木荷种群在演替系列群落中的遗传多样性

利用ISSR分子标记对木荷种群在3个演替系列群落中的遗传多样性进行了研究。12个随机引物共检测到203个可重复的位点,其中多态位点183个,总多态位点百分率（P）为90.15%,平均多态位点百分率为82.27%。Shannon信息指数（I）估算的总遗传多样性为0.524 4,平均为0.477 8。Nei指数（h）计算的总基因多样性为0.358 7,平均为0.326 5。3个种群的P、I、h大小顺序均为针叶林>针阔混交林>常绿阔叶林。AMOVA分子变异显示91.56%变异来源于种群内,8.44%变异来源于种群间。种群间的遗传分化系数（G_ST）为0.089 7,基因流（N_m）为5.073 1。种群间的遗传相似度平均为0.928 4,遗传距离平均为0.074 4,针叶林种群与针阔混交林种群遗传相似度最高。     

Conservation genetics of the highly endangered Azorean endemics <Emphasis Type="Italic">Euphrasia azorica</Emphasis> and <Emphasis Type="Italic">Euphrasia grandiflora</Emphasis> using new SSR data

In the Azores Islands, two Euphrasia L. (Orobanchaceae) endemic species are recognized: Euphrasia azorica H.C.Watson, an annual herb, in Flores and Corvo, and Euphrasia grandiflora Hochst. ex Seub., a semi-shrub, in Pico, São Jorge and Terceira. Both species are highly endangered and protected by the Bern Convention and Habitats Directive. A population genetics study was conducted with new microsatellite primer pairs in 159 individuals of E. azorica and E. grandifolia, sampled from populations in Flores, Corvo, Pico and São Jorge. Allele sizing suggested that E. azorica is a diploid while E. grandiflora is a tetraploid. Euphrasia grandiflora revealed higher genetic diversity then E. azorica. The E. grandiflora population of Morro Pelado in São Jorge, displayed higher genetic diversity when compared with all others, while the E. azorica population of Madeira Seca in Corvo, showed the lowest. Private and less common bands were also overall higher in E. grandiflora populations. Population genetic structure analysis confirmed a distinctiveness between the two Azorean endemic Euphrasia, in addition to island-specific genetic patterns in E. azorica. The genetic structure obtained for E. grandiflora was complex with the populations of Cabeço do Mistério in Pico Island and of Pico da Esperança in São Jorge sharing the same genetic group, while a putative spatial barrier to gene flow was still retrieved between both islands. Although some populations of both species might benefit from propagation actions, studies are needed on plant host species and translocations between islands or between some populations of a same island should be avoided, due to the occurrence of putative ESUs. Eradication of invasive species and control of grazing will be fundamental to promote in situ restauration.     

The Historical Demography and Genetic Variation of the Endangered Cycas multipinnata (Cycadaceae) in the Red River Region,Examined by Chloroplast DNA Sequences and Microsatellite Markers

Cycas multipinnata C.J. Chen & S.Y. Yang is a cycad endemic to the Red River drainage region that occurs under evergreen forest on steep limestone slopes in Southwest China and northern Vietnam. It is listed as endangered due to habitat loss and over-collecting for the ornamental plant trade, and only several populations remain. In this study, we assess the genetic variation, population structure, and phylogeography of C. multipinnata populations to help develop strategies for the conservation of the species. 60 individuals from six populations were used for chloroplast DNA (cpDNA) sequencing and 100 individuals from five populations were genotyped using 17 nuclear microsatellites. High genetic differentiation among populations was detected, suggesting that pollen or seed dispersal was restricted within populations. Two main genetic clusters were observed in both the cpDNA and microsatellite loci, corresponding to Yunnan China and northern Vietnam. These clusters indicated low levels of gene flow between the regions since their divergence in the late Pleistocene, which was inferred from both Bayesian and coalescent analysis. In addition, the result of a Bayesian skyline plot based on cpDNA portrayed a long history of constant population size followed by a decline in the last 50,000 years of C. multipinnata that was perhaps affected by the Quaternary glaciations, a finding that was also supported by the Garza-Williamson index calculated from the microsatellite data. The genetic consequences produced by climatic oscillations and anthropogenic disturbances are considered key pressures on C. multipinnata. To establish a conservation management plan, each population of C. multipinnata should be recognized as a Management Unit (MU). In situ and ex situ actions, such as controlling overexploitation and creating a germplasm bank with high genetic diversity, should be urgently implemented to preserve this species.     

Genetic and phenotypic changes in an Atlantic salmon population supplemented with non-local individuals: a longitudinal study over 21 years

While introductions and supplementations using non-native and potentially domesticated individuals may have dramatic evolutionary effects on wild populations, few studies documented the evolution of genetic diversity and life-history traits in supplemented populations. Here, we investigated year-to-year changes from 1989 to 2009 in genetic admixture at 15 microsatellite loci and in phenotypic traits in an Atlantic salmon (Salmo salar) population stocked during the first decade of this period with two genetically and phenotypically distinct source populations. We detected a pattern of temporally increasing introgressive hybridization between the stocked population and both source populations. The proportion of fish returning to the river after a single winter at sea (versus several ones) was higher in fish assigned to the main source population than in local individuals. Moreover, during the first decade of the study, both single-sea-winter and multi-sea-winter (MSW) fish assigned to the main source population were smaller than local fish. During the second decade of the study, MSW fish defined as hybrids were lighter and smaller than fish from parental populations, suggesting outbreeding depression. Overall, this study suggests that supplementation with non-local individuals may alter not only the genetic diversity of wild populations but also life-history traits of adaptive significance.     

Morphometric and molecular differences among Calvertius tuberosus (Coleoptera: Curculionidae) populations associated with Andean and coastal populations of Araucaria araucana in the La Araucanía Region,Chile

Calvertius tuberosus (Curculionidae) lives exclusively on Araucaria araucana trees (commonly known as pehuen) in southern Chile. In this study, morphometric and molecular genetic analyses of Andean and coastal populations of C. tuberosus were performed to evaluate evolutionary divergence associated with the discontinuity of the Araucaria forest between the coastal and Andean regions. Specimens of C. tuberosus were collected in Nahuelbuta National Park, Villa Las Araucarias, and Malalcahuello National Reserve and were classified and stored at the Animal Biotechnology Researching Laboratory (LINBA), University of La Frontera, Temuco, Chile. Thirteen morphometric parameters and the expression patterns of ISSR (inter-simple sequence repeat) markers were analyzed. Morphometric data revealed high phenotypic similarity between coastal populations. The genetic analysis revealed a high similarity between coastal populations (genetic identity, 93%), which were differentiated from the Andean population (genetic identity, 84%). This study contributes new genotypic and phenotypic data for the C. tuberosus populations in forest ecosystems of A. araucana, and clarifies the associations between these characteristics and the geographic distributions of populations.     

Anthropogenic dispersion of selected germplasm creates a geographic mosaic of contrasting maternal lineages in <Emphasis Type="Italic">Crescentia cujete</Emphasis> from Mesoamerica

The modification of the genetic/phenotypic composition of plant populations through artificial selection occurs both through time and space. We analyzed the role of human dispersal on the geographic distribution of maternal lineages of Crescentia cujete in Mesoamerica. We sampled 28 homegarden (224 individuals) and 12 wild populations (159 individuals). Semi-structured interviews provided information on the origin of cultivated trees. Six chloroplast microsatellites allowed for the identification of 21 haplotypes, four of them exclusively in 83% of homegarden trees. Wild haplotypes from local C. cujete and Crescentia alata were found at low frequencies (17%) under cultivation. Cultivated and wild haplotypes constituted two different haplogroups. Accordingly, barriers to seed dispersal were detected among neighboring cultivated and wild populations. Recorded events of human dispersal of cuttings and seeds attaining up to >?200 km agreed with homegardens’ lower diversity (Nei’s h?=?0.55, dropping to 0.32 when excluding wild haplotypes). Wild populations displayed high diversity (h?=?0.71) and isolation by distance, in agreement with physiographic provinces. Our results support the native status of wild C. cujete and a Pre-Columbian introduction of cultivated lineages that generated a novel genetic mosaic superimposed on native maternal lineages. The results reveal the active role of farmers in maintaining the identity of cultivated lineages through time, while chloroplast capture from local congeners has increased the diversity of maternal lineages under cultivation. Additional data are needed on the origins of cultivated lineages, but our results contribute new insights into tree domestication in this center of crop diversity.     

Genomics reveals the history of a complex plant invasion and improves the management of a biological invasion from the South African–Australian biotic exchange

Many plants exchanged in the global redistribution of species in the last 200 years, particularly between South Africa and Australia, have become threatening invasive species in their introduced range. Refining our understanding of the genetic diversity and population structure of native and alien populations, introduction pathways, propagule pressure, naturalization, and initial spread, can transform the effectiveness of management and prevention of further introductions. We used 20,221 single nucleotide polymorphisms to reconstruct the invasion of a coastal shrub, Chrysanthemoides monilifera ssp. rotundata (bitou bush) from South Africa, into eastern Australia (EAU), and Western Australia (WAU). We determined genetic diversity and population structure across the native and introduced ranges and compared hypothesized invasion scenarios using Bayesian modeling. We detected considerable genetic structure in the native range, as well as differentiation between populations in the native and introduced range. Phylogenetic analysis showed the introduced samples to be most closely related to the southern‐most native populations, although Bayesian analysis inferred introduction from a ghost population. We detected strong genetic bottlenecks during the founding of both the EAU and WAU populations. It is likely that the WAU population was introduced from EAU, possibly involving an unsampled ghost population. The number of private alleles and polymorphic SNPs successively decreased from South Africa to EAU to WAU, although heterozygosity remained high. That bitou bush remains an invasion threat in EAU, despite reduced genetic diversity, provides a cautionary biosecurity message regarding the risk of introduction of potentially invasive species via shipping routes.     

Complete chloroplast genome sequence of Magnolia grandiflora and comparative analysis with related species

Magnolia grandiflora is an important medicinal,ornamental and horticultural plant species.The chloroplast(cp) genome of M.grandiflora was sequenced using a 454 sequencing platform and the genome structure was compared with other related species.The complete cp genome of M.grandiflora was 159623 bp in length and contained a pair of inverted repeats(IR) of 26563 bp separated by large and small single copy(LSC,SSC) regions of 87757 and 18740 bp,respectively.A total of 129 genes were successfully annotated,18 of which included introns.The identity,number and GC content of M.grandiflora cp genes were similar to those of other Magnoliaceae species genomes.Analysis revealed 218 simple sequence repeat(SSR) loci,most composed of A or T,contributing to a bias in base composition.The types and abundances of repeat units in Magnoliaceae species were relatively conserved and these loci will be useful for developing M.grandiflora cp genome vectors.In addition,results indicated that the cp genome size in Magnoliaceae species and the position of the IR border were closely related to the length of the ycf1 gene.Phylogenetic analyses based on 66 shared genes from 30 species using maximum parsimony(MP) and maximum likelihood(ML) methods provided strong support for the phylogenetic position of Magnolia.The availability of the complete cp genome sequence of M.grandiflora provides valuable information for breeding of desirable varieties,cp genetic engineering,developing useful molecular markers and phylogenetic analyses in Magnoliaceae.     

Geographical barriers and climate influence demographic history in narrowleaf cottonwoods

Studies of genetic variation can clarify the role of geography and spatio-temporal variation of climate in shaping demography, particularly in temperate zone tree species with large latitudinal ranges. Here, we examined genetic variation in narrowleaf cottonwood, Populus angustifolia, a dominant riparian tree. Using multi-locus surveys of polymorphism in 363 individuals across the species'' 1800 km latitudinal range, we found that, first, P. angustifolia has stronger neutral genetic structure than many forest trees (simple sequence repeat (SSR) F_ST=0.21), with major genetic groups corresponding to large apparent geographical barriers to gene flow. Second, using SSRs and putatively neutral sequenced loci, coalescent simulations indicated that populations diverged before the last glacial maximum (LGM), suggesting the presence of population structure before the LGM. Third, the LGM and subsequent warming appear to have had different influences on each of these distinct populations, with effective population size reduction in the southern extent of the range but major expansion in the north. These results are consistent with the hypothesis that climate and geographic barriers have jointly affected the demographic history of P. angustifolia, and point the importance of both factors as being instrumental in shaping genetic variation and structure in widespread forest trees.     

Genetic diversity analysis of Hepatacodium miconioides at different altitude in Tiantai Mountain, Zhejiang Province, China and its relationship with environmental factors

The genetic diversity within and among populations of Hepatacodium miconioides collected at three different altitudes in Tiantai Mountain, Zhejiang Province and its relationships to environmental factors were analyzed by random amplified polymorphic DNA (RAPD) technique. Amplification using 12 random primers of 60 plants and 122 repetitive loci were produced. The percentage of polymorphic loci of three populations ranged from 18.85% to 23.77% with an average of 21.86%, indicating the relatively low genetic diversity of H. miconioides. The average Shannon index of phenotypic diversity (0.1329) and Nei index (0.0925) within populations were relatively low. A distinct genetic differentiation existed among populations of H. miconioides in spite of the relatively small geographical distribution. The average genetic diversity within populations of H. miconioides accounted for 33.58% of the total genetic diversity while the genetic diversity among populations accounted for 66.42% as estimated by the Shannon index of phenotypic diversity, The genetic differentiation among populations of H. miconioides was 0.6546, as estimated by Nei index. The gene flow estimated from G _ST was only 0.2656 and it indicated that gene flow among populations of H. miconioides was relatively low. The mean value of the genetic identity among populations of H. miconioides was 0.7126 and the average of genetic distance of H. miconioides was 0.3412. The genetic identity between populations at the elevation of 990 m and at the elevation of 780 m was the highest. The genetic identity between population at the elevation 500 m and other two populations was relatively low. The correlation analysis showed that the genetic diversity within populations was significantly related with the soil total nitrogen.     

Development of microsatellite markers in Qualea grandiflora (Vochysiaceae) and transferability to congeneric species,typical trees of the Brazilian savanna

This study aimed to isolate and characterize microsatellite markers for Qualea grandiflora and to test their transferability to congeneric species Qualea multiflora and Qualea parviflora. These three species are widespread in the Cerrado, the largest, richest and probably the most threatened tropical savanna in the world. We characterized ten markers in 40 individuals belonging to two populations of Q. grandiflora and eight markers in 20 individuals belonging to one population of Q. multiflora and Q. parviflora. In Q. grandiflora, considering all 40 analyzed individuals, the number of alleles per locus ranged from eight to 21, and the average was 11.60. The mean number of alleles per locus was 8.8 and 7.3 in each population. The observed and expected heterozygosities (H_o and H_e) within populations varied from 0.235 to 0.944 and from 0.225 to 0.932, respectively. In Q. multiflora the number of alleles varied from two to 11 with an average of 5.75; the H_o ranged from 0.150 to 0.950, while H_e ranged from 0.191 to 0.817. In Q. parviflora, considering the seven polymorphic loci, the number of alleles ranged from two to 13, with an average of 7.5, while H_o ranged from 0.211 to 0.944, and H_e ranged from 0.193 to 0.906. The polymorphism level of the microsatellite markers here described enable them as powerful tools for future population genetic studies in these species, helping to answer ecological and evolutionary questions.     

A comparison of the population genetic structure of parasitic Viscum album from two landscapes differing in degree of fragmentation

Parasite populations do not necessarily conform to expected patterns of genetic diversity and structure. Parasitic plants may be more vulnerable to the negative consequences of landscape fragmentation because of their specialized life history strategies and dependence on host plants, which are themselves susceptible to genetic erosion and reduced fitness following habitat change. We used AFLP genetic markers to investigate the effects of habitat fragmentation on genetic diversity and structure within and among populations of hemiparasitic Viscum album. Comparing populations from two landscapes differing in the amount of forest fragmentation allowed us to directly quantify habitat fragmentation effects. Populations from both landscapes exhibited significant isolation-by-distance and sex ratios biased towards females. The less severely fragmented landscape had larger and less isolated populations, resulting in lower levels of population genetic structure (F _ST = 0.05 vs. 0.09) and inbreeding (F _IS = 0.13 vs. 0.27). Genetic differentiation between host-tree subpopulations was also higher in the more fragmented landscape. We found no significant differences in within-population gene diversity, percentage of polymorphic loci, or molecular variance between the two regions, nor did we find relationships between genetic diversity measures and germination success. Our results indicate that increasing habitat fragmentation negatively affects population genetic structure and levels of inbreeding in V. album, with the degree of isolation among populations exerting a stronger influence than forest patch size.     

Purification by Immunoadsorption and Immunochemical Properties of NADP-Dependent Malic Enzymes from Leaves of C(3), C(4), and Crassulacean Acid Metabolism Plants

NADP:malic enzyme from corn (Zea mays L.) leaves was purified by conventional techniques to apparent homogeneity as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Antibodies raised against this protein in rabbits were purified, coupled covalently to protein A-Sepharose CL-4B, and used as an immunoaffinity resin to purify the NADP:malic enzymes of the C₃ plants spinach (Spinacia oleracea L.) and wheat (Triticum aestivum L.), of the Crassulacean acid metabolism (CAM) plant Bryophyllum daigremontianum R. Hamed et Perr. de la Bathie and the C₄ plants corn, sugarcane (Saccharum officinarum L.), and Portulaca grandiflora L. Such procedures yielded homogeneous protein preparations with a single protein band, as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, except for P. grandiflora L. with two bands. The specific activities of the purified proteins ranged between 56 and 91 units (milligrams per protein). NADP:malic enzyme represented up to 1% of the total soluble protein in C₄ plants, 0.5% in the CAM plant, and less than 0.01% in C₃ plants. In immunotitration tests involving immunoprecipitation and immunoinhibition of activity by an antiserum against the corn leaf enzyme, the NADP:malic enzymes of corn and sugarcane showed virtually full identity of epitopes, while the NADP:malic enzymes of the C₃ and CAM plants exhibited a cross-reaction of one-twentieth and one-fourth by these tests, respectively. The NADP:malic enzyme of P. grandiflora exhibited characteristics more closely related to the enzymes of C₃ and CAM plants than to those of C₄ plants.     

Dispersal ecology of the endangered woodland lichen Lobaria pulmonaria in managed hemiboreal forest landscape

Changes in the forest management practices have strongly influenced the distribution of species inhabiting old-growth forests. The epiphytic woodland lichen Lobaria pulmonaria is frequently used as a model species to study the factors affecting the population biology of lichens. We sampled 252 L. pulmonaria individuals from 12 populations representing three woodland types differing in their ecological continuity and management intensity in Estonia. We used eight mycobiont-specific microsatellite loci to quantify genetic diversity among the populations. We calculated the Sørensen distance to estimate genetic dissimilarity among individuals within populations. We revealed that L. pulmonaria populations have significantly higher genetic diversity in old-growth forests than in managed forests and wooded meadows. We detected a significant woodland-type-specific pattern of genetic dissimilarity among neighbouring L. pulmonaria individuals, which suggests that in wooded meadows and managed forests dominating is vegetative reproduction. The vegetative dispersal distance between the host trees of L. pulmonaria was found to be only 15–30 m. Genetic dissimilarity among individuals was also dependent on tree species and trunk diameter. Lobaria pulmonaria populations in managed forests included less juveniles compared to old-growth forests and wooded meadows, indicating that forest management influences life stage structure within populations. We conclude that as intensive stand management reduces the genetic diversity of threatened species in woodland habitats, particular attention should be paid to the preservation of remnant populations in old-growth habitats. Within managed habitats, conservation management should target on maintenance of the stand’s structural diversity and availability of potential host trees.     

浙江天台山甜槠种群遗传结构的空间自相关分析

采用空间自相关分析方法对浙江天台山亚热带常绿阔叶林优势种甜槠种群全部个体及不同年龄级个体的小尺度空间遗传结构进行了分析,以探讨甜槠种群内遗传变异的分布特征及其形成机制。根据11个ISSR引物所提供的多态位点,经GenAlEx 6软件计算地理坐标和遗传距离矩阵在10个距离等级下的空间自相关系数。在样地内,甜槠种群内个体在空间距离小于10 m时存在显著的正空间遗传结构,其X-轴截矩为9.945。甜槠种群的空间遗传结构与其种子短距离传播和广泛的花粉传播有关。Ⅰ年龄级、Ⅱ年龄级和III年龄级个体在空间距离小于10 m时存在显著的正空间遗传结构,其X-轴截矩分别为11.820、9.746和9.792。当距离等级为5 m时,其空间自相关系数r分别为0.068、0.054和0.070。Ⅳ年龄级个体在所有空间距离等级中均不存在显著的空间遗传结构。甜槠是多年生、长寿命植物,自疏作用是导致IV年龄级个体空间遗传结构消失的主要原因。     

Genetic Diversity and Spatial Genetic Structure of an Epiphytic Bromeliad in Costa Rican Montane Secondary Forest Patches

Information on genetic variation and its distribution in tropical plant populations relies mainly on studies of ground‐rooted species, while genetic information of epiphytic plants is still limited. Particularly, the effect of forest successional condition on genetic diversity and structure of epiphytes is scanty in the literature. We evaluated the genetic variation and spatial genetic structure of the epiphytic bromeliad Guzmania monostachia (Bromeliaceae, Tillandsioideae) in montane secondary forest patches in Costa Rica. The sampling design included plants on the same trees (i.e., populations), populations within forest patches and patches within secondary forest at two different successional stages (early vs. mid‐succession). Six microsatellites revealed low levels of population genetic variation (A = 2.06, A_E = 1.61, H_E = 0.348), a marked deficiency of heterozygotes (H_O = 0.031) and high inbreeding (f = 0.908). Genetic differentiation was negligible among populations within the same forest patch, but moderate (G_ST = 0.123 ± 0.043) among forest patches. Genetic relatedness between individuals was significantly higher for plants located within the same forest patch and separated by <60 m and decreased as distance between plants increased, becoming significantly negative at distances >400 m. An analysis of molecular variance (AMOVA) showed significant genetic variation between forest patches, but non‐significant variation between successional stages. The selfing breeding system and limited seed dispersal capabilities in G. monostachia could explain the observed levels and partitioning of genetic diversity at this geographic scale. However, these results also suggest that forest fragmentation is likely to influence the degree of local genetic structuring of epiphytic plants by limiting gene flow.     

Genomic Identification of Founding Haplotypes Reveals the History of the Selfing Species Capsella rubella

The shift from outcrossing to self-fertilization is among the most common evolutionary transitions in flowering plants. Until recently, however, a genome-wide view of this transition has been obscured by both a dearth of appropriate data and the lack of appropriate population genomic methods to interpret such data. Here, we present a novel population genomic analysis detailing the origin of the selfing species, Capsella rubella, which recently split from its outcrossing sister, Capsella grandiflora. Due to the recency of the split, much of the variation within C. rubella is also found within C. grandiflora. We can therefore identify genomic regions where two C. rubella individuals have inherited the same or different segments of ancestral diversity (i.e. founding haplotypes) present in C. rubella''s founder(s). Based on this analysis, we show that C. rubella was founded by multiple individuals drawn from a diverse ancestral population closely related to extant C. grandiflora, that drift and selection have rapidly homogenized most of this ancestral variation since C. rubella''s founding, and that little novel variation has accumulated within this time. Despite the extensive loss of ancestral variation, the approximately 25% of the genome for which two C. rubella individuals have inherited different founding haplotypes makes up roughly 90% of the genetic variation between them. To extend these findings, we develop a coalescent model that utilizes the inferred frequency of founding haplotypes and variation within founding haplotypes to estimate that C. rubella was founded by a potentially large number of individuals between 50 and 100 kya, and has subsequently experienced a twenty-fold reduction in its effective population size. As population genomic data from an increasing number of outcrossing/selfing pairs are generated, analyses like the one developed here will facilitate a fine-scaled view of the evolutionary and demographic impact of the transition to self-fertilization.     

Dispersal of the Japanese Pine Sawyer,Monochamus alternatus (Coleoptera: Cerambycidae), in Mainland China as Inferred from Molecular Data and Associations to Indices of Human Activity

The Japanese pine sawyer, Monochamus alternatus Hope (Coleoptera: Cerambycidae), is an important forest pest as well as the principal vector of the pinewood nematode (PWN), Bursaphelenchus xylophilus (Steiner et Buhrer), in mainland China. Despite the economic importance of this insect-disease complex, only a few studies are available on the population genetic structure of M. alternatus and the relationship between its historic dispersal pattern and various human activities. The aim of the present study was to further explore aspects of human activity on the population genetic structure of M. alternatus in mainland China. The molecular data based on the combined mitochondrial cox1 and cox2 gene fragments from 140 individuals representing 14 Chinese populations yielded 54 haplotypes. Overall, a historical (natural) expansion that originated from China’s eastern coast to the western interior was revealed by the haplotype network, as well as several recent, long-distant population exchanges. Correlation analysis suggested that regional economic status and proximity to marine ports significantly influenced the population genetic structure of M. alternatus as indicated by both the ratio of shared haplotypes and the haplotype diversity, however, the PWN distribution in China was significantly correlated with only the ratio of shared haplotypes. Our results suggested that the modern logistical network (i.e., the transportation system) in China is a key medium by which humans have brought about population exchange of M. alternatus in mainland China, likely through inadvertent movement of infested wood packaging material associated with trade, and that this genetic exchange was primarily from the economically well-developed east coast of China, westward, to the less-developed interior. In addition, this study demonstrated the existence of non-local M. alternatus in new PWN-infested localities in China, but not all sites with non-local M. alternatus were infested with PWN.     

Switchgrass (Panicum virgatum L.) Genotypes Differ between Coastal Sites and Inland Road Corridors in the Northeastern US

Switchgrass (Panicum virgatum L.) is a North American grass that exhibits vast genetic diversity across its geographic range. In the Northeastern US, local switchgrass populations were restricted to a narrow coastal zone before European settlement, but current populations inhabit inland road verges raising questions about their origin and genetics. These questions are important because switchgrass lines with novel traits are being cultivated as a biofuel feedstock, and gene flow could impact the genetic integrity and distribution of local populations. This study was designed to determine if: 1) switchgrass plants collected in the Long Island Sound Coastal Lowland coastal Level IV ecoregion represented local populations, and 2) switchgrass plants collected from road verges in the adjacent inland regions were most closely related to local coastal populations or switchgrass from other geographic regions. The study used 18 microsatellite markers to infer the genetic relationships between 122 collected switchgrass plants and a reference dataset consisting of 28 cultivars representing ecotypes, ploidy levels, and lineages from North America. Results showed that 84% of 88 plants collected in the coastal plants were most closely aligned with the Lowland tetraploid genetic pool. Among this group, 61 coastal plants were similar to, but distinct from, all Lowland tetraploid cultivars in the reference dataset leading to the designation of a genetic sub-population called the Southern New England Lowland Tetraploids. In contrast, 67% of 34 plants collected in road verges in the inland ecoregions were most similar to two Upland octoploid cultivars; only 24% of roadside plants were Lowland tetraploid. These results suggest that cryptic, non-local genotypes exist in road verges and that gene flow from biofuels plantations could contribute to further changes in switchgrass population genetics in the Northeast.     

Patch size and isolation influence genetic patterns in black-and-white ruffed lemur (Varecia variegata) populations

Land use in Madagascar has resulted in extensive deforestation and forest fragmentation. Endemic species, such as the black-and-white ruffed lemur (Varecia variegata), may be vulnerable to habitat fragmentation due to patchy geographic distributions and sensitivities to forest disturbance. We tested for genetic differentiation among black-and-white ruffed lemur groups in two sites in a large forest patch and three sites in smaller patches. We also investigated the relationship between the genetic diversity of populations and patch configuration (size and isolation), as well as the presence or absence of past genetic bottlenecks. We collected blood (n = 22 individuals) or fecal (n = 33) samples from lemurs and genotyped the extracted DNA for 16 polymorphic microsatellites. Bayesian cluster analysis and F_ST assigned individuals to three populations: Ranomafana (two sites in continuous forest), Kianjavato (two fragments separated by 60 m of non-forest), and Vatovavy (a single fragment, more isolated in time and space). Vatovavy showed significantly lower allelic richness than Ranomafana. Kianjavato also appeared to have lower allelic richness than Ranomafana, though the difference was not significant. Vatovavy was also the only population with a genetic bottleneck indicated under more than one mutation model and a significant F_IS value, showing excess heterozygosity. These results indicate that a small geographic separation may not be sufficient for genetic differentiation of black-and-white ruffed lemur populations and that patch size may influence the rapidity with which genetic diversity is lost following patch isolation.