Genetically monomorphic invasive populations of the rapa whelk,Rapana venosa

Rapana venosa is a predatory marine gastropod native to the coastal waters of China, Korea, and Japan. Since the 1940s, R. venosa has been transported around the globe and introduced populations now exist in the Black Sea, the Mediterranean Sea, the Adriatic and Aegean seas, off the coasts of France and the Netherlands, in Chesapeake Bay, Virginia, USA, and in the Rio de la Plata between Uruguay and Argentina. This study surveyed variation in two mitochondrial gene regions to investigate the invasion pathways of R. venosa, identify likely sources for introduced populations, and evaluate current hypotheses of potential transportation vectors. Sequence data were obtained for the mitochondrial cytochrome c oxidase I and NADH dehydrogenase subunit 2 gene regions of 178 individuals from eight native locations and 106 individuals from 12 introduced locations. Collections from within the native range displayed very high levels of genetic variation while collections from all introduced populations showed a complete lack of genetic diversity; a single haplotype was common to all introduced individuals. This finding is consistent with the hypothesis that R. venosa was initially introduced into the Black Sea, and this Black Sea population then served as a source for the other secondary invasions by various introduction vectors including ballast water transport. Although non‐native R. venosa populations currently appear to be thriving in their new environments, the lack of genetic variability raises questions regarding the evolutionary persistence of these populations.     

Invasion genetics of <Emphasis Type="Italic">Senecio vulgaris</Emphasis>: loss of genetic diversity characterizes the invasion of a selfing annual,despite multiple introductions

Genetic variation in invasive populations is affected by a variety of processes including stochastic forces, multiple introductions, population dynamics and mating system. Here, we compare genetic diversity between native and invasive populations of the selfing, annual plant Senecio vulgaris to infer the relative importance of genetic bottlenecks, multiple introductions, post-introduction genetic drift and gene flow to genetic diversity in invasive populations. We scored multilocus genotypes at eight microsatellite loci from nine native European and 19 Chinese introduced populations and compared heterozygosity and number of alleles between continents. We inferred possible source populations for introduced populations by performing assignment analyses and evaluated the relative contributions of gene flow and genetic drift to genetic diversity based on correlations of pairwise genetic and geographic distance. Genetic diversity within Chinese populations was significantly reduced compared to European populations indicating genetic bottlenecks accompanying invasion. Assignment tests provided support for multiple introductions with populations from Central China and southwestern China descended from genotypes matching those from Switzerland and the UK, respectively. Genetic differentiation among populations in China and Europe was not correlated with geographic distance. However, European populations exhibited less variation in the relation between G _ST and geographical distance than populations in China. These results suggest that gene flow probably plays a more significant role in structuring genetic diversity in native populations, whereas genetic drift appears to predominate in introduced populations. High rates of selfing in Chinese populations may restrict opportunities for pollen-mediated gene flow. Repeated colonization-extinction cycles associated with ongoing invasion is likely to maintain low genetic diversity in Chinese populations.     

Genetic variation of <Emphasis Type="Italic">Spartina alterniflora</Emphasis> intentionally introduced to China

Spread of smooth cordgrass (Spartina alterniflora) in China is an exceptional example of unanticipated outcomes arising from intentional introductions. It has been proposed that in China, management strategies used to establish S. alterniflora inadvertently promoted evolutionary outcomes that have contributed to other Spartina invasions. In this study, we assessed whether S. alterniflora in China exhibits genetic signatures of mechanisms known to promote invasion success, including large founding populations, evolved self-fertility, ‘superior source ecotypes’, and post-introduction admixture. This involved comparing microsatellite genotype and chloroplast haplotype variation among Chinese populations to other invasive S. alterniflora populations as well as native range populations, inclusive of samples from all reported source areas. We found distinct signatures of source population contributions to Chinese populations, as well as evidence of post-introduction admixture, and no evidence of limitations from a genetic bottleneck. Measures of inbreeding were well below what has been found in other non-native populations that have evolved self-fertility. Differences in genetic diversity among sites were similar to latitudinal patterns in the native range, but could be attributable to introduction history. Comparisons to other invasive populations indicate that a combination of common and idiosyncratic processes have contributed to the success of S. alterniflora in China and elsewhere, with intentional introductions promoting mechanisms that accelerate rates of spread and widespread invasion.     

Historic speciation and recent colonization of Eurasian monkey gobies (Neogobius fluviatilis and N. pallasi) revealed by DNA sequences,microsatellites, and morphology

Aim Hidden diversity within an invasive ‘species’ can mask both invasion pathways and confound management goals. We assessed taxonomic status and population structure of the monkey goby Neogobius fluviatilis across Eurasia, comparing genetic variation across its native and invasive ranges. Location Native populations were analysed within the Black and Caspian Sea basins, including major river drainages (Dnieper, Dniester, Danube, Don and Volga rivers), along with introduced locations within the upper Danube and Vistula river systems. Methods DNA sequences and 10 nuclear microsatellite loci were analysed to test genetic diversity and divergence patterns of native and introduced populations; phylogenetic analysis of mtDNA cytochrome b and nuclear RAG‐1 sequences assessed taxonomic status of Black and Caspian Sea lineages. Multivariate analysis of morphology was used to corroborate phylogenetic patterns. Population genetic structure within each basin was evaluated with mtDNA and microsatellite data using F_ST analogues and Bayesian assignment tests. Results Phylogenetic analysis of mitochondrial and nuclear sequences discerned a pronounced genetic break between monkey gobies in the Black and Caspian Seas, indicating a long‐term species‐level separation dating to c. 3 million years. This pronounced separation further was confirmed from morphological and population genetic divergence. Bayesian inference showed congruent patterns of population structure within the Black Sea basin. Introduced populations in the Danube and Vistula River basins traced to north‐west Black Sea origins, a genetic expansion pattern matching that of other introduced Ponto‐Caspian gobiids. Main conclusions Both genetic and morphological data strongly supported two species of monkey gobies that were formerly identified as subspecies: N. fluviatilis in the Black Sea basin, Don and Volga Rivers, and the Kumo‐Manych Depression, and Neogobius pallasi in the Caspian Sea and Volga River delta. Genetic origins of introduced N. fluviatilis populations indicated a common invasion pathway shared with other introduced Ponto‐Caspian fishes and invertebrates.     

Genetic diversity and structure of the globally invasive tree, <Emphasis Type="Italic">Paraserianthes lophantha</Emphasis> subspecies <Emphasis Type="Italic">lophantha</Emphasis>, suggest an introduction history characterised by varying propagule pressure

An emerging insight in invasion biology is that intra-specific genetic variation, human usage, and introduction histories interact to shape genetic diversity and its distribution in populations of invasive species. We explore these aspects for the tree species Paraserianthes lophantha subsp. lophantha, a close relative of Australian wattles (genus Acacia). This species is native to Western Australia and is invasive in a number of regions globally. Using microsatellite genotype and DNA sequencing data, we show that native Western Australian populations of P. lophantha subsp. lophantha are geographically structured and are more diverse than introduced populations in Australia (New South Wales, South Australia, and Victoria), the Hawaiian Islands, Portugal, and South Africa. Introduced populations varied greatly in the amount of genetic diversity contained within them, from being low (e.g. Portugal) to high (e.g. Maui, Hawaiian Islands). Irrespective of provenance (native or introduced), all populations appeared to be highly inbred (F _IS ranging from 0.55 to 0.8), probably due to selfing. Although introduced populations generally had lower genetic diversity than native populations, Bayesian clustering of microsatellites and phylogenetic diversity indicated that introduced populations comprise a diverse array of genotypes, most of which were also identified in Western Australia. The dissimilarity in the distribution and number of genotypes in introduced regions suggests that non-native populations originated from different native sources and that introduction events differed in propagule pressure.     

Genetic diversity of native and introduced populations of the invasive house crow (<Emphasis Type="Italic">Corvus splendens</Emphasis>) in Asia and Africa

The common house crow (Corvus splendens) is one of the best known and most wide spread species of the family Corvidae. It is a successful invasive species able to exploit urban environments, well removed from its natural distribution. It is considered a pest as it attains high population densities, can cause serious economic losses and has many adverse effects on native fauna and flora, including predation, competitive displacement and disease transmission. Little genetic research on the house crow has been undertaken so we have only a limited understanding of its natural genetic population structure and invasion history. In this study, we employ microsatellite and mitochondrial DNA markers to assess genetic diversity, phylogeography and population structure of C. splendens within its native range represented by Sri Lanka and Bangladesh and introduced range represented by Malaysia, Singapore, Kenya and South Africa. We found high levels of genetic diversity in some of the invasive populations for which multiple invasions are proposed. The lowest genetic diversity was found for the intentionally introduced population in Selangor, Malaysia. Sri Lanka is a possible source population for Malaysia Selangor consistent with a documented introduction over 100 years ago, with port cities within the introduced range revealing possible presence of migrants from other unsampled locations. We demonstrate the power of the approach of using multiple molecular markers to untangle patterns of invasion, provide insights into population structure and phylogeographic relationships and illustrate how historical processes may have contributed to making this species such a successful invader.     

Evidence of multiple introductions and genetic admixture of the Asian brush-clawed shore crab <Emphasis Type="Italic">Hemigrapsus takanoi</Emphasis> (Decapoda: Brachyura: Varunidae) along the Northern European coast

The Asian brush-clawed shore crab Hemigrapsus takanoi is a non-indigenous species along the Northern European coast. Although the history of range expansion of European H. takanoi has been well-documented, little is known about the genetic compositions of either the introduced European populations or the native Asian ones. We therefore collected H. takanoi broadly from their native Asian sites and introduced European ranges, and genotyped them by sequencing the mitochondrial 16S RNA gene and by analyzing nuclear microsatellite loci. Our results revealed that the H. takanoi Bay of Seine (France) populations consisted of a genetic admixture between populations in Japan and those in the Yellow Sea region. These French populations should be carefully monitored in the future, since the genetic admixture of multiple source populations may accelerate range expansion in non-indigenous organisms. Our results also suggested that shipping lines from East Asia were more probable vectors than historical juvenile oyster transportations from Japan for the foundation of present European H. takanoi populations. Interestingly, gene flow between populations in Japan and those in the Yellow Sea region (i.e., domestic invasion) was not observed despite the higher potential for artificial translocations via shipping lines in the native Asian range compared with those from Asia to Europe. The lack of domestic invasions implied that intra-specific priority effects of the resident H. takanoi populations played an important role in preventing the successful colonization of artificially-transferred individuals.     

Genetic diversity and invasion history of the European subterranean termite <Emphasis Type="Italic">Reticulitermes urbis</Emphasis> (Blattodea,Termitoidae, Rhinotermitidae)

Biological invasions are among key factors of ecological changes, and social insects appear as highly successful invasive animals. Subterranean termites of the holarctic genus Reticulitermes are present in Europe with six native and one invasive (the nearctic R. flavipes) species. The species R. urbis shows a disjunct distribution in the Western Balkans, Eastern Italy and Southern France. Previous molecular and population genetics data suggested that the taxon originated from the Balkans, and that Italian and French populations are invasive, but it is still unknown how many introduction events occurred and from which Balkan source populations. To address these questions, a population genetics analysis was performed on a larger sampling than previous studies, using mitochondrial cytochrome oxidase II and 6 microsatellite markers on 47 colonies collected across the whole distribution area. Mitochondrial analysis confirmed the presence of two major lineages where colonies from Balkans, Italy, and France intermingle. Similarly, microsatellite loci analysis indicated the presence of two genetic clusters, though not corresponding to the two mitochondrial clades, each including colonies from the three sampled areas and with individuals showing mixed cluster membership. Overall, French and Italian populations showed indications of bottleneck (reduced genetic diversity and change of allele frequencies) and do not appear genetically differentiated from the Balkan population. Results presented here support a history of multiple introductions in Italy and France, in a scenario consistent with continuous exchanges between native and invasive areas, as expected along human trades routes.     

Genetic diversity and population structure identify the potential source of the invasive red clover casebearer moth, <Emphasis Type="Italic">Coleophora deauratella</Emphasis>, in North America

The red clover casebearer, Coleophora deauratella, is an invasive pest of red clover grown for seed in North America. In 2006, an outbreak in Alberta, Canada was discovered that resulted in significant seed losses, while further invasion threatens the world’s largest red clover forage seed production region in Oregon, USA. Prior to the recent outbreak, C. deauratella was thought to be restricted to eastern North America in its invasive range. We sequenced a 615-bp fragment of the mitochondrial cytochrome c oxidase subunit 1 gene, and developed three microsatellite markers to assess the genetic diversity and population structure of C. deauratella in North America and its native range in Europe. We observed signatures of a founder effect in North American populations and a further loss of genetic diversity within Alberta populations. Most genetic differentiation was found between continents, with no evidence of isolation-by-distance within each continent. From the limited number of European populations sampled, a single introduction from Switzerland is the most probable source of North American populations based on similar mitochondrial diversity and lack of population differentiation. Within North America, based on increased genetic diversity compared to the rest of the continent, the first North American record from Ithaca, NY, and the first documented outbreak in southern Ontario in 1989, the initial C. deauratella invasion most likely occurred in southern Ontario, Canada or adjacent states in the USA, followed by transport throughout the continent. This study provides insight into the phylogeographic history of C. deauratella in North America and Europe and may help to identify a regional source of future classical biological control agents.     

Reconciling the biogeography of an invader through recent and historic genetic patterns: the case of topmouth gudgeon <Emphasis Type="Italic">Pseudorasbora parva</Emphasis>

The genetic variability and population structure of introduced species in their native range are potentially important determinants of their invasion success, yet data on native populations are often poorly represented in relevant studies. Consequently, to determine the contribution of genetic structuring in the native range of topmouth gudgeon Pseudorasbora parva to their high invasion success in Europe, we used a dataset comprising of 19 native and 11 non-native populations. A total of 666 samples were analysed at 9 polymorphic microsatellite loci and sequenced for 597 bp of mitochondrial DNA. The analysis revealed three distinct lineages in the native range, of which two haplogroups were prevalent in China (100%), with a general split around the Qinling Mountains. Dating of both haplogroups closely matched past geological events. More recently, its distribution has been influenced by fish movements in aquaculture, resulting in gene flow between previously separated populations in Northern and Southern China. Their phylogeography in Europe indicate as few as two introductions events and two dispersal routes. Microsatellite data revealed native populations had higher genetic diversity than those in the invasive range, a contrast to previous studies on P. parva. This study confirms the importance of extensive sampling in both the native and non-native range of invasive species in evaluating the influence of genetic variability on invasion success.     

Haplotype diversity of mt<Emphasis Type="Italic">COI</Emphasis> in the fall webworm <Emphasis Type="Italic">Hyphantria cunea</Emphasis> (Lepidoptera: Arctiidae) in introduced regions in China,Iran, Japan,Korea, and its homeland,the United States

Hyphantria cunea (Drury) has colonized many countries outside its native range of North America and has become a model species for studies of the colonization and subsequent adaptation of agricultural pests. Molecular genetic analyses can clarify the origin and subsequent adaptations to non-native habitats. Using the mitochondrial COI gene, we examined the genetic relationships between invasive populations (China, Iran, Japan, and Korea) and native populations (i.e., the United States). The Jilin (China) and Guilan (Iran) populations showed nine previously unknown haplotypes that differed from those found in the south–central United States, suggesting multiple colonization events and different regions of invasion. A dominant mtDNA haplotype in populations in the United States was shared by all of the populations investigated, suggesting that H. cunea with that haplotype have successfully colonized China, Iran, Japan, and Korea.     

Out of the Black Sea: Phylogeography of the Invasive Killer Shrimp Dikerogammarus villosus across Europe

The amphipod Dikerogammarus villosus has colonized most of the European main inland water bodies in less than 20 years, having deteriorating effect on the local benthic communities. Our aim was to reveal the species phylogeography in the native Black Sea area, to define the source populations for the colonization routes in continental Europe and for the newly established UK populations. We tested for the loss of genetic diversity between source and invasive populations as well as along invasion route. We tested also for isolation by distance. Thirty three native and invasive populations were genotyped for mtDNA (COI, 16S) and seven polymorphic nuclear microsatellites to assess cryptic diversity (presence of deeply divergent lineages), historical demography, level of diversity within lineage (e.g., number of alleles), and population structure. A wide range of methods was used, including minimum spanning network, molecular clock, Bayesian clustering and Mantel test. Our results identified that sea level and salinity changes during Pleistocene impacted the species phylogeography in the Black Sea native region with four differentiated populations inhabiting, respectively, the Dnieper, Dniester, Danube deltas and Durungol liman. The invasion of continental Europe is associated with two sources, i.e., the Danube and Dnieper deltas, which gave origin to two independent invasion routes (Western and Eastern) for which no loss of diversity and no isolation by distance were observed. The UK population has originated in the Western Route and, despite very recent colonization, no drastic loss of diversity was observed. The results show that the invasion of the killer shrimp is not associated with the costs of loosing genetic diversity, which may contribute to the success of this invader in the newly colonized areas. Additionally, while it has not yet occurred, it might be expected that future interbreeding between the genetically diversified populations from two independent invasion routes will potentially even enhance this success.     

Genetic diversity of invasive populations of the florida crab (<Emphasis Type="Italic">Rhithropanopeus harrisii</Emphasis> (Gould, 1841): (Decapoda,Panopidae))

The variability of the mtDNA locus COI in the Florida crab (Rhithropanopeus harrisii) of coastal populations of the northern Black Sea is studied. The introduction of this crab species is demonstrated to originate from European populations, most likely the Netherlands. The studied populations experienced a strong decline in the level of genetic variability based on the haplotype diversity, but to a lesser extent based on the nucleotide diversity. Analysis of the structure of decapod community of Crimea makes it possible to discuss the reasons underlying invasive success of the Florida crab in the region.     

Genetic diversity and population structure of the northern snakehead (<Emphasis Type="Italic">Channa argus</Emphasis> Channidae: Teleostei) in central China: implications for conservation and management

Major threats to freshwater fish diversity now include loss of native genetic diversity as a consequence of translocations of fishes between sites and from hatcheries to sites, and small effective population sizes resulting from overfishing and/or habitat loss. Ten polymorphic microsatellite markers were employed to evaluate genetic diversity, population genetic structure and gene flow amongst nine populations of the ecologically and economically important fish, the northern snakehead (Channa argus), in three river systems in central China. Multiple analyses revealed evidence of high genetic diversity and pronounced subdivision based on both regional separation and on river systems. A lack of evidence of genetic bottleneck over recent generations was consistent with the long-term stability of population size and contemporary distribution. The effective population sizes for most C. argus populations were small, suggesting the need for future conservation efforts focusing on these populations. Different lines of evidence point to the local enhancement of stocks by both aquaculture-reared fish and the transfer of wild fish. This study illustrates how human activities may affect genetic diversity and population genetic structure of C. argus populations, and highlights the need for new management regimes to protect native freshwater fish genetic diversity.     

Human-mediated lineage admixture in an expanding Ponto-Caspian crustacean species <Emphasis Type="Italic">Paramysis lacustris</Emphasis> created a novel genetic stock that now occupies European waters

Identifying the origins and colonization routes of alien species is critical to understanding the mechanisms, consequences and management of invasions. This study aims to demonstrate and explain conflicting genetic signals in a widespread invasive Ponto-Caspian mysid Paramysis lacustris using mitochondrial DNA and microsatellite markers. Native Black Sea populations of P. lacustris are divided into three distinct phylogeographic groups: Danube–Dniester region, coastal Danube lakes, and Dnieper River delta. In the 1950s–1970s the species has been extensively used for relatively well documented transplantations in Eastern Europe. However, the populations in the newly established distribution area do not match any of the known native groups, and their genetic signal does not correspond with the recorded transplantation history. Using Bayesian Approximate Computation we explore alternative scenarios that could explain the unexpected mitochondrial and nuclear signals in the introduced populations. We suggest that reservoir construction and break-up of natural dispersal barriers on the River Dnieper have brought about a novel stock, probably admixed from a previously isolated and unknown “relict” population in the middle Dnieper and the genetically distinct Dnieper delta lineage. Through further intentional transfers this new P. lacustris lineage is now widely present in Eastern Europe and is likely to have new gene and trait combinations. The conflicting mitochondrial-nuclear signal in non-native populations also highlights the importance of using multiple genetic markers when tracing invasion sources and pathways.     

Historical range contraction,and not taxonomy,explains the contemporary genetic structure of the Australian tree <Emphasis Type="Italic">Acacia dealbata</Emphasis> Link

Irrespective of its causes, strong population genetic structure indicates a lack of gene flow. Understanding the processes that underlie such structure, and the spatial patterns it causes, is valuable for conservation efforts such as restoration. On the other hand, when a species is invasive outside its native range, such information can aid management in the non-native range. Here we explored the genetic characteristics of the Australian tree Acacia dealbata in its native range. Two subspecies of A. dealbata have previously been described based on morphology and environmental requirements, but recent phylogeographic data raised questions regarding the validity of this taxonomic subdivision. The species has been widely planted within and outside its native Australian range and is also a highly successful invasive species in many parts of the world. We employed microsatellite markers to investigate the population genetic diversity and structure among 42 A. dealbata populations from across the species’ native range. We also tested whether environmental variables purportedly relevant for the putative separation of subspecies are linked with population genetic differentiation. We found no relationship between population genetic structure of A. dealbata in Australia and these environmental features. Rather, we identified two geographically distinct genetic clusters that corresponded with populations in the northeastern part of mainland Australia, and the southern mainland and Tasmanian range of the species. Our results do not support the taxonomic subdivision of the species into two distinct subspecies based on environmental features. We therefore assume that the observed morphological differences between the putative subspecies are plastic phenotypic responses. This study provides population genetic information that will be useful for the conservation of the species within Australia as well as to better understand the invasion dynamics of A. dealbata.     

Genetic diversity of a hitchhiker and prized food source in the Anthropocene: the Asian green mussel <Emphasis Type="Italic">Perna viridis</Emphasis> (Mollusca,Mytilidae)

Insight into a species’ native and introduced range is essential in understanding the invasion process. Genetic diversity, propagule pressure and environmental conditions all have been recognised as playing a determinant role in invasion success. Here, we aimed to investigate the genetic diversity and population genetic structure (using the COI mtDNA gene region and 22 nDNA microsatellite markers) of the Asian green mussel Perna viridis within its potential native range in Asia and at introduced locations in the USA and the Caribbean. We also analyse genetic data from vessel intercepts and an incursion. By doing so, we aimed to identify genetic signatures that could allow to track vessel samples to their source and provide further insight into potential high-risk invasive populations or areas. Three top hierarchical clusters were identified using the individual-based Bayesian clustering method in STRUCTURE, corresponding to populations in three world regions: (1) USA and Caribbean, (2) India and (3) Southeast Asia. Within Southeast Asia, additional analysis indicate a shallow genetic differentiation of three subgroups consisting of (3a) Thailand, (3b) Taiwan and Hong-Kong, and (3c) a cluster of Singapore–Indonesia samples. Overall, the population structure found in this study suggests that the markers used could be useful in identifying source populations, particularly between the three mains world regions. Most surprisingly however, this study shows that the genetic diversity of samples collected from vessel intercepts and incursions did not differ significantly from established populations in Southeast Asia. In this region, in addition to the high vessel connectivity and number of P. viridis transported, all sampled populations are likely to pose a comparable risk in terms of genetic diversity. The present work represents the most comprehensive population genetic study of P. viridis, and the first to address the potential genetic introduction risk posed by populations of this species. The information and genetic markers in this study constitute a valuable addition to the tools already used to infer on potential high-risk source populations of P. viridis. They should therefore prove useful for biosecurity surveillance and management actions directed at this species.     

Evaluation and comparison of the genetic structure of <Emphasis Type="Italic">Bunias orientalis</Emphasis> populations in their native range and two non-native ranges

We studied the invasive warty cabbage Bunias orientalis (Brassicaceae) in three geographically distinct areas. Using inter-simple sequence repeat fingerprinting, we analyzed warty cabbages, including non-native populations, from the eastern Baltic and western Siberian regions and native populations from southwestern Russia. The eastern Baltic region and western Siberia represent the two opposite directions of B. orientalis spread in climatically different zones. The genetic structures of the native and non-native B. orientalis populations were assessed through analysis of molecular variance (AMOVA) and the Bayesian clustering method and by determining the main measures of genetic diversity. AMOVA revealed considerable population differentiation in both the native and invasive ranges. Our results did not indicate a decrease in genetic diversity in the non-native populations of B. orientalis. Similar measures of genetic diversity and genetic structure were determined in the invasive populations in two geographically and ecologically distinct, non-native regions located in Europe and Asia. In both of these regions, higher genetic diversity was detected in the non-native populations than in the native region populations, which may be due to multiple introductions. However, Bayesian clustering analysis revealed slightly different sources of invasive populations in the two non-native regions. Genetic diversity patterns revealed the lack of isolation by distance between populations and confirmed the influence of anthropogenic factors on the spread of B. orientalis. The significance of native populations as germplasm resources for breeding is discussed.     

Genetic diversity and structure analyses on the natural populations of diploids and triploids of tiger lily, <Emphasis Type="Italic">Lilium lancifolium</Emphasis> Thunb., from Korea,China, and Japan

Tiger lily, Lilium lancifolium Thumb. is an endemic species in Korea. Genetic structure and diversity of diploid and triploid tiger lily accessions were analyzed using SSRP and IRAP molecular markers. All genetic indices analyzed showed that the diploids hold higher genetic variations compared to the triploids which were collected from Korea, China, and Japan. All variations found in triploids were also found in diploids to support the autotriploidy of L. lancifolium. It was also revealed that the triploid populations have experienced population regrowth from small population after population bottleneck. The population and phylogenetic analyses showed that analyzed tiger lilies were partitioned into three populations, Pop 1 from West Sea of Korean Peninsula, Pop 2 from South Sea of Korean Peninsula and Pop 3 of triploids in which many accessions of West Sea and South Sea were admixed in each partitioned group. Although the level of population differentiation is not extensive, F_ST analysis revealed some level of differentiation among the three populations. The analyses of genetic structure and phylogenetic dendrogram revealed admixture in some accessions among populations. All the results obtained in our analyses imply that autotriploid tiger lilies were originated from a small number of accessions of diploid L. lancifolium.     

Different dispersal histories of lineages of the earthworm <Emphasis Type="Italic">Aporrectodea caliginosa</Emphasis> (Lumbricidae,Annelida) in the Palearctic

Earthworms are among the most abundant and ecologically important invasive species, and are therefore a good object for studying genetic processes in invasive populations. Aporrectodea caliginosa is one of the most widespread invasive earthworms in the temperate zone. It is believed to have dispersed from Europe to all continents except Antarctica. It is known that A. caliginosa consists of three genetic lineages, and genetic diversity is high both among and between them. We attempted to use that high genetic diversity to study A. caliginosa dispersal in the Palearctic based on a sample of 40 localities ranging from eastern Europe to the Russian Far East, and to compare our data to other studies on this species in western Europe and North America. Two genetic lineages were found in the studied sample. Only negligible decrease in genetic diversity was observed for the lineage 2 of A. caliginosa from West Europe to the Far East, suggesting multiple human-mediated introductions. In contrast, lineage 3 is abundant in West Europe and Belarus, but is absent from the East European Plain, the Urals, and the Far East. However, it is present in West Siberia, where it has greatly reduced genetic diversity, indicating long-distance dispersal accompanied by a bottleneck event. Thus, although these two lineages of A. caliginosa are morphologically indistinguishable, they have dramatic differences in their distributions and dispersal histories.