Evolution and systematics of Green Bush-crickets (Orthoptera: Tettigoniidae: <Emphasis Type="Italic">Tettigonia</Emphasis>) in the Western Palaearctic: testing concordance between molecular,acoustic, and morphological data

The genus Tettigonia includes 26 species distributed in the Palaearctic region. Though the Green Bush-crickets are widespread in Europe and common in a variety of habitats throughout the Palaearctic ecozone, the genus is still in need of scientific attention due to the presence of a multitude of poorly explored taxa. In the present study, we sought to clarify the evolutionary relationships of Green Bush-crickets and the composition of taxa occurring in the Western Palaearctic. Based on populations from 24 disjunct localities, the phylogeny of the group was estimated using sequences of the cytochrome oxidase subunit I (COI) and the internal transcribed spacers 1 and 2 (ITS1 and ITS2). Morphological and acoustic variation documented for the examined populations and taxa was interpreted in the context of phylogenetic relationships inferred from our genetic analyses. The trees generated in the present study supported the existence of three main lineages: “A”—composed of all sampled populations of Tettigonia viridissima and the Tettigonia vaucheriana complex, “B”—comprising Tettigonia caudata, Tettigonia uvarovi, and the Tettigonia armeniaca complex, and “C”—consisting of Tettigonia cantans. The present study provides the first phylogenetic foundation for reviewing the systematics of Tettigonia (currently classified mostly according to morphological characteristics), proposing seven new synonymies.     

MACRO- AND MICROGEOGRAPHIC STRUCTURE OF A SPATIALLY SUBDIVIDED BEETLE SPECIES IN NATURE

Spatial subdivision of species can affect their population structure by allowing processes such as limited dispersal, spatial heterogeneity in selective pressures, small population sizes, and random events to operate. By studying species restricted to islands or “island” habitats, one can attempt to determine which of these factors have affected the current structure of the population. Collops georgianus (Coleoptera: Melyridae), a beetle species endemic to the “island” habitat of granitic rock outcrops, was chosen to see how its spatially subdivided distribution has affected its genetic structure. Its genetic structure was examined on both a macrogeographic and a microgeographic level using protein electrophoresis. Macrogeographically, 12 populations throughout its range were sampled. The discontinuous distribution of outcrops, and thus populations, throughout its range, has determined the connectivity of the populations. Significant variation in allele frequencies and substructuring (F_ST = 0.192) was found throughout the range, but there was no spatial autocorrelation. Microgeographically, in the central part of the range, where outcrops are denser and more continuously distributed in space, there was evidence of isolation by distance. Very little variation in allele frequencies was found, but a low but significant level of substructuring occurred among the populations. Comparison of disjunct and continuous populations microgeographically revealed no effect of disjunct distributions, although a significant effect of distance was detected. Effective population size variation among populations and between years, compounded with the effects of local extinctions, suggest that random processes such as drift and founder effects are important determinants of the population's genetic structure.     

Multiple evolutionary processes drive the patterns of genetic differentiation in a forest tree species complex

Forest trees frequently form species complexes, complicating taxonomic classification and gene pool management. This is certainly the case in Eucalyptus, and well exemplified by the Eucalyptus globulus complex. This ecologically and economically significant complex comprises four taxa (sspp. bicostata, globulus, maidenii, pseudoglobulus) that are geographically and morphologically distinct, but linked by extensive “intergrade” populations. To resolve their genetic affinities, nine microsatellites were used to genotype 1200 trees from throughout the natural range of the complex in Australia, representing 33 morphological core and intergrade populations. There was significant spatial genetic structure (F_ST = 0.10), but variation was continuous. High genetic diversity in southern ssp. maidenii indicates that this region is the center of origin. Genetic diversity decreases and population differentiation increases with distance from this area, suggesting that drift is a major evolutionary process. Many of the intergrade populations, along with other populations morphologically classified as ssp. pseudoglobulus or ssp. globulus, belong to a “cryptic genetic entity” that is genetically and geographically intermediate between core ssp. bicostata, ssp. maidenii, and ssp. globulus. Geography, rather than morphology, therefore, is the best predictor of overall genetic affinities within the complex and should be used to classify germplasm into management units for conservation and breeding purposes.     

Genetic Variation and Differentiation of Peat-Bog and Dry-Meadow Populations of the Dwarf Mountain Pine Pinus mugo Turra in the Highlands of the Ukrainian Carpathians

Based on electrophoretic analysis of 21 isozyme loci controlling 10 enzyme systems, the intra- and interpopulation variation was studied in two peat-bog and three dry-meadow populations of the dwarf mountain pine Pinus mugoTurra from the highlands of the Ukrainian Carpathians. In the studied samples (a total of 164 trees), on average 62% of the studied genes were polymorphic; the mean heterozygosity was 21.3%. The dry-meadow populations differed from the peat-bog populations by allele and genotype diversity and by heterozygosity although the indices characterizing population heterogeneity (F _st and G _st) were small (0.027 and 0.032, respectively). Nei's genetic distances between the populations ranged of 0.011 to 0.032 with the mean of 0.018.     

EFFECT OF TEMPERATURE ON SEXUAL POPULATIONS OF GONIUM PECTORALE (VOLVOCALES)

Experiments were designed to study the effect of temperature on interpopulation crosses of Gonium pectorale. Both interpopulation and intrapopulation crosses were made at 10, 15, 20 and 25 C. Of the 34 populations studied, one-third were definitely affected by temperature, showing that temperature is one factor in sexual isolation in at least some populations. Only two populations were completely incompatible with others. In some populations with both mating types, one mating type (the one designated “minus”) was found to be more compatible, possibly reflecting further genetic difference between mating types.     

Genetic structure of Hypochaeris uniflora (Asteraceae) suggests vicariance in the Carpathians and rapid post-glacial colonization of the Alps from an eastern Alpine refugium

Aim The range of the subalpine species Hypochaeris uniflora covers the Alps, Carpathians and Sudetes Mountains. Whilst the genetic structure and post‐glacial history of many high‐mountain plant taxa of the Alps is relatively well documented, the Carpathian populations have often been neglected in phylogeographical studies. The aim of the present study is to compare the genetic variation of the species in two major European mountain systems – the Alps and the Carpathians. Location Alps and Carpathians. Methods The genetic variation of 77 populations, each consisting of three plants, was studied using amplified fragment length polymorphism (AFLP). Results Neighbour joining and principal coordinate analyses revealed three well‐supported phylogeographical groups of populations corresponding to three disjunct geographical regions – the Alps and the western and south‐eastern Carpathians. Moreover, two further clusters could be distinguished within the latter mountain range, one consisting of populations from the eastern Carpathians and the second consisting of populations from the southern Carpathians. Populations from the Apuseni Mountains had an intermediate position between the eastern and southern Carpathians. The genetic clustering of populations into four groups was also supported by an analysis of molecular variance, which showed that most genetic variation (almost 46%) was found among these four groups. By far the highest within‐population variation was found in the eastern Carpathians, followed by populations from the southern and western Carpathians. Generally, the populations from the Alps were considerably less variable and displayed substantially fewer region‐diagnostic markers than those from the south‐eastern Carpathians. Although no clear geographical structure was found within the Alps, based on neighbour joining or principal coordinate analyses, some trends were obvious: populations from the easternmost part were genetically more variable and, together with those from the south‐western part, exhibited a higher proportion of rare AFLP fragments than populations in other areas. Moreover, the total number of AFLP fragments per population, the percentage of polymorphic loci and the proportion of rare AFLP fragments significantly decreased from east to west. Main conclusions Deep infraspecific phylogeographical gaps between the populations from the Alps and the western and south‐eastern Carpathians suggest the survival of H. uniflora in three separate refugia during the last glaciation. Our AFLP data provide molecular evidence for a long‐term geographical disjunction between the eastern and western Carpathians, previously suggested from the floristic composition at the end of 19th century. It is likely that Alpine populations survived the Last Glacial in the eastern part of the Alps, from where they rapidly colonized the rest of the Alps after the ice sheet retreated. Multiple founder effects may explain a gradual loss of genetic variation during westward colonization of the Alps.     

Stand structure and dynamics of sand pine differ between the Florida panhandle and peninsula

Size and age structures of stand populations of numerous tree species exhibit uneven or reverse J-distributions that can persist after non-catastrophic disturbance, especially windstorms. Among disjunct populations of conspecific trees, alternative distributions are also possible and may be attributed to more localized variation in disturbance. Regional differences in structure and demography among disjunct populations of sand pine (Pinus clausa (Chapm. ex Engelm.) Vasey ex Sarg.) in the Florida panhandle and peninsula may result from variation in hurricane regimes associated with each of these populations. We measured size, age, and growth rates of trees from panhandle and peninsula populations and then compiled size and age class distributions. We also characterized hurricanes in both regions over the past century. Size and age structures of panhandle populations were unevenly distributed and exhibited continuous recruitment; peninsula populations were evenly sized and aged and exhibited only periodic recruitment. Since hurricane regimes were similar between regions, historical fire regimes may have been responsible for regional differences in structure of sand pine populations. We hypothesize that fires were locally nonexistent in coastal panhandle populations, while periodic high intensity fires occurred in peninsula populations over the past century. Such differences in local fire regimes could have resulted in the absence of hurricane effects in the peninsula. Increased intensity of hurricanes in the panhandle and current fire suppression patterns in the peninsula may shift characteristics of sand pine stands in both regions.     

Quantitative analyses of the genetic structure of closely related conifers with disparate distributions and demographics: the Cupressus arizonica (Cupressaceae) complex

Seedling populations of seven Cupressus taxa were compared in common gardens to assess relationships among taxa and to elucidate the genetic structure of three taxa with different distributions and demographics. Discriminant analyses of 15 quantitative traits separated C. sargentii and C. forbesii from taxa within the C. arizonica complex (C. arizonica, C. glabra, C. stephensonii, C. nevadensis, and C. montana); aligned a population of C. arizonica from Sierra de Arteaga, Mexico, with families of the same taxon from southwestern United States; and described a close relationship between C. nevadensis and C. glabra. but nevertheless separated taxa within the C. arizonica complex. Analyses of wind-pollinated progenies of single trees showed the narrow endemic, C. glabra, to have a greater degree of population differentiation than the more broadly dispersed C. arizonica. In addition, genetic variances within the numerically small populations of C. arizonica were about the same as in the much larger populations of C. glabra. The results also suggested that genetic variability in C. stephensonii, a taxon occurring in a single population, may occur primarily among inbred lines. While the genetic structures of C. arizonica and C. glabra have counterparts among broadly dispersed conifers, that of C. stephensonii appears to be unique. Together, the results support the view that genetic structure primarily reflects the uncertain, chance events that are interspersed throughout evolutionary history.     

REGIONAL,LOCAL AND MICROGEOGRAPHIC ALLELE FREQUENCY VARIATION BETWEEN APPLE AND HAWTHORN POPULATIONS OF RHAGOLETIS POMONELLA IN WESTERN MICHIGAN

In the preceding study (Feder et al., 1990), we report that paired apple and hawthorn infesting populations of Rhagoletis pomonella are genetically differentiated for six allozymes. Here, we show that patterns of intra- and inter-host allele frequency variation seen for these six loci across the eastern United States are consistent on a more fine grained spatial scale in western Michigan. Malic enzyme, Aconitase-2, Mannose phosphate isomerase, and Hydroxyacid dehydrogenase all displayed significant linear relationships with latitude among five “regional” hawthorn populations sampled along a north-south transect between the cities of Cadillac and Portage, Michigan. Clines were not as evident among “regional” apple populations in western Michigan, although allele frequencies for Malic enzyme¹⁰⁰, Mannose phosphate isomerase¹⁰⁰ and Aconitase-2⁹⁵ varied with latitude among six “local” apple populations within a 60 km² area near the town of Grant. Significant allele frequency differences were observed between hawthorn and apple populations at all “regional” and “local” collecting sites analyzed in the study (a total of 20 different apple and hawthorn populations). As was the case in the geographic survey of the eastern United States, the magnitude and pattern of inter-host frequency differences at “regional” and “local” sites were a function of latitude. Host related genetic differentiation was consistent on a “microgeographic” scale as well. Allele frequencies for Malic enzyme¹⁰⁰ and Aconitase-2⁹⁵ were significantly higher over a four-year period (1984 to 1987) for flies sampled from individual hawthorn trees (N = 6) than apple trees (N = 7) within an old field (0.09-km² area) located near Grant. The fine level of genetic subdivision between hawthorn and apple populations of R. pomonella in western Michigan substantiates the existence of host associated polymorphism in the fly and supports a sympatric mode of divergence for the “apple race”.     

Assessment of genetic variation in Sicilian Helichrysum (Asteraceae) and implication to germplasm conservation

Abstract

Some taxa of Sicilian Helichrysum related to sect. Stoeachadina have an uncertain systematic position; moreover, they are rare and endangered. In order to preserve these taxa in a genebank, a strategy to keep their genetic variation as high as possible is required. The high informative content of AFLP markers was used to assess genetic variations within and between populations and their relationships. The results show that all populations are genetically similar, even though there are two distinct groups: the first is the population referred to H. pendulum, and the second is represented by other populations belonging to several different specific and intraspecific taxa. The H. pendulum population is homogeneous, and characterised by the lowest genetic variation among all the populations considered. The second group shows a greater variation as evidenced by the presence of three subgroups: (i) populations referred to H. panormitanum var. panormitanum and H. panormitanum var. stramineum, (ii) populations referred to H. errerae var. errerae and H. errerae var. messerii, (iii) a population referred to H. hyblaeum, which, despite morphological and chorological differences, is similar to the other populations of the second group from a genetic stand point. Each population of the above-mentioned taxa has local fragment markers whose frequency is useful to determine how many plants should be sampled in order to collect the seeds necessary to preserve the population's genetic diversity in a genebank.     

Central Asian origin of and strong genetic differentiation among populations of the rare and disjunct Carex atrofusca (Cyperaceae) in the Alps

Aim Carex atrofusca has an arctic–alpine distribution in the Northern Hemisphere, with only a few, disjunct localities known in the European Alps. These alpine populations are declining in number and size. In contrast, C. atrofusca has a wide circumpolar distribution range and is abundant in large parts of the Arctic. The degree of genetic differentiation of the alpine populations and their importance for the conservation of the intraspecific genetic variation of the species is unknown. Location Eurasia and Greenland, with emphasis on the European Alps. Methods We applied amplified fragment length polymorphism (AFLP) fingerprinting and sequences of chloroplast DNA to determine the position of the alpine populations in a circumpolar phylogeography of C. atrofusca and to unravel the patterns of genetic diversity and differentiation within the Alps. Results Two distinct major groups were detected in a neighbour‐joining analysis of AFLP data and in parsimony analysis of chloroplast DNA sequences: one consisting of the populations from Siberia and Greenland and one consisting of all European populations as sister to the populations from Central Asia. Within Europe, the populations from the Tatra Mountains and those from Scotland and Scandinavia formed two well‐supported groups, whereas the alpine populations did not constitute a group of their own. The genetic variation in the Alps was almost completely partitioned among the populations, and the populations were almost invariable. Main conclusions The alpine populations possibly originated due to immigration from Central Asia. The strong differentiation among them suggests that genetic drift has been strongly acting on the populations, either as a consequence of founder events during colonization or due to subsequent reduction of population sizes during warm stages of the Holocene.     

Assessment of genetic structure within and among Bulgarian populations of the common ash (Fraxinus excelsior L.)

We analysed genetic variation within and between populations of the common ash from Bulgaria in order to extract biological information useful in the context of conservation management of eastern European genetic resources of noble hardwood species. A total of 321 trees from three regions of Bulgaria were typed at six highly polymorphic microsatellite loci. Analysis of within-population inbreeding suggests an upper boundary value of 2.7% for the selfing rate. Significant spatial genetic structure consistent with models of isolation by distance was detected within four out of 10 populations as well as among populations. Estimates of neighbourhood size in the range 38-126 individual trees were obtained based on spatial genetic structure analyses at either the intrapopulation or interpopulation level. Differentiation among populations explained only about 8.7% of total genetic diversity. These results are discussed in comparison with data from social broad-leaved species such as oak and beech.     

INTRASPECIFIC CHLOROPLAST DNA VARIATION AND BIOGEOGRAPHY OF NORTH AMERICAN LIRIODENDRON L. (MAGNOLIACEAE)

Restriction site variation in chloroplast DNA (cpDNA) was surveyed to analyze population dynamics in Liriodendron tulipifera L., a woody angiosperm found in eastern North America. Two cpDNA haplotypes, differing by the presence or absence of five restriction site changes (nucleotide sequence divergence estimated as approximately 0.15%) are geographically structured; 61 widespread populations possess the “northern” haplotype and three isolated populations of central Florida possess the “southern” haplotype. This geographic break in cpDNA distribution corresponds to patterns of geographic distribution revealed by a previous survey of allozyme variation, with the exception that analyses of allozyme data further divided the populations containing the northern cpDNA haplotype into two groups, a widespread upland group and a coastal intermediate group. Analyses of these two independent data sets together support the hypothesis that L. tulipifera survived the glacial advances of the Pleistocene in two distinct refugia, possibly as different taxa, and the intermediate coastal group was putatively formed from recent hybridizations between these entities.     

Genetic Differentiation Among Annual Fishes of the Genus Cynolebias (Cyprinodontiformes, Rivuluidae) in a Biosphere Reserve Site from Uruguay

The annual killifishes of the genus Cynolebias include one well supported clade composed of three taxa: Cynolebias adloffi, from Porto Alegre (southern Brazil), C. cf. adloffi and Cynolebias viarius, parapatrically distributed in southeastern Uruguay. Cynolebias cf. adloffi has always been considered an intergradation complex of populations between C. adloffi and C. viarius showing high levels of morphological variability and its systematic affinities have been historically discussed. This study clarified the patterns of genetic differentiation of C. cf. adloffi by means of RAPD markers to define its taxonomic status as a possible separated taxon. Multidimensional scaling analysis reveals that C. cf. adloffi is composed of two highly structured genetic groups (northern and southern) with discrete geographical distributions. The estimate of gene diversity for RAPD markers could suggest a scenario in which the rainy season flood pool populations across large distances could make intrapopulation variation high but interpopulation variation low. Phylogenetic analyses (UPGMA and parsimony) show different and unstable patterns of relationships among the taxa analyzed. In the UPGMA tree, C. viarius and C. cf. adloffi appear as sister taxa, while parsimony analysis does not support a unique hypothesis of relationship. Our analyses are in agreement with the hypothesis that C. cf. adloffi may well be a case of ancient hybrid ancestry followed by its divergence associated with Pleistocene and post-Pleistocene environmental changes in this region.     

Widespread inbreeding and unexpected geographic patterns of genetic variation in eastern hemlock (Tsuga canadensis), an imperiled North American conifer

Eastern hemlock (Tsuga canadensis [L.] Carr.) is an ecologically important tree species experiencing severe mortality across much of its eastern North American distribution, caused by infestation of the exotic hemlock woolly adelgid (Adelges tsugae Annand). To guide gene conservation strategies for this imperiled conifer, we conducted a range-wide genetic variation study for eastern hemlock, amplifying 13 highly polymorphic nuclear microsatellite loci in 1,180 trees across 60 populations. The results demonstrate that eastern hemlock exhibits moderate inbreeding, possibly a signature of a prehistoric decline associated with a widespread insect outbreak. Contrary to expectations, populations in formerly glaciated regions are not less genetically diverse than in the putative southern refugial region. As expected, peripheral disjunct populations are less genetically diverse than main-range populations, but some are highly genetically differentiated or contain unique alleles. Spatially explicit Bayesian clustering analyses suggest that three or four Pleistocene glacial refuges may have existed in the Southeastern United States, with a main post-glacial movement into the Northeast and the Great Lakes region. Efforts to conserve eastern hemlock genetic material should emphasize the capture of broad adaptability that occurs across the geographic range of the species, as well as genetic variability within regions with the highest allelic richness and heterozygosity, such as the Southern Appalachians and New England, and within disjunct populations that are genetically distinct. Much genetic variation exists in areas both infested and uninfested by the adelgid.     

Within-population structure highlighted by differential introgression across semipermeable barriers to gene flow in Anguilla marmorata

In the marine environment, differential gene exchange between partially reproductively isolated taxa can result in introgression that extends over long distances due to high larval dispersal potential. However, the degree to which this process contributes to interlocus variance of genetic differentiation within introgressed populations remains unclear. Using a genome-scan approach in the Indo-Pacific eel Anguilla marmorata, we investigated the degree of interpopulation genetic differentiation, the rate of introgression, and within-population genetic patterns at 858 AFLP markers genotyped in 1117 individuals. Three divergent populations were identified based on clustering analysis. Genetic assignments of individuals revealed the existence of different types of hybrids that tended to co-occur with parental genotypes in three population contact zones. Highly variable levels of genetic differentiation were found between populations across the AFLP markers, and reduced rates of introgression were shown at some highly differentiated loci. Gene flow across semipermeable genetic barriers was shown to generate spatial introgression patterns at some loci which define within-population structure over long distances. These results suggest that differential introgression in subdivided populations may be relevant when interpreting spatial variation patterns displayed by outlying loci in other marine fish populations.     

Studies in the Melica ciliata – complex: 1. Distribution of allozyme variation within and among individuals, populations and geographic regions

Allozyme variation in 83 European populations of the Melica ciliata/ transsilvanica species complex has been investigated. In spite of a diploid chromosome number, most loci were duplicated and patterns of within-population variation were not explainable unless apomixis or uncommon patterns of chromosomal segregation were assumed. Allelic richness and genetic diversity were very high but most of the variation (55-98%) was due to population differentiation. Geographic patterns were analysed both using phenetic, based on allele frequencies within populations, and cladistic, based on multi-locus genotypes, methods. Both methods congruently recognised three large groups of populations with discrete geographic distributions, in addition to a number of smaller groups. Of the three main groups, one was distributed in eastern and central Europe, one was restricted to western Europe north of the Alps and one was distributed in Iberia, Brittany and along the western shores of the Mediterranean. These groups are likely to have had separate histories but there appears to have been significant gene-flow among them. Among the less distinct groups, it was suggestive that some, e.g. the group containing all populations from the disjunct distribution in the Baltic basin, have been formed by introgression between the three major groups, whereas other deviating populations may represent additional distinct entities.     

Long distance kelp rafting impacts seaweed biogeography in the Northeast Pacific: the kelp conveyor hypothesis

Routine DNA barcoding of the Haida Gwaii seaweed flora revealed “endemic species” attributed initially to this region's past as a glacial refugium. However, subsequent barcode records from central California rapidly eroded this list leaving species characterized by disjunct distributions (DD) between California and Haida Gwaii. This observation prompted a more detailed look at species for California and British Columbia and revealed that 33 of 180 DNA‐barcoded genetic groups in common between these regions (~18%) predominantly displayed DD between California and northern British Columbia. A previous discovery that a red abalone shell found in Haida Gwaii (far north of its range) had a float‐bearing kelp (Nereocystis luetkeana) holdfast attached to it prompted a closer consideration of the COI‐5P barcode data in support of a “kelp conveyor hypothesis.” The hypothesis posits that there has been a net migration of Californian species to northern British Columbia the vector being species growing on substrata carried along with kelp rafts on the winter Davidson Current.     

甘蔗野生种滇蔗茅利用研究 Ⅲ.滇蔗茅杂种F1群体的表型变异与遗传多样性分析

选用8个数量性状和18个质量性状对滇蔗茅杂种F1群体的表型变异、多样性及聚类关系进行分析。结果表明：数量性状的遗传变异主要来自于有效茎、单茎重及糖分;质量性状的叶鞘背毛群与内叶耳形状多样性丰富,根点排列、芽位、茎形、节间性状、生长裂缝等5个性状均表现一致;聚类分析表明62份后代材料可分为4大类群和10个亚类群。遗传多样性和聚类分析为杂交后代的筛选及其杂交或回交利用提供了科学依据。