Variability of enzyme systems in the coenopopulation of Taraxacum officinale s.l. from the zone of East-Ural- radioactive trace

Levels of soil contamination with 90Sr and 137Cs radionuclides on the plots within the zone of Eastern-Ural radioactive trace exceed values of the global level 4-240 times. We have carried out allozyme analysis of apomict species Taraxacum officinale s.l. from this zone. Zimogrammes were interpreted as allozyme phenotypes. In condition of chronic irradiation the plants had increased phenogenetic variability of majority enzymes systems and high frequency of rare morphs. Thus, in plant coenopopoulations situated in radioactive-polluted zone, genomic recombination processes show higher intensity. High enzymatic variability provides the material for natural selection and increase the adaptive potential of coenopopulations.     

Remote effects in plant populations from zones of radiation and chemical pollution

A comparative research of dandelion seed progeny from the coenopopulations growing for a long time in a gradient of radioactive (zone of the East-Ural radioactive trace--EURT) or chemical (zone exposure Nizhny Tagil Metallurgical Plant--NTMP) pollution was carried out. It was revealed that the viability of seeds declined similarly in gradient of the man-caused stress regardless of its nature. Dandelion coenopopulations from the EURT zone, NTMP and the background area significantly differed in the qualitative and quantitative allozyme specifications. The analysis of clonal diversity revealed phenogenetic uniqueness of all coenopopulations. Study of F1-generation metal and radio resistance showed that the seed progeny from the impact EURT zone possessed a high viability but had hidden damage that led to a low resistance to additional man-caused influences. High viability of the seeds in the F1-generation from the NTMP zone combined with increased resistance to the provocative effects of radiation and heavy metals. Significant differences in responses to the "habitual" and "n ew" factors of influence, i.e. effect of pre-adaptation in samples from EURT and NTMP zones were not found.     

入侵植物凤眼蓝繁育系统在中国境内的地理变异

 对中国境内的凤眼蓝（Eichhornia crassipes）进行了大规模地理范围的调查,分析了24个地点40个种群的克隆繁殖与有性繁殖的相对水平、三型花柱的花型变化以及花部综合特征的变异。40个种群都以克隆繁殖为主要更新方式。其中36个种群只有三型花柱中的M花型;南宁、重庆的种群中出现了频率极低的L花型;南宁、重庆、福州和海口种群内,出现了具有促进花内自交潜能的半同长花柱花型（柱头与花药相靠拢的M花型变异体或L花型变异体）。与其它地方种群相比,西南和海南岛的种群表现出较多样化的繁育系统。M和L花型个体的结实个体率都约为4％,没有显著差异,种子产量在两花型个体之间也没有差异。由于种群内花型的残缺,作为促进花型之间异交传粉适应机制的三型花柱繁育系统已经解体,部分种群中出现了可以促进花内自交的半同长花柱变异体。克隆繁殖是凤眼蓝适应入侵生境的一种形式,花内自交是凤眼蓝繁育系统在入侵过程中可能的进化方向,这些繁育系统上的变化对该植物的入侵机制和途径产生了深远影响。     

Genetic structure of a population sample of apomictic dandelions

In Northern Europe, dandelion populations consist solely of triploid or higher polyploid apomicts. Without a regular sexual cycle or lateral gene transmission, a clonal structure is expected for Taraxacum apomicts, although this was not found by compatibility analysis. In this study, we investigate whether this observation could be suported by performing independent tests based on data from hypervariable microsatellite markers as well as more conservative data based on allozymes and matrilinear cpDNA markers. In addition, population genetic methods were used to test departure from panmictic expectations, which is expected for clonal populations. Results indicated that many data sets, again, did not agree with expectations from clonal evolution because only small groups of genotypes exhibit no marker incompatibility. Population genetic analysis revealed that virtually all genotypes, but not individuals, agreed with random segregation and genotypic equilibria. Exceptions were genotypes with rare allozyme alleles or nearly identical microsatellite genotypes. Consequently, a population sample of apomictic dandelions essentially harbours genotypes that resulted from segregation and/or recombination and only a few genotypes that may have differentiated by somatic mutations.     

Productivity differences between dandelion (Taraxacum officinale; Asteraceae) clones from pollution impacted versus non-impacted soils

Common dandelions (Taraxacum officinale Weber, sensu lato; Asteraceae) introduced to North America form an assemblage of asexual (agamospermous), clonal lineages derived from Eurasian mixed sexual and asexual populations. We investigated whether selection for more pollution tolerant clonal lineages occurs at polluted sites and selection for more pollution intolerant lineages occurs at unpolluted sites. We tested the above hypothesis by performing reciprocal greenhouse productivity experiments in which unique dandelion clones (12 clones, identified by DNA fingerprinting, from each site type) sampled from two unpolluted and two polluted (moderately enhanced Cu, Pb and Zn soil concentrations) sites were grown pairwise in both unpolluted (nutrient solution only) and polluted (nutrient solution + Cu, Pb and Zn) media (n?=?48 paired tests for each media type). Dandelion clones from polluted sites produced fewer and smaller leaves, shorter roots and smaller root diameters, reduced shoot and root dry weights, and reduced total biomass compared to clones from unpolluted sites when clones were grown in unpolluted-media (P?≤?0.05). In contrast, clones taken from unpolluted sites were shown to produce significantly fewer and shorter leaves, shorter roots and smaller root diameters, reduced shoot and root dry weights, reduced total biomass, a reduced shoot : root biomass ratio, and have much lower survival compared to clones from polluted sites when both were grown in polluted-media (P?≤?0.05). These results reveal that there was increased selection against unpolluted-site clonal lineages in polluted-media and against polluted-site clonal lineages in unpolluted-media. Across all treatments, clones from unpolluted sites growing in unpolluted-media had the highest proximate measures of fitness. Overall, these findings provide insight into the relationships among anthropogenic environmental contamination and the consequent effects of selective forces acting on dandelion clones and their population genetic architecture.     

Association between host wing morphology polymorphism and Wolbachia infection in Vollenhovia emeryi (Hymenoptera: Myrmicinae)

Many eusocial insects, including ants, show complex colony structures, distributions, and reproductive strategies. In the ant Vollenhovia emeryi Wheeler (Hymenoptera: Myrmicinae), queens and males are produced clonally, while sterile workers arise sexually, unlike other ant species and Hymenopteran insects in general. Furthermore, there is a wing length polymorphism in the queen caste. Despite its evolutionary remarkable traits, little is known about the population structure of this ant species, which may provide insight into its unique reproductive mode and polymorphic traits. We performed in‐depth analyses of ant populations from Korea, Japan, and North America using three mitochondrial genes (COI, COII, and Cytb). The long‐winged (L) morph is predominant in Korean populations, and the short‐winged (S) morph is very rare. Interestingly, all L morphs were infected with Wolbachia, while all Korean S morphs lacked Wolbachia, demonstrating a association between a symbiont and a phenotypic trait. A phylogenetic analysis revealed that the S morph is derived from the L morph. We propose that the S morph is associated with potential resistance to Wolbachia infection and that Wolbachia infection does not influence clonal reproduction (as is the case in other ant species).     

Clonal growth is enhanced in the absence of a mating morph: a comparative study of fertile stylar polymorphic and sterile monomorphic populations of Nymphoides montana (Menyanthaceae)

Background and Aims

Many aquatic species with stylar polymorphisms have the capacity for clonal and sexual reproduction and are sensitive to the balance of the two reproductive modes when there are a limited number of mating morphs within a population. This study asked how the clonal and sexual reproductive modes perform in populations that contain only a single morph and where fitness gain through sexual reproduction is rare. In clonal aquatic Nymphoides montana, polymorphic populations normally contain two mating morphs in equal frequencies. Populations are sexually fertile and appear to be maintained by pollen transfer between the two partners. However, in a monomorphic population of N. montana where mating opportunities are unavailable, female and male function is impaired and clonality maintains the population. Here, the consequences of intraspecific variation in sexuality were explored between monomorphic and polymorphic N. montana populations in eastern Australia.

Methods

Comparative measurements of male and female fertility, total dry mass and genotypic diversity using ISSR markers were made between populations with variable sexuality.

Key Results and Conclusions

Very few seeds were produced in the monomorphic population under natural and glasshouse conditions due to dysfunctional pollen and ovules. Stigma–anther separation was minimal in the monomorphic population, which may be a consequence of the relaxed selective pressures that regulate the maintenance of sexual function. However, clonal reproduction was favoured at the expense of sexual reproduction in the monomorphic population; this may facilitate the establishment of sterility throughout the population via resource reallocation or pleiotropic effects. The ISSR results showed that the monomorphic population was one large, single genotype, unlike the multi-genotypic fertile polymorphic populations. Evolutionary loss of sex in a clonal population in which a mating morph is absent was evident; under these conditions clonal growth may assure reproduction and expand the population via spreading stolons.     

Gamasid mites of common voles in the central Volga River region

The specific composition of gamasid mites from three species of voles (Microtus arvalis Pall., M. agrestis L., M. oeconomus Pall.) is given. Forest, field and flood-land groupings of the common vole having distinct phenotypical differences are characterized by differences in the structure of their parasite fauna. In the forest the number of meadow and meadow-field species decreases while that of forest species of mites regularly increases.     

Stylar polymorphism, reciprocity and incompatibility systems in Nymphoides montana (Menyanthaceae) endemic to southeastern Australia

Heterostyly is a stylar polymorphism that has been shaped by the evolution of floral characters adapted for efficient pollen transfer. Different types of stylar polymorphism are described in which the discrete characterization of the exact polymorphic type (e.g., distyly vs. stigma-height dimorphism) requires detailed floral measurements (e.g., sex-organ reciprocity). In clonal and aquatic Nymphoides montana, although the presence of two floral morphs that contain styles of two lengths has been previously reported, no studies have quantitatively estimated the level of reciprocity and/or described the stylar condition. Morphological variations and incompatibility relationships were explored between the two morphs in three southeastern Australian populations. In this study, one population is characterized as stigma-height dimorphism (i.e., two morphs with discrete variation in stigma height but little variation in anther height), whereas the other two populations are typical distylous (i.e., two morphs for reciprocal stigma and anther height). Nymphoides montana is dimorphic in a wide range of ancillary characters, including corolla size, stigma size, shape and papillae morphology, and pollen size, number and exine sculpture. Following glasshouse pollinations, full incompatibility systems were observed in the distylous populations, whereas the stigma-height dimorphic population showed between-morph variation in the extent of incompatibility. Despite the variation in sex-organ reciprocity and incompatibility, other lines of evidence appear to assure the maintenance of the stylar polymorphism in the N. montana study populations. All populations are nearly isoplethic (i.e., both morphs in equal frequencies), which is indicative of balanced polymorphisms that appear to be maintained by legitimate pollen transfer between the morphs.     

Morphological evidence of correlational selection and ecological segregation between dextral and sinistral forms in a polymorphic flatfish, Platichthys stellatus

Phenotypic polymorphisms in natural systems are often maintained by ecological selection, but only if niche segregation between morphs exists. Polymorphism for eyed-side direction is rare among the approximately 700 species of flatfish (Pleuronectiformes), and the evolutionary mechanisms that maintain it are unknown. Platichthys stellatus (starry flounder) is a polymorphic pleuronectid flatfish exhibiting large, clinal variation in proportion of left-eyed (sinistral) morphs, from 50% in California to 100% in Japan. Here I examined multiple traits related to swimming and foraging performance between sinistral and dextral morphs of P. stellatus from 12 sites to investigate if the two morphs differ in ways that may affect function and ecology. Direction of body asymmetry was correlated with several other characters: on an average, dextral morphs had longer, wider caudal peduncles, shorter snouts and fewer gill rakers than sinistral morphs. Although the differences were small in magnitude, they were consistent in direction across samples, implying that dextral and sinistral starry flounder may be targeting different prey types. Morphological differences between morphs were greatest in samples where the chances of competitive interactions between them were the greatest. These results suggest that the two morphs are not ecologically identical, may represent a rare example of divergent selection maintaining polymorphism of asymmetric forms, and that correlational selection between body asymmetry and other characters may be driven by competitive interactions between sinistral and dextral flatfish. This study is one of very few that demonstrates the ecological significance of direction in a species with polymorphic asymmetric forms.     

Genome size variation among common dandelion accessions informs their mode of reproduction and suggests the absence of sexual diploids in North America

Apomixis is the ability of plants to produce asexual seeds, which are clones of the mother plant. The phenomenon of apomixis is tightly linked to ploidy, where diploids lack apomixis and reproduce sexually, while higher ploidy levels can exhibit apomixis. Taraxacum F.H.Wigg. species (dandelions) commonly exhibit apomixis; however, only limited studies have evaluated genome size variation of the iconic weedy dandelion, Taraxacum officinale F.H.Wigg. (common dandelion), particularly in North America. To evaluate the ploidy and reproductive biology of common dandelion, we created a global collection, with an emphasis on North America and determined genome size by evaluating seeds with flow cytometry. A total of 635 accessions were screened, and with the exception of two accessions from Germany and Austria, all were found to exclusively contain polyploid seed. The mode of reproduction of a sample of 96 of these accessions was observed by conducting emasculations. Our results indicate that the diploid, sexual cytotype of common dandelion may be absent in North America, while diploids were found in previously described areas of Central Europe. This suggests that the clonal lineages of common dandelion in North America may largely be derivative from apomictic plants introduced from abroad. Furthermore, if all North American common dandelion is apomictic, it may be unreceptive to pollen, which may isolate it from other dandelion species and inform the potential for gene flow.     

蒲公英研究进展和用生物技术培育耐盐蒲公英展望

蒲公英属（Taraxacum）植物种类多,分布广,是常见的农业杂草,还是重要的中药材。目前,蒲公英作为蔬菜食用得到了人们的充分重视,并逐渐成为时尚。近年来,人们深入研究了蒲公英的化学成分和药理作用,关于蒲公英的组织培养、核型与分子水平的研究也已开展,但蒲公英的生物技术培育工作鲜有报道。在对蒲公英的开发利用和研究现状作概述的同时,结合我们的工作提出生物技术培育抗盐、耐海水蒲公英的努力方向,以期为进一步开发利用蒲公英打下基础。     

Clonal variation in floral stage timing in the common dandelion Taraxacum officinale (Asteraceae)

We investigated the hypothesis that dandelion clones (Taraxacum officinale Weber, sensu lato; Asteraceae) differ in their floral stage timing characteristics under a constant set of environmental conditions. To test this hypothesis, plants representing nine different dandelion clones (identified by DNA fingerprinting) were grown in groups of five (N = 45) in a growth chamber for a period of 8 mo, with chamber settings similar to environmental conditions at peak dandelion flowering time for their population sites. Five flowering phenology parameters were monitored daily for a total of 301 buds developing during this time: (1) time to bud; (2) time to full opening and inflorescence maturation (i.e., first anthesis); (3) time to re-closure of an inflorescence; (4) time to fruit (full re-opening of the inflorescence); and (5) total flowering time. Scape length at the appearance of a fully expanded infructescence was also measured for each individual. Significant differences in mean time to inflorescence, mean time to re-closure, mean time to fruit, and mean total flowering time were revealed among some dandelion clones (Kruskal-Wallis, P ≤ 0.0005). No differences in mean number of inflorescence buds per plant (P = 0.2217), mean time to bud (P = 0.2396), or mean scape length (P = 0.3688) were detected among the nine clones. These results suggest that differences in floral stage timing may in part involve varying genotypic environmental response characteristics and that these differences may have potential fitness effects. Further research is needed to determine if such clonal differences are observed under a broader range of uniform environmental conditions.     

Inter- and intra-morph patterns in helminth communities of sympatric whitefish morphs

Infection patterns of trophically transmitted helminth parasites were compared with feeding ecology in two sympatric whitefish Coregonus lavaretus morphs from two lake systems in northern Norway. In both lakes, the pelagic morph was an obligate zooplanktivore, while the benthic morph utilized both the benthivore and zooplanktivore trophic niches. The differences in niche utilization between the two morphs were associated with differences in trophic morphology (gill raker numbers), suggesting that they were genetically dissimilar and reproductively isolated. The benthic morph had the highest number of helminth species, probably because they exhibited a broader niche width compared to the pelagic morph. In both lakes, the species composition and intensities of helminths reflected the trophic diversification of the whitefish ecotypes with respect to different habitat choice (benthic v . pelagic) and dietary specialization (benthivore v . zooplanktivore feeding strategies within the benthic whitefish morph). Zooplanktivorous fish from both morphs acquired parasites mainly from pelagic copepods and in almost equal quantities. The benthivore feeders within the benthic morph had the highest proportion of parasites with transmission stages from benthic organisms. Host feeding behaviour seemed to be a major determinant of the helminth community structure, and helminths appeared to be useful indicators of long-term trophic specialization of whitefish ecotypes.     

Vitality Structure of Colchicum bulbocodium subsp. versicolor (Colchicaceae,Liliopsida) Populations in the Lower Volga Region

Biology Bulletin - Abstract—The vitality structure of 23 natural coenopopulations of Colchicum bulbocodium subsp. versicolor from the Lower Volga region has been analyzed in 2014–2019....     

Genetic structure of natural populations of black locust (Robinia pseudoacacia L.) at Coweeta, North Carolina

Natural population of black locust maintains very high levels of genetic diversity within populations without any noticeable geographic patterns. In order to assess the species' potential for manipulation through breeding programs, more detailed spatial pattern analyses of fine-scale population structure was attempted in the two study sites (watershed 2 and 21) in the Coweeta River Basin of southern Appalachian mountains using allozyme markers. Of the 200 and 420 plants examined in watershed 21 and 2 respectively, 13 and 15 major genotypes of clone were distinguished. Within watersheds 2 and 21, 60% of the pairwise clone combinations had three or four loci differences out of the 8 loci investigated. No correlation between distance between clones and the number of allele difference was found. The similarity values (16 highest and 0 lowest value) among clones for watershed 2 and 21 were 12.82 and 10.19 respectively. Typical distances between clones on both watershed 2 and 21 were from 90 and 190 m, but the range varied from several meters up to 300 m. An average distance among clones were 140.9±66.0 m and 239.4±108.6 m in watershed 2 and 21 respectively, whereas an average distance within clone was 38.7±36.2 m and 145.0±123.6 m in watershed 2 and 21. Genotype diversity indices (DG) for watershed 2 and 21 were 0.89 and 0.86 respectively. The largest clones on both watersheds covered more than 100 m×100 m. On the other hand, some clones on watershed 2, which had a few fallen trees with many young sprouts (up to 200 individuals), were 45 m×30 m in size under the open habitat. Although clonal substructure and limited seed dispersal may cause near neighbor mating interaction, significant genetic patchiness among clones of black locust was not evident. Although the first establishment of a black locust population would have relied on an off-site seed source, it is more likely that asexual reproduction has occurred for many generations in these black locust populations because of the presence of many different sizes of trees (or ages) in one clone despite widespread opportunities for sexual reproduction. Presence of three or four different sizes of trees within a clone implies that the trees has developed from a clone at each different time. The current study suggested that the amount of sexual reproduction and dispersal rate (especially seed dispersal) should be determined. It would be useful to examine whether or not clonal strategies and patterns of clonal growth of black locust are influenced by density dependent regulation of ramet recruitment and death.     

Fruit color,chemical and genetic diversity and structure of Myrtus communis L. var. italica Mill. morph populations

Myrtus communis presents two morphologies based on fruit color. Both morphs are present in some region of Tunisia, with the white morph being rare. In the present study, essential oil composition and AFLP markers were used to assess the chemical and genetic diversity and structure of four myrtle populations from each morph. A chemical polymorphism attributed to the morphs and the origin of populations was detected.The genetic diversity within population varied according to morphs. Variation in the dark blue morph populations was higher than that observed for the white ones. For each morph, a high genetic differentiation among populations was observed. Population structure based on AFLP markers is in accordance with that based on oil composition. Furthermore, a significant correlation between chemical and genetic data was observed. The conservation strategies of populations should be made for each morph according to its level of diversity and bioclimate.     

Ecological and evolutionary opportunities of apomixis: insights from Taraxacum and Chondrilla

The ecological and evolutionary opportunities of apomixis in the short and the long term are considered, based on two closely related apomictic genera: Taraxacum (dandelion) and Chondrilla (skeleton weed). In both genera apomicts have a wider geographical distribution than sexuals, illustrating the short-term ecological success of apomixis. Allozymes and DNA markers indicate that apomictic populations are highly polyclonal. In Taraxacum, clonal diversity can be generated by rare hybridization between sexuals and apomicts, the latter acting as pollen donors. Less extensive clonal diversity is generated by mutations within clonal lineages. Clonal diversity may be maintained by frequency-dependent selection, caused by biological interactions (e.g. competitors and pathogens). Some clones are geographically widespread and probably represent phenotypically plastic 'general-purpose genotypes'. The long-term evolutionary success of apomictic clones may be limited by lack of adaptive potential and the accumulation of deleterious mutations. Although apomictic clones may be considered as 'evolutionary dead ends', the genes controlling apomixis can escape from degeneration and extinction via pollen in crosses between sexuals and apomicts. In this way, apomixis genes are transferred to a new genetic background, potentially adaptive and cleansed from linked deleterious mutations. Consequently, apomixis genes can be much older than the clones they are currently contained in. The close phylogenetic relationship between Taraxacum and Chondrilla and the similarity of their apomixis mechanisms suggest that apomixis in these two genera could be of common ancestry.     

Does melanism influence the diet of the mountain stone weta

Melanic and non-melanic mountain stone weta Hemideina maori (Orthoptera: Anostostomatidae) from the Rock and Pillar Range exhibit differential rates of melanotic encapsulation, a response to the presence of pathogens within the body. Because pathogens normally enter the body via food contamination, we hypothesised that dietary differences between the colour morphs might exist. We used faecal pellet analysis to determine the diet of the mountain stone weta. We then tested for differences between the two colour morphs in overall diet composition and the proportional contribution of invertebrate fragments to faecal pellets. The number of invertebrate fragments to the diet did not differ between the two colour morphs. Only when the plant species that were eaten infrequently were given greater weight in an Analysis of Similarity (ANSOM) did significant differences emerge in the diet of the two colour morphs. Hence, there was a weak but significant difference in the overall composition of their diets, but the ecological significance of this difference is unclear. Experimental studies could be used to determine if the dietary differences shown reflect true feeding preferences, or were due to small-scale differences in food availability or stochastic variation.     

Impact of mate availability, population size, and spatial aggregation of morphs on sexual reproduction in a distylous, aquatic plant

In distylous, self-incompatible plants, clonal propagation, unbalanced floral morph frequencies, and reduced population size can interfere with the functioning of distyly by compromising legitimate intermorph pollinations, resulting in reduced reproductive output. Here, we examined the mating system and the impact of mate availability, population size, and spatial aggregation of morphs on reproductive output in the distylous, clonal, aquatic plant Hottonia palustris. Controlled pollinations under greenhouse conditions detected no spontaneous selfing without the action of a pollen vector (autonomous autogamy) and demonstrated very low fruit and seed development after self-pollination. Intermorph (legitimate) crossings resulted in high reproductive output in both floral morphs (long- and short-styled individuals), whereas intramorph (illegitimate) crossings decreased fruit and seed development by more than 50%, indicating that the species has partial intramorph-incompatibility. In natural populations, small population size and increasing deviation of floral morph frequencies negatively affected reproductive outcome. Individuals of the majority morph type developed significantly fewer fruit and seeds than individuals of the minority morph type. This rapid decline in fecundity was symmetrical, indicating that regardless of which morph was in the majority, the same patterns of negative frequency-dependent mating occurred. Increasing spatial isolation between compatible morphs significantly reduced fruit and seed set in both morphs similarly. This study provides clear indications of frequency- and context-dependent mating in natural populations of a distylous plant species.