Comparative analysis of biological and ecological differentiation of Anemone palmata L. (Ranunculaceae) in the western Mediterranean (France and Spain): an assessment of rarity and population persistence

The western Mediterranean geophyte Anemone palmata L. is one of the most endangered angiosperm taxa in France. The biological and ecological characteristics of French populations are contrasted with those of populations from near the centre of the species distribution in east Spain. A Correspondence Analysis discriminates the French and Spanish populations according to substrate and the composition of the plant communities where they grow. The karyological study reveals that east Spanish plants are autotetraploid, whilst the French are all diploid. In addition, morphological differences were registered, Spanish plants generally being more vigorous. French populations consist mostly of senile plants, without or with very low rates of sexual reproduction, whereas the populations from Spain include all age groups with an important percentage of juvenile plants. The main factors which could affect the French populations are habitat destruction and modification of plant communities due to land-abandonment. Conservation measures should be supported by immediate protection of the French localities and habitats to prevent the total decline of this rare species.  © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 140 , 95–114.     

Variation in species richness within and between calcareous (alvar) grassland stands: the role of core and satellite species

Anoda cristata is a widelydistributed annual weed in Mexico, which grows as agrestal or naturally indisturbed and undisturbed vegetation, respectively. Plants of this species aretolerated in orchards and corn-bean fields by Mexican ethnic groups ofCentral Mexico. Leaves of the plants are used as a food source, andoccasionallyseeds are sown in orchards. Because Mexicans have used Anodacristata for a long time, it is possible that ecological andmorphological characteristics of managed populations differ from those of wildpopulations. In this study, we analyzed phenotypic responses of two populationsof A. cristata (wild and agrestal) growing in twohabitats (forest and cultivated field) comparing survivorship, andlife history traits. Natural progenies from wild and agrestal populations ofA. cristata were transplanted into a cultivated field andin the understory of a pine forest in a reciprocal transplant experiment.Results showed that the habitat of transplant and the origin of populations hadsignificant effect on all plant characters measured (growth, phenology, andbiomass allocation), but the habitat x origin interaction wasnon-significant. In general, plants from the agrestal population grewfaster, reproduced earlier, and allocated more biomass to reproduction, thanplants from the wild population. Similarly, significant effects of habitat andorigin on plant survivorship were detected, but the origin of populationsexplained the largest proportion of variance in plant survival. Most traitswerephenotypically plastic but there were no differences in the magnitude ordirection of the response between populations. In contrast both populationsshowed differentiation for most character mean values. Populationdifferentiation is possibly the result of genetic differences driven byprocesses other than incipient domestication.     

中国蜘蛛抱蛋属植物形态演化趋势及其新分类系统

简述了蜘蛛抱蛋属的研究历史 ,着重探讨它的主要器官分类性状的进化趋势 ,揭示了有关它的性别、花被、花被裂片、雄蕊、雌蕊、柱头、果实、花葶、花梗、叶、根状茎等 14个方面的演化趋势。依据这些演化趋势尤其是柱头构造的差异 ,并参考了形态分类学、细胞分类学、孢粉学和解剖学研究的结果 ,提出了蜘蛛抱蛋属的新分类系统     

鹅掌楸（Liriodendronchinense）遗传多样性的等位酶论证

选择５个具有地理代表性的鹅掌楸种群,分析６种酶系统９个位点上２７个等位基因的遗传变异。结果表明鹅掌楸种内保存较高的等位酶变异。     

Systematics and distribution of Thorea (Thoreaceae, Rhodophyta) from central Mexico and south-eastern Brazil

Thirteen populations of Thorea were analyzed from central Mexico and south‐eastern Brazil. All populations were considered as belonging to a single species [Thorea hispida (Thore) Desvaux], with wide variation of morphological features. Secondary branches varying in frequency were observed in several populations with an overlapping in the range of branch density for Thorea violacea Bory and T hispida (0–9 and 11–41 per 30 mm, respectively). As this is the most distinguishing character and on the basis of the overlapping (within a same population or even a single plant), we regarded T. violacea as a synonym of T hispida.‘Chantransia’ stage in culture, as well as gametophyte and carposporophyte were described in detail. We confirmed tine coexistence of asexual monosporangia with sexual reproductive structures (carpogonia and spermatangia) and carposporangia. Size, content, arrangement and chromosome number were the most distinctive characteristics among spermatangia, carposporangia and monosporangia. Monosporangia can be promptly differentiated from spermatangia by their granulated content and larger size but they are similar to carposporangia in shape and size; however, monosporangia are not arranged in fascicles. Structures resembling bisporangia were observed in female plants of some populations. Chromosome numbers were n = 4 for spermatangia and fascicle cells, and 2n ca 8 for gonimoblast filaments, carpospores and the ‘Chantransia’ stage cells. The populations of Thorea from central Mexico and south‐eastern Brazil corroborated the known world distribution for T. hispida, consisting dommantly of tropical to subtropical rainforests, sometimes extending into warm temperate areas. Thorea hispida occurred in warm (temperature 17.6–28.O°C), neutral to alkaline (pH 7.0–8.0), high ion content (specific conductance 59–2140 μS cm^?1), moderate flowing (current velocity 17–43 cm/s) and shallow waters (depth <50cm); these data are essentially similar to previous reports.     

Demography of the seedling bank of Manilkara zapota (L.) Royen,in a subtropical rain forest of Mexico

Selection of individuals in tropical trees, occurs mainly in the seedling phase, which in part explains the low densities of most species. The main objective of this work was to gain an insight into those factors that influence growth and survival of Manilkara zapota seedlings, one of the most abundant species in the lowland forests of Mexico and Central America. Eight 10-m² rectangular plots (5m×2m) were established, in which all < 35-cm-high M. zapota seedlings were marked, measured and enumerated at bimonthly intervals. In each census seedling height, number of leaves, length of largest leaf, type of damage and seedling death were registered. Seedling survival during 2 yr was high, reaching 82% including newly emerged seedlings. A maximum likelihood regression analysis showed that both number of leaves and length of largest leaf had a direct influence on seedling survival; however, neither type of damage nor seedling density and height had significant effect. Seedling height growth averaged 2.8 cm in the 2 yr of study. The combined effect of high seedling survival, reduced growth, and impact of physical damage mainly due to falling branches and leaves reveals the occurrence of a persistent seedling bank. Such a bank would contribute to recruitment of individuals in the juvenile and eventually in the adult stages. This seedling bank could explain the high density of individuals of M. zapota in the tropical forests of Mexico.     

Characteristics, linkage-map positions, and allelic differentiation of Sorghum bicolor (L.) Moench DNA simple-sequence repeats (SSRs)

Fifty one clones isolated from a size-fractionated genomic DNA library of Sorghum bicolor (L.) Moench, that had been probed with four radiolabeled di- and tri-nucleotide oligomers, were sequenced. Fifty of the clones contained one or more simple-sequence repeats (SSRs) [72% of which were (AG/TC) _n SSRs] and, following analysis of the clones, polymerase-chain-reaction primer sets that amplify 38 unique SSR loci were developed. Genotyping of the 38 loci in 18 sorghum accessions, including the parents of a recombinant inbred (RI) mapping population, revealed polymorphism at 36 of the loci among the 18 accessions and at 31 of the loci (not including null alleles at two loci) between the parents of the RI population. All of the latter 31 loci were mapped. The genotypes at 17-mapped SSR loci were assayed in 190 S. bicolor accessions in order to determine δ* _T , the estimated level of allelic differentiation (the estimated probability that two members of a population, chosen at random and without replacement, differ in allelic composition), at each of the loci. The mean δ* _T value determined for S. bicolor overall was 0.89, the range of mean δ* _T values for ten S. bicolor races was from 0.88 to 0.83, and the range of mean δ* _T values for ten working groups (= sub-races) of the race caudatum, with only two exceptions, was from 0.87 to 0.79. The lowest δ* _T values for six of the loci among the ten race-caudatum working groups ranged from 0.86 to 0.70; thus, the probability that different alleles will be present at one or more of these loci in two accessions chosen at random from a working group is > 0.996 when three of the loci are genotyped, and > 0.9999 when all six of the loci are genotyped. The results of this study confirm that most S. bicolor SSR loci are sufficiently polymorphic to be useful in marker- assisted selection programs and they indicate that the levels of polymorphism at some loci are high enough to allow the vast majority of S. bicolor accessions, even accessions within working groups, to be distinguished from one another by determining the genotypes at a small number, perhaps as few as a half-dozen, SSR loci. Received: 13 September 1999 / Accepted: 2 December 1999     

苹果蠹蛾种群遗传多样性研究进展

苹果蠹蛾是重要的世界性果树害虫,寄主广泛,通过形成各种生态型或种群适应新入侵环境,对当地果品生产造成严重损失。本文综述了国内外有关苹果蠹蛾遗传多样性的研究进展。相关研究表明,寄主植物、地理隔离和杀虫剂等因素影响种群间的遗传多样性和遗传分化。其中,地理隔离是种群间形成遗传分化的主要原因之一,寄主分布格局、气候条件、虫体飞行能力和人为活动等因素都会影响种群间遗传分化的程度。苹果蠹蛾是我国重要的入侵害虫,我国东北地区和西北地区的苹果蠹蛾种群具有不同的遗传多样性水平,并且种群间有一定程度的分化,今后需要进一步研究影响我国苹果蠹蛾种群遗传的重要因素,明确该虫种群间分化情况、入侵来源和扩散路径,这对于延缓苹果蠹蛾在我国的扩散,制定合理有效的综合防治策略具有重要意义。     

Admixture and skin color in the transplanted Tlaxcaltecan population of Saltillo,Mexico

Ethnohistoric accounts and serological analyses have documented the genetic effects of transplantation and admixture of several subpopulations of Tlaxcaltecans in Saltillo, Mexico. Interpopulational affinities are assessed using skin reflectance readings taken at the upper inner arm site with a Photovolt Model 670 reflectance spectrophotometer for these groups, focusing on the barrios of La Minita and Chamizal. Genetic distance analyses based on blood groups and skin reflectance data are in close agreement and reflect differential rates of admixture for these groups. Admixture estimates for a dihybrid model (Indian-Spanish) were derived from skin reflectances and show a slight tendency for underestimation of Spanish admixture when compared to blood group estimates. Application of a trihybrid model incorporating West African admixture shows similar estimates based on blood groups, immunoglobulins, and skin color.     

Comparative phylogeography of livebearing fishes in the genera Poeciliopsis and Poecilia (Poeciliidae: Cyprinodontiformes) in central Mexico

Aim To test the hypothesis that the vicariant event responsible for north–south divergences in two clades of the fish genus Poeciliopsis Regan was also responsible for north–south divergences in the fish Poecilia butleri Jordan. Location Central Mexico. Methods Parsimony, distance, maximum likelihood and Bayesian phylogenetic analyses of a mitochondrial gene. Molecular clock test and Bayesian analyses of divergence time. Results We report concordant phylogeographical patterns between two clades in the genus Poeciliopsis (i.e. the other formed by P. latidens Garman and P. fasciata Meek, and the other formed by P. presidionis Jordan and P. turneri Miller) and the clade of Poecilia butleri, with northern and southern individuals within each clade grouping into separate lineages. There is also evidence for slower substitution rates in Poecilia compared with Poeciliopsis. After taking into account these substitution rate discrepancies with Bayesian relaxed molecular clock analyses, north–south divergences in Poecilia butleri were equivalent to those reported for Poeciliopsis latidens‐fasciata and P. presidionis‐turneri. Main conclusions The same Plio‐Pleistocene vicariant event associated with geological activity of the Trans‐Mexican Volcanic Belt (TMVB) appears to have caused divergence in three different freshwater fish lineages. This study is an example of how comparative phylogeography can strengthen inferences about vicariant events in regions of high biological diversity and complex geological history such as the TMVB.     

Phytochemical Analysis,Biological Activity,and Secretory Structures of Stachys annua (L.) L. subsp. annua (Lamiaceae) from Central Italy

Stachys annua subsp. annua, well‐known in central Italy as ‘stregona annuale’, is an annual, small, slightly‐scented herb, commonly found in fields and uncultivated areas in almost all regions of Italy. In folk medicine, its aerial parts were used as anti‐catarrhal, febrifuge, tonic, and vulnerary. In the present work, the chemical composition of the flowering aerial parts was studied. The hydrodistilled volatile oil, analysed by GC/MS, showed sesquiterpenoids as the major fraction (42.5%); phytol (9.8%), germacrene D (9.2%), and spathulenol (8.5%) were the most abundant constituents. The volatile oil was assayed for antioxidant and cytotoxic activity by DPPH, ABTS, FRAP, and MTT methods. The cytotoxicity results against HCT116, A375, and MDA‐MB 231 human tumor cell lines were significant, with IC₅₀ values of 23.5, 37.2, and 41.5 μg/ml, respectively, whereas the antioxidant power was negligible. The EtOH extract was composed mainly of three glycosidic flavonoids, namely 7‐{[2‐O‐(6‐O‐acetyl‐β‐D ‐allopyranosyl)‐β‐D ‐glucopyranosyl]oxy}‐5,8‐dihydroxy‐2‐(4‐methoxyphenyl)‐4H‐1‐benzopyran‐4‐one ( 1 ), 7‐{[6‐O‐acetyl‐2‐O‐(6‐O‐acetyl‐β‐D ‐allopyranosyl)‐β‐D ‐glucopyranosyl]oxy}‐2‐(3,4‐dihydroxyphenyl)‐5,8‐dihydroxy‐4H‐1‐benzopyran‐4‐one ( 2 ), and 7‐{[6‐O‐acetyl‐2‐O‐(β‐D ‐allopyranosyl)‐β‐D ‐glucopyranosyl]oxy}‐2‐(3‐hydroxy‐4‐methoxyphenyl)‐5,8‐dihydroxy‐4H‐1‐benzopyran‐4‐one ( 3 ). On the contrary, iridoids, considered chemotaxonomic markers of the genus Stachys, were absent in this species. Finally, the morphological and histochemical survey showed that glandular trichomes were composed of two main types, i.e. peltate type A and capitate types B and C giving positive response for both lipids and polyphenols.     

Aneuploidal population differentiation in Curex sociata Boott (Cyperaceae) of the Ryukyu Islands, Japan

Chromosome numbers and configuration patterns were investigated at meiotic metaphase I in pollen mother cells of Carex sociata Boott collected from the Ryukyu Islands. Intraspecific aneuploidy composed of five consecutive chromosome numbers from 2 n = 40 to 2 n = 44 was found, and 2 n = 42 and 2 n = 44 aneuploids were both common. Almost all individuals examined showed stable chromosome associations at meiosis and almost all populations were characterized by a single chromosome number. These facts indicate the establishment of cytodemes in all localities, but the geographical distribution of each aneuploid type is widely overlapping. However, no obvious differences were found with respect to morphological, ecological, and genetic traits between the 2 n = 42 and 2n = 44 aneuploids. Wright's inbreeding coefficients were highly positive, suggesting high levels of inbreeding of this species. The F _st-values calculated among 11 populations were significantly positive at all examined loci, indicating the high levels of genetic differentiation among populations. Spatial autocorrelation analysis showed small-scale genetic structure in a population. These facts with respect to breeding system and genetic structure indicate the extreme genetic differentiation and sub structuring of C. sociata populations. We concluded that these reproductive traits such as restricted gene flow and inbreeding resulted in aneuploid differentiation among populations in C. sociata .     

Phylogeography and freshwater basins in central Mexico: recent history as revealed by the fish parasite Rhabdochona lichtenfelsi (Nematoda)

Aim The phylogeography of Rhabdochona lichtenfelsi, a nematode parasite specific to endemic goodeids in Mexico, is used to infer the biogeographical history of fragmentation and recent evolution of the Mesa Central drainages. Geological history of the west‐central region of Mexico suggests that extant freshwater basins are the result of different vicariant events that fragmented ancient watercourses and lakes within the Mesa Central. Location Major freshwater river basins of the Mesa Central, Mexico: Ameca, Cotija, Lerma, Rio Verde, Panuco, and lakes Cuitzeo and Zacapu. Methods Haplotype diversity and phylogeographical structure of 10 populations of R. lichtenfelsi, sampled from the complete range of this species, were analysed with partial sequences of cytochrome c oxidase subunit I (456 bp). Analyses performed included phylogenetic tree estimation methods (neighbour‐joining, maximum parsimony and maximum likelihood), genetic diversity, distance and structure estimates, and nested clade analysis. Results High overall haplotype diversity, unique haplotypes, and strongly structured populations were found in the basins sampled. Three phylogenetically and demographically identifiable clades were recovered. These clades fit an isolation‐by‐distance model. Significant population expansion was observed for two clades and for the entire population. Time of divergence was estimated as 1.0 and 0.84 Ma for the different clades. Main conclusions The distribution of R. lichtenfelsi haplotypes does not correspond to the present distribution of the basins of Mesa Central, but instead reflects the distribution of those basins during a recent geological period (Pleistocene). While our current knowledge of the evolution and geographical relationships of the Mesa Central basins comes from studies of freshwater fish encompassing a more ancient history, our results suggest that, during the past million years, old basins and connections existed where today isolated freshwater bodies stand, thus unravelling a novel biogeographical history for the Mesa Central of Mexico.     

Gametophyte development of Woodwardia radicans (L.) Sm.: Effect of population density and antheridiogen on sex expression

Abstract

Gametophyte development of Woorwardia radicans was studied in controlled culture conditions, as well as the effect of population density and antheridiogen on sex expression. The pattern of gametophyte development is not affected by temperature, while sex expression of gametophytes is affected by sowing density, by the presence in the culture medium of «antheridiogen» and by the nutritional conditions of gametophytes. The probable effects of antheridiogen and population density on the observed developmental pattern are considered.     

Genetic diversity and geographic differentiation in the alternative legume Tripodion tetraphyllum (L.) Fourr. in North African populations

Wild legumes constitute an important component of widespread pastures in the Mediterranean basin. This region is experiencing remarkable effects from climate change, and continuous monitoring of species and population dynamics is important in order to plan and enact valuable conservation programmes. Tripodion tetraphyllum (L.) Fourr. [=Anthyllis tetraphylla L.] (2n=16), belongs to the tribe Loteae (Fabaceae), and could be very important for soil protection and sward improvement in abandoned or degraded Mediterranean areas. This alternative pasture legume is very closely related to Lotus japonicus and has some important characteristics for survival of the species in difficult and overgrazed Mediterranean areas. In this study, we have investigated the molecular diversity and population structure of T. tetraphyllum from North Africa using ISSR markers and plastidial microsatellites. To date, this is the first study concerning the genetic diversity and geographic differentiation of T. tetraphyllum. Ninety genotypes from three North African countries were analysed according to ISSRs, cpSSRs and one phenotypic trait. T. tetraphyllum shows a clear geographical structure, with differentiation associated with longitudinal differences; moreover, there is a general reduction in genetic diversity from Morocco to Tunisia. With all the markers used, strong differentiation was seen among collection sites. Our data highlight a genetic diversity gradient and cline of distribution, indicating that T. tetraphyllum has extended its area of distribution from Morocco to Tunisia.     

Natural parasitism of Metaparasitylenchus hypothenemi (Tylenchida: Allantonematidae) on the coffee berry borer in Chiapas,Mexico

We assessed the parasitism of Metaparasitylenchus hypothenemi on its host, the coffee berry borer, in 20 coffee plantations of Mexico. A total of 23,568 adult borers were dissected, with 179 of these infected with nematodes (0.76% infection rate). Although the level of parasitism is not encouraging, the nematode is another natural enemy, which limits the population growth of this pest in Mexico.     

Ethnobotany of Ferocactus histrix and echinocactus platyacanthus (Cactaceae) in the Semiarid Central Mexico: Past,Present and Future

Ferocactus histrix and Echinocactus platyacanthus are two common barrel cacti of the semiarid highlands of Central Mexico. In pre-Columbian times, these plants were sacred, used for sacrifices, food and medicine. Today, these cacti are used in the candy industry, as medicine, as a source of food and water for goats and as ornamental plants. The floral buds and fruits ofF. histrix are consumed by the local people; the latter are sold in local markets. Until recently, the apical indument ofE. platyacanthus was used for padding and weaving. The importance of these species increases with the aridity of the land and its inadequacy for agriculture. Habitat protection and artificial propagation are needed to avoid the extinction of these species.     

Structural and ultrastructural differentiation of the thyroid gland during embryogenesis in the grass snake Natrix natrix L. (Lepidosauria, Serpentes)

The differentiation of the thyroid primordium of reptilian species is poorly understood. The present study reports on structural and ultrastructural studies of the developing thyroid gland in embryos of the grass snake Natrix natrix L. At the time of oviposition, the thyroid primordium occupied its final position in the embryos. Throughout developmental stages I-IV, the undifferentiated thyroid primordium contained cellular cords, and the plasma membranes of adjacent cells formed junctional complexes. Subsequently, the first follicular lumens started to form. The follicular lumens were of intracellular origin, as in other vertebrate species, but the mechanism of their formation is as yet unclear. At developmental stages V-VI, the thyroid anlage was composed of small follicles with lumens and cellular cords. Cells of the thyroid primordium divided, and follicles were filled with a granular substance. At developmental stage VI, the cells surrounding the follicular lumen were polarized, the apical cytoplasm contained dark granules and the Golgi complex and the rough endoplasmic reticulum (RER) developed gradually. Resorption of the colloid began at developmental stage VIII. At the end of this stage, the embryonic thyroid gland was surrounded by a definitive capsule. During developmental stages IX-X, the follicular cells contained granules and vesicles of different sizes and electron densities and a well-developed Golgi apparatus and RER. At developmental stage XI, most follicles were outlined by squamous epithelial cells and presented wide lumens filled with a light colloid. The Golgi complex and RER showed changes in their morphology indicating a decrease in the activity of the thyroid gland. At developmental stage XII, the activity of the embryonic thyroid gradually increased, and at the time of hatching, it exhibited the features of a fully active gland.