Genetic diversity and sex‐biased dispersal in the brown spotted pitviper (Protobothrops mucrosquamatus): Evidence from microsatellite markers

Dispersal plays a vital role in the geographical distribution, population genetic structure, quantity dynamics, and evolution of a species. Sex‐biased dispersal is common among vertebrates and many studies have documented a tendency toward male‐biased dispersal in mammals and female‐biased dispersal in birds. However, dispersal patterns in reptiles remain poorly understood. In this study, we explored the genetic diversity and dispersal patterns of the widely distributed Asian pitviper Protobothrops mucrosquamatus. In total, 16 polymorphic microsatellite loci were screened in 150 snakes (48 males, 44 females, 58 samples without sex information) covering most of their distribution. Microsatellite analysis revealed high genetic diversity in P. mucrosquamatus. Bayesian clustering of population assignment identified two major clusters for all populations, somewhat inconsistent with the mitochondrial DNA phylogeny of P. mucrosquamatus reported in previous research. Analyses based on 92 sex‐determined and 37 samples of P. mucrosquamatus from three small sites in Sichuan, China (Mingshan, Yibin, and Zizhong) consistently suggested female‐biased dispersal in P. mucrosquamatus, which is the first example of this pattern in snakes. The female‐biased dispersal patterns in P. mucrosquamatus may be explained by local resource competition.     

Lichens buffer tundra microclimate more than the expanding shrub Betula nana

Background and AimsIn tundra systems, soil-borne lichens are often the dominant groundcover organisms, and act to buffer microclimate extremes within or at the surface of the soil. However, shrubs are currently expanding across tundra systems, potentially causing major shifts in the microclimate landscape.MethodsHere, we compared soil temperature and moisture underneath the dwarf birch Betula nana and seven abundant lichen species in sub-alpine Norway. We also examined mixtures of lichens and dwarf birch – an intermediate phase of shrubification – and measured several functional traits relating to microclimate.Key ResultsWe found that all lichen species strongly buffered the daily temperature range, on average reducing maximum temperatures by 6.9 °C (± 0.7 s.d.) and increasing minimum temperatures by 1.0 °C (± 0.2 s.d.) during summer. The dwarf birch had a much weaker effect (maximum reduced by 2.4 ± 5.0 °C and minimum raised by 0.2 ± 0.9 °C). In species mixtures, the lichen effect predominated, affecting temperature extremes by more than would be expected from their abundance. Lichens also tended to reduce soil moisture, which could be explained by their ability to intercept rainfall. Our trait measurements under laboratory conditions suggest that, on average, lichens can completely absorb a 4.09 mm (± 1.81 s.d.) rainfall event, which might be an underappreciated part of lichen–vascular plant competition in areas where summer rainfall events are small.ConclusionsIn the context of shrubification across tundra systems, our findings suggest that lichens will continue to have a large effect on microclimate until they are fully excluded, at which point microclimate extremes will increase greatly.     

Retrotransposons in <Emphasis Type="Italic">Betula nana</Emphasis>, and interspecific relationships in the Betuloideae,based on inter-retrotransposon amplified polymorphism (IRAP) markers

The Betulaceae family comprises two subfamilies, Betuloideae and Corylaceae. The subfamily Betuloideae contains two genera, Alnus Mill. and Betula L. Twenty putative long terminal repeat (LTR) retrotransposons were mined from 171 scaffolds containing 5,208,995 bp of dwarf birch (Betula nana) genome sequences. Five retrotransposons were finally selected after filtering the retrotransposon canonical features and nucleotide similarities between left and right LTR sequences. Of the five retroelements, three elements were found to be Ty1/Copia retrotransposons; identity of the other two elements could not be ascertained due to sequence undetermined ‘N’ bases in the sequence database. Inter-retrotranposon amplified polymorphism (IRAP) analysis, based on the LTR sequences of the mined LTR-retrotransposons, produced 179 discernible IRAP bands among the Alnus and Betula genera. Sequence analysis revealed no size homoplasy among the homologous IRAP bands. Phylogenetic and principle coordinate analysis, based on the band sharing among the taxa, showed the species in two different genera were clearly separated. The subgenera in each genus of Alnus and Betula were also distinguishable from the IRAP profiles. In the genus Betula, the species in subgenus Betula showed mixed clustering between species. This is incongruent with the phylogeographical distribution of the species.     

Synchronized inter‐annual fluctuation of flowering intensity affects the exposure to allergenic tree pollen in North Europe

Many anemophilous, early‐flowering tree genera include allergy plants of world‐wide significance. We studied the synchronisation of high and low pollen years in the genera Betula, Alnus, Corylus, Salix and Populus and the cumulative effects that an increasing number of taxa has on the number of days of exposure to different levels of allergenic pollen in North Europe. The proximal causes of the inter‐annual variations of airborne pollen loads were analysed with a multiple regression analysis. The annual fluctuations of airborne pollen sums were compared between genera and found to be positively correlated among all combinations of genera at the three study sites. Most correlations were statistically significant (p<0.05). The comparison between Betula and Alnus is discussed first. Betula pollen was clearly the most abundant airborne pollen type. The presence of Alnus pollen, however, significantly increased the predisposal to allergenic pollen. At all sites, the number of days per year when the Betula and Alnus pollen counts together exceeded 10 and 100?grains m^?3 of air, was found to be greater than the number of days when the Betula pollen counts alone exceeded 10 and 100?m^?3 of air. The difference was statistically significant. In Kuopio, the difference was found to be statistically significant even for grains per 1?000?m^?3 of air of Betula and Alnus together compared with the same count of Betula pollen alone. Betula, Alnus and Corylus belong to the order Fagales and have cross‐reacting main allergens. The flowering of Alder and Corylus culminate at the same time, two to four weeks earlier than that of Betula. Due to synchronization of high and low years and the mostly non‐overlapping flowering seasons, the time of exposure to pollen may be very long during the high years. Furthermore, Alnus and Corylus pollen may prime allergic people before the onset of the Betula season.     

SNP detection and population structure evaluation of Salix gordejevii Y. L. Chang et Skv. in Hunshandake Sandland,Inner Mongolia,China

Single nucleotide polymorphisms (SNPs) are the most abundant and richest form of genomic polymorphism and, hence, are highly favorable markers for genetic map construction and genome-wide association studies. Based on the DNA specific-locus amplified fragment sequencing (SLAF-seq) for large-scale SNP detection, the genetic diversity and population structure of Salix gordejevii Y. L. Chang et Skv., a valuable sand-fixing shrub, was assessed in 199 accessions from 20 populations in Hunshandake Sandland of northern China. A total of 623.15 M reads resulted in 30.49 × sequencing depth on average and a mean Q30 of 95.70%, and 2,287,715 SNPs in 178,509 polymorphic SLAF tags were obtained. By discarding minor allele frequency > 0.05 and integrity > 0.8, a total of 93,600 SNPs were retained for population genetic analyses, which revealed that 199 individuals could be divided into six groups based on cross-validation errors. However, this grouping pattern did not match the geographical distribution, indicating that there is no apparent geographic barrier in the blank areas where S. gordejevii was not distributed in Hunshandake Sandland. In addition, the physical distance of linkage disequilibrium decay in the analyzed S. gordejevii individuals was 18.5 kb when r² = 0.1. The linkage disequilibrium decay distances for different chromosomes varied from 4.6 kb (chromosome 16) to 37.8 kb (chromosome 3). The obtained SNPs offer suitable marker resources for further genetic and genomic studies and will benefit S. gordejevii breeding programs.     

Early stages of speciation with gene flow in the Amazilia Hummingbird (Amazilis amazilia) subspecies complex of Western South America

Disentangling the factors underlying the diversification of geographically variable species with a wide geographical range is essential to understanding the initial stages and drivers of the speciation process. The Amazilia Hummingbird, Amazilis amazilia, is found along the Pacific coast from northern Ecuador down to the Nazca Valley of Peru, and is currently classified as six phenotypically differentiated subspecies. We aimed to resolve the evolutionary relationships of the six subspecies, to assess the geographical pattern and extent of evolutionary divergence, and to test for introgression using both a mtDNA marker and a genome‐by‐sequencing dataset from 86 individuals from across the species range. The consensus phylogenetic tree separated the six subspecies into three distinct clades, corresponding with the Ecuador lowlands (A. amazilia dumerilii), the Ecuador highlands (A. amazilia alticola and A. amazilia azuay), and the Peruvian coast (A. amazilia leucophoea, A. amazilia amazilia, and A. amazilia caeruleigularis). However, an unresolved mtDNA network suggests that the diversification of the subspecies was recent and rapid. We found evidence of gene flow among the subspecies A. amazilia dumerilii, A. amazilia alticola, and A. amazilia leucophoea, with strong genetic isolation of the subspecies A. amazilia azuay in the isolated Yunguilla Valley of Ecuador. Finally, environmental data from each subspecies’ capture locations were concordant with the three distinct clades. Overall, our results suggest that both expansions into new habitats and geographic isolation shaped the present‐day phylogeny and range of the A. amazilia subspecies, and that A. amazilia azuay may be genetically divergent enough to be considered a separate species.     

Genetic diversity and structure of Rhododendron meddianum,a plant species with extremely small populations

Rhododendron meddianum is a critically endangered species with important ornamental value and is also a plant species with extremely small populations. In this study, we used double digest restriction-site-associated DNA sequencing (ddRAD) technology to assess the genetic diversity, genetic structure and demographic history of the three extant populations of R. meddianum. Analysis of SNPs indicated that R. meddianum populations have a high genetic diversity (π = 0.0772 ± 0.0024, H_E = 0.0742 ± 0.002). Both F_ST values (0.1582–0.2388) and AMOVA showed a moderate genetic differentiation among the R. meddianum populations. Meanwhile, STRUCTURE, PCoA and NJ trees indicated that the R. meddianum samples were clustered into three distinct genetic groups. Using the stairway plot, we found that R. meddianum underwent a population bottleneck about 70,000 years ago. Furthermore, demographic models of R. meddianum and its relative, Rhododendron cyanocarpum, revealed that these species diverged about 3.05 (2.21–5.03) million years ago. This divergence may have been caused by environmental changes that occurred after the late Pliocene, e.g., the Asian winter monsoon intensified, leading to a drier climate. Based on these findings, we recommend that R. meddianum be conserved through in situ, ex situ approaches and that its seeds be collected for germplasm.     

High genetic differentiation of Indo‐Pacific humpback dolphins (Sousa chinensis) along the Asian Coast of the Pacific Ocean

The Indo‐Pacific humpback dolphin (Sousa chinensis) is a vulnerable marine mammal species that inhabits shallow, coastal waters from Southeast China, southward throughout Southeast Asia, and westward around the Bay of Bengal to eastern India. Polymorphic microsatellites are useful for elucidating ecological and population genetics‐related questions. Here, 18 new polymorphic microsatellites were developed from S. chinensis genomic DNA by Illumina MiSeq sequencing. Population genetic analyses were conducted on 42 S. chinensis individuals from three geographic locations, including the Xiamen Bay of China, the Western Gulf of Thailand, and Andaman Sea. Our microsatellite data revealed a strong and significant population structure among the three sampling regions (overall F _ST = 0.371, p = .001). Pairwise mutual information index also demonstrated high levels of genetic differentiation between different region pairs (values range from 0.272 to 0.339, p < .001). Moreover, Structure analysis inferred three genetic clusters, with the high assignment probabilities of 95.92%, 99.47%, and 99.68%, respectively. Principal coordinate analysis plots of individuals divided entire genotypes into three clusters, indicating high level of genetic differentiation. Our results indicated the strong genetic structure in S. chinensis populations is a result of geographic distances. Other factors such as environmental variables, anthropogenic interference, and social behavior may also have contributed to population differentiation.     

Genetic differentiation and connectivity of morphological types of the broadcast‐spawning coral Galaxea fascicularis in the Nansei Islands,Japan

Population connectivity resulting from larval dispersal is essential for the maintenance or recovery of populations in marine ecosystems, including coral reefs. Studies of species diversity and genetic connectivity within species are essential for the conservation of corals and coral reef ecosystems. We analyzed mitochondrial DNA sequence types and microsatellite genotypes of the broadcast‐spawning coral, Galaxea fascicularis, from four regions in the subtropical Nansei Islands in the northwestern Pacific Ocean. Two types (soft and hard types) of nematocyst morphology are known in G. fascicularis and are significantly correlated with the length of a mitochondrial DNA noncoding sequence (soft type: mt‐L; hard type: mt‐S type). Using microsatellites, significant genetic differentiation was detected between the mitochondrial DNA sequence types in all regions. We also found a third genetic cluster (mt‐L+), and this unexpected type may be a cryptic species of Galaxea. High clonal diversity was detected in both mt‐L and mt‐S types. Significant genetic differentiation, which was found among regions within a given type (F _ST = 0.009–0.024, all Ps ≤ 0.005 in mt‐L; 0.009–0.032, all Ps ≤ 0.01 in mt‐S), may result from the shorter larval development than in other broadcast‐spawning corals, such as the genus Acropora. Nevertheless, intraspecific genetic diversity and connectivity have been maintained, and with both sexual and asexual reproduction, this species appears to have a potential for the recovery of populations after disturbance.     

Phylogenetic relationship,biogeography, and conservation genetics of endangered Fraxinus chiisanensis (Oleaceae), endemic to South Korea

Endemic plants are important for understanding phylogenetic relationships, biogeographical history, and genetic variation because of their restricted distribution and their role in conserving biodiversity. Here, we investigated the phylogenetic relationships of the Korean endemic Fraxinus chiisanensis by reconstructing the molecular phylogeny of Fraxinus based on two nuclear DNA (nrITS and phantastica) and two chloroplast DNA (psbA-trnH and rpl32-trnL) regions. Within our fossil-calibrated phylogenetic framework, we also inferred the biogeographical history of F. chiisanensis. To provide a scientific basis for the conservation of F. chiisanensis, we determined the levels of genetic diversity and genetic differentiation in this species. Combining information from nuclear and chloroplast DNA sequence data, our molecular phylogenetic analyses identified F. chiisanensis as a genetically distinct unit from its sister group, Fraxinus platypoda from Japan. Our molecular dating analyses using nuclear and chloroplast DNA data sets show F. chiisanensis diverged from its sister F. platypoda in the Early or Middle Miocene and differentiated in the Late Miocene on the Korean Peninsula. Our results suggest that the divergence of F. chiisanensis was associated with the submergence of the East China Sea land bridge and enhanced monsoons in East Asia. When compared to F. platypoda, F. chiisanensis exhibits low genetic diversity within populations and high genetic differentiation among populations. These results help us to understand the evolutionary history of F. chiisanensis and to develop a conservation strategy for this species.     

The complete chloroplast genomes of three Hamamelidaceae species: Comparative and phylogenetic analyses

Hamamelidaceae is an important group that represents the origin and early evolution of angiosperms. Its plants have many uses, such as timber, medical, spice, and ornamental uses. In this study, the complete chloroplast genomes of Loropetalum chinense (R. Br.) Oliver, Corylopsis glandulifera Hemsl., and Corylopsis velutina Hand.‐Mazz. were sequenced using the Illumina NovaSeq 6000 platform. The sizes of the three chloroplast genomes were 159,402 bp (C. glandulifera), 159,414 bp (C. velutina), and 159,444 bp (L. chinense), respectively. These chloroplast genomes contained typical quadripartite structures with a pair of inverted repeat (IR) regions (26,283, 26,283, and 26,257 bp), a large single‐copy (LSC) region (88,134, 88,146, and 88,160 bp), and a small single‐copy (SSC) region (18,702, 18,702, and 18,770 bp). The chloroplast genomes encoded 132–133 genes, including 85–87 protein‐coding genes, 37–38 tRNA genes, and 8 rRNA genes. The coding regions were composed of 26,797, 26,574, and 26,415 codons, respectively, most of which ended in A/U. A total of 37–43 long repeats and 175–178 simple sequence repeats (SSRs) were identified, and the SSRs contained a higher number of A + T than G + C bases. The genome comparison showed that the IR regions were more conserved than the LSC or SSC regions, while the noncoding regions contained higher variability than the gene coding regions. Phylogenetic analyses revealed that species in the same genus tended to cluster together. Chunia Hung T. Chang, Mytilaria Lecomte, and Disanthus Maxim. may have diverged early and Corylopsis Siebold & Zucc. was closely related to Loropetalum R. Br. This study provides valuable information for further species identification, evolution, and phylogenetic studies of Hamamelidaceae plants.     

Comparison of Alnus,Corylus, Betula pollen seasons in Riga,Moscow and Vilnius

Research characterizes differences and similarities of the seasonal behaviour of Alnus, Betula, Corylus pollen in Riga, Moscow and Vilnius. An important uniting factor dealing with the research is that on the selected territories in spring there are abundance of Alnus, Corylus and Betula airborne pollen. The study is based on the 2004–2011 atmospheric pollen records. Differences and similarities of the analysed territories include the following: (1) the beginning of the Alnus and Corylus pollen season usually coincided in Riga and Vilnius, whereas significantly differed between Riga and Moscow; (2) no significant differences among separate stations have been estimated concerning the beginning of the Betula pollen season; (3) Moscow differed by the shortest period of pollen season, independently of the pollen type; (4) the biennial cycle of Betula pollen is characteristic to Riga only; (5) in the spectrum of spring plants’ pollen, Corylus pollen was found in the least amount (10–23 pgm^?3 per day on the average); (6) average concentration of Betula pollen per day significantly differed in all locations of the survey, in Moscow, the concentration (853 pgm^?3) was twice higher that in Riga and Vilnius; (7) Alnus, Corylus and Betula pollen seasons overlap each other in all locations surveyed, thus creating additional load of pollen; (8) in each of the stations, there were 13–15 days when concentration of Betula pollen exceeded 100 pgm^?3.     

Evaluation of environmental factors affecting the genetic diversity,genetic structure,and the potential distribution of Rhododendron aureum Georgi under changing climate

Understanding genetic variation and structure, adaptive genetic variation, and its relationship with environmental factors is of great significance to understand how plants adapt to climate change and design effective conservation and management strategies. The objective of this study was to (I) investigate the genetic diversity and structure by AFLP markers in 36 populations of R. aureum from northeast China, (Ⅱ) reveal the relative contribution of geographical and environmental impacts on the distribution and genetic differentiation of R. aureum, (Ⅲ) identify outlier loci under selection and evaluate the association between outlier loci and environmental factors, and (Ⅳ) exactly calculate the development trend of population of R. aureum, as it is confronted with severe climate change and to provide information for designing effective conservation and management strategies. We found high genetic variation (I = 0.584) and differentiation among populations (Φ_ST  = 0.703) and moderate levels of genetic diversity within populations of R. aureum. A significant relationship between genetic distance and environmental distance was identified, which suggested that the differentiation of different populations was caused by environmental factors. Using BayeScan and Dfdist, 42 outlier loci are identified and most of the outlier loci are associated with climate or relief factors, suggesting that these loci are linked to genes that are involved in the adaptability of R. aureum to the environment. Species distribution models (SDMs) showed that climate warming will cause a significant reduction in suitable areas for R. aureum, especially under the RCP 85 scenario. Our results help to understand the potential response of R. aureum to climatic changes and provide new perspectives for R. aureum resource management and conservation strategies.     

Genetic differentiation and signatures of local adaptation revealed by RADseq for a highly dispersive mud crab Scylla olivacea (Herbst, 1796) in the Sulu Sea

Connectivity of marine populations is shaped by complex interactions between biological and physical processes across the seascape. The influence of environmental features on the genetic structure of populations has key implications for the dynamics and persistence of populations, and an understanding of spatial scales and patterns of connectivity is crucial for management and conservation. This study employed a seascape genomics approach combining larval dispersal modeling and population genomic analysis using single nucleotide polymorphisms (SNPs) obtained from RADseq to examine environmental factors influencing patterns of genetic structure and connectivity for a highly dispersive mud crab Scylla olivacea (Herbst, 1796) in the Sulu Sea. Dispersal simulations reveal widespread but asymmetric larval dispersal influenced by persistent southward and westward surface circulation features in the Sulu Sea. Despite potential for widespread dispersal across the Sulu Sea, significant genetic differentiation was detected among eight populations based on 1,655 SNPs (F_ST = 0.0057, p < .001) and a subset of 1,643 putatively neutral SNP markers (F_ST = 0.0042, p < .001). Oceanography influences genetic structure, with redundancy analysis (RDA) indicating significant contribution of asymmetric ocean currents to neutral genetic variation (Radj2 = 0.133, p = .035). Genetic structure may also reflect demographic factors, with divergent populations characterized by low effective population sizes (N _e < 50). Pronounced latitudinal genetic structure was recovered for loci putatively under selection (F_ST = 0.2390, p < .001), significantly correlated with sea surface temperature variabilities during peak spawning months for S. olivacea (Radj2 = 0.692–0.763; p < .050), suggesting putative signatures of selection and local adaptation to thermal clines. While oceanography and dispersal ability likely shape patterns of gene flow and genetic structure of S. olivacea across the Sulu Sea, the impacts of genetic drift and natural selection influenced by sea surface temperature also appear as likely drivers of population genetic structure. This study contributes to the growing body of literature documenting population genetic structure and local adaptation for highly dispersive marine species, and provides information useful for spatial management of the fishery resource.     

Predicting tree pollen season start dates using thermal conditions

Thermal conditions at the beginning of the year determine the timing of pollen seasons of early flowering trees. The aims of this study were to quantify the relationship between the tree pollen season start dates and the thermal conditions just before the beginning of the season and to construct models predicting the start of the pollen season in a given year. The study was performed in Krakow (Southern Poland); the pollen data of Alnus, Corylus and Betula were obtained in 1991–2012 using a volumetric method. The relationship between the tree pollen season start, calculated by the cumulated pollen grain sum method, and a 5-day running means of maximum (for Alnus and Corylus) and mean (for Betula) daily temperature was found and used in the logistic regression models. The estimation of model parameters indicated their statistically significance for all studied taxa; the odds ratio was higher in models for Betula, comparing to Alnus and Corylus. The proposed model makes the accuracy of prediction in 83.58 % of cases for Alnus, in 84.29 % of cases for Corylus and in 90.41 % of cases for Betula. In years of model verification (2011 and 2012), the season start of Alnus and Corylus was predicted more precisely in 2011, while in case of Betula, the model predictions achieved 100 % of accuracy in both years. The correctness of prediction indicated that the data used for the model arrangement fitted the models well and stressed the high efficacy of model prediction estimated using the pollen data in 1991–2010.     

Molecular evolution and SSRs analysis based on the chloroplast genome of Callitropsis funebris

Chloroplast genome sequences have been used to understand evolutionary events and to infer efficiently phylogenetic relationships. Callitropsis funebris (Cupressaceae) is an endemic species in China. Its phylogenetic position is controversial due to morphological characters similar to those of Cupressus, Callitropsis, and Chamaecyparis. This study used next‐generation sequencing technology to sequence the complete chloroplast genome of Ca. funebris and then constructed the phylogenetic relationship between Ca. funebris and its related species based on a variety of data sets and methods. Simple sequence repeats (SSRs) and adaptive evolution analysis were also conducted. Our results showed that the monophyletic branch consisting of Ca. funebris and Cupressus tonkinensis is a sister to Cupressus, while Callitropsis is not monophyletic; Ca. nootkatensis and Ca. vietnamensis are nested in turn at the base of the monophyletic group Hesperocyparis. The statistical results of SSRs supported the closest relationship between Ca. funebris and Cupressus. By performing adaptive evolution analysis under the phylogenetic background of Cupressales, the Branch model detected three genes and the Site model detected 10 genes under positive selection; and the Branch‐Site model uncovered that rpoA has experienced positive selection in the Ca. funebries branch. Molecular analysis from the chloroplast genome highly supported that Ca. funebris is at the base of Cupressus. Of note, SSR features were found to be able to shed some light on phylogenetic relationships. In short, this chloroplast genomic study has provided new insights into the phylogeny of Ca. funebris and revealed multiple chloroplast genes possibly undergoing adaptive evolution.     

Tropical Plant Extracts Modulating the Growth of Mycobacterium ulcerans

Mycobacterium ulcerans, the etiologic agent of Buruli ulcer, has been detected on aquatic plants in endemic tropical regions. Here, we tested the effect of several tropical plant extracts on the growth of M. ulcerans and the closely related Mycobacterium marinum. M. ulcerans and M. marinum were inoculated on Middlebrook 7H11 medium with and without extracts from tropical aquatic plants, including Ammannia gracilis, Crinum calamistratum, Echinodorus africanus, Vallisneria nana and Vallisneria torta. Delay of detection of the first colony and the number of colonies at day 7 (M. marinum) or day 16 (M. ulcerans) were used as endpoints. The first M. ulcerans colonies were detected at 8 ± 0 days on control Middlebrook 7H11 medium, 6.34 ± 0.75 days on A. gracilis-enriched medium (p<0.01), 6 ± 1 days on E. africanus- and V. torta-enriched media (p<0.01), 6 ± 0 days on V. nana-enriched medium (p<0.01) and 5.67 ± 0.47 days on C. calamistratum-enriched medium (p<0.01). Furthermore, the number of detected colonies was significantly increased in C. calamistratum- and E. africanus-enriched media at each time point compared to Middlebrook 7H11 (p<0.05). V. nana- and V. torta-enriched media significantly increased the number of detected colonies starting from day 6 and day 10, respectively (p<0.001). At the opposite, A. gracilis-enriched medium significantly decreased the number of detected colonies starting from day 8 PI (p<0.05). In conclusion, some aquatic plant extracts, could be added as adjuvants to the Middlebrook 7H11 medium for the culturing of M. marinum and M. ulcerans.     

Environmental Limits of Tall Shrubs in Alaska’s Arctic National Parks

We sampled shrub canopy volume (height times area) and environmental factors (soil wetness, soil depth of thaw, soil pH, mean July air temperature, and typical date of spring snow loss) on 471 plots across five National Park Service units in northern Alaska. Our goal was to determine the environments where tall shrubs thrive and use this information to predict the location of future shrub expansion. The study area covers over 80,000 km² and has mostly tundra vegetation. Large canopy volumes were uncommon, with volumes over 0.5 m³/m² present on just 8% of plots. Shrub canopy volumes were highest where mean July temperatures were above 10.5°C and on weakly acid to neutral soils (pH of 6 to 7) with deep summer thaw (>80 cm) and good drainage. On many sites, flooding helped maintain favorable soil conditions for shrub growth. Canopy volumes were highest where the typical snow loss date was near 20 May; these represent sites that are neither strongly wind-scoured in the winter nor late to melt from deep snowdrifts. Individual species varied widely in the canopy volumes they attained and their response to the environmental factors. Betula sp. shrubs were the most common and quite tolerant of soil acidity, cold July temperatures, and shallow thaw depths, but they did not form high-volume canopies under these conditions. Alnus viridis formed the largest canopies and was tolerant of soil acidity down to about pH 5, but required more summer warmth (over 12°C) than the other species. The Salix species varied widely from S. pulchra, tolerant of wet and moderately acid soils, to S. alaxensis, requiring well-drained soils with near neutral pH. Nearly half of the land area in ARCN has mean July temperatures of 10.5 to 12.5°C, where 2°C of warming would bring temperatures into the range needed for all of the potential tall shrub species to form large canopies. However, limitations in the other environmental factors would probably prevent the formation of large shrub canopies on at least half of the land area with newly favorable temperatures after 2°C of warming.     

Genetic studies of various Prosopis species (Leguminosae,Section Algarobia) co‐occurring in oases of the Atacama Desert (northern Chile)

In the Atacama Desert from northern Chile (19–24°S), Prosopis (Leguminosae) individuals are restricted to oases that are unevenly distributed and isolated from each other by large stretches of barren landscape constituting an interesting study model as the degree of connectivity between natural populations depends on their dispersal capacity and the barriers imposed by the landscape. Our goal was to assess the genetic diversity and the degree of differentiation among groups of Prosopis individuals of different species from Section Algarobia and putative hybrids (hereafter populations) co‐occurring in these isolated oases from the Atacama Desert and determine whether genetic patterns are associated with dispersal barriers. Thirteen populations were sampled from oases located on three hydrographic basins (Pampa del Tamarugal, Rio Loa, and Salar de Atacama; northern, central, and southern basins, respectively). Individuals genotyped by eight SSRs show high levels of genetic diversity (H _O = 0.61, A _r = 3.5) and low but significant genetic differentiation among populations (F _ST = 0.128, F _ST‐ENA = 0.129, D _JOST = 0.238). The AMOVA indicates that most of the variation occurs within individuals (79%) and from the variance among individuals (21%); almost, the same variation can be found between basins and between populations within basins. Differentiation and structure results were not associated with the basins, retrieving up to four genetic clusters and certain admixture in the central populations. Pairwise differentiation comparisons among populations showed inconsistencies considering their distribution throughout the basins. Genetic and geographic distances were significantly correlated at global and within the basins considered (p < .02), but low correlation indices were obtained (r < .37). These results are discussed in relation to the fragmented landscape, considering both natural and non‐natural (humans) dispersal agents that may be moving Prosopis in the Atacama Desert.     

Development of a Site-Directed Integration Plasmid for Heterologous Gene Expression in Mycoplasma gallisepticum

Deciphering the molecular basis of the interactions between the parasite Mycoplasma gallisepticum and its avian hosts suffers from the lack of genetic tools available for the pathogen. In the absence of well established methods for targeted disruption of relevant M. gallisepticum genes, we started to develop suicide vectors and equipped them with a short fragment of M. gallisepticum origin or replication (oriC _MG). We failed to create a disruption vector, although by adding a further short fragment of the M. gallisepticum tufB upstream region we created a “Trojan horse” plasmid. This is fully integrated into the genomic DNA of M. gallisepticum, always at the same site, oriC _MG, and is able to carry and express any gene of interest in the genetic background of M. gallisepticum. Successful expression of a heterologous gene was shown with the lacZ gene of E. coli. When used for gene complementation or expression of hybrid genes in M. gallisepticum, a site-specific combined integration/expression vector constitutes an improvement on randomly integrating transposons, which might have unexpected effects on the expression of chromosomal genes.