通过RAPD分析揭示五种淡水无齿蚌（软体动物门：双壳类）的遗传多样性

Unionidae(Bivalvia)are distributed infreshwaters,and represent a significanttaxonof benthic community[1].In China,freshwater mussels are abundant resources[2].Since1949,substantial investigations onthe unionidfau-na had been undertakenin China[3—8].Withreference tooverseas research[9,10],a preliminary reorganization onthe Unionidae was performed accordingtosome classifica-tion characteristics such as shell shape,larvae character-istics,and breeding habit[11].Due tothe serious conver-gence o…     

Testing hypotheses on the dispersal and evolutionary history of freshwater mussels (Mollusca: Bivalvia: Unionidae)

The relationship between dispersal and differentiation of the European freshwater mussel Unio pictorum (Linnaeus, 1758) was studied with molecular genetic methods. Forty‐two populations from France, Italy and central Europe were analysed. Genetic relationships were assessed from the geographical distribution of allele frequencies at 17 enzyme loci. Neighbouring groups of populations show small to moderate mean genetic distances (0.020 < D_mean < 0.263). With a few exceptions the genetic affinities of the populations are the closest within the same drainage basin. In central Europe and Northern Italy genetic differences between drainage systems are relatively large. Populations from north‐eastern Italy are genetically similar to Danubian populations. Mussels from the islands of Corsica and Sardinia are more closely related to populations from the Italian peninsula than to French populations from the Rhône drainage system. Genetic relationships within U. pictorum from central Europe reflect palaeogeographical relationships between river systems during the Pliocene and Pleistocene. Literature data on two North American unionid species and one European fish species show the same relationship between genetic diversity and the history of drainage systems, although the correlations are less strong. In France and Italy this correspondence is much less evident. Population dynamic processes and human activities leading to populational bottlenecks might have obscured it.     

Individual Growth of Anodonta beringiana (Unionidae,Bivalvia) in Postlarval Ontogenesis

Russian Journal of Developmental Biology - Individual linear growth in 26 specimens of Anodonta beringiana is studied by measuring the successive annual rings on the surface of the shells. It is...     

Biogeography and conservation of freshwater mussels (Bivalvia: Unionidae) in Texas: patterns of diversity and threats

Aim Geographic patterns of species distributions and the factors contributing to species endangerment are necessary for the development of integrative conservation strategies. Freshwater mussels Unionidae have among the highest levels of imperilment recorded in North America. This paper describes the biogeography and diversity of Unionidae along climate and habitat gradients in Texas, evaluates human impact, and identifies the hot spots of diversity and endemism that should be targeted for conservation. Location Texas, North America. Methods Unionids were surveyed in all major Texas river basins in 2003–2009. Multivariate statistics were used to test for differences in environmental parameters and among unionid assemblages in different bioprovinces, and to determine to what extent the multivariate pattern of species distribution was affected by environmental factors. To estimate human impact, we examined the relationship between human population density and the proportion of rare species, as well with the proportion of historically present species that persist in the watershed. Results Correlation between biotic and environmental similarity matrices indicated concordance in the differences among unionid assemblages and environmental factors that could cause these differences. Lake surface evaporation rate and percentage of forest cover in the watershed were among the most important parameters explaining the differences in unionid assemblages. Human population density was negatively correlated with the proportion of rare species. The proportion of species found live relative to the total number of live and relic species found in our surveys and to the number of historically known species decreased with the increase in human population density. Main conclusions Climate, landscape, geology, and land use type were important factors influencing unionid distribution patterns among biotic provinces. Increased human population density was associated with the loss of rare species over several decades, but this loss was not recognized because of a lack of assessing the conservation status of unionids.     

Phylogeographic analysis of the threatened and endangered superconglutinate-producing mussels of the genus Lampsilis (Bivalvia: Unionidae)

Several species of freshwater unionid mussels in the genus Lampsilis exhibit a remarkable reproductive strategy. Female mussels of these species enclose their larvae in a minnow-like lure, called a 'superconglutinate', to attract piscivorous fishes. When a fish attempts to ingest the superconglutinate the lure ruptures and the larvae are released to parasitize the fish. Of the four species of mussel which exhibit this strategy and are endemic to the Gulf Coast drainages of the southeastern United States, three are protected under the Endangered Species Act, and one is recognized as imperiled. Phylogenetic analysis of nucleotide sequences of the mitochondrial 16S ribosomal RNA and the first subunit of the cytochrome oxidase c genes was conducted on 18 individual specimens representing these four species and six outgroup taxa. Phylogenetic analyses of these data support the monophyly of the superconglutinate-producing mussels, and indicates a strong geographical component to the data. The zoogeographic patterns of the four taxa included in the study are congruent with those seen in freshwater vertebrates, and are consistent with a vicariant pattern resulting from fluctuations in sea level during the Pleistocene. Despite the strong geographical structuring of the data, only one species, Lampsilis subangulata, was recovered as monophyletic. The authors attribute the lack of support for the monophyly of the remaining species to insufficient sequence variation and the recent origin of the ancestor of these taxa. Based on these data, any future captive breeding projects aimed at augmenting or re-establishing populations should do so only from the appropriate source populations so as to maintain the genetic integrity of these nascent species.     

Estimating the biomass of freshwater mussels (Bivalvia: Unionidae) from shell dimensions

Packs of autumn-shed maple leaves were placed at coal ash effluent-exposed and reference sites in streams on December 5, 1977 and removed after 27 and 96 days. Leaf surface area (cm²/leaf) and disc weight (ash-free dry wt/15 mm disc) were greater at the effluent-exposed site than at the reference site after 96 days (p < .001). ATP content of leaves from the reference stream quadrupled between 27 and 96 days while ATP content of effluent-exposed leaves remained low. Macroinvertebrates colonized the leaf packs in the reference site but were not found on or in effluent-exposed packs. We concluded that leaf processing beyond the leaching of soluble organics did not occur in the effluent-exposed packs owing to reduced colonization and decomposition by fungi. Since stream invertebrates prefer decomposed leaf material and animals grow faster on leaves colonized by microbes, the ash effuent appears to indirectly affect macroinvertebrates by interfering with leaf decomposition and thus reducing the quality of their food.     

Reach- and catchment-scale determinants of the distribution of freshwater mussels (Bivalvia: Unionidae) in south-eastern Michigan, U.S.A.

1. We investigated the diversity and distribution of freshwater mussels at 40 sites in an agricultural catchment, the River Raisin in south‐eastern Michigan, to relate mussel assemblages and individual taxa to reach and catchment‐scale variables. Unionids were surveyed by timed searches in 100‐m reaches, and in‐stream and riparian habitat were quantified as well as flow, water chemistry and channel morphology. Land use/cover and surficial geology were determined for site subcatchments and riparian buffers. 2. Some 21 mussel species were found overall; richness ranged from 0 to 12 living species per site. From the upper to middle to lower catchment, the number of individuals, number of species, Shannon–Weaver diversity and relative abundance of intolerant unionids all declined significantly. 3. Four groupings based on overall mussel diversity and abundance were significantly related to reach‐scale habitat variables. The richest mussel assemblages were associated with sites with higher overall habitat quality, greater flow stability, less fine substratum, and lower specific conductance. 4. Stepwise multiple regressions revealed that the distribution and abundance of the total mussel assemblage, as well as the most common species, could be predicted from a combination of reach‐ and catchment‐scale variables (R² = 0.63 for total mussels, R² = 0.51–0.86 for individual species). 5. Flow stability, substratum composition and overall reach habitat quality were the most commonly identified reach‐scale variables, and measures of surficial geology were the most effective catchment‐scale variables. The spatial pattern of geology is likely to be responsible for the diversity gradient from the upper to the lower catchment. 6. Prior studies, attempting to explain mussel distributions from local habitat features alone, have found relatively weak relationships. By employing a combination of reach‐ and catchment‐scale habitat variables, this study was able to account for a substantial amount of the spatial variability in mussel distributions.     

Length‐specific growth rates in freshwater mussels (Bivalvia: Unionidae): extreme longevity or generalized growth cessation?

1. North American lacustrine freshwater mussels (Bivalvia: Unionidae) are one of the world's most imperilled groups of organisms. Knowledge of their age structure and longevity is needed for the understanding and management of mussels. Current methods for age estimation in freshwater mussels are insufficient and may have resulted in an erroneous view of the ages of lacustrine freshwater mussels.
2. We collected growth data through mark-recapture in Minnesota and Rhode Island, U.S.A., examining four lentic populations of three of the most common species of freshwater mussels, Elliptio complanata , Lampsilis siliquoidea , and Pyganodon grandis . Using an inversion of the von Bertalanffy growth equation, we estimated age at length from length-specific growth relationships.
3. In some populations, lacustrine mussels may be much older than previously predicted. Ages predicted from actual growth rates suggest that individuals in some populations frequently reach ages in excess of a century, placing unionid mussels among the Earth's longest-lived animals. Alternatively, if growth has only recently slowed in these populations, generalized growth cessation may be occurring over a broad distributional range of some common North American lacustrine mussels.     

Turcichondrostoma,a new genus for the Leuciscidae (Teleostei: Cypriniformes) from Southwestern Anatolia

Turcichondrostoma, a new genus, from the Southwestern Anatolia is distinguished by having fewer gill rakers on first gill arch and morphologies of premaxilla and dentary bones. In addition, as a result of the phylogenetic analyses based on combine data set (mtDNA COI + Cytb) sequences (1706 bp.), Turcichondrostoma genus was recovered with high posterior probability value (BI PP:1.0) and strong-supported bootstrap value (ML BP: 100%) among the former Chondrostoma groups. Also, high K2P mean genetic distance values (more than 7.84%) differentiated genus Turcichondrostoma from the other genera of former Chondrostoma group. The results of both morphological-osteological and molecular analyses are congruent with each other. The results of this study revealed that the genus Turcichondrostoma is easily distinguished from the genera in Chondrostoma group.     

Phosphorus cycling by mussels (Unionidae : Bivalvia) in Lake St. Clair

The role of mussels in cycling phosphorus in Lake St. Clair during the May–October period was examined by measuring concentrations in the water column and in mussel tissue, and by measuring rates of biodeposition and excretion. Mean rates of biodeposition and excretion for Lampsilis radiata siliquoidea, the most abundant species, were 6.3 µg P (g shell-free dry wt)^-1 h^-1 and 1.3 µg P (g shell-free dry wt)^-1 h^-1, respectively; body tissue phosphorus content was 2.7 percent of dry wt. Seasonal changes in excretion rates appeared to be related to the gametogenic cycle of the organism, but seasonal changes in biodeposition rates were not apparent. Phosphorus assimilation efficiency for this species was about 40 percent. Overall, the mussel population in Lake St. Clair filtered about 210 MT of phosphorus, or about 13.5 percent of the total phosphorus load for the May–October study period. Of this amount, about 134 MT was sedimented to the bottom via biodeposition. Mussel biodeposition may be an important source of nutrients to other biotic components in the lake such as macrophytes and invertebrate deposit-feeders.     

Molecular phylogeny of the genus Capoeta (Teleostei: Cyprinidae) in Anatolia,Turkey

Phylogeny of Capoeta genus distributed in Anatolia were carried out by analysing mitochondrial cytochrome b gene (1140 bp) sequences from 332 samples representing 59 populations of 15 species across their geographical distribution. Haplotype network and phylogenetic analysis (neighbor-joining, maximum-likelihood, maximum parsimony, and bayesian inference) of the 103 cytochrome b haplotypes detected in Capoeta species resulted in similar tree topologies including four distinct clades, in congruent with taxonomic classification of Capoeta based on morphological characteristics such as scale size, mouth shape, and body spotting. Based on cyt b nucleotide sequences, the present study suggests that four undescribed Capoeta species may exist in Anatolia freshwater; one species in the Kizilirmak River, the second species in the Dirgine River, the third species B. Menderes River, and the fourth species in the some Yesilirmak tributaries that run into the Black Sea Basin. Capoeta taxa distributed in the rivers of Anatolian freshwater basins are isolated from each other during middle Miocene (Serravallian)-late Pleistocene (Ionian) (about 13.75–0.41 million years). This suggests that distribution and presence of Capoeta species were shaped under paleogeographic conditions such as Pleistocene climate changes in Quarternary period as well as tectonic uplift and faulting, which probably has not changed up to now.     

On the relationships between absolute and allometric shell growth in unionid mussels (Bivalvia,Unionidae) from European Russia

The heuristic analysis of the relationship between the parameters of equations of linear (L. von Bertalanffy) and allometric shell growth was carried out on Unio pictorum (Linnaeus, 1758), U. tumidus Retzius, 1778, and U. crassus Retzius 1778 (Unionidae) from European Russia. Growth constants of the shell, k, were studied for length (k _L ), height (k _h ), and convexity (k _C ). It was shown that the ratios of growth constants (k _h /k _L , k _C /k _h , and k _C/k _L ) and parameter bfrom the allometric equations (h=aL ^b ;B=ah ^b ; C=aL ^b ) are connected by a strong negative correlation. If the b parameter is more than 1 (positive allometry), the growth constant relations are less than one, if b < 1 (negative allometry), the growth constant proportions are more than 1, and, in case when b is close to 1, (isometry), the growth constant proportions are also close to 1. All three types of allometric growth (isometry and both positive and negative allometry) are observed in the studied mussels.     

A new Pseudophoxinus (Teleostei,Cyprinidae) species from Southwestern Anatolia,with remarks on the distribution of the genus in western Anatolia

Pseudophoxinus burduricus sp. n. is described from drainages of Salda and Burdur lakes, southwestern Turkey. It is distinguished from other Anatolian Pseudophoxinus by a combination of characters: lateral line incomplete, with 21–39 (commonly 26–37) perforated scales and 47–57+1-2 scales in lateral series; 10½–12½ scale rows between lateral line and dorsal fin origin, 3–4(5) scale rows between lateral line and the pelvic fin origin; dorsal fin commonly with 7½ branched rays; anal fin commonly with 6½ branched rays; 7–8(9) gill rakers on the first branchial arch; a faint and diffuse epidermal black stripe from eye to caudal fin base in alive and preserved individuals; mouth slightly subterminal, tip of mouth cleft on about level of lower margin of eye; snout rounded, its length greater than eye diameter. Comparison is given with all Pseudophoxinus species from western Anatolia.     

Growth patterns of the pan‐European freshwater mussel,Anodonta anatina (Linnaeus, 1758) (Bivalvia: Unionidae), vary with sex and mortality in populations

1. Post‐maturation growth leading to indeterminate growth patterns is widespread in nature. However, its adaptive value is unclear. Life history theory suggests this allocation strategy may be favored by temporal pulses in the intensity of mortality and/or the capacity to produce new tissues.
2. Addressing the origin of indeterminate growth and the variability of growth patterns, we studied the growth of duck mussels, Anodonta anatina, a pan‐European unionid, in 18 Polish lakes. For each population, the sex, size, and age of collected mussels were measured to estimate Bertalanffy''s growth curve parameters. We integrated information on A. anatina mortality rates, lake trophy, biofouling by zebra mussels, Dreissena polymorpha, and the prevalence of parasitic trematode larvae to identify selective conditions in lakes.
3. We found two sources of mortality in A. anatina populations, pertaining to adverse effects of zebra mussel biofouling and trophy state on mussel survival. Additionally, populations with heavier biofouling presented a smaller abundance of parasites, indicative of a relationship between filtering intensity and contraction of water‐borne trematode larvae by filtering A. anatina.
4. Consistently for each sex, populations with a greater trophy‐related mortality were characterized in A. anatina by a smaller asymptotic size L_max, indicative of a life history response to mortality risk involving early maturation at a smaller body size. In all populations, females featured higher mortality and larger asymptotic size versus males.
5. Our findings support a theoretical view that adaptive responses to selection involve adjustments in the lifetime resource allocation patterns. These adjustments should be considered drivers of the origin of indeterminate growth strategy in species taking parental care by offspring brooding in body cavities.

     

Evolution of bilaterally asymmetrical larvae in freshwater mussels (Bivalvia: Unionoida: Unionidae)

Bilaterally asymmetrical glochidia (i.e. bivalved parasitic larvae bearing a large marginal appendage on a single valve) have been reported from five Asian freshwater mussel genera belonging to two separate subfamilies, the Gonideinae (i.e. Pseudodon, Solenaia, and Physunio) and Rectidentinae (i.e. Contradens and Trapezoideus). This classification requires that the bilaterally asymmetrical glochidium‐bearing mussels are not monophyletic, and suggests that this atypical larval morphology evolved twice in the same geographic region. Although homoplastic glochidium characters are known (e.g. marginal appendages and size), we hypothesized that bilaterally asymmetrical glochidia represent a novel morphological synapomorphy. We tested the monophyly of the mussels bearing bilaterally asymmetrical glochidia using a molecular matrix consisting of representatives from all six freshwater mussel families and three molecular markers (28S, 16S, and COI). Bayesian inference, maximum likelihood, and ancestral state reconstruction were employed to estimate the phylogeny and larval trait transformations. The reconstructed phylogeny rejects the monophyly of the asymmetrical glochidium‐bearing mussels and resolves two putative origins of asymmetrical glochidia; however, ancestral state reconstruction supports asymmetrical glochidia as a synapomorphy of only one supraspecific taxon of the Rectidentinae. In the Gonideinae, asymmetrical glochidia were autapomorphic of Pseudodon cambodjensis (Petit, 1865). That is, no other taxa resolved among the Gonideinae had bilaterally asymmetrical glochidia, including other Pseudodon species. We describe how the alleged intrageneric glochidial variation in Pseudodon, and in the other genera of the Gonideinae reported to have asymmetrical glochidia (i.e. Solenaia and Physunio), challenge the resolved convergence of asymmetrical glochidia. Our results are discussed in the context of freshwater mussel larval evolution, patterns in life‐history traits, and the classification of freshwater mussels generally. © 2015 The Linnean Society of London     

Development and characterization of microsatellite loci in the endangered oyster mussel Epioblasma capsaeformis (Bivalvia: Unionidae)

Primers for 10 polymorphic microsatellite loci were developed and characterized for the endangered oyster mussel Epioblasma capsaeformis from the Clinch River, Tennessee. Microsatellite loci also were tested in four other populations or species. Amplification was successful for most loci in these closely related endangered species or populations; therefore, a high level of flanking sequence similarity was inferred for this group of species and populations. Allelic diversity ranged from nine to 20 alleles/locus, and averaged 13.6/locus. This study demonstrated the feasibility of using polymerase chain reaction (PCR) primers to amplify microsatellite loci across freshwater mussel species to conduct population genetics studies.     

A new species of Arabis (Brassicaceae) from inner Anatolia

A new species of Arabis L., A. erikii Mutlu sp. nov. , is described and illustrated. The species is restricted to inner Anatolia, south-west of Sivas. It grows on steppes. Diagnostic morphological characters are given for discrimination from the most similar taxa.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 145 , 251–256.     

Genetic variability among freshwater mussel Anodonta woodiana (Lea, 1834) (Bivalvia: Unionidae) populations recently introduced in Poland

The alien Chinese mussel Anodonta woodiana was first reported in Poland in the system of heated lakes near Konin in 1993. Genetic studies with use of three molecular techniques (isoenzyme electrophoresis, PCR-RFLP and sequence analysis of a COI gene fragment) were carried out on the Polish first populations of A. woodiana. The studies have revealed low genetic variation between the populations (Nei's genetic distance for 12 loci ranged 0.000 to 0.007) as well as their considerable polymorphism. Each population averaged 2.28 alleles per locus, 2.72 alleles per polymorphic locus, and 75% polymorphic loci. Restriction analysis of the COI gene fragment have not revealed variability between the analysed specimens, including males and females. Restriction enzymes, ScrFI, Csp6I, and EcoRI used in the COI gene fragment PCR-RFLP generate distinct restriction patterns, which can be molecular markers for A. woodiana. The sequence obtained for COI fragment was the same in the examined female and male specimens and represents F mitotype (DNA was isolated from somatic tissues). The divergence between A. woodiana F and M mitotypes is high (34%), however it remains within the range of the general character of the DUI (doubly uniparental inheritance) phenomenon in freshwater bivalves (Unionidae).