Genetic Structure of Pyricularia grisea (Cooke) Sacc. Isolates from Italian Paddy Fields

Rice blast disease, caused by the fungus Pyricularia grisea (Cooke) Sacc., is responsible for considerable damages in rice crops in Italy and in other parts of the world. This study was conducted in order to investigate the genetic structure of a P. grisea population in the Po area, the largest rice area in Italy. Rice leaves showing blast symptoms were collected in three successive years (1998–2000) and 43 P. grisea monoconidial culture samples were isolated from infected rice leaves. Fungal DNAs were obtained from mycelia. Moreover, six additional P. grisea DNA samples representative for the five characterized European lineages were also investigated. All 49 DNAs were fingerprinted using the Pot2‐based repetitive polymerase chain reaction specific for the blast pathogen. Unweighted pair‐group method with arithmetic averages cluster analysis shows the presence of three main Italian lineages. Within lineages, similarity was higher than 80%. Samples representative of the three of five known European lineages grouped within these three Italian lineages confirming the presence of three European lineages in Italy. Furthermore, cluster analysis shows the presence of two new haplotypes never found before in the Italian lineage.     

Geographic Patterns of Genetic Variation in a Broadly Distributed Marine Vertebrate: New Insights into Loggerhead Turtle Stock Structure from Expanded Mitochondrial DNA Sequences

Previous genetic studies have demonstrated that natal homing shapes the stock structure of marine turtle nesting populations. However, widespread sharing of common haplotypes based on short segments of the mitochondrial control region often limits resolution of the demographic connectivity of populations. Recent studies employing longer control region sequences to resolve haplotype sharing have focused on regional assessments of genetic structure and phylogeography. Here we synthesize available control region sequences for loggerhead turtles from the Mediterranean Sea, Atlantic, and western Indian Ocean basins. These data represent six of the nine globally significant regional management units (RMUs) for the species and include novel sequence data from Brazil, Cape Verde, South Africa and Oman. Genetic tests of differentiation among 42 rookeries represented by short sequences (380 bp haplotypes from 3,486 samples) and 40 rookeries represented by long sequences (∼800 bp haplotypes from 3,434 samples) supported the distinction of the six RMUs analyzed as well as recognition of at least 18 demographically independent management units (MUs) with respect to female natal homing. A total of 59 haplotypes were resolved. These haplotypes belonged to two highly divergent global lineages, with haplogroup I represented primarily by CC-A1, CC-A4, and CC-A11 variants and haplogroup II represented by CC-A2 and derived variants. Geographic distribution patterns of haplogroup II haplotypes and the nested position of CC-A11.6 from Oman among the Atlantic haplotypes invoke recent colonization of the Indian Ocean from the Atlantic for both global lineages. The haplotypes we confirmed for western Indian Ocean RMUs allow reinterpretation of previous mixed stock analysis and further suggest that contemporary migratory connectivity between the Indian and Atlantic Oceans occurs on a broader scale than previously hypothesized. This study represents a valuable model for conducting comprehensive international cooperative data management and research in marine ecology.     

Genetic evidence of multiple matrilineal lineages of the channel catfish, Ictalurus punctatus in North America

Using mitochondrial DNA control region (mtDNA CR) sequence data the present study evaluates the genetic status of the wild populations of channel catfish, Ictalurus punctatus, in North America. A total of 584 individuals representing 56 drainages across its distributional range in the United States were collected. There were 105 mtDNA CR haplotypes defined by 51 variable sites. Phylogenetic analyses have revealed the existence of six distinct matrilineal genetic lineages of channel catfish in the United States. Four of these lineages were restricted to southeast Gulf Coast, a region that never glaciated during the Pleistocene. While samples from the Mississippi river and its tributaries represent a single genetic lineage, samples from the southeast Atlantic coastal plain drainages formed a unique lineage. Each lineage should be regarded as an evolutionarily significant unit/management unit and therefore separate management and conservation strategies should be undertaken in order to conserve the genetic resources.     

Avian haematozoan parasites and their associations with mosquitoes across Southwest Pacific Islands

The degree to which haematozoan parasites can exploit a range of vectors and hosts has both ecological and evolutionary implications for their transmission and biogeography. Here we explore the extent to which closely related mosquito species share the same or closely related haematozoan parasites, and examine the overlap in parasite lineages with those isolated from avian hosts, Zosterops species, sampled across the same study sites. Mosquito samples were collected and analysed (14 species, n = 804) from four islands in Vanuatu and the main island of New Caledonia. Using polymerase chain reaction, 15.5% (14/90) of pooled mosquito (thoracic) samples showed positive amplifications. Subsequent phylogenetic analysis of the cytochrome b gene identified four genetically distinct Plasmodium and two Haemoproteus lineages from these samples, five of which were identical to parasite lineages (n = 21) retrieved from the avian hosts. We found that three Plasmodium lineages differing by a maximum of 0.9% sequence divergence were recovered from different species and genera of mosquitoes and two Haemoproteus lineages differing by 4.6% sequence divergence were carried by 10 distantly related (11-21% divergent) mosquito species. These data suggest a lack of both cospeciation and invertebrate host conservatism. Without experimental demonstration of the transmission cycle, it is not possible to establish whether these mosquitoes are the biological vectors of isolated parasite lineages, reflecting a limitation of a purely polymerase chain reaction-based approach. Nonetheless, our results raise the possibility of a new transmission pathway and highlight extensive invertebrate host shifts in an insular mosquito-parasite system.     

Molecular diversity and distribution of marine fungi across 130 European environmental samples

Environmental DNA and culture-based analyses have suggested that fungi are present in low diversity and in low abundance in many marine environments, especially in the upper water column. Here, we use a dual approach involving high-throughput diversity tag sequencing from both DNA and RNA templates and fluorescent cell counts to evaluate the diversity and relative abundance of fungi across marine samples taken from six European near-shore sites. We removed very rare fungal operational taxonomic units (OTUs) selecting only OTUs recovered from multiple samples for a detailed analysis. This approach identified a set of 71 fungal ‘OTU clusters'' that account for 66% of all the sequences assigned to the Fungi. Phylogenetic analyses demonstrated that this diversity includes a significant number of chytrid-like lineages that had not been previously described, indicating that the marine environment encompasses a number of zoosporic fungi that are new to taxonomic inventories. Using the sequence datasets, we identified cases where fungal OTUs were sampled across multiple geographical sites and between different sampling depths. This was especially clear in one relatively abundant and diverse phylogroup tentatively named Novel Chytrid-Like-Clade 1 (NCLC1). For comparison, a subset of the water column samples was also investigated using fluorescent microscopy to examine the abundance of eukaryotes with chitin cell walls. Comparisons of relative abundance of RNA-derived fungal tag sequences and chitin cell-wall counts demonstrate that fungi constitute a low fraction of the eukaryotic community in these water column samples. Taken together, these results demonstrate the phylogenetic position and environmental distribution of 71 lineages, improving our understanding of the diversity and abundance of fungi in marine environments.     

Prevalence patterns of avian haemosporida on Hispaniola

We used PCR to screen for the presence of haemosporidian parasites (Phylum: Apicomplexa; Order: Haemosporida) in avian blood samples, and sequenced the parasite mitochondrial cytochrome b gene from infected hosts, to study patterns in the prevalence of haemosporidians in 1,166 individuals of 50 species in four habitats along an elevation gradient in the Sierra de Bahoruco, Dominican Republic, island of Hispaniola. We found an overall prevalence of 0.44 among species with ≥10 individuals sampled per year, but this varied considerably among species. We found no difference in infection rates between years, between males and females, between second‐year (<1 y old) and older birds, or among members of different foraging guilds. Prevalence differed significantly among migratory, endemic resident, and non‐endemic resident species, with endemics having the highest rates of infection. Prevalence also varied among habitats, decreasing with increasing elevation, but the pattern was confounded by variation in the host species present at each elevation. From 215 sequenced parasites from 17 species of avian hosts, we recovered multiple examples of 12 lineages of Haemoproteus (Parahaemoproteus), two lineages of a Columbiformes‐specific clade of H. (Haemoproteus), and 10 lineages of Plasmodium, with an additional seven lineages sampled only once. A single parasite lineage was responsible for 34.4% of all infections, but five more lineages made up 41.8% of all infections. Several lineages were broadly distributed across multiple host species, but six lineages, all H. (Haemoproteus) or H. (Parahaemoproteus), were recorded from at least five individuals of a single host, suggesting host specialization. The number of host species from which each parasite lineage was recovered varied from one to nine; several host species harbored as many as 5–9 parasite lineages. Longitudinal data suggest that while hosts might harbor the same parasite lineage for more than a year, some hosts appear to clear infections from their circulating blood, while others manifested infections by a different parasite lineage.     

The Genetic Structure of Populations of Potato virus Y in Japan; Based on the Analysis of 20 Full Genomic Sequences

The genetic structure of Potato virus Y (PVY) populations in Japan was analysed using 20 isolates; five were retrieved from the public DNA sequence databases, and an additional 15 complete genomic sequences were determined using field samples collected in Japan. Recombination and phylogenetic analyses of a total of 149 isolates from Japan and other countries showed that PVY has three major lineages (C, N and O); at least one, two and six sublineages in C, N and O lineages, respectively. One recombination pattern was newly found among Japanese PVY^NTN strain isolates, which was most closely related to the PVY^NTN strain isolates previously found in Europe and North America. On the other hand, PVY^O was a complex of several divergent lineages, and there were at least three non‐recombinant subpopulations in Japan. Studies on nucleotide diversities of populations and phylogenetic relationships of the isolates in the PVY sequences showed that Japanese PVY populations were in part distinct from the European and North American populations.     

Revealing cryptic diversity using molecular phylogenetics and phylogeography in frogs of the Scinax ruber and Rhinella margaritifera species groups

Few studies to date have examined genetic variability of widespread tropical amphibian species over their distributional range using different kinds of molecular markers. Here, we use genetic data in an attempt to delimit evolutionary entities within two groups of Neotropical frogs, the Scinax ruber species group and the Rhinella margaritifera species group. We combined mitochondrial and nuclear markers for a phylogenetic (a total of approximately 2500 bp) and phylogeographic study (approximately 1300 bp) to test the reliability of the currently accepted taxonomic assignments and to explore the geographic structure of their genetic variation, mainly based upon samples from the French Guianan region. Phylogenetic analyses demonstrated the polyphyly of Scinax ruber and Rhinella margaritifera. S. ruber consists of six lineages that may all merit species status. Conflicting signals of mitochondrial and nuclear markers indicated, among some Scinax lineages and species, the possibility of ongoing hybridization processes. R. margaritifera consisted of 11 lineages which might represent distinct species as well. Phylogeographic analyses added further information in support of the specific status of these lineages. Lineages of low divergence were found in sympatry and were reciprocally monophyletic for mitochondrial as well as nuclear genes, indicating the existence of young lineages that should be awarded species status. Our results highlight the utility of combining phylogenetic and phylogeographic methods, as well as the use of both mitochondrial and nuclear markers within one study. This approach helped to better understand the evolutionary history of taxonomically complex groups of species. The assessment of the geographic distribution of genetic diversity in tropical amphibian communities can lead to conclusions that differ strongly from prior analyses based on the occurrence of currently recognized species alone. Such studies, therefore, hold the potential to contribute to a more objective assessment of amphibian conservation priorities in tropical areas.     

Characterizing genetic diversity of contemporary pacific chickens using mitochondrial DNA analyses

Background

Mitochondrial DNA (mtDNA) hypervariable region (HVR) sequences of prehistoric Polynesian chicken samples reflect dispersal of two haplogroups—D and E—by the settlers of the Pacific. The distribution of these chicken haplogroups has been used as an indicator of human movement. Recent analyses suggested similarities between prehistoric Pacific and South American chicken samples, perhaps reflecting prehistoric Polynesian introduction of the chicken into South America. These analyses have been heavily debated. The current distribution of the D and E lineages among contemporary chicken populations in the Western Pacific is unclear, but might ultimately help to inform debates about the movements of humans that carried them.

Objectives

We sought to characterize contemporary mtDNA diversity among chickens in two of the earliest settled archipelagoes of Remote Oceania, the Marianas and Vanuatu.

Methods

We generated HVR sequences for 43 chickens from four islands in Vanuatu, and for 5 chickens from Guam in the Marianas.

Results

Forty samples from Vanuatu and three from Guam were assigned to haplogroup D, supporting this as a Pacific chicken haplogroup that persists in the Western Pacific. Two haplogroup E lineages were observed in Guam and two in Vanuatu. Of the E lineages in Vanuatu, one was identical to prehistoric Vanuatu and Polynesian samples and the other differed by one polymorphism. Contrary to our expectations, we observed few globally distributed domesticate lineages not associated with Pacific chicken dispersal. This might suggest less European introgression of chickens into Vanuatu than expected. If so, the E lineages might represent lineages maintained from ancient Pacific chicken introductions. The Vanuatu sample might thus provide an opportunity to distinguish between maintained ancestral Pacific chicken lineages and replacement by global domesticates through genomic analyses, which could resolve questions of contemporary haplogroup E chicken relationships and inform interpretations of debated sequences from archaeological samples.     

Spatial framework of nine distinct local populations of the Japanese dormouse Glirulus japonicus based on matrilineal cytochrome b and patrilineal SRY gene sequences

We previously revealed the presence of six genetically distinct matrilineal populations of the Japanese dormouse Glirulus japonicus in the distribution range of Honshu, Shikoku, and Kyushu islands. In this study, we extended this analysis using mitochondrial cytochrome b gene sequences (n = 96) and Y-chromosome-specific SRY gene sequences (n = 22) from individuals collected from Honshu, Shikoku, Kyushu, and Oki Dogo I. The cytochrome b sequence data allowed us to define precise geographic ranges of the six previously known and three newly found distinct matrilineal lineages: northeastern Honshu (I), east-central Honshu (II), west-central Honshu and the Kii Peninsula (III), the western part of Honshu (IV), Shikoku (V), westernmost Honshu and Kyushu (VI), the northern part of central Honshu (VII), the southern part of central Honshu (VIII), and Oki Dogo I. (IX). Our inference of geographic borders suggests that regions of lower and higher altitudes in the mountain systems played important roles in driving the hosting and separation of lineages, respectively. Six matrilineal lineages (I, II, V, VI, VIII, and XI) were shown to possess their own SRY haplotypes, while lineages III and IV shared one haplotype. These data together with our previous observation of nuclear ribosomal RNA gene variation indicate advanced populational subdivision in this species. It is thus evident that each of the populations, including those living at high latitudes and in limited geographic spaces, have survived for several million years. A specific ability to tolerate cold may have permitted G. japonicus to preserve anciently diverged lineages in each locality.     

Interplay of host specificity and biogeography in the population structure of a cosmopolitan endoparasite: microsatellite study of Ligula intestinalis (Cestoda)

Organisms with wide geographical or phenotypic diversity often constitute assemblages of genetically distinct species or lineages. Within parasites, an emergence of host-specific lineages is assumed to create such cryptic variability; however, empirical evaluation of these processes is scarce. Here, we analyse populations of a parasite with a complex life cycle, wide host spectrum and global distribution, with the aim to reveal factors underlying the evolution of host- or geography-dependent lineages. Using 15 microsatellite loci, deep genetic distances were observed between populations from distant geographical areas. On the local scale, host-mediated genetic structure was found among sympatric samples. Two lineages differing in the spectrum of infected hosts co-occurred in the Euro-Mediterranean area, and two distinct lineages were recovered from Lake Tana in Ethiopia. Although sampled across several host taxa and multiple localities, a lack of marked genetic structure was seen in the populations belonging to one of the European lineages. Only weak genetic differentiation between sympatric samples from two host species was found. Complexity of the parasite life-cycle contributed to such a stratified pattern. Differences in the immune response between fish hosts were suggested as the factor diversifying the populations locally; conversely, high mobility of the parasite due to migration with its bird (definitive) host were assessed to homogenize populations across the area of distribution. However, despite the high mobility, large bodies of salt water prevent the parasite from long-distance migrations, as was demonstrated in an example of the Mediterranean Sea which represented an effective barrier to gene flow.     

Molecular epidemiology of rabies in Thailand.

For the purpose of making clear the dynamics of rabies viruses that are prevalent among dogs in Asia, especially Thailand, nucleoprotein (N) genes of isolates derived from Thailand were partially sequenced, and a phylogenetic analysis was performed on the basis of the sequencing data. Firstly, all 27 isolates from Thailand belonged to one group that was distantly related to an isolate from China and was separated into at least six lineages. On the other hand, the isolate from Japan was related to viruses from the Arctic. Secondly, in order to analyze the diversity of the N gene more conveniently, restriction fragment length polymorphism (RFLP) analysis was performed on the N gene of 27 isolates from Thailand. The RFLP analysis could distinguish the lineages of each isolate, and the lineages of additional 34 isolates were deduced by this method. On examination of the geographical distribution of the six lineages, based on the results of phylogenetic and RFLP analyses, it was clear that infection cycles of the rabies virus in Thailand have tended to be maintained endemically.     

Mito‐nuclear discord in six congeneric lineages of Holarctic ducks (genus Anas)

Many species have Holarctic distributions that extend across Europe, Asia and North America. Most genetics research on these species has examined only mitochondrial (mt) DNA, which has revealed wide variance in divergence between Old World (OW) and New World (NW) populations, ranging from shallow, unstructured genealogies to deeply divergent lineages. In this study, we sequenced 20 nuclear introns to test for concordant patterns of OW–NW differentiation between mtDNA and nuclear (nu) DNA for six lineages of Holarctic ducks (genus Anas). Genetic differentiation for both marker types varied widely among these lineages (idiosyncratic population histories), but mtDNA and nuDNA divergence within lineages was not significantly correlated. Moreover, compared with the association between mtDNA and nuDNA divergence observed among different species, OW–NW nuDNA differentiation was generally lower than mtDNA divergence, at least for lineages with deeply divergent mtDNA. Furthermore, coalescent estimates indicated significantly higher rates of gene flow for nuDNA than mtDNA for four of the six lineages. Thus, Holarctic ducks show prominent mito‐nuclear discord between OW and NW populations, and we reject differences in sorting rates as the sole cause of the within‐species discord. Male‐mediated intercontinental gene flow is likely a leading contributor to this discord, although selection could also cause increased mtDNA divergence relative to weak nuDNA differentiation. The population genetics of these ducks contribute to growing evidence that mtDNA can be an unreliable indicator of stage of speciation and that more holistic approaches are needed for species delimitation.     

Cryptic diversity in the pen shell Atrina pectinata (Bivalvia: Pinnidae): high divergence and hybridization revealed by molecular and morphological data

Cryptic species have been increasingly revealed in the marine realm through an analytical approach incorporating multiple lines of evidence (e.g., mtDNA, nuclear genes and morphology). Illustrations of cryptic taxa improve our understanding of species diversity and evolutionary histories within marine animals. The pen shell Atrina pectinata is known to exhibit extensive morphological variations that may harbour cryptic diversity. In this study, we investigated A. pectinata populations along the coast of China and one from Japan to explore possible cryptic diversity and hybridization using a combination of mitochondrial (cytochrome c oxidase subunit I, mtCOI) and nuclear (ribosomal internal transcribed spacer, nrITS) genes as well as morphology. Phylogenetic analyses of mtCOI ‘DNA barcoding gene’ sequences resolved six divergent lineages with intralineage divergences between 0.4% and 0.8%. Interlineage sequence differences ranged from 4.3% to 22.0%, suggesting that six candidate cryptic species are present. The nrITS gene revealed five deep lineages with Kimura 2‐parameter distances of 3.7–30.3%. The five nuclear lineages generally corresponded to mtCOI lineages 1–4 and (5 + 6), suggestive of five distinct evolutionary lineages. Multiple nrITS sequences of significant variance were found within an individual, clearly implying recent hybridization events between/among the evolutionary lineages, which contributed to cytonuclear discordance. Morphologically, five morphotypes matched the five genetic lineages, although the intermediates may well blur the boundaries of different morphotypes. This study demonstrates the importance of combining multiple lines of evidence to explore species cryptic diversity and past evolutionary histories.     

Distribution patterns and phylogeny of marine stramenopiles in the north pacific ocean

Marine stramenopiles (MASTs) are a diverse suite of eukaryotic microbes found in marine environments. Several MAST lineages are thought to contain heterotrophic nanoflagellates. However, MASTs remain uncultured and data on distributions and trophic modes are limited. We investigated MASTs in provinces on the west and east sides of the North Pacific Subtropical Gyre, specifically the East China Sea (ECS) and the California Current system (CALC). For each province, DNA was sampled from three zones: coastal, mesotrophic transitional, and more oligotrophic euphotic waters. Along with diatoms, chrysophytes, and other stramenopiles, sequences were recovered from nine MAST lineages in the six ECS and four CALC 18S rRNA gene clone libraries. All but one of these libraries were from surface samples. MAST clusters 1, 3, 7, 8, and 11 were identified in both provinces, with MAST cluster 3 (MAST-3) being found the most frequently. Additionally, MAST-2 was detected in the ECS and MAST-4, -9, and -12 were detected in the CALC. Phylogenetic analysis indicated that some subclades within these lineages differ along latitudinal gradients. MAST-1A, -1B, and -1C and MAST-4 size and abundance estimates obtained using fluorescence in situ hybridization on 79 spring and summer ECS samples showed a negative correlation between size of MAST-1B and MAST-4 cells and temperature. MAST-1A was rarely detected, but MAST-1B and -1C and MAST-4 were abundant in summer and MAST-1C and MAST-4 were more so at the coast, with maximum abundances of 543 and 1,896 cells ml(-1), respectively. MAST-4 and Synechococcus abundances were correlated, and experimental work showed that MAST-4 ingests Synechococcus. Together with previous studies, this study helps refine hypotheses on distribution and trophic modes of MAST lineages.     

Phylogeography of the flathead mullet Mugil cephalus in the north-west Pacific as inferred from the mtDNA control region

The population genetic structure and historical demography of the flathead mullet Mugil cephalus were investigated using the mtDNA control region (CR) sequences (909–1015 bp) of 126 individuals collected from seven locations in the north-west Pacific between 2005 and 2007. Haplotype diversity ( h = 0·9333–1·000) and nucleotide diversity (π = 0·0046–0·1467) varied greatly among the sampling locations. Phylogenetic analysis of the CR sequences indicated that M. cephalus in the north-west Pacific belongs to two highly divergent lineages (lineages 1 and 2), with the inferred population structure being closely associated with the distribution of both lineages. Two populations were identified, one from the East China Sea and the other from the South China Sea. The former samples were obtained from Taiwan and Qingdao of north China and associated with lineage 1 haplotypes. The latter samples were collected from the Philippines, Pearl River of South China and two samples from Japan, all of which were associated with lineage 2. Japanese samples from Okinawa and Yokosuka had different degrees of mixing between lineages 1 and 2. Historical demographic variables in both populations indicated that Pleistocene glaciations had a strong impact on M. cephalus in the north-west Pacific, resulting in a recent demographic decline of the East China Sea population but in demographic equilibrium for the South China Sea population. Japan appears to be a contact zone between lineages 1 and 2, but it may also be indicative of coexistence between resident and migratory populations. Further global studies are required to clarify the taxonomic status of this cosmopolitan species.     

Cryptic lineages and potential introgression in a mixed-ploidy species (Phragmites australis) across temperate China

Polyploidization and hybridization are very common in natural plant species, and mixed-ploidy species provide a unique opportunity to study the effects of evolutionary history, local abundance, and ploidy level on the direction and extent of introgression between intraspecific lineages. First, we delimited two morphologically cryptic lineages of Phragmites australis Trin. ex Steud. in temperate China using 11 nuclear microsatellites and two chloroplast DNA fragments with 225 samples from China as well as 11 samples from Oceania and Europe. Our evidence supported that haplotype O and haplotype P were two relatively independent lineages with low and high ploidy levels, respectively; haplotype M might be ancient and could have undergone a complex evolutionary history. Then we examined the lineage divergence and compared the introgression patterns between two major lineages along geographical and abundance gradients with a large number of samples (n = 1067) collected from China. The sympatric coexistence of two lineages in north and northeast China implies an ongoing or potential introgression between them. Cline analysis showed that the level of genetic admixture were significantly correlated with longitude rather than latitude. Our results also suggested that ploidy level could deeply influence the introgression asymmetry, and the effect of the current local abundance on introgression might be covered by the past coexistence time driven by phylogeographic history. Our study draws a baseline for future research on the ecological and evolutionary consequences of migration and introgression of Chinese P. australis under global change.     

The evolutionary history of a mammal species with a highly fragmented range: the phylogeography of the European snow vole

The European snow vole Chionomys nivalis has a patchy distribution restricted to rocky habitats across southern Europe and the Near and Middle East. We carried out a phylogeographic study to provide a biogeographic scenario, based on molecular data, outlining the major processes that determined the current distribution of the species. The samples include 26 snow voles from 14 different populations across the entire species range from Spain to Anatolia and Israel. Nearly complete sequences (1037 bp) of the mitochondrial gene for cytochrome b were sequenced. Relationships among haplotypes were inferred with neighbour-joining, maximum likelihood, maximum parsimony analyses and minimum spanning network. An analysis of mismatch distribution was used to cast light on past demographic expansion. We found 22 different haplotypes that fall into six distinct lineages, all but one is supported by high bootstrap values with all methods. Four lineages are allopatric (Tatra Mts., Iberia, Balkans and Middle East) while divergent haplotypes from two lineages show sympatry in the Alps and the Apennines. The basal relationships of these lineages could not be established by any tree. The mean pairwise genetic distance between lineages ranges from 2.4 to 4.2%. The shape of the mismatch distribution indicated a past expansion event dating back to between 158 000 and 84 000 years ago. These data can be interpreted with the existence of southern glacial refugia (Iberia, Balkans, Middle East and Italy) and one additional northern glacial refugium. The lack of phylogenetic resolution among lineages and the shape of mismatch distribution are indicative of a simultaneous and rapid splitting due to a relatively fast initial expansion of populations. Moreover, the analysis supports the hypothesis of the European origin of C. nivalis and its subsequent eastward dispersion during the Middle Pleistocene.     

Connectivity,small islands and large distances: the Cellana strigilis limpet complex in the Southern Ocean

The Southern Ocean contains some of the most isolated islands on Earth, and fundamental questions remain regarding their colonization and the connectivity of their coastal biotas. Here, we conduct a genetic investigation into the Cellana strigilis (limpet) complex that was originally classified based on morphological characters into six subspecies, five of which are endemic to the New Zealand (NZ) subantarctic and Chatham islands (44–52°S). Previous genetic analyses of C. strigilis from six of the seven island groups revealed two lineages with little or no within‐lineage variation. We analysed C. strigilis samples from all seven island groups using two mitochondrial (COI and 16S), one nuclear (ATPase β) and 58 loci from four randomly amplified polymorphic DNA markers (RAPDs) and confirmed the existence of two distinct lineages. The pronounced genetic structuring within each lineage and the presence of private haplotypes in individual islands are the result of little genetic connectivity and therefore very high self‐recruitment. This study supports the significance of the subantarctic islands as refugia during the last glacial maximum and adds to the knowledge of contemporary population connectivity among coastal populations of remote islands in large oceans and the distance barrier to gene flow that exists in the sea (despite its continuous medium) for most taxa.