On the affinities of three fossil ocypodid crabs and their relevance to the time and place of origin of the genus Macrophthalmus (Crustacea: Brachyura)

All the species of Macrophthalmus described from fossil material belong to the still extant subgenus Venitus. M. vindobonensis and M. aquensis , the two earliest known species of the genus, are closely related to the extant M. latreillei , while M. guamensis is conspecific with M. leptophthalmus.
Doubt is cast on Remy's (1952) theory of the late Tertiary migration of Macrophthalmus from the Mediterranean, its suggested place of origin, to the Indo-West Pacific, its present distributional range. Instead it is proposed that Macrophthalmus arose in the Indo-West Pacific during the late Eocene-Oligocene, and extended its range into the Mediterranean during the early-middle Miocene. The Mediterranean species became isolated during the late Miocene by a land bridge, and probably became extinct following the elevation of their brackish habitat during the late Miocene-Pliocene.     

Genetic divergence and analysis of the relationships between species of Mosla (Labiatae)

Seven species were recognized in Mosla in China. M. pauciflora (C. Y. Wu) C. Y. Wu et H. W. Li is an allotetraploid (2n=36 ), while the other six species are diploids (2n=18). Cluster analysis based on allozyme data from 28 loci of 15 enzyme systems reveals that the six diploid species formed three species pairs. M. cavaleriei Lévl.is closely related to M. dianthera (Buch.-Ham. ex Roxb. ) Maxim., M. chinensis and M. hangchouensis Matsuda are sibling species, and M. scabra (Thunb.) C. Y. Wu et H. W. Li is allied to M. soochouensis. Although M. cavaleriei and M. dianthera are close relatives, considerable genetic divergence has been detected between them. One third of alleles are unique to either of them, and 28.6 % of their loci have different alleles fixed. The average genetic identity ( 1 ) between populations of these two species is 0.770, and the average genetic distance (D) is 0.261. M. scabra and M. soochouensis are the least divergent species pair (I =0.979, D＝0.025). No completely divergent locus was detected, and the percentages of unique alleles are 11.1% to M. scabra and 16.7 % to M. soochouensis. This finding indicates that a high level of genetic differentiation is unnecessarily a prerequisite of speciation. A moderate divergence is detected between M. chinensis and M. hangchouensis (I＝0.899, D=0.107, and 7.1% of completely diverged loci) yet the latter harbors four times as many unique alleles (45.1% ) as the former does(11.8 % ). Compared to the genetic divergence between M. scabra and M. soochouensis, M. dianthera and M. hangchouensis and may well been undergoing active speciation have the high genetic distance betweenpopulations (0.034 and 0.026 respectively).     

Variability of United States Isolates of Macrophomina phaseolina Based on Simple Sequence Repeats and Cross Genus Transferability to Related Genera Within Botryosphaeriaceae

Twelve simple sequence repeat (SSRs) loci were used to evaluate genetic diversity of 109 isolates of Macrophomina phaseolina collected from different geographical regions and host species throughout the United States (US). Genetic diversity was assessed using Nei’s minimum genetic distance, and the usefulness of each locus was determined by calculating the polymorphism information content (PIC). A total of 98 alleles were detected and of these 31 were unique to individual genotypes. Eight of twelve loci were highly informative with PIC values greater than 0.50. The majority of pairwise comparisons of genetic distance were greater than 0.60 indicating moderate to high genetic diversity. Dendrograms based on the genetic dissimilarities were created for the 109 isolates of which 79 were from soybean. Some clustering by host and geography was noted, but, the dendrograms generally grouped isolates independent of host or geography. Additionally, sequencing of the internal transcribed spacer region (ITS) for 10 isolates revealed that all of these isolates were 99% similar. Three SSR loci from M. phaseolina were cross amplified in other genera in the Botryosphaeriaceae. This was the first study of genotyping and assessing genetic diversity of M. phaseolina isolates collected from a widespread host and geographic range across the US with SSRs. With an additional 34 loci publically available for M. phaseolina, the results indicate that previously developed SSRs from one species can be used in future population, ecological, and genetic studies of M. phaseolina and other genera within the Botryosphaeriaceae.     

Concluding contribution towards a revision of, and a key to, the genus Macrophthalmus (Crustacea: Brachyura)

In this ninth and final part of a revision of the ocypodid genus Macrophthalmus Latreille (Crustacea: Brachyura), eight species are considered— M. leptophthalmus (H. M. Edw.), M. boteltobagoe (Sakai), M. philippinensis SereGne, M. consobrinus Nobili, M. gastrodes Kemp, M. franchettii Maccagno, M. gallardoi SereGne and M. vietnamensis SereGne—and the status of a species previously considered valid, M. holthuisi SereGne, is reconsidered. Only M. leptophthalmus, M. boteltobagoe and M. philippinensis are considered valid. Macrophthalmus , as here revised, contains 38 living and three extinct species, whilst 33 species have been reduced to synonyms. These various species are summarily listed and a key to the living species is provided.     

Red kite (Milvus milvus) and black kite (M. migrans): minute genetic interspecies distance of two raptors breeding in a mixed community (Falconiformes: Accipitridae)

Allozyme analysis of 24 loci in 154 red kites (Milvus milvus) and 36 black kites (Milvus migrans) from die Hakel forest (Sachsen-Anhalt, Germany) revealed a Nei's interspecies genetic distance of D = 0.009. Of die observed genetic variance of four polymorphic enzymes, 15.4% referred to die differentiation between die kite species, but 84.6% were contributed by the ingroup polymorphism widiin diese species. Allozymes permit the identification of some 78% of samples as orignating from M. milvus , but only of 5.4% of samples obtained from M. migrans. Akhough the genetic distance is slight, die Milvus kites are valid biospecies which, despite occasional instances of hybridization, coexist sympatrically and may breed in mixed breeding aggregations. Mate choice in die largely separate winter quarters of diese migratory birds or chromosomal incompatibility are hypodietical isolation mechanisms stabilizing die species boundary. Moreover, the range sympatry could have developed fairly recendy widi die spread of human agriculture.     

Genetic variation,population structure and identification of yellow catfish, <Emphasis Type="Italic">Mystus nemurus</Emphasis> (C&;V) in Thailand using RAPD,ISSR and SCAR marker

Random amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (ISSR) markers were used to investigate the genetic structure of four subpopulations of Mystus nemurus in Thailand. The 7 RAPD and 7 ISSR primers were selected. Of 83 total RAPD fragments, 80 (96.39%) were polymorphic loci, and of 81 total ISSR fragments, 75 (92.59%) were polymorphic loci. Genetic variation and genetic differentiation obtained from RAPD fragments or ISSR fragments showed similar results. Percentage of polymorphic loci (%P), observed number of alleles, effective number of alleles, Nei’s gene diversity (H) and Shannon’s information index revealed moderate to high level of genetic variations within each M. nemurus subpopulation and overall population. High levels of genetic differentiations were received from pairwise unbiased genetic distance (D) and coefficient of differentiation. Mantel test between D or gene flow and geographical distance showed a low to moderate correlation. Analysis of molecular variance indicated that variations among subpopulations were higher than those within subpopulations. The UPGMA dendrograms, based on RAPD and ISSR, showing the genetic relationship among subpopulations are grouped into three clusters; Songkhla (SK) subpopulation was separated from the other subpopulations. The candidate species-specific and subpopulation-specific RAPD fragments were sequenced and used to design sequence-characterized amplified region primers which distinguished M. nemurus from other species and divided SK subpopulation from the other subpopulations. The markers used in this study should be useful for breeding programs and future aquacultural development of this species in Thailand.     

Comparison of genetic diversity at microsatellite loci in near-extinct and non-endangered species of Mexican goodeine fishes and prediction of cross-amplification within the family

The cross-utility of 12 microsatellite loci (including nine newly developed loci) amongst the viviparous subfamily, the Mexican Goodeinae, was assessed, examining both the probability of amplification and the potential incidence of null alleles from tests of F _IS. Genetic diversity was relatively high in comparison to other freshwater species. Amplification success was not correlated with genetic distance between microsatellite source and target species, but taxa that were more distantly related were less likely to be cross-polymorphic for microsatellite loci. On average, species that were cross-polymorphic were separated by a genetic distance of 15% at the cytochrome oxidase I locus, while those that were monomorphic were separated by 19%. There was no evidence that null alleles become more frequent at greater source-target genetic distance.     

An estimation of the degree of the genetic divergence of sibling species Microtus arvalis and Microtus subarvalis (Rodentia) based on electrophoretic analysis

The electrophoretic mobilities of 52 enzymes and proteins were used as measures of the genetic similarity between the sibling species Microtus arvalis and M. subarvalis. The two vole species differed in the electrophoretic mobilities of seven (glucose-6-phosphate dehydrogenase, adenylate kinase, diaphorase, lactate dehydrogenase-A, alpha-galactosidase, 6-phosphogluconate dehydrogenase, and hemoglobin) of these markers. This allowed us to accept the seven markers assayed as species-specific markers. Based on the frequency distribution of the genes at the polymorphic loci of M. arvalis and M. subarvalis, the degree of their genetic similarity was estimated as 0.312 and the genetic distance as 1.164 by Nei's formula. The estimates for genetic similarity were close to those obtained for species recognized as distinct.     

Microsatellite genetic variation in small and isolated populations of Magnolia sieboldii ssp. japonica

Magnolia sieboldii ssp. japonica, distributed mainly in western Japan, is restricted to high elevation areas (1000-2000 m above sea level) and usually forms small isolated populations. Four microsatellite loci were assayed for 19 populations from six regions spanning the range of distribution, and the levels and distribution of genetic variation were estimated. All four loci were variable, with a total of 39 alleles, but the overall level of microsatellite genetic variation was low, especially compared with a related species, M. obovata. Genetic structure in M. sieboldii was characterised by low intrapopulational genetic variation (A = 3.74 and H(o) = 0.366 on average) and high genetic differentiation even among regional populations. Highly significant isolation-by-distance (IBD) models at the short distance were detected. Genetic drift and limited gene flow was considered to be important in determining the genetic structure within regions. Total genetic differentiation was remarkably high (F(ST) = 0.488 and R(ST) = 0.538), suggesting genetic barriers among regions. Neighbour-joining dendrograms relating the 19 populations, and further analysis on the IBD models, revealed that a stepwise mutation model was more suited than an infinite allele model to explain the genetic differentiation among regions. It is suggested that mutation at microsatellite loci might be influential in generating the genetic differentiation among regions. These results showed the potential of hypervariable microsatellite loci to evaluate the effects of genetic drift and population isolation within regions, and to detect genetic distinctiveness, in spite of the loss of overall genetic variation in M. sieboldii.     

Genetic differentiation of Culex pipiens (Diptera: Culicidae) in China

The population genetic structures of Culex pipiens Linnaeus were evaluated in China over a 2000 km transect that encompasses the two subspecies, C. p. pallens and C. p. quinquefasciatus. Four polymorphic allozyme loci were investigated in 1376 mosquitoes sampled from 20 populations across four provinces. These loci were not statistically dependent with no apparent heterozygote deficit or excess. On a regional scale (intra-province), a low (Fst=0.007-0.016) and significant genetic differentiation was found, with no clear geographical pattern. On a wider scale (inter-province), the genetic differentiation was higher (Fst=0.059), and an isolation by distance emerged. The results are compared with previous population genetic surveys of this mosquito species in different geographic areas over the world. The overall pattern suggests that Culex pipiens requires considerable distance (500-1000 km) to show isolation by distance, irrespective of the subspecies (C. p. pipiens, C. p. quinquefasciatus and C. p. pallens) or the geographic location.     

重金属污染下曼陀罗种群分化的RAPD分析

将不同空间地段上获得的同一种质但污染年代各不相同的4个曼陀罗材料种子易地种植在同一模拟重金属污染生境中,对这4个曼陀罗种群进行RAPD分析,结果表明,在105个检测位点中发现有78个位点呈多态性。在这些多态位点中未发现与重金属抗性有关的特异性多态DNA片段。S hannon-Weiner指数计算结果表明,在短期污染时间内曼陀罗种群遗传多样性水平降低。随着污染时间的推移,曼陀罗种群逐渐在污染迹地上稳定下来,曼陀罗种群遗传多样性水平有所回升和提高,4个曼陀罗种群遗传多样性由高到低排列顺序为L＞CK＞M＞S。遗传多样性指数表明曼陀罗种群间变异程度远小于种群内的遗传变异。4个种群两两间遗传距离较小,遗传距离最大的种群为L和S,最小的为L和CK种群。因此,在重金属胁迫环境选择下,曼陀罗种群发生了一定程度的分化与微进化,轻高水平的遗传多样性可能是植物适应重金属污染胁迫环境的基础。     

入侵植物薇甘菊种群的遗传分化

利用简单重复序列区间(Inter simple sequence repeat, ISSR)分子标记技术分析了入侵植物薇甘菊(Mikania micrantha)8个种群的遗传多样性及遗传分化。12个引物共扩增出171个位点,其中多态位点有103个,多态位点百分率(P%)为60.23%,Shannon信息指数(I)为0.281 8,Nei指数(h)为0.184 9,薇甘菊在物种水平具有较高的遗传多样性。AMOVA显示薇甘菊具有较高的遗传分化,36.49%的变异发生在种群间,63.51%的变异发生于种群内,基因分化系数(G_ST)为0.352 4。种群间的基因流较高,为0.918 7。薇甘菊8个种群之间的遗传相似性很高,平均为0.915 5;遗传距离很小,平均为0.088 4。采用UPGMA法对8个种群进行聚类,可以将8个种群分为两大类群,即内伶仃岛为一个类群,而深圳与东莞内陆种群组成另一类群。薇甘菊现有遗传结构的形成与其生活史特性及入侵生态学特性有关。     

Genetic differentiation among the Maculinea species (Lepidoptera: Lycaenidae) in eastern Central Europe

The present study aimed to analyse the level of genetic variation in the eastern Central European (Slovenia, Hungary, and Romania/Transylvania) populations of the Large Blues ( Maculinea ) to analyse the pattern of differentiation both between and within the species. One objective was to compare the level of differentiation between the two disputed species ( Maculinea alcon and Maculinea rebeli ) with that among the other species. Imagos were collected from 23 localities in eastern Central Europe in 2002. Enzyme polymorphism was analysed using polyacrylamide gel electrophoresis. Fourteen enzyme loci were studied in all samples. In the analysis of the data, F -statistics and Nei's genetic distances were calculated and a dendrogram (unweighted pair group method with arithmetic mean) was constructed on the basis of the distance matrix. A multivariate analysis of variance was performed to study the pattern of genetic differentiation among the samples. Principal component analysis analysis was also carried out using the allele frequency data of the samples. Our results indicated that the large blues are generally less polymorphic than other European lycaenid butterflies studied. At the same time, the level of genetic differentiation was high, even among local populations within the species. A low level of genetic variation within the populations coupled with strong differentiation among them implies the effect of genetic drift. Strong genetic differentiation of four Maculinea species ( M. alcon , Maculinea teleius, Maculinea nausithous , and Maculinea arion ) was confirmed. Significant differentiation was not found between M. alcon and M. rebeli .  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 91 , 11–21.     

Cross-species amplification of cassava (Manihot esculenta) (Euphorbiaceae) microsatellites: allelic polymorphism and degree of relationship

Microsatellite amplification was performed on cassava (Manihot esculenta) and six other different species (all wild) of the Manihot genus. We used ten pairs of microsatellite primers previously developed from cassava, detecting 124 alleles in a sample of 121 accessions of the seven species. The number of alleles per locus ranged from four to 21 alleles, and allelic diversity was greater in the wild species than in cassava. Seventy-nine alleles, including unique ones, were detected in the wild species but were not found in the crop. The lower level of heterozygosity in some wild species probably resulted from a combination of fine-scale differentiation within the species and the presence of null alleles. Overall, microsatellite primers worked across the genus, but, with increasing genetic distance, success in amplifying loci tended to decrease. No accession of M. aesculifolia, M. carthaginensis, and M. brachyloba presented a banding pattern at locus Ga-140; neither did one appear for M. aesculifolia at locus Ga-13. Previous work with amplified fragment length polymorphism (AFLP) markers and this microsatellite analysis show that these three wild taxa are the most distant relatives of the crop, whereas the wild forms M. esculenta subsp. flabellifolia and M. esculenta subsp. peruviana appear to be the closest.     

Genetic distance between two sibling species of the Aedes mariae complex (Diptera, Culicidae)

Two sibling species of the mariae complex of the Aedes genus have been studied: Ae. mariae and Ae. zammitii. Thee mosquitoes are allopatric and show similar adaptations to rocky mediterranean coasts. The isolating mechanisms between the two species are well studied. A partial sterility of hybrid F1, limited to males, has been found with laboratory cross experiments. Strong pre-mating isolating mechanisms were shown in nature by means of release experiments, the frequency of hybrids never exceeding 2% without evidence of introgression. We analyzed genetic variation at 26 enzyme loci in a population of each species: 35% of loci were polymorphic, with an observed mean heterozygosity of 0.07 in Ae. mariae and 0.06 in Ae. zammitii; 6 loci allow discrimination between the two species at a probability of at least .99. Nei's measures of genetic identity and genetic distance are respectively I = 0.6096 and D = 0.2828. The distribution of genetic identities relative to loci is strongly bimodal, reflecting a different contribution of highly variable and fast evolving loci on one side and conservative and slowly evolving loci on the other. We consider, on the base of various experimental data (see Powell, 1975), in the first class ("fast evolving" loci) both variable substrate and regulatory enzymes, in the second ("slow evolving" loci) non regulatory enzymes. Values of genetic distance calculated separately for the "fast" (54% of the loci studied) and "slow" (46%) evolving loci are respectively Df = 0.41 and Ds = 0.03, showing that the main contribution to genetic distance in the first period of divergence is due to fast evolving loci, whose rate of evolution is about ten times more rapid with respect to slow evolving loci.     

广东省十种卷柏属植物RAPD初步分析

采用RAPD标记对卷柏属10种植物进行了分类鉴定、种间亲缘关系及遗传多样性的初步分析。结果显示:10个RAPD引物很好地区分了10个种,每个种均有2~12个种单态特征位点;UPGMA聚类树与有关文献表型分类结果不尽一致;卷柏属不同种具有不同的遗传多样性水平。     

Allozyme diversity and morphometrics of Melocactus paucispinus (Cactaceae) and evidence for hybridization with M. concinnus in the Chapada Diamantina, North-eastern Brazil

BACKGROUND AND AIMS: Melocacatus paucispinus (Cactaceae) is endemic to the state of Bahia, Brazil, and due to its rarity and desirability to collectors it has been considered threatened with extinction. This species is usually sympatric and inter-fertile with M. concinnus, and morphological evidence for hybridization between them is present in some populations. Levels of genetic and morphological variation and sub-structuring in populations of these species were assessed and an attempt was made to verify the occurrence of natural hybridization between them. METHODS: Genetic variability was surveyed using allozymes (12 loci) and morphological variability using multivariate morphometric analyses (17 vegetative characters) in ten populations of M. paucispinus and three of M. concinnus occurring in the Chapada Diamantina, Bahia. KEY RESULTS: Genetic variability was low in both species (P = 0.0-33.3, A = 1.0-1.6, H(e) = 0.000-0.123 in M. paucispinus; P = 0.0-25.0, A = 1.0-1.4, H(e) = 0.000-0.104 in M. concinnus). Deficit of heterozygotes within the populations was detected in both species, with high values of F(IS) (0.732 and 0.901 in M. paucispinus and M. concinnus, respectively). Evidence of hybridization was detected by the relative allele frequency in the two diaphorase loci. High levels of genetic (F(ST) = 0.504 in M. paucispinus and 0.349 in M. concinnus) and morphological (A = 0.20 in M. paucispinus and 0.17 in M. concinnus) structuring among populations were found. CONCLUSIONS: The Melocactus spp. displayed levels of genetic variability lower than the values reported for other cactus species. The evidence indicates the occurrence of introgression in both species at two sites. The high F(ST) values cannot be explained by geographical substructuring, but are consistent with hybridization. Conversely, morphological differentiation in M. paucispinus, but not in M. concinnus, is probably due to isolation by distance.     

Genetic divergence between populations of two closely related troglobitic beetle species (Speonomus: Bathysciinae,Coleoptera)

Genetic variability and divergence at 13 enzyme loci were studied in two species of troglobitic beetles (Speonomus zophosinus andhydrophilus 12 populations) collected from the Pyrenees mountains. These allopatric species exhibit a high degree of specialization to underground life and a very small geographical range. Four diagnostic loci arePgi, Est-2, Pac-1, Phi. Within each species polymorphic loci exhibited marked spatial variation of allele frequencies, sometimes over short distances (5–10 km). The levels of genetic variability are comparable to those observed in non-cave invertebrates (frequency of polymorphic loci: 0.31; average expected heterozygosity: 0.112±0.015). Moreover, a single species showed variability in the average level of heterozygosity (0.06 to 0.172). Patterns of genetic differentiation among species were also studied; mean genetic distance (D: 0.263±0.010) between the twoSpeonomus species was of the same order of magnitude as most data reported in the literature between species. A significant heterozygote deficiency occurs in local populations and for all loci. This deficit does not vary from locus to locus. Several hypotheses were examined in an attempt to account for these observations in connection with the species biology. This deficit probably is due to the breeding structure of the population (inbreeding and assortative mating) coupled with limited dispersal ability.     

PERMANENT GENETIC RESOURCES: Cross-family amplification: microsatellites isolated from Macropodidae are polymorphic in Potoroidae

The superfamily Macropodoidea consists of two families - the Macropodidae and Potoroidae. Cross-species amplification and polymorphism of microsatellite loci is widely recognized within the macropodid family; however, the success of macropodid loci in potoroid species has not been as widely published. In this study, we tested the amplification and polymorphism of 17 cross-species microsatellite loci isolated from macropodids and potoroids in Bettongia lesueur (a potoroid). Success varied between loci and was not predicted by genetic distance from the species of isolation.     

Accuracy of estimated phylogenetic trees from molecular data

The accuracies and efficiencies of three different methods of making phylogenetic trees from gene frequency data were examined by using computer simulation. The methods examined are UPGMA, Farris' (1972) method, and Tateno et al.'s (1982) modified Farris method. In the computer simulation eight species (or populations) were assumed to evolve according to a given model tree, and the evolutionary changes of allele frequencies were followed by using the infinite-allele model. At the end of the simulated evolution five genetic distance measures (Nei's standard and minimum distances, Rogers' distance, Cavalli-Sforza's f theta, and the modified Cavalli-Sforza distance) were computed for all pairs of species, and the distance matrix obtained for each distance measure was used for reconstructing a phylogenetic tree. The phylogenetic tree obtained was then compared with the model tree. The results obtained indicate that in all tree-making methods examined the accuracies of both the topology and branch lengths of a reconstructed tree (rooted tree) are very low when the number of loci used is less than 20 but gradually increase with increasing number of loci. When the expected number of gene substitutions (M) for the shortest branch is 0.1 or more per locus and 30 or more loci are used, the topological error as measured by the distortion index (dT) is not great, but the probability of obtaining the correct topology (P) is less than 0.5 even with 60 loci. When M is as small as 0.004, P is substantially lower. In obtaining a good topology (small dT and high P) UPGMA and the modified Farris method generally show a better performance than the Farris method. The poor performance of the Farris method is observed even when Rogers' distance which obeys the triangle inequality is used. The main reason for this seems to be that the Farris method often gives overestimates of branch lengths. For estimating the expected branch lengths of the true tree UPGMA shows the best performance. For this purpose Nei's standard distance gives a better result than the others because of its linear relationship with the number of gene substitutions. Rogers' or Cavalli-Sforza's distance gives a phylogenetic tree in which the parts near the root are condensed and the other parts are elongated. It is recommended that more than 30 loci, including both polymorphic and monomorphic loci, be used for making phylogenetic trees. The conclusions from this study seem to apply also to data on nucleotide differences obtained by the restriction enzyme techniques.