Cryptic anuran biodiversity in Bangladesh revealed by mitochondrial 16S rRNA gene sequences

To survey the diversity of anuran species in Bangladesh, we compared mitochondrial 16S rRNA gene sequences (approximately 1.4 kbp) from 107 Bangladesh frog specimens. The results of genetic divergence and phylogenetic analyses incorporating data from related species revealed the occurrence of at least eight cryptic species. Hoplobatrachus tigerinus from two districts diverged considerably, indicating the involvement of a cryptic species. Two Fejervarya sp. (large and medium types) and Hylarana cf. taipehensis formed lineages distinct from related species and are probably new species. Microhyla cf. ornata differed from M. ornata with respect to type locality area and involved two distinct species. In addition, we found that Hylarana sp. and Microhyla sp. did not match congeners examined to date in either morphology or 16S rRNA sequence. The occurrence of M. fissipes was tentatively suggested. Consequently, at least, 19 species were found from Bangladesh in this study. These findings revealed a rich anuran biodiversity in Bangladesh, which is unexpected considering the rather simple topographic features of the country.     

泽蛙、日本林蛙、饰纹姬蛙不同地理居群的核型多样性

本文研究了温州地区的泽蛙、日本林蛙、饰纹姬蛙的核型,并分析了9个地理居群泽蛙的核型、4个地理居群日本林蛙的核型和3个地理居群饰纹姬蛙的核型。结果表明,不同地理居群的同种蛙均有相同的染色体数和核型模式。泽蛙、日本林蛙都为 2n=26,NF=52,核模式5＋8;饰纹姬蛙 2n=24,NF=48,核模式6＋6。但同一种蛙的不同地理居群之间在SM数目和顺序、次缢痕或随体的位置等都有所不同,说明不同地理居群的同种蛙的染色体具有丰富的多样性。故保护蛙品种资源多样性,不仅要从整个群体上考虑,而且要针对每个品种（或类群）进行保护。 Abstract：The karyotypes of Rana limmocharis boie,Rana j.Japonica,and Microhyla ornata from Wenzhou were studied.The karyotypes of nine populations of Rana limmocharis boie,four populations of Rana j.Japonica and three populations of Microhyla ornata from different geographical regions were compared.The results demonstrated that the same species of different geographical populations have the same amount of chromosome and karyotypic formulae. Rana limmocharis boie and Rana j.Japonica have 2n=26,NF=52 and 5＋8 karyotypic formulae.Microhyla ornata has 2n=24,NF=48 and 6＋6 karyotypic formulae.But some dissimilarities were found among them.First,the number and sequence of submetacentric chromosome were different among them,and then the secondary contriction （SC）or satellite （Sat）were also different.It was showed that the chromosomes of same species of different geographical population have diversities.Conservation of frog genetic diversity must be considered of not only the genetic diversity conservation of the total frog population but also that of every frog breed.     

Multiple invasions of the Ryukyu Archipelago by Oriental frogs of the subgenus Odorrana with phylogenetic reassessment of the related subgenera of the genus Rana

The genus Rana, notably diversified in Oriental regions from China to Southeast Asia, includes a group of cascade frogs assigned to subgenera Odorrana and Eburana. Among them, R. ishikawae and the R. narina complex represent the northernmost members occurring from Taiwan to the Ryukyu Archipelago of Japan. Relationships of these frogs with the continental members, as well as the history of their invasions to islands, have been unclear. The taxonomic status of Odorrana and related genera varies among authors and no phylogenetic reassessment has been done. Using partial sequences of mitochondrial 12S and 16S rRNA genes, we estimated phylogenetic relationships among 17 species of the section Hylarana including Odorrana and Eburana, and related species from the Ryukyus, Taiwan, China, Thailand, Malaysia, and Indonesia. We estimate that (1) Odorrana is monophyletic and encompasses species of Eburana and R. hosii, which is now placed in Chalcorana, (2) the ancestor of R. ishikawae separated from other Rana in the middle to late Miocene prior to its entry to the Ryukyu Archipelago, (3) the ancestor of the R. narina complex later diversified in continental Asia, and invaded the Ryukyu Archipelago through Taiwan, (4) the R. narina complex attained its current distribution within the Ryukyus through niche segregations, and (5) vicariance of R. hosii between Malay Peninsula and Borneo occurred much later than the divergence events in the R. narina complex. Current subgeneric classification of Rana, at least of Southeast Asian members, requires full reassessment in the light of phylogenetic relationships.     

Relict distribution of Microhyla (Amphibia: Microhylidae) in the Ryukyu Archipelago: High diversity in East Asia maintained by insularization

The Ryukyu Archipelago, located at the southwestern part of Japan, is known as a group of continental islands and harbours many endemic taxa, supposedly reflecting its fairly long isolation from the Eurasian continent, Taiwan and the Japanese main islands. Microhyla okinavensis has been known as an endemic member of the terrestrial fauna of this archipelago. Molecular phylogenetic analyses using samples from nearly all island populations of the species and representative samples of other east Asian congeneric species revealed that M. okinavensis consists of four distinct subclades, of which the Amami, Okinawa and Miyako subclades, though exhibiting distinct genetic differentiations from each other, formed a monophyletic group (clade A). The remaining Yaeyama subclade was exclusively sister to M. mixtura from inland China, forming another monophyletic group (clade B), rendering M. okinavensis in the current definition paraphyletic. These results, as well as estimated dates of divergence from related taxa, indicate that M. okinavensis actually includes more than one distinct species. The results indicate that M. okinavensis and M. mixtura are relict species with disjunct distributions which had been most probably caused by invasion of M. fissipes in intervening areas.     

Genetic characteristics and possible introduced origin of the paradise fish <Emphasis Type="Italic">Macropodus opercularis</Emphasis> in the Ryukyu Archipelago,Japan

It has hitherto been unknown whether the paradise fish Macropodus opercularis that inhabits the Ryukyu Archipelago, Japan, is native to the region or was introduced. This study examined the genetic identity of fish from five islands in the Ryukyu Archipelago (Okinoerabu, Okinawa, Yagaji, Kume, and Minamidaito islands) and compared it with those from Taiwan Island, mainland China, and Hainan Island. Analyses of the mtDNA control (760 bp) and cytb (660 bp) regions showed that haplotypes of specimens from the Ryukyu Archipelago were the same as or were very similar (with a 1- or 2-bp difference) to those from Taiwan. In addition, haplotypes from the Ryukyu Archipelago also showed lower genetic diversity than those from Taiwan Island, mainland China, and Hainan Island. These results suggest a high likelihood that the fish in the Ryukyu Archipelago were artificially introduced from Taiwan. However, the possibility that the fish is indigenous to the Ryukyu Archipelago cannot be completely ruled out, because some haplotypes and a clade from the Ryukyu Archipelago have not been found in the other areas. Regardless of its origin, we emphasize the importance of the conservation of the paradise fish in the Ryukyu Archipelago as an indicator of the threatened wetland environment as well as for its cultural value.     

Contrasting phylogeographical patterns between mainland and island taxa of the Pinus luchuensis complex

Species whose geographical distribution encompasses both mainland and island populations provide an ideal system for examining isolation and genetic divergence. In this study, paternally transmitted chloroplast DNA (cpDNA) and maternally transmitted mitochondrial DNA (mtDNA) were used to estimate population structure and phylogeography of Pinus luchuensis, a species found in eastern China (ssp. hwangshanensis), Taiwan (ssp. taiwanensis), and the Ryukyu Archipelago (ssp. luchuensis). Gene genealogies of both mtDNA and cpDNA reveal two major lineages. Molecular dating indicates that these lineages diverged before the colonization of P. luchuensis subspecies in Taiwan and the Ryukyu Archipelago. Both mtDNA and cpDNA show a lack of correspondence between molecular phylogeny and subspecies designation. Phylogeographical analysis suggests that paraphyly of the subspecies is the result of recent divergence rather than secondary contacts. In spite of the short divergence history of P. luchuensis on islands, the island populations show the same degree of genetic divergence as mainland populations. Low levels of genetic diversity in the mainland ssp. hwangshanensis suggest demographic bottlenecks. In contrast, the high heterogeneity of genetic composition for island populations is likely to be associated with a history of multiple colonization from the mainland. The spatial apportionment of organelle DNA polymorphisms is consistent with a pattern of stepwise colonization on island populations.     

Phylogeography of Ophiorrhiza japonica (Rubiaceae) in continental islands,the Ryukyu Archipelago,Japan

Aim Phylogeographical patterns in the Ryukyu Archipelago have been explained primarily by landbridge formation and the opening of two straits in the Pliocene, namely the Tokara and Kerama gaps. These old straits have been considered to be the barriers most likely to determine genetic boundaries. To test this, we conducted a molecular analysis of the herb Ophiorrhiza japonica. We discuss the causes of and processes involved in its phylogeographical structure and explore aspects of island separation other than the duration of the straits to explain genetic boundaries at the gaps. Location Ryukyu Archipelago, Japan. Methods Plants were collected from 40 localities in the archipelago and vicinity. Non‐coding regions of chloroplast DNA were sequenced. The genealogical relationships among haplotypes were estimated using a statistical parsimony network. To examine the phylogeographical structure, we compared two parameters of population differentiation, namely G_ST and N_ST, and conducted correlation analysis of genetic and geographical distances. Genetic boundaries were identified using Monmonier’s maximum difference algorithm. To test vicariance–dispersal hypotheses, that is, vicariance after migration via the Pliocene landbridge or over‐sea dispersal in the Pleistocene, molecular dating analysis was conducted. Results A statistical parsimony network revealed that the haplotypes from the Ryukyu Archipelago and northwards coalesce to one ancestral haplotype in Taiwan. A clear phylogeographical structure was observed: plants within the same population and populations in geographical proximity were phylogenetically close. A genetic boundary was recognized across the Kerama Gap, but not across the Tokara Gap. Dating analysis suggested that population divergence across the Kerama Gap occurred in the early to late Pleistocene. Main conclusions The statistical parsimony network suggests migration from Taiwan and northward range expansion in the archipelago. Based on the divergence time, over‐sea dispersal in the Pleistocene is likely, although migration via a Pliocene landbridge is not totally rejected. Negligible genetic differentiation across the Tokara Gap suggests recent over‐sea dispersal, possibly facilitated by the small geographical width of the gap. Conversely, the large genetic differentiation across the Kerama Gap is probably explained by the large geographical distance across it. The past splitting of a landbridge would have had a significant influence on population differentiation after a certain geographical distance was reached.     

The phylogeography and connectivity of the latitudinally widespread scleractinian coral Plesiastrea versipora in the Western Pacific

Whereas terrestrial animal populations might show genetic connectivity within a continent, marine species, such as hermatypic corals, may have connectivity stretching to all corners of the planet. We quantified the genetic variability within and among populations of the widespread scleractinian coral, Plesiastrea versipora along the eastern Australian seaboard (4145 km) and the Ryukyu Archipelago (Japan, 681 km) using sequences of internal transcribed spacers (ITS1-2) from ribosomal DNA. Geographic patterns in genetic variability were deduced from a nested clade analysis (NCA) performed on a parsimony network haplotype. This analysis allowed the establishment of geographical associations in the distribution of haplotypes within the network cladogram, therefore allowing us to deduce phylogeographical patterns based under models of restricted gene flow, fragmentation and range expansion. No significant structure was found among Ryukyu Archipelago populations. The lack of an association between the positions of haplotypes in the cladogram with geographical location of these populations may be accounted for by a high level of gene flow of P. versipora within this region, probably due to the strong Kuroshio Current. In contrast, strong geographical associations were apparent among populations of P. versipora along the south-east coast of Australia. This pattern of restricted genetic connectivity among populations of P. versipora on the eastern seaboard of Australia seems to be associated with the present surface ocean current (the East Australian Current) on this side of the south-western Pacific Ocean.     

High levels of genetic diversity in island populations of the island endemic Suzukia luchuensis (Labiatae)

Genetic diversity and genetic differentiation within and among island populations was examined by allozyme electrophoresis in Suzukia luchuensis (Labiatae), which is endemic to four of the Ryukyu Islands, southern Japan, and one island near Taiwan. Intrapopulation allozyme diversity was very low in all the four Ryukyu Islands, probably due to the effects of random drift in small populations. In contrast, genetic diversity at the species level was high, possibly because of an ancient origin of populations and/or multiple colonization of the species on different islands. Genetic differentiation among the overall populations was high (G(ST)=0.863), while gene flow (Nm) as estimated from allozyme frequency data was 0.041, suggesting that its occurrence among populations is highly restricted. Hierarchical analysis of genetic differentiation indicated that a high proportion of the total allelic variance is attributed to variation among islands, corresponding to the fact that several alleles were fixed on only one island. However, intraisland genetic differentiation was small on all islands except Yonaguni Island, where S. luchuensis is relatively widely distributed. Most diversity was thus due to differences among islands.     

Analyses of genetic population structure of two ecologically important mangrove tree species, Bruguiera gymnorrhiza and Kandelia obovata from different river basins of Iriomote Island of the Ryukyu Archipelago, Japan

We analyzed nuclear and chloroplast microsatellite makers to assess genetic diversity and examine genetic structure of two mangrove tree species, Bruguiera gymnorrhiza and Kandelia obovata recovered from nine major river basins of Iriomote Island of the Ryukyu Archipelago, Japan. The average number of alleles per nuclear locus per population was 2.6 in B. gymnorrhiza and 1.7 in K. obovata. Bayesian clustering analysis using InStruct identified two genetic clusters in B. gymnorrhiza and three clusters in K. obovata. Chloroplast microsatellites revealed two dominant haplotypes from B. gymnorrhiza and three haplotypes from K. obovata. The overall result suggests low genetic diversity for both species. AMOVA for nuclear microsatellites showed 9.3?% of population variation in B. gymnorrhiza. Although genetic differentiation between several populations was significant in this species, F _ST suggested low to moderate level of differentiations between most of the populations. Distribution of genetic clusters and chloroplast haplotypes also suggested weak differentiations among B. gymnorrhiza populations. In K. obovata, population variation was, however, relatively high (27.8?%). The high differentiation between K. obovata populations was also suggested from the F _ST and genetic clusters from nuclear microsatellites, and chloroplast haplotypes. A significant correlation between chloroplast genetic distances and coastline distances as well as haplotype distributions for both species suggest that propagules from each species mostly disperse to the neighboring river basins. While significant F _IS and higher percentage of admixed clusters from nuclear microsatellites suggested inbreeding, continual gene exchange by propagule dispersal among populations especially among neighboring populations was suggested for both species from maternally inherited chloroplast microsatellites analyses.     

Distribution and molecular characterization of distinct Asian populations of Bemisia tabaci (Hemiptera: Aleyrodidae) in Japan

Bemisia tabaci (Gennadius) is considered to be the most economically important pest insect worldwide. The invasive variant, the Q biotype of B. tabaci was first identified in 2004, and has caused significant crop yield losses in Japan. The distribution and molecular characterization of the different biotypes of B. tabaci in Japan have been little investigated. In this study, B. tabaci populations were sampled from the Japanese Archipelago, the Amami Archipelago and the Ryukyu Islands between 2004 and 2008, and the nucleotide sequences of their mitochondrial cytochrome oxidase I genes were determined. Bayesian phylogenetic relationship analysis provided the first molecular evidence that the indigenous Japanese populations could be separated into four distinct genetic groups. One major native population from the Japanese Archipelago, given the genetic group name Lonicera japonica, was separated into an independent group, distinct from the other genetic groups. The second major population, the Nauru biotype in the Asia II genetic group, was identified in the Amami Archipelago and the Ryukyu Islands. Two distinct minor genetic groups, the Asia I and the China, were also identified. One invasive B‐related population belonging to the Mediterranean/Asia Minor/Africa genetic group has been identified in Honshu. All lineages generated by the phylogenetic analyses were supported by high posterior probabilities. These distinct indigenous B. tabaci populations developed in Japan under geographical and/or biological isolation, prior to recent invasions of the B and Q biotypes.     

Genetic variation and gene flow of broadcast spawning and planula brooding coral,Goniastrea aspera (Scleractinia) in the Ryukyu Archipelago,southern Japan

The scleractinian coral Goniastrea aspera (Verrill) undergoes both broadcast spawning and planulae brooding in the Ryukyu Archipelago of southern Japan. Genetic variation and gene flow in G. aspera were studied using allozyme electrophoresis. We tested the hypothesis that gene flow is determined by the competency period of the planulae. We also assessed the relative contributions of sexual and asexual reproduction to recruitment. For the five staining systems surveyed, G. aspera encoded five polymorphic loci and one monomorphic locus. The genotype frequencies in each population significantly differed from the expected Hardy-Weinberg equilibrium (HWE), indicating that the local populations of G. aspera are not fully panmictic. The high ratio of the observed number of genotypes to the number of individuals (0.90 +/- 0.07, mean NG:N +/- SD) and the observed to expected genotypic diversity (0.84 +/- 0.11, mean GO:GE +/- SD) suggested that each population is likely maintained by sexual reproduction. The genetic differentiation (FST) and value of average number of migrants per generation (Nem) among and within regions ranged from 0.025 to 0.104 and 2.2 to 9.6, respectively. Comparisons with other species demonstrated that larva survival rates also influence gene flow. In addition, gene flow on distant reefs by planulae originating from spawning might prevent divergence by planulae originating from brooding for short-distant dispersal among and within populations of G. aspera in the Ryukyu Archipelago.     

Fine-Scale Genetic Structure and Demographic History in the Miyako Islands of the Ryukyu Archipelago

The Ryukyu Archipelago is located in the southwest of the Japanese islands and is composed of dozens of islands, grouped into the Miyako Islands, Yaeyama Islands, and Okinawa Islands. Based on the results of principal component analysis on genome-wide single-nucleotide polymorphisms, genetic differentiation was observed among the island groups of the Ryukyu Archipelago. However, a detailed population structure analysis of the Ryukyu Archipelago has not yet been completed. We obtained genomic DNA samples from 1,240 individuals living in the Miyako Islands, and we genotyped 665,326 single-nucleotide polymorphisms to infer population history within the Miyako Islands, including Miyakojima, Irabu, and Ikema islands. The haplotype-based analysis showed that populations in the Miyako Islands were divided into three subpopulations located on Miyakojima northeast, Miyakojima southwest, and Irabu/Ikema. The results of haplotype sharing and the D statistics analyses showed that the Irabu/Ikema subpopulation received gene flows different from those of the Miyakojima subpopulations, which may be related with the historically attested immigration during the Gusuku period (900 − 500 BP). A coalescent-based demographic inference suggests that the Irabu/Ikema population firstly split away from the ancestral Ryukyu population about 41 generations ago, followed by a split of the Miyako southwest population from the ancestral Ryukyu population (about 16 generations ago), and the differentiation of the ancestral Ryukyu population into two populations (Miyako northeast and Okinawajima populations) about seven generations ago. Such genetic information is useful for explaining the population history of modern Miyako people and must be taken into account when performing disease association studies.     

Elucidating the multiple genetic lineages and population genetic structure of the brooding coral <Emphasis Type="Italic">Seriatopora</Emphasis> (Scleractinia: Pocilloporidae) in the Ryukyu Archipelago

The elucidation of species diversity and connectivity is essential for conserving coral reef communities and for understanding the characteristics of coral populations. To assess the species diversity, intraspecific genetic diversity, and genetic differentiation among populations of the brooding coral Seriatopora spp., we conducted phylogenetic and population genetic analyses using a mitochondrial DNA control region and microsatellites at ten sites in the Ryukyu Archipelago, Japan. At least three genetic lineages of Seriatopora (Seriatopora-A, -B, and -C) were detected in our specimens. We collected colonies morphologically similar to Seriatopora hystrix, but these may have included multiple, genetically distinct species. Although sexual reproduction maintains the populations of all the genetic lineages, Seriatopora-A and Seriatopora-C had lower genetic diversity than Seriatopora-B. We detected significant genetic differentiation in Seriatopora-B among the three populations as follows: pairwise F _ST = 0.064–0.116 (all P = 0.001), pairwise G′′_ST = 0.107–0.209 (all P = 0.001). Additionally, only one migrant from an unsampled population was genetically identified within Seriatopora-B. Because the peak of the settlement of Seriatopora larvae is within 1 d and almost all larvae are settled within 5 d of spawning, our observations may be related to low dispersal ability. Populations of Seriatopora in the Ryukyu Archipelago will probably not recover unless there is substantial new recruitment from distant populations.     

Species delimitation and biogeography of the Ryukyu ground geckos,Goniurosaurus kuroiwae ssp. (Squamata: Eublepharidae), by use of mitochondrial and nuclear DNA analyses

In the Ryukyu Archipelago, Japan, Goniurosaurus geckos are currently divided into six allopatric taxa among nearby islands. Recent studies suggested the occurrence of large genetic divergence within a single island and the possible non‐monophyly of a few taxa, but their species delimitation is not well resolved. We investigated the taxonomic relationships between the possibly geographically overlapped, highly diverged entities as well as other island populations via dense sampling. Our mitochondrial and nuclear DNA analyses showed that the two genetic groups were distributed in parapatry within Okinawajima Island and that they were hybridizing in narrow area around the contact zone. Geohistorical evidence suggests that the restricted gene flow has been caused by some intrinsic isolation mechanisms. Thus, we conclude that the two lineages represent full species. Mitochondrial analysis also showed that the genetic differences among other island populations were comparable to those between these species, thereby suggesting the presence of seven full species, including one unnamed taxon. We also discuss the possible cause of this divergence and why it has occurred at such a fine geographic scale.     

A new species of Orobdella (Hirudinida, Arhynchobdellida, Orobdellidae) from Taipei, Taiwan

A new quadrannulate species of Orobdella, Orobdella ketagalansp. n., from Taipei, Taiwan, is described. This is the first record of Orobdella and the family Orobdellidae from Taiwan. This new species possesses small, paired sperm duct bulbs in the male reproductive system. In addition to these bulbs, the following combination of characters distinguishes this new species from other quadrannulate species: somite IV uniannulate, male gonopore at XI b6, female gonopore at XIII a1, 1/2 + 4 + 1/2 between gonopores, simple tubular gastroporal duct, lacking epididymides, and undeveloped atrial cornua. Phylogenetic analyses using nuclear 18S rDNA and histone H3 as well as mitochondrial COI, 12S rDNA, tRNA(Val), and 16S rDNA markers showed that Orobdella ketagalan is related to the two Ryukyu Archipelago species Orobdella dolichopharynx Nakano, 2011 and Orobdella shimadae Nakano, 2011.     

A taxonomic study of the Rana narina complex, with description of three new species (Amphibia: Ranidae)

A morphometric and electrophoretic survey was conducted to examine taxonomic relationships among eight population samples of the Rana narina complex from the Ryukyu Archipelago of Japan and Taiwan. Five discrete morphotypes are differentiated, and these showed considerable genetic differentiation from each other. From the available information, each of the five morphotypes is judged to represent a species, and three are described as new. Rana utsunomiyaorum sp. nov. and R. supranarina sp. nov. are sympatric in Ishigakijima and Iriomotejima islands of the Yaeyama Group, and differ from the other members by having a shorter hindlimb. Rana utsunomiyaorum is the smallest in the complex, while R. supranarina is the largest. Rana amamiensis sp. nov . occurs on Amamioshima and Tokunoshima islands of the Amami Group and, like R. narina from Okinawajima of the Okinawa Group, has a long hindlimb; it differs from the latter species by having a larger body and relatively small tympanum. These two species differ from R. swinhoana from Taiwan by having a narrower disk on the third finger. A key to known species of the complex is given. Further, syslematics of the R. narina complex within Rana , body size in the two sympatric species, and sexual dimorphism found in this complex are discussed.     

High levels of genetic variability and differentiation in hilsa shad, Tenualosa ilisha (Clupeidae, Clupeiformes) populations revealed by PCR-RFLP analysis of the mitochondrial DNA D-loop region

The hilsa shad, Tenualosa ilisha (Clupeidae, Clupeiformes) is an important anadromous clupeid species from the Western division of the Indo-Pacific region. It constitutes the largest single fishable species in Bangladesh. Information on genetic variability and population structure is very important for both management and conservation purposes. Past reports on the population structure of T. ilisha involving morphometric, allozyme and RAPD analyses are contradictory. We examined genetic variability and divergence in two riverine (the Jamuna and the Meghna), two estuarine (Kuakata and Sundarbans) and one marine (Cox's Bazar) populations of T. ilisha by applying PCR-RFLP analysis of the mtDNA D-loop region. The amplified PCR products were restricted with four restriction enzymes namely, XbaI, EcoRI, EcoRV, and HaeIII. High levels of haplotype and gene diversity within and significant differentiations among, populations of T. ilisha were observed in this study. Significant F(ST) values indicated differentiation among the river, estuary and marine populations. The UPGMA dendrogram based on genetic distance resulted in two major clusters, although, these were subsequently divided into three, corresponding to the riverine, estuarine and marine populations. The study underlines the usefulness of RFLP of mtDNA D-loop region as molecular markers, and detected at least two differentiated populations of T. ilisha in Bangladesh waters.     

光裸方格星虫野生与养殖群体线粒体控制区序列的遗传差异分析

基于线粒体控制区序列对光裸方格星虫（Sipunculus nudus Linnaeus,1766）的2个养殖群体（营盘YP、竹林ZL）和4个野生群体（防城港FC、钦州QZ、大冠沙DG和越南海防YN）的91个个体进行遗传差异分析,研究光裸方格星虫养殖和野生群体的遗传变异情况。结果显示:获得的514 bp DNA序列中,野生与养殖群体的多态性位点数分别为82和60,均显示出对AT的偏倚性。共定义85个单倍型,共享单倍型4个,其中共享单倍型Hap5为原始单倍型,营盘群体均为独享单倍型。各群体的单倍型多样性（H_d）相同,野生群体的平均核苷酸多样性（P_i）（0.01531）略高于养殖群体（0.01514）,6个群体的遗传多样性水平依次为YN > YP > QZ > FC > ZL > DG。各群体间的遗传分化并不显著（P>0.05）,光裸方格星虫的遗传变异主要来自群体内个体间（99.08%）,同时未发现明显的地理谱系结构。研究表明,光裸方格星虫野生群体的遗传多样性水平总体略高于养殖群体;滩涂底播养殖方式较池塘养殖更利于维持光裸方格星虫遗传多样性;各群体间不存在显著的遗传分化,养殖群体正逐渐积累遗传变异,但尚未足够以形成其独立的遗传结构。