Intraspecific mitochondrial DNA variation in the Colorado potato beetle,Leptinotarsa decemlineata (Coleoptera: Chrysomelidae)

Restriction endonuclease analyses of mitochondrial DNA (mtDNA) were used to examine genetic variability and population structure inLeptinotarsa decemlineata (Say). A group of three enzymes, EcoRI, HpaI, and PstI, was used to reveal polymorphism both within and among some of the 10 populations tested, yielding 16 haplotypes in combination. The frequencies of these 16 haplotypes differed significantly across geographic regions, indicating some partitioning of mtDNA haplotypes. Estimates of mtDNA sequence divergence (δ) between haplotypes ranged from 0.016 to 0.135%, suggesting local differentiation of mtDNA in some populations. Analysis of these data suggests that Texas was colonized by more than one mtDNA lineage, most likely originating in Mexico. We hypothesize that a larger founder size for the initial introductions or high levels of variability in the parent population at the edge of the CPB expanding range led to the initial partitioning of haplotypes observed in samples from Texas.     

Spatial analysis of nuclear and mitochondrial RFLP genotypes in populations of the chestnut blight fungus, Cryphonectria parasitica

Spatial structure of both nuclear and mitochondrial RFLPs were studied in several populations of the chestnut blight fungus, Cryphonectria parasitica, using a variety of spatial autocorrelation tests designed to detect nonrandom patterns. Fungal individuals were sampled from cankers on infected chestnut trees, and the location of each tree was mapped. Single-locus nuclear RFLPs, nuclear fingerprints, and mitochondrial DNA haplotypes were determined for each individual. Individuals with the same DNA fingerprint genotypes occurred closer together than would be expected at random in four of the five plots, while mitochondrial DNA haplotypes were aggregated in all five plots. Genetic distances between individuals, expressed as one minus the proportion of shared restriction fragment size classes for fingerprints and mitochondrial haplotypes, were significantly correlated with Euclidean distances between individuals in four of the five populations, but these correlations were very weak (r < 0.18). The same DNA fingerprint and single-copy nuclear RFLP alleles occurred on the same trees or immediately neighbouring trees more often than would be expected at random. Most of the aggregation for all three genetic markers occurred among individuals within the same cluster of chestnut stems or on neighbouring trees. Lack of spatial autocorrelation in one population was probably due to sampling on a larger scale that was too coarse to detect any patterns. Significant aggregation of genotypes in C. parasitica is most likely caused by some degree of restricted dispersal within populations. The implications of restricted dispersal are discussed in relation to the breeding system and isolation by distance in populations of. C. parasitica.     

Mitochondrial haplotypes in populations of the plant-infecting fungus Sclerotinia sclerotiorum: wide distribution in agriculture, local distribution in the wild

Analysis of mitochondrial DNA (mtDNA) haplotypes of Sclerotinia sclerotiorum points to a common origin of some genotypes from agricultural populations, especially when compared with two wild populations that are sharply distinguished from the agricultural sample and from each other. Five agricultural population samples from canola (Alberta, Canada and Norway), cabbage (North Carolina, USA), sunflower (Manitoba, Canada and Queensland, Australia) and two Norwegian populations from a wild plant, Ranunculus ficaria were compared. Haplotypes were determined by Southern hybridization of purified organelle DNA from S. sclerotiorum and Neurospora crassa to total genomic DNA of S. sclerotiorum. Each isolate had one haplotype. Haplotypes of S. sclerotiorum from R. ficaria were different between the two wild populations and also from all haplotypes observed in the agricultural populations. Among the wild isolates, DNA fingerprint, mtDNA haplotype and location in the sampling transect were all associated. Among the agricultural isolates, four haplotypes were observed in at least two agricultural populations and one haplotype was observed in all agricultural populations. In the Canadian canola sample some clones had one mtDNA haplotype, indicating association with DNA fingerprint, some clones had more than one haplotype, and some groups of clones shared haplotypes. Some of the haplotype diversity may be due to the presence of extra-chromosomal elements associated with the mitochondria of S. sclerotiorum.     

The structure and interrelationship of fungal populations in native and cultivated soils

Mitochondrial DNA haplotypes have been characterized for 120 isolates of the asexual fungus Fusarium oxysporum. Sixty of these isolates were obtained from soil in a native grassland in the San Joaquin Valley of California, including 20 isolates from each of six different sampling locations. The same sampling strategy was used to obtain 60 additional isolates from an agricultural field of the same soil type directly adjacent to the native soil. Twenty-three different mitochondrial DNA haplotypes were identified among the 120 isolates, including 11 haplotypes represented by two or more isolates and 12 that were unique. The five most common mitochondrial DNA haplotypes accounted for 93 (78%) of the 120 isolates. Isolates representing each of these five mitochondrial DNA haplotypes were found both in the cultivated and in the native soil. Seventy-two per cent of the isolates found in the cultivated soil were associated with the same mitochondrial DNA haplotype as one or more isolates in the native soil. The remaining isolates in the cultivated soil were associated with comparatively rare mitochondrial DNA haplotypes, most of which showed a close relationship to one of the haplotypes found in the native soil. Hierarchial gene diversity analysis indicated that a significant proportion of the mitochondrial DNA haplotype diversity was attributable to differences between sampling sites in the native soil but not in the cultivated soil. This may reflect significant spatial structuring of genetic diversity in populations of F. oxysporum in a native soil. The proportion of mtDNA haplotype diversity attributable to differences between populations in the native and cultivated soils was not significant. This suggests that our entire collection, encompassing strains from both native and cultivated soils, is representative of a single population of F. oxysporum.     

Mitochondrial DNA variation among populations of Oedura reticulata (Gekkonidae) in remnant vegetation: implications for metapopulation structure and population decline

Restriction fragment length polymorphism (RFLP) analysis of mitochondrial DNA was used to examine the regional population structure of a species of gecko (Oedura reticulata) in vegetation remnants within the Western Australian wheatbelt. The species exhibited considerable polymorphism within and between populations with 22 haplotypes recognized among 12 populations. Phylogenetic analysis of haplotypes and clustering of nucleotide divergence among populations demonstrated little regional structure within the species with several haplotypes present in all three regions surveyed. This contrasted markedly with variation in haplotype frequency among populations which showed a high degree of independence between populations indicating that current levels of maternal gene flow are low and that the populations are too small to prevent genetic drift. This conclusion is supported by generally lower numbers of haplotypes in remnant populations than in nearby nature reserves. These findings, combined with demographic data from a previous study, suggest that post-fragmentation populations of O. reticulata are unable to form a metapopulation structure in the habitat that remains and that stochastic extinction forces alone will be sufficient to severely reduce the regional distribution of this species. This study demonstrates that mtDNA is a useful tool for detecting contemporary population phenomena and can provide qualitative information of practical importance to wildlife managers.     

Population differentiation in the redshank (<Emphasis Type="Italic">Tringa totanus</Emphasis>) as revealed by mitochondrial DNA and amplified fragment length polymorphism markers

The redshank (Tringa totanus) is declining throughout Europe and to implement efficient conservation measures, it is important to obtain information about the population genetic structure. The aim of the present study was two-fold. First, we analysed the genetic variation within and between populations in the Baltic region in southern Scandinavia. Evidence of genetic structure would suggest that different populations might require separate management strategies. Second, in an attempt to study large-scale genetic structure we compared the Baltic populations with redshanks from northern Scandinavia and Iceland. This analysis could reveal insights into phylogeography and long-term population history. DNA samples were collected from six breeding sites in Scandinavia presumed to include two subspecies (totanus and britannica) and a further sample from Iceland (subspecies robusta). Two methods were used to study the population genetic structure. Domain II and III of the mitochondrial control region was analysed by DNA sequencing and nuclear DNA was analysed by screening amplified fragment length polymorphism (AFLP) markers. Mitochondrial DNA showed no variation between individuals in domain II. When analysing an 481 bp fragment of domain III seven haplotypes were found among birds. On the basis of mtDNA sequences, redshanks showed some evidence of a recent expansion from a bottlenecked refugial population. Bayesian analyses of AFLP data revealed a significant genetic differentiation between suggested subspecies but not between populations within the Baltic region. Our results indicate that populations of redshanks in Europe constitute at least three separate management units corresponding to the recognised subspecies.     

Analysis of Amblyomma sculptum haplotypes in an area endemic for Brazilian spotted fever

Amblyomma sculptum (Ixodida: Ixodidae) Berlese, 1888, a member of the Amblyomma cajennense complex, is the major vector of Brazilian spotted fever (BSF) in southeastern Brazil. In this study, the genetic diversity of A. sculptum populations in the state of Rio de Janeiro (RJ), Brazil, was investigated because genetic variability in tick populations may be related to vector competence. Samples of A. sculptum from 19 municipalities in 7 regions of RJ were subjected to DNA extraction, amplification and sequencing of D‐loop, cytochrome oxidase II and 12S rDNA mitochondrial genes. These sequences were used to map the genetic diversity of this tick. Amblyomma sculptum populations are genetically diverse in RJ, especially in the South Centre and Highland regions. Few unique haplotypes were observed in all populations, and the majority of genetic variation found was among ticks within each population. Phylogenetic reconstruction reinforced the assumption that all the haplotypes identified in RJ belong to A. sculptum. However, some RJ haplotypes are closer to A. sculptum from Argentina than to A. sculptum from elsewhere in Brazil. In RJ, A. sculptum has high genetic diversity, although little genetic differentiation. Observations also indicated a high level of gene flow among the studied populations and no evidence of population structure according to region in RJ.     

Genetic diversity and population structure of the endangered ripon barbel,Barbus altianalis (Boulenger, 1900) in Lake Victoria catchment,Kenya based on mitochondrial DNA sequences

Approximately 850 bp of the mitochondrial control region was used to assess the genetic diversity, population structure and demographic expansion of the endangered cyprinid Barbus altianalis, a species known to be potamodramous in the Lake Victoria drainage system. The 196 samples taken from the four main rivers draining the Lake Victoria catchment (Nzoia, Yala, Nyando and Sondu–Miriu) yielded 49 mitochondrial DNA haplotypes; 83.7% thereof were private haplotypes restricted to particular rivers. The overall mean haplotype diversity was high (0.93663 ± 0.008) and ranged between 0.566 (Sondu – Miriu) and 0.944 (Nzoia). The overall mean nucleotide diversity was low (0.01322 ± 0.00141), ranging from 0.0342 (Sondu – Miriu) to 0.0267 (Nzoia). Population differentiation tests revealed strong and highly significant (P ≤ 0.001) segregation of populations in the four river basins. F_ST values among the four river‐based populations ranged from 0.05202 to 0.44352. The samples formed two main haplotype networks based on a 95% parsimony criterion, each exhibiting a strong signature of past population expansion. The smaller network was restricted to the River Nzoia, whereas the larger network contained representatives from all four rivers; within this the central haplotypes were found in more than one river, whereas the peripheral haplotypes tended to be river‐specific. The degree of population differentiation and the number of river‐specific haplotypes are too high to be explained by recent anthropogenic impacts alone and suggest that the species has probably existed in the Lake Victoria catchment as two populations: the now ‘extinct’ migratory population and the extant river restricted non‐migratory populations.     

淮河水系日本沼虾群体遗传结构和系统演化的线粒体COI序列分析

测定了淮河水系17个日本沼虾(Macrobrachium nipponense)野生群体共248个个体的线粒体细胞色素氧化酶亚基I(COI)部分序列,获得623 bp核苷酸片段,包括48个变异位点,定义了31个单倍型,共享单倍型有12个,整体单倍型多样性和平均核苷酸多样性均处于中间水平。AMOVA分析表明,17个群体间的遗传分化系数Fst=0.041 3(P0.05),群体间遗传分化较小。Kimura 2-paramter遗传距离在五河与焦岗湖、花家湖及瓦埠湖群体间最大,为0.014,在高邮和邵伯湖群体之间最小,为0.003。MP系统树与单倍型进化网络关系图具有较高的一致性,31个单倍型被分为3个进化枝,其中一个进化枝主要以下游群体为主,另外2个进化枝主要以中游群体为主。群体中性检验、错配分析表明,淮河日本沼虾近期曾经历过种群扩张。     

Genetic integrity and individual identification-based population size estimate of the endangered long-tailed goral,Naemorhedus caudatus from Seoraksan National Park in South Korea,based on a non-invasive genetic approach

ABSTRACT

The long-tailed goral (also called the Amur goral) Naemorhedus caudatus (subfamily Caprinae), a vulnerable and protected species designated by IUCN and CITES, has sharply been declining in the population size and is now becoming critically endangered in South Korea. This species has been conserved as a natural monument by the Korean Cultural Heritage Administration since 1968. In this study, using 78 fecal DNA samples with a non-invasive genetic approach, we assessed the genetic integrity and individual identification-based population size for the goral population from Seoraksan National Park representing the largest wild population in Korea. Using the successfully isolated 38 fecal DNA, phylogeographic and population genetic analyses were performed with mitochondrial DNA control region (CR) sequences and nine microsatellite loci. We found seven CR haplotypes, of which five were unique to the Seoraksan population, considering previously determined haplotypes in Korean populations. The Seoraksan population showed higher haplotype diversity (0.777?±?0.062) and mean number of alleles (4.67?±?1.563) relative to southern populations in Korea reported from previous studies, with no signal of a population bottleneck. Microsatellite-based individual identification estimate based on probability of identity (PID) indicated a population size of ≥30 in this population. Altogether, we suggest that for future management efforts of this species in the Seoraksan National Park, conserving its genetic integrity as an ‘endemic’ lineage, and curbing a decrease in its number through mitigating habitat destruction might be key to secure the population for the long term.     

Mitochondrial DNA diversity, population structure, and gender association in the gynodioecious plant Silene vulgaris

A highly variable mitochondrial DNA (mtDNA) restriction fragment length polymorphism (RFLP) locus is used to assess the population structure of mitochondrial genomes in the gynodioecious plant Silene vulgaris at two spatial scales. Thirteen mtDNA haplotypes were identified within 250 individuals from 18 populations in a 20-km diameter region of western Virginia. The population structure of these mtDNA haplotypes was estimated as thetaST = 0.574 (+/- 0.066 SE) and, surprisingly, genetic differentiation among populations was negatively correlated with geographic distance (Mantel r = -0.246, P < 0.002). Additionally, mtDNA haplotypes were spatially clumped at the scale of meters within one population. Gender in S. vulgaris is determined by an interaction between autosomal male fertility restorers and cytoplasmic male sterility (CMS) factors, and seed fitness is affected by an interaction between gender and population sex ratio; thus, selection acting on gender could influence the distribution of mtDNA RFLP haplotypes. The sex ratio (females:hermaphrodites) varied among mtDNA haplotypes across the entire metapopulation, possibly because the haplotypes were in linkage disequilibrium with different CMS factors. The gender associated with some of the most common haplotypes varied among populations, suggesting that there is also population structure in male fertility restorer genes. In comparison with reports of mtDNA variation from other published studies, we found that S. vulgaris exhibits a large number of mtDNA haplotypes relative to that observed in other species.     

Mitochondrial DNA of the Mauritian macaques (Macaca fascicularis): An example of the founder effect

Macaque monkeys (Macaca fascicularis) were introduced to the island of Mauritius approximately 400 years ago. This study compares the mitochondrial DNA of macaques on Mauritius with those from Indonesia and the Philippines. The goal is to measure the amount of evolutionary change that has occurred in this isolated population over 400 years, and to address questions regarding the origin of the Mauritian founders. Amplification of the control region of the mitochondrial genome via the polymerase chain reaction yielded an 1800 base pair DNA fragment which was surveyed for variation using restriction endonucleases. Fifty-two macaques were separated into 17 haplotypes by mapping the restriction sites. No haplotypes were shared among the three populations, and only two closely related haplotypes appeared in the Mauritian sample. Nucleotide variation in the mitochondrial DNA in the Mauritian sample was 10-fold less than the Indonesian and Filipino samples. In contrast, allozyme data estimates of genetic diversity on Mauritius are similar to populations from the ancestral range. The evidence of the more severe bottleneck as measured by mitochondrial data may be explained in part by almost exclusive male dispersal in this species, and may support models of founder events in which rapid population growth prevents substantial loss of nuclear variation. The mitochondrial evidence supports the morphologically and historically based hypothesis that the original founders came from Indonesia. © 1995 Wiley-Liss, Inc.     

Population structure of Magnaporthe oryzae isolates from green foxtail in Japan examined by DNA fingerprint analysis

The population structure of Magnaporthe oryzae from green foxtail (Setaria viridis) in Japan was examined by DNA fingerprint analyses using the transposable elements MGR586 and MAGGY as probes. Fifteen M. oryzae isolates from green foxtail were collected from 11 Japanese prefectures so that a macrogeographic population of this pathogen is represented. All the 15 isolates were sorted into distinct haplotypes by DNA fingerprint analyses with both probes. Furthermore, similarities between the DNA fingerprint profiles of the 15 isolates were exclusively low; i.e., if lineages are arbitrarily established based on greater than 70% similarities in isolates, the 15 isolates could be categorized into 13 distinct lineages by DNA fingerprinting with both probes. We also examined the MGR586 DNA fingerprint variations of this pathogen in 9 microgeographic populations each of which contained 20 to 24 isolates collected from a 1 m² or 50 m² area. In all the 9 populations, more than 2 haplotypes, which shared less than 70% similarities, were identified in the DNA fingerprint profiles. These results suggested that M. oryzae isolates from the green foxtail in Japan possessed a complex lineage structure, even at the microgeographic scale.     

An association between chloroplast DNA haplotypeand gender in a plant metapopulation

Theoretical models have shown that metapopulation structure can influence the evolution of the sex ratio in gynodioecious plants when the fitness of females and/or hermaphrodites varies among populations with the local sex ratio. Such frequency-dependent fitness has been demonstrated previously in natural populations of Silene vulgaris, a gynodioecious plant in which sex determination is cytonuclear. We investigated whether there was an association between chloroplast DNA (cpDNA) haplotype and sex expression, with the assumption that cpDNA haplotypes could be associated with specific male sterility variants likely found in the mitochondrial DNA, owing to co-transmission of the two cytoplasmic genomes. Two cpDNA haplotypes were studied in a collection of 111 individuals of known sex taken from 20 natural populations found in Virginia, USA. The set of haplotype 1 individuals consisted of 71.4% hermaphrodites, where as only 7.7% of the haplotype 2 individuals were hermaphroditic; a highly statistically significant difference. By extension of a previous model it was also shown that the differential clustering of these two haplotypes into local populations contributes to among-population sex ratio variation and has the potential to lower the fitness of haplotype 2 by greater than 50%, relative to that expected with no population structure. This revised version was published online in July 2006 with corrections to the Cover Date.     

Population Structure of the Giant Garter Snake, Thamnophis gigas

The giant garter snake, Thamnophis gigas, is a threatened species endemic to California’s Central Valley. We tested the hypothesis that current watershed boundaries have caused genetic differentiation among populations of T. gigas. We sampled 14 populations throughout the current geographic range of T. gigas and amplified 859 bp from the mitochondrial gene ND4 and one nuclear microsatellite locus. DNA sequence variation from the mitochondrial gene indicates there is some genetic structuring of the populations, with high F_ST values and unique haplotypes occurring at high frequency in several populations. We found that clustering populations by watershed boundary results in significant between-region genetic variance for mtDNA. However, analysis of allele frequencies at the microsatellite locus NSU3 reveals very low F_ST values and little between-region variation in allele frequencies. The discordance found between mitochondrial and microsatellite data may be explained by aspects of molecular evolution and/or T. gigas life history characteristics. Differences in effective population size between mitochondrial and nuclear DNA, or male-biased gene flow, result in a lower migration rate of mitochondrial haplotypes relative to nuclear alleles. However, we cannot exclude homoplasy as one explanation for homogeneity found for the single microsatellite locus. The mitochondrial nucleotide sequence data supports conservation practices that identify separate management units for T. gigas.     

Genetic population structure of the paper wasp Polistes olivaceus (Hymenoptera: Vespidae) in Bangladesh

Dispersal triggers gene flow, which in turn strongly affects the ensuing genetic population structure of a species. Using nuclear microsatellite loci and mitochondrial DNA (mtDNA), we estimated the genetic population structure of the wasp Polistes olivaceus throughout Bangladesh. The level of population differentiation using nuclear markers (F _ST) appeared to be much lower than that estimated using mtDNA haplotype sequences (Ф_ST), even after correcting for effective population size differences between the two markers. These results suggest a philopatric tendency, in which gynes disperse less than males. We observed no isolation by distance among the study populations at either the nuclear or mtDNA level, suggesting nonequilibrium between gene flow and drift as a result of very frequent interpopulation movement. For the nuclear markers, an individual assignment test showed no genetically and geographically distinct groups. Instead, phylogenetic analyses as well as a minimum spanning network using mtDNA haplotypes consistently revealed two distinct lineages. The distribution of haplotypes indicated western populations with a single lineage and offered clear evidence for restricted gene flow across the Jamuna–Padma–Upper Meghna river system. Mismatch distributions exhibited a unimodal distribution, which along with a starlike haplotype network, suggested a population expansion in lineage I but not in lineage II. Overall, these results suggest that gene flow among populations of P. olivaceus was affected by both female philopatry and a major river system across Bangladesh.     

Genetic Population Structure of Chum Salmon in the Pacific Rim Inferred from Mitochondrial DNA Sequence Variation

We examined the genetic population structure of chum salmon, Oncorhynchus keta, in the Pacific Rim using mitochondrial (mt) DNA analysis. Nucleotide sequence analysis of about 500 bp in the variable portion of the 5′ end of the mtDNA control region revealed 20 variable nucleotide sites, which defined 30 haplotypes of three genealogical clades (A, B, and C), in more than 2,100 individuals of 48 populations from Japan (16), Korea (1), Russia (10), and North America (21 from Alaska, British Columbia, and Washington). The observed haplotypes were mostly associated with geographic regions, in that clade A and C haplotypes characterized Asian populations and clade B haplotypes distinguished North American populations. The haplotype diversity was highest in the Japanese populations, suggesting a greater genetic variation in the populations of Japan than those of Russia and North America. The analysis of molecular variance and contingency χ² tests demonstrated strong structuring among the three geographic groups of populations and weak to moderate structuring within Japanese and North American populations. These results suggest that the observed geographic pattern might be influenced primarily by historic expansions or colonizations and secondarily by low or restricted gene flow between local groups within regions. In addition to the analysis of population structure, mtDNA data may be useful for constructing a baseline for stock identification of mixed populations of high seas chum salmon.     

Patterns of gene flow and source‐sink dynamics in high altitude populations of the common toad Bufo bufo (Anura: Bufonidae)

Understanding patterns of genetic structure is fundamental for developing successful management programmes for deme‐structured organisms, such as amphibians. We used five microsatellite loci and DNA sequences of the mitochondrial control region to assess the relative influences of landscape (geographic distance, altitude and rivers as corridors for dispersal) and historical factors on patterns of gene flow in populations of the toad Bufo bufo in Central Spain. We sampled 175 individuals from eight populations distributed along two major river drainages and used maximum‐likelihood and Bayesian approaches to infer patterns of gene flow and population structure. The mitochondrial DNA data show closely‐related haplotypes distributed across the Iberian Peninsula with no geographic structuring, suggesting recent differentiation of haplotypes and extensive gene flow between populations. On the other hand, microsatellites provide finer resolution, showing that high altitude populations (> 2000 m) exchange lower numbers of migrants with other populations. The results of Bayesian estimates for recent migration rates in high altitude populations suggest source‐sink dynamics between ponds that are consistent with independent data from monitoring over the past 20 years. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 824–839.     

Population genetics and conservation of the threatened southeastern beach mouse (Peromyscus polionotus niveiventris): subspecies and evolutionary units

We investigated genetic diversity within the southeastern beach mouse (SEBM-Peromyscus polionotus niveiventris) and also tested the hypothesis that the subspecies recognition of P.p. niveiventris, based on size and color differences, is congruent with this taxon representing a discrete evolutionary lineage. We used ten polymorphic microsatellite loci and mitochondrial cytochrome-b gene DNA sequences to investigate genetic diversity and population structure within the SEBM, and to determine the level of divergence between the SEBM and the nearest known inland subspecies of the oldfield mouse (Peromyscus polionotus rhoadsi). Moderate genetic distances were observed between the SEBM and the inland oldfield mouse based on microsatellite data, with F _ST values ranging from 0.11 to 0.22 between these taxa. Additionally, mitochondrial DNA haplotypes of the SEBM formed a distinct monophyletic group relative to haplotypes sampled from P. p. rhoadsi. Based on previous estimates of rates of mitochondrial DNA evolution in rodents, we inferred that Pleistocene sea-level fluctuations are likely responsible for the historical isolation of the SEBM lineage from mainland P. polionotus. Our data demonstrate the genetic distinctiveness of the SEBM, justifying the current subspecies designation for the SEBM and its continued protection under the United States Endangered Species Act. We classify the Cape Canaveral and Smyrna Dunes Park populations of SEBM as a single evolutionary significant unit. The two known extant allopatric populations of the SEBM showed some differentiation in microsatellite frequencies and were moderately reciprocally distinguishable based on assignment to distinct genetic clusters by a Bayesian admixture procedure. These results justify the classification of these two extant SEBM populations as distinct management units that should be independent targets of management and conservation attention.     

Survey of mitochondrial DNA haplotypes of Potamopyrgus antipodarum (Caenogastropoda: Hydrobiidae) introduced into Japan

Potamopyrgus antipodarum from 13 locations in central and western Japan were investigated for mitochondrial DNA haplotypes. Two haplotypes (JA and JB) were found based on an analysis of a 343-bp sequence of the cytochrome c oxidase subunit I gene. The JB type comprised two subhaplotypes (JB-I and JB-II), which were distinguishable by an additional sequence of 289 bp. Eleven populations were likely monomorphic in the mtDNA haplotype, while two populations, which were supposed to have been established recently, were polymorphic, encompassing JA and JB haplotypes. This result suggests that different haplotypes invaded Japan via different routes and that polymorphic populations were formed by colonization from more than one source population.