Patterns of genetic structure in the endangered aquatic gastropod Valvata utahensis (Mollusca: Valvatidae) at small and large spatial scales

1. The aquatic snail Valvata utahensis (Gastropoda: Valvatidae) is a federally endangered aquatic mollusk known only from the Snake River in southern Idaho, U.S.A. The Snake River, like many other large river systems in the western United States, has undergone substantial anthropogenic modifications in recent history that have altered water flows, changed physicochemical attributes of the water and produced an overall spatially fragmented aquatic system. 2. Because little is currently known about the basic biology and life history of V. utahensis, we conducted a detailed genetic analysis of amplified fragment length polymorphism (AFLP) and mitochondrial DNA sequence variation in this species from six locations along the Snake River. This study was designed to discern (i) levels of within‐location genetic diversity, (ii) patterns of genetic structure at small spatial scales (i.e. within sampling locations) and (iii) patterns of genetic structure at large spatial scales (among sampling locations). 3. We show that comparable levels of nuclear genetic variation exist within each of the six locations examined. However, reduced mitochondrial sequence diversity was observed at Thousand Springs compared with the other locations examined. 4. We further illustrate that V. utahensis shows no genetic structure within locations over relatively small physical distances up to approximately 3 km. We suggest that active dispersal of individuals via crawling and passive dispersal because of downstream displacement or floating behaviours may have produced this pattern. However, at large spatial scales genetic structure generally followed an isolation‐by‐distance pattern. This pattern was not directly correlated with the connectivity of locations through the river corridor and suggested the possible role of episodic passive dispersal via avian waterfowl or the effects of historical floods throughout the Snake River c. 14 000 years ago.     

SPERMATOZA AND SPERMIOGENESIS OF CORNIROSTRA, VALVATA AND ORBITESTELLA (GASTROPODA: HETEROBRANCHIA) WITG A DISCUSSION OF VALVATOIDEAN SPERM MORPHOLOGY

Transmission electron microscopy reveals that spermatozoa ofthe marine gastropods Cornirostra peleucida (Laseron) (Cornirostridate—genusand family newly proposed by Ponder, 1990a) and Orbitestellasp. (Orbitestellidae) closely resemble those of the freshwaterfamily valvatidae. In particular, spermatozoa of Cornirostra,Orbitestella and Valvata share a unique arrangement of helicalridges or channels within the glycogen piece. The sperm midpieceof Orbitestella and Valvata has a lamellar substructure, whilein Cornirostra thus region exhibits a single, continuous mitochondrialsheath around the axoneme. An acrosome could not be positivelyidentified in either Valvata or Orbitestella but appears tobe present in Cornirostra in the form of a hollow, irregularvesicle. Mature sperm nuclei of the three taxa are long, filiformand almost totally penetrated by the axoneme. Nuclei of Orbitestellapossess one or more helical keels (keels absent in Cornirostraand Valvata). The pattern of spermiogenesis observed suportsthe view expressed by recent authors that the Valvatoidea areclosely related to heterobrach gastropods, and should be formallytransferred to the Heterobranchia. (Received 9 September 1989; accepted 30 December 1989)     

GENETIC VARIATION IN SYMPATRIC AND ALLOPATRIC POPULATIONS OF HYBRIDIZING FRESHWATER SNAIL SPECIES(VIVIPARUS ATER AND V. CONTECTUS)

To estimate the geographical extent of introgression, we studiedthe genetic structure of sympatric and allopatric populationsof hybridizing freshwater snail species Viviparus ater and V.contectus in central Europe. Six allozyme loci which were variablein Lake Garda, Italy in a previous study (five nearly diagnosticloci between the two species and one highly polymorphic locusin V. contectus) were analyzed from ten sympatric locationsand four allopatric populations each for the two species. Presumablyintrogressed genes (low allele frequencies) were found fromat least one locus in seven out of the ten sympatric sites.These seven sites covered most of northern Italy. The data indicatethat introgression has occurred from Viviparus contectus toV. ater and vice versa. Therefore, there is a possibility ofwidespread introgression or mosaic zones in nature. However,we cannot rule out that the observed patterns are due to theshared ancestry. V. ater possessed low genetic variation (thejackknifed mean of Wright's F_ST±S.E. over four loci was0.041±0.004). On the other hand, V. contectus showedhigh genetic differentiation (the jackknifed mean of F_ST±S.E. over six loci was 0.546±0.166). Although introgressionmay have caused evolutionary changes in V. ater and V. contectus,it was not strong enough to level out the genetic differencesbetween the two species, which may have originated from isolationamong populations in V. contectus and a past bottleneck eventin V. ater. (Received 21 June 1996; accepted 31 January 1997)     

Isozyme and RAPD Analysis of the Genetic Diversity Within and BetweenVigna luteolaandV. marina

Nineteen accessions ofVigna luteola,five ofV. marinassp.oblonga,and two ofV. marinassp.marinawere analysed using variation ofisozymes and RAPD markers to obtain better insight into geneticrelationships within and between these taxonomic entities. Thirteenputative isozyme loci were scored, seven of which were polymorphic.Both species showed very low genetic diversity indices and mostof the variation was detected among populations. Pairwise Nei'sgenetic distances based on allozyme frequencies were also verylow and the accessions ofV. marinassp.marinawere the least relatedto the others. RAPD analysis was more discriminating and 66bands out of a total of 85 were polymorphic. Based on the presenceor absence of bands, Jaccard's similarity index was calculated.Similarity ranged from 0.476 to 0.98. Matrices derived fromboth isozyme and RAPD data were used to construct UPGMA dendrograms.In the tree obtained from Nei's genetic distance, based on allozymefrequencies, accessions belonging toV. marinassp.oblongaweremixed withV. luteolaaccessions; on the other hand, the twoV.marinassp.marinaclustered separately, with oneV. luteola.Thedendrogram derived from RAPD data showed three main groups correspondingto the three taxa analysed. Moreover, according to these data,V.marinassp.oblongais more closely related toV. luteolathan toV.marinassp.marina.Copyright 1997 Annals of Botany Company Vigna luteola(Jacq.) Benth.; Vigna marina(Burm.) Merrill; isozymes; RAPDs; genetic relationships; genetic variation     

Complete genome sequence of Halorhabdus utahensis type strain (AX-2)

Halorhabdus utahensis Wainø et al. 2000 is the type species of the genus, which is of phylogenetic interest because of its location on one of the deepest branches within the very extensive euryarchaeal family Halobacteriaceae. H. utahensis is a free-living, motile, rod shaped to pleomorphic, Gram-negative archaeon, which was originally isolated from a sediment sample collected from the southern arm of Great Salt Lake, Utah, USA. When grown on appropriate media, H. utahensis can form polyhydroxybutyrate (PHB). Here we describe the features of this organism, together with the complete genome sequence, and annotation. This is the first complete genome sequence of the a member of halobacterial genus Halorhabdus, and the 3,116,795 bp long single replicon genome with its 3027 protein-coding and 48 RNA genes is part of the Genomic Encyclopedia of Bacteria and Archaea project.     

Discovery Of Genetically Distinct Sympatric Lineages in the Freshwater Mussel Cyprogenia Aberti (Bivalvia: Unionidae)

The western fanshell, Cyprogenia aberti, occurs in the CentralHighlands region of North America and is the only congener ofthe federally endangered fanshell, C. stegaria. Due to a reductionin range size and local extirpations, extant populations ofC. aberti have become increasingly isolated. Consequently, C.aberti has been the focus of numerous conservation efforts,yet no work has examined the degree of genetic variation amongthe species' disjunct populations. Phylogenetic analyses ofnucleotide sequences from two mitochondrial gene portions (CO1and ND1) revealed results important to the conservation managementof C. aberti. First, phylogenetic analyses do not support amonophyletic C. aberti. Second, C. aberti is comprised of asmany as five independent lineages, one of which includes thefederally endangered C. stegaria. Third, analysis recoveredtwo genetically distinct sympatric lineages of C. aberti inthe Ouachita River Drainage. These phylogenetic results suggestthat the five distinct evolutionary lineages of C. aberti shouldbe managed as separate conservation units. This study illustrateswhy it is critical to evaluate genetic variability in endangeredand threatened ‘species’ prior to implementing arecovery program. These data also reveal the value of assessingbiological diversity of nonimperiled taxa before populationsare extirpated and valuable genetic data necessary for reconstructionof evolutionary relationships is lost. (Received 24 October 2005; accepted 8 June 2006)     

Isozyme Evidence for Natural Hybridization in Phlomis (Lamiaceae): Hybrid Origin of the RareP.xmargaritae

Phlomisxmargaritae is a rare and sterile hybrid taxon foundin a single endangered population in southern Spain. It waspreviously described as a morphologically intermediate hybrid,putatively between Phlomis purpurea and P. composita. The presentstudy used allozymes as molecular markers to assess the hybrididentity ofP.xmargaritae . Ten putative loci from seven enzymesystems were resolved: five were monomorphic and fixed acrossall taxa studied and the rest (Aat-1, Aat-2, 6-Pgdh-2, Pgi andPgm) were polymorphic in at least one taxon. The two parentaltaxa are fixed for different alleles at 6-Pgdh-2 and show distinctallelic frequency differences for four other loci. Phlomisxmargaritaedisplays fixed heterozygous phenotypes for four of the fivepolymorphic loci, these being composed of combinations of thealleles found in the parental taxa. No unique alleles were detectedin P.xmargaritae. We conclude that this taxon is of hybrid originand confirm the identity of the parental taxa involved. It isfurther suggested that this population is composed of individualsthat are recent F₁hybrids that have not undergone backcrossingor introgression. Global conservation measures are necessaryfor the whole hybrid system in this location since further continuousassessment could reveal the evolutionary input of hybridizationin Phlomis.Copyright 2000 Annals of Botany Company Endangered species, genetic diversity, isozyme variation, hybrid species, Phlomisxmargaritae, plant conservation, population genetics, Lamiaceae, Spain.     

Molecular markers reveal no genetic differentiation between Myrica rivas-martinezii and M. faya (Myricaceae)

Background and Aims

Myrica rivas-martinezii is a critically endangered endemic of the laurel forest of the Canary Islands and co-occurs very close to M. faya. Some authors suggest that M. rivas-martinezii and M. faya are two morphs of the same species, so molecular markers were used to estimate the levels and structuring of genetic variation within and among natural populations in order to evaluate genetic relationships between these two congeners.

Methods

Six polymorphic microsatellite (simple sequence repeat, SSR) markers were used to determine the genetic diversity and the genetic relationship between both Myrica species.

Key Results

Most of the natural populations analysed were in Hardy–Weinberg equilibrium for both taxa. Analysis of molecular variance (AMOVA) for both species revealed that most of the genetic variability detected was contained within populations (92·48 and 85·91 % for M. faya and M. rivas-martinezii, respectively), which it is consistent with outcrossing and dioecious plants. Estimates of interpopulation genetic variation, calculated from F_ST and G′_ST, were quite low in the two taxa, and these values did not increase substantially when M. rivas-martinezii and M. faya populations were compared. The UPGMA dendrogram based on Nei''s genetic distance clustered the populations by their island origin, independently of taxon. In fact, the mixture of individuals of both taxa did not appreciably disrupt the intrapopulational genetic cohesion, and only 3·76 % variation existed between species.

Conclusions

All the results obtained using molecular markers indicate clearly that both taxa share the same genetic pool, and they are probably the same taxa. Considering that M. rivas-martinezii is classified as at risk of extinction, there should be a change of focus of the current management actions for the conservation of this putatively endangered Canarian endemic.Key words: Canary Islands, conservation genetics, microsatellites, Myrica rivas-martinezii, Myrica faya, plant conservation     

Testing two contrasting evolutionary patterns in ancient lakes: species flock versus species scatter in valvatid gastropods of Lake Ohrid

Ancient lakes have long been recognized as “hot spots of evolution” and “evolutionary theatres” and they have significantly contributed to a better understanding of speciation and radiation processes in space and time. Yet, phylogenetic relationships of many ancient lake taxa, particularly invertebrate groups, are still unresolved. Also, the lack of robust morphological, anatomical, and phylogeographical data has largely prevented a rigorous testing of evolutionary hypotheses. For the freshwater gastropod genus Valvata—a group with a high degree of endemism in several ancient lakes—different evolutionary scenarios are suggested for different ancient lakes. Lake Baikal, for example, is inhabited by several endemic Valvata taxa that presumably do not form a monophyletic group. For such an evolutionary pattern, the term ancient lake species scatter is introduced here. In contrast, for the Balkan Lake Ohrid, workers previously suggested the presence of a monophyletic group of endemic Valvata species, that is, an ancient lake species flock. Sequence data of the mitochondrial cytochrome oxidase c subunit I gene (COI) from worldwide taxa, with a strong emphasis on Balkan species, are here used to test whether the putative Ohrid Valvata endemics represent an ancient lake species flock and to study patterns of speciation both on the Ohrid and the Balkan scale. The study reveals three distinct clades of endemic Valvata in Lake Ohrid. Monophyly of these taxa, however, is rejected, and they therefore do not represent an ancient lake species flock, but rather an ancient lake species scatter. Also, in contrast to many other gastropod groups in Lake Ohrid, the valvatids apparently did not radiate. Many Valvata taxa in ancient lakes are characterized by enhanced levels of shell complexity. However, it remains unclear whether these patterns are associated with ancient lake environments per se. It is here suggested that similarities in shell structure between North American and Balkan taxa might simply be due to convergent evolution.     

Isolation and characterization of adenosine triphosphatase from Salicornia pacifica var. utahensis

Membrane-bound ATPase associated with plasma membrane and solubleATPase associated with the cytoplasm were prepared from shootsof Salicornia pacifica var. utahensis by sucrose density gradientcentrifugation. The isolated ATPases were tolerant to high concentrationsof NaCl. The Km for membrane-bound ATPase was 1.75 mM and forsoluble ATPase, it was 1.4 mM. The relative effectiveness ofdivalent cations for stimulation of membrane-bound ATPase wasMg²⁺>Fe²⁺>Mn²⁺>Co²⁺>Cu²⁺. Soluble ATPase activitywas stimulated by Ba²⁺>Ca²⁺>Mg²⁺ and was inhibited byCu²⁺, Zn²⁺, Co²⁺ and Fe²⁺. The compounds N,N¹-dicyclohexylcarbodiimide,NaF and ADP, did inhibit the ATPases but ouabain, triphenyltinhydroxide, sodium azide, indoleacetic acid and abscisic aciddid not inhibit the ATPases from s. pacifica var. utahensis. ¹ Present address: Department of Biology, Kong-Ju National College,Kong-Ju, Korea. (Received April 1, 1980; )     

Isozyme diversity in some Canarian woody endemisms of the genus Echium L. (Boraginaceae)

Oceanic archipelagos are considered hot-spots of biodiversity because they harbor unique biota with a high level of endemicity. However, the endemic biodiversity of oceanic islands is very vulnerable to extinction. In recent decades, intensive exploitation of these territories and human-mediated introduction of alien species have posed unprecedented threats to the long-term survival of the endemic contingent. The very limited population genetic information available until now for the 28 Canarian endemic Echium taxa has hindered the development of conservation strategies for the ca. 25% of them that are under threat. In this paper, we analyze the levels and distribution of genetic isozyme diversity in 23 natural populations of three endangered endemics of restricted distribution (E. acanthocarpum, CR; E. onosmifolium ssp. spectabile, EN; and E. callithyrsum, VU), and two endemics of wide distribution and in principle free of threat (E. decaisnei and E. onosmifolium). Our results reveal high levels of genetic variability in all these taxa that have plausibly been reached despite a predominance of selfing. They also point out a high incidence of inbreeding in the reproductive dynamics of populations and suggest the potential value of hybridisation processes in shaping the genetic makeup of these species. Among-population differentiation, as estimated by Gst, and genetic distances within taxa are low overall, but they do support the current taxonomic separation between the two subspecies of E. onosmifolium and do not furnish evidence that the current status of the endangered species may be attributed to genetic factors. We use the genetic parameters to suggest some guidelines to help implement a conservation strategy of these taxa.     

Eimeria utahensis sp. n. from Kangaroo Rats (Dipodomys ordii and D. microps) in Northwestern Utah*

SYNOPSIS. The sporulated oocysts of Eimeria utahensis sp. n. from 2 species of kangaroo rats in northwestern Utah are described. The oocysts averaged 42.0 by 39.3 μ, and had rough, yellow-brown walls, about 3 μ thick. In each sporocyst, a substiedal body was seen beneath the Stieda body; this is the 1st report of such a structure in any Eimeria species. E. utahensis was found in 3.6% of 196 Dipodomys ordii and 19.4% of 36 D. microps. The incidence was higher in young adult than in adult Ord kangaroo rats and lowest in juveniles; in D. microps only adults were infected. The mean prepatent period was 9.8 days. The patent period could not be determined because of apparent reinfections; there was no evidence of immunity.     

The life history and in vivo culture of Coelomomyces utahensis (Blastocladiomycetes)

Coelomomyces utahensis is a fungal parasite of several genera of mosquitoes that inhabit rock-pools in southern Utah. Studies of the biology of Coelomomyces and their potential use in biological control of mosquitoes have been hindered by their complex life history, lack of axenic culture methods, and logistical problems producing their arthropod hosts for in vivo culture. In the case of C. utahensis, we have identified the alternate microcrustacean host as Potamocypris unicaudata, which is an ostracod that can be easily reared in abundance and stored for long periods. Described here are the life cycle and culturing of C. utahensis.     

Cryphodera utahensis n. sp., (Heteroderidae), A New Species from Wild Rose in Utah

A new species of Cryphodera Colbran, 1966, parasitic on wild rose (Rosa sp. L.), is described from Utah, USA. Cryphodera utahensis n. sp. most closely resembles C. podocarpi (Wouts, 1973) Luc et al., 1978, but is distinct with respect to a number of characters including juveniles with a longer esophagus (206 versus 142 μm), shorter tail (47 versus 69 μn), and four rather than three incisures in the lateral field. Females of C. utahensis have a terminal protuberance which is more pronounced than in other species. Scanning electron microscope observations of the lip region of males indicate a labial disc surrounded by six lip sectors. However, the remainder of the lip region is comprised of irregularly-shaped plates; similar patterns with longitudinal striae apparently characterize males throughout the genus. The lip pattern of juveniles of C. utahensis n. sp. includes an oval labial disc surrounded by six lip sectors; transverse striae extend the height of the lip region without longitudinal striae. The type locality of C. utahensis confirms a broader distribution of the genus than was indicated for other species, which are limited to Australia (Queensland) and New Zealand.     

Genetic analyses of the federally endangered Echinacea laevigata using amplified fragment length polymorphisms (AFLP)—Inferences in population genetic structure and mating system

Echinacea laevigata (Boynton and Beadle) Blake is a federally endangered flowering plant species restricted to four states in the southeastern United States. To determine the population structure and outcrossing rate across the range of the species, we conducted AFLP analysis using four primer combinations for 22 populations. The genetic diversity of this species was high based on the level of polymorphic loci (200 of 210 loci; 95.24%) and Nei’s gene diversity (ranging from 0.1398 to 0.2606; overall 0.2611). There was significant population genetic differentiation (G_ST = 0.294; Ө^II = 0.218 from the Bayesian f = 0 model). Results from the AMOVA analysis suggest that a majority of the genetic variance is attributed to variation within populations (70.26%), which is also evident from the PCoA. However, 82% of individuals were assigned back to the original population based on the results of the assignment test. An isolation by distance analysis indicated that genetic differentiation among populations was a function of geographic distance, although long-distance gene dispersal between some populations was suggested from an analysis of relatedness between populations using the neighbor-joining method. An estimate of the outcrossing rate based on genotypes of progenies from six of the 22 populations using the multilocus method from the program MLTR ranged from 0.780 to 0.912, suggesting that the species is predominantly outcrossing. These results are encouraging for conservation, signifying that populations may persist due to continued genetic exchange sustained by the outcrossing mating system of the species.     

Conservation genetics of an ex situ population of <Emphasis Type="Italic">Primula reinii</Emphasis> var. <Emphasis Type="Italic">rhodotricha</Emphasis>, an endangered primrose endemic to Japan on a limestone mountain

Primula reinii var. rhodotricha is a perennial herb endemic to the limestone slope of Mt. Buko, located approximately 50 km northwest of central Tokyo, Japan. In recent years, its natural population size has decreased markedly due to limestone mining, and this species has been assigned to the ‘Critically Endangered (CR)’ category on the latest Japanese Red List. Although a remnant population of this species has been protected by a mining company outside their historical distribution range on Mt. Buko, the ex situ conservation of this endangered plant has been difficult because of insufficient low seed production. The genetic status of ex situ P. reinii var. rhodotricha and related species were investigated to develop an effective conservation plan for this species. Microsatellite analysis indicated that the ex situ population harbors lower genetic diversity than sister taxa, providing molecular evidence for the recent critical status designation of the ex situ population, whereas the presence of rare alleles may imply further potential for seed reproduction by outcrossing. Therefore, an appropriate propagation strategy that considers genetic diversity is needed for restoration and recovery of this critically endangered ex situ primrose population.     

Molecular evidence on the species status and phylogenetic relationships of Spiranthes parksii, an endangered orchid from Texas

New genetic information on the taxonomic status of an endangered species may have strong implications for its continued protection and that of other listed taxa with questionable species status. While analyzing a more comprehensive project on the molecular phylogeny of North American Spiranthes (Orchidaceae), lack of genetic differentiation between endangered S. parksii, endemic only to Texas, and a common local congener, S. cernua, was discovered. To confirm these results in a comparative context, we focused parsimony analyses on a subset of data from local Spiranthes and the same congeners found elsewhere, expanded by additional local samples of the two focal species. Four DNA sequence segments (two chloroplast, one mitochondrial, one nuclear ribosomal) totaling 3191 base pairs were used separately and together to verify that S. parksii is nested within the same clade as S. cernua, and thus likely to be the same species. Our results concur with another recent investigation using AFLP and microsatellite data that also suggests S. parksii is not unique genetically. Therefore, based on empirical data and the phylogenetic species concept, endangered S. parksii is merely an aberrant local phenotype of and a synonym for S. cernua sensu lato. Our results should be considered during the current review of this orchid’s listing status, despite some recent policy changes on consideration of genetic data after listing.     

Genetic Diversity inBrassica oleraceaL. (Cruciferae) and Wild Relatives (2n=18) using RAPD Markers

This paper presents the evaluation of genetic diversity in 29populations of wild taxa of theBrassica oleraceaL. group (2n=18)and two cultivars, using RAPDs as molecular markers. In a previouspaper (Lázaro and Aguinagalde,Annals of Botany82: 000–000,1998), 11 isozymes were used for the same purpose. Results obtainedwith the two molecular markers (isozymes and RAPDs) are compared.DNA from ten individuals per population was analysed using sixdifferent primers; the 151 detected bands were polymorphic,11 were common to all species, six to all taxa, only one toevery population; and no bands were shared by every individual.The dendrogram obtained using genetic distances clustersB. oleraceapopulationswithB. bourgeaui, B. alboglabra, B. montanaandB. incana. B.insularis, B. macrocarpa, B. villosaandB. rupestrispopulationsform another cluster. Populations ofB. creticaandB. hilarionisformthe third cluster. Genetic diversity inB. oleraceapopulations,theB. rupestriscomplex andB. creticasubspecies was estimatedusing the AMOVA programme; the latter was the most diverse.Copyright1998 Annals of Botany Company. Brassica oleraceaL., wild relatives, genetic diversity, genetic resources, RAPD markers, AMOVA.     

POPULATION GENETIC STRUCTURE IN DIPLOID BLUEBERRY VACCINIUM SECTION CYANOCOCCUS (ERICACEAE)

Vaccinium section Cyanococcus comprises diploid, tetraploid, and hexaploid species (x = 12) all of which are highly self-sterile. In order to assess the distribution of genetic variation within and among the diploids, population genetic analyses of allozyme data were conducted on three species: V. elliottii, V. myrtilloides, and V. tenellum. Populations were located throughout the range of these taxa in eastern North America. Data were collected at 20 loci, 12 of which are mendelian based on formal genetic analyses. Consistent with expectations for out-crossing taxa, these species exhibited high levels of variation within populations. Eighteen loci were polymorphic with the number and frequency of alleles varying among taxa. Mean values for the number of alleles per polymorphic locus, proportion of polymorphic loci, and expected heterozygosity were 2.8, 48.2, and 0.148, respectively. High infraspecific genetic identities exceeding 0.9 indicated that these taxa are homogeneous. All populations were in Hardy-Weinberg equilibrium with slight heterozygote excess observed in V. myrtilloides and V. tenellum. Although total genetic diversity was lower than that observed for other predominantly out-crossing species, it was apportioned similarly. The majority could be attributed to differences among individuals within populations. Conspecific populations were relatively undifferentiated with genetic differentiation similar to other self-incompatible species.     

POPULATION GENETICS OF EUROPEAN ANODONTINAE (BIVALVIA: UNIONIDAE)

Enzyme electrophoresis was used to study population geneticsand molecular differentiation of European Anodontmae. The existenceof two genera (Anodonta Lamarck 1799 and Pseudanodonta Bour-guignat1876) is supported by the number of diagnostic loa (4) and Net'sD > 0.463 in all cases. In western and central Europe thereare two species of Anodonta, A. anatina (Linnaeus 1758) andA cygnea (Linnaeus 1758) while two other taxa of still uncertainrank were identified in the Mediterranean area. An estimatedmedium level of gene flow and pronounced genetic differentiationbetween-the taxa support this view. Data on genetic distancessuggest that the diversification of European Anodontinae tookplace in the middle-late Pleistocene (Received 15 August 1995; accepted 5 February 1996)