystems, it represents a valuable model for studying the impacts of climate change on species life‐history diversity and adaptability. Using a genotyping‐by‐sequencing approach, we identified 5,976 neutral single nucleotide polymorphisms and found evidence for reduced gene flow between allopatric morphs from two high Arctic lakes, Linne'vatn (Anadromous, Normal, and Dwarf) and Ellasjøen (Littoral and Pelagic). Within each lake, the degree of genetic differentiation ranged from low (Pelagic vs. Littoral) to moderate (Anadromous and Normal vs. Dwarf). We identified 17 highly diagnostic, putatively adaptive SNPs that differentiated the allopatric morphs. Although we found no evidence for adaptive differences between morphs within Ellasjøen, we found evidence for moderate (Anadromous vs. Normal) to high genetic differentiation (Anadromous and Normal vs. Dwarf) among morphs within Linne'vatn based on two adaptive loci. As these freshwater ecosystems become more productive, the frequency of sympatric morphs in Ellasjøen will likely shift based on foraging opportunities, whereas the propensity to migrate may decrease in Linne'vatn, increasing the frequency of the Normal morph. The Dwarf charr was the most genetically distinct group. Identifying the biological basis for small body size should elucidate the potential for increased growth and subsequent interbreeding with sympatric morphs. Overall, neutral and adaptive genomic differentiation between allopatric and some sympatric morphs suggests that the response of Arctic charr to climate change will be variable across freshwater ecosystems.     

Genetic diversity and differentiation of <Emphasis Type="Italic">Fagus orientalis</Emphasis> Lipsky in Hyrcanian forests revealed by nuclear and chloroplast microsatellite markers

Oriental beech (Fagus orientalis Lipsky) is a widespread monoecious and wind-pollinated tree species. It is one of the major components of the Hyrcanian forests of Iran and it is of both ecological and economical importance. Twelve beech stands were surveyed at 9 chloroplast (cp) and 6 nuclear (n) polymorphic microsatellite loci (simple sequence repeats, SSR) to provide information on distribution of genetic diversity within and among populations and on gene conservation and silvicultural management of this species. High levels of genetic differentiation were detected for the chloroplast genome (F _ST = 0.80 and R _ST = 0.95), in sharp contrast to the nuclear genome (F _ST = 0.06, R _ST = 0.05). The analysis of molecular variance (AMOVA) showed that 48% of the total cpSSR variation was attributable to differences among regions and 30% to differences among populations within regions, suggesting multiple origins of beech populations in Hyrcanian forests. Nuclear SSRs confirmed the presence of significant differentiation among populations and among geographic regions, even if, as expected, this was less pronounced than that found with cpSSRs (based on AMOVA, differences among regions and among populations within regions each contribute 5% to total nSSR variance). A highly significant correlation between genetic (nSSRs) and geographic distances (R ² = 0.522) was estimated, thus showing an isolation by distance effect. The application of spatial analysis of molecular variance (SAMOVA) using both marker data allowed identification of genetically homogeneous groups of populations. Possible applications of these results for the certification of provenances and/or seed lots and for designing conservation programs are presented and discussed.     

Lipid‐rich zooplankton subsidise the winter diet of benthivorous Arctic charr (Salvelinus alpinus) in a subarctic lake

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Differentiation of deep-water lake charr <Emphasis Type="Italic">Salvelinus namaycush</Emphasis> in North American lakes

Deep-water morphs of lake charr, Salvelinus namaycush, are found, with one exception, in four of the largest lakes in the world: lakes Superior and Mistassini (QC) and Great Bear and Slave lakes. This paper advances a hypothesis for resource polymorphisms involving two types of deep-water morph, one of which is characteristic of the humper and the other of the siscowet charrs of Lake Superior. My hypothesis states that, first, the humper, or a humper-like morph, diverged postglacially in sympatry from the ancestral common (shallow-water) lake charr and became a feeding specialist on Mysis relicta. Second, in at least two of the four lakes the siscowet, or a siscowet-like charr, diverged as a feeding specialist on postglacially derived forms of deep-water ciscoes. In Lake Superior a successional process may have resulted in dominance of the siscowet at the expense of the humper charr. I concur with a previous inference that the one occurrence of a deep-water charr in a small lake (the above exception) represents emigration from Lake Superior. I further infer that this event involved an early humper charr, which implies that this morphotype had differentiated in Lake Superior in less than 1,900 year. I suggest that innate differences in plasticity, breeding behavior and assortive mating, and philopatry account for why Arctic charr isolate readily in small lakes whereas lake charr do not. My hypothesis assumes divergence of deep-water morphs occurred postglacially, an idea consistent with genetic and biogeographical evidence.     

On the Origin of the Lacustrine Charr <Emphasis Type="Italic">Salvelinus alpinus</Emphasis> Complex from the Kolyma and Sea of Okhotsk Basins

Morphological and genetic characteristics are used for the analysis of the origin of charrs from the lakes of the Kolyma basin (Chuk, Gek, Gulyaevskoe-4, Gulyaevskoe-6, and Lenkovoe) and the Sea of Okhotsk basin (Lake Chistoe). In addition to these samples, the fragments of the control region of mitochondrial DNA (CR mtDNA, 550-bp) and exon 2 of recombination activating gene 1 (RAG1, 899-bp) are sequenced in the charrs from lakes Dzhul’etta and Cherechen’ (Kolyma basin) and lakes Elikchanskie, Bol’shoi Mak-Mak, Ueginskoe (Sea of Okhotsk basin), Ulakhan-Silyan-Kyuel’ (Yana River basin) as well as in northern Dolly Varden from the Kamchatka River. The charr from Lake Chistoe is represented by northern Dolly Varden. In the charrs from lakes Chuk, Gek, Gulyaevskoe-4, Gulyaevskoe-6, Lenkovoe, Cherechen’, Elikchanskie, Bol’shoi Mak-Mak, and Ueginskoe, the haplotypes of mtDNA of the Bering group (a haplogroup of northern Dolly Varden) are revealed. Based on the morphological and RAG1 data, populations of charrs from these lakes belong to the Salvelinus alpinus complex. A transfer of mtDNA of northern Dolly Varden to the charrs from the Kolyma and Sea of Okhotsk basins occurred during the last postglacial expansion and subsequent hybridization. Based on the results of morphological and genetic analysis, the charrs from the Kolyma and Sea of Okhotsk basins cannot be unambiguously referred to the phylogenetic groups of Eurasian Arctic charr or Taranets charr. The presence of mtDNA haplotypes of the Arctic group (a haplogroup of Taranets charr) in the populations of lakes Dzhul’etta, Maksi, and Ueginskoe shows a possibility of their belonging to the group of Taranets charr.     

The Arctic charr (<Emphasis Type="Italic">Salvelinus alpinus</Emphasis>) populations of Windermere,UK: population trends associated with eutrophication,climate change and increased abundance of roach (<Emphasis Type="Italic">Rutilus rutilus</Emphasis>)

The north and south basins of Windermere in the English Lake District, UK, support autumn- and spring-spawning populations of Arctic charr, Salvelinus alpinus, which have been studied since the 1930s. Continuous investigations of the population dynamics of Arctic charr at this lake have involved gill netting since 1939, collection of fishery catch-per-unit-effort data since 1966, and hydroacoustic surveys since 1990. Analysis of these and associated long-term data on the abiotic environment and other components of the fish communities revealed recently contrasting fortunes of the Arctic charr populations of the north and south basins, the latter of which has been significantly impacted by eutrophication while both basins have shown elevated water temperatures and increasing roach, Rutilus rutilus, populations. Despite the introduction of phosphate stripping in 1992 and some subsequent initial improvement, the hypolimnion of the south basin still remains significantly eutrophicated and the fishery catch-per-unit-effort in this basin is now at record low levels. In addition, the spatial distribution of roach has expanded to form significant components of the fish communities of inshore and offshore surface habitats, where this cyprinid may compete with Arctic charr for zooplanktonic prey. It is concluded that the Arctic charr populations of Windermere, particularly those of the south basin, currently face a number of significant environmental pressures and continued management action is required to ensure their survival.