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Genetic and morphological variation in Chara contraria and a taxon morphologically resembling Chara connivens
Abstract
Charophyte species delineation is regularly based on a set of thallus morphological characteristics, but considering pronounced phenotypic plasticity, difficulties and doubts commonly occur in Chara species determination. DNA barcoding may contribute to solving these challenges. Here we characterize Chara contraria with an unusual set of morphological characteristics, and specimens morphologically resembling Chara connivens collected in Serbia, by describing their morphological traits and analysing matK barcoding results. Our results indicated that dioecious Chara specimens, tentatively determined as Chara “connivens” based on morphological traits, were genetically more closely related to C. globularis. These Chara “connivens” specimens formed a sister group to a monophyletic C. globularis cluster, suggesting that it may be neither C. connivens nor C. globularis. We strongly encourage further barcoding of C. “connivens” samples from freshwater, in order to find out if there are consistent genetic differences between the dioecious freshwater C. “connivens” and monoecious C. globularis. Barcoding of matK placed the monoecious Chara specimens, which based on morphological characteristics initially were determined as C. virgata, into the C. contraria group. This indicates that the microscopic traits which commonly are used for Chara species determination sometimes are misleading. In general, our study challenges the commonly used phenetic species concept in Charophyte taxonomy and illustrates the importance of molecular approaches to evaluate the validity of morphological characteristics of the plant thallus in species delineation.
... An exception is a case of Sava Lake, where in a recent study, only one previously detected species was reconfirmed-C. contraria, while Tolypella intricata and Nitella sp. are newly recorded [91]. Findings in Sava Lake and a nearby small lake Ada Safari [87,91] are at least intriguing, considering high anthropogenic pressure on this recreational center. ...
... contraria, while Tolypella intricata and Nitella sp. are newly recorded [91]. Findings in Sava Lake and a nearby small lake Ada Safari [87,91] are at least intriguing, considering high anthropogenic pressure on this recreational center. Wider area in this region, despite formerly recorded extraordinary and unique diversity and presence of even 10 charophyte species (which is, disregarding SNR "Gornje Podunavlje" in WBR, more than in any other region reviewed here (Table 8.2)), have not been the subject of any recent algological studies. ...
... Unfortunately, charophytes were detected in very few localities-in two oxbow lakes near Tamiš, a brickyard pond, Danube bay Dolnice, and a pond near Nera. In 2017, Trbojević et al. [91] started detailed surveys in the Labudovo Okno wetland area, finding unique and intriguing diversity in one new locality-Dulin Pond. All the other records from this area (in total 17 localities) are old, sporadic, and single records (some of which very old, i.e. finding of Chara vulgaris near Vršac dates from 1902). ...
The shallow aquatic ecosystems of Serbia are treasuries of algal biodiversity, unfairly neglected in both scientific studies and legislation concerning species and habitat protection. Underestimating the algal diversity in these ecosystems derives primarily from poor knowledge and/or interest in algal taxonomy and phylogeny, as well as ignorance of their role in the maintenance of ecosystem equilibrium and in the bioindication of water quality. The issue of conserving algae (i.e. their habitats) is challenging due to many aspects, including the problematic biogeography concept (particularly for microalgae), low taxonomic resolution of available data, and undersampling. Still, progress in the conservation of algae is noticeable worldwide. Although macroalgae are mainly recognized as endangered and protected species, they are still overlooked in conservation management in Serbia. Simultaneously, the data on microalgal diversity in shallow and small water bodies are scarce and sporadic. There are no long term monitoring programs towards recognizing the remarkable algal diversity characteristic for these habitats. This chapter offers an overview of the biodiversity of algae—both microscopic and macroscopic in shallow and small water bodies of Serbia, along with the frame and guidelines for protecting algae and their habitats.
... The first is Srebrno Lake near Veliko Gradište, where it was recorded in 1983 and 1984 and no later records are known (Blaženčić 2014). The second record was made in Dulin Pond at the Labudovo Okno Ramsar site (the Deliblato Sands Nature Reserve) where it was first recorded in 2017, in a stable population (dominating this shallow waterbody) (Trbojević et al. 2020). In the following seasons this population was monitored by the authors. ...
... The Chara connivens specimens from the Dulin Pond in Serbia were subjected to the matK region barcoding and the results showed that it clusters more closely with C. globularis and not with the other C. connivens specimens included in the study (Trbojević et al. 2020). Thus, finding more populations in remote localities in Serbia and comparing barcode results is highly important to resolve this peculiarity of the Dulin Pond population. ...
This paper presents new records and noteworthy data on the following taxa in SE Europe and adjacent regions: diatom algae Cyclostephanos invisitatus, Cyclotella meduanae, and Stephanodiscus lacustris, mycorrhizal fungi Alessioporus ichnusa-nus and Amanita mairei, saprotrophic fungi Diaporthe oncostoma, Stropharia albo-nitens and Pseudomassaria chondrospora, lichenised fungus Acrocordia subglobosa, stonewort Chara connivens, mosses Buxbaumia viridis, Tortella fasciculata and Tor-tula protobryoides, monocots Epipactis pontica Gymnadenia frivaldii, and Orchis italica and dicots Callitriche brutia, Callitriche platycarpa and Epilobium nutans are given within SE Europe and adjacent regions.
... Schneider et al. 2016;Pérez et al. 2014) and to assign specimens that are morphologically not clearly demarcated to genetic units (e.g. Nowak et al. 2019;Trbojević et al. 2020). MatK sequence data obtained substantial genetic differences among morphologically similar species such as C. virgata and C. globularis (Schneider et al. 2016). ...
... The genetic clusters identified here are comparable to previous molecular results (Schneider et al. 2016;Trbojević et al. 2020). Species of the Chara hispida cluster (section Hartmania) and the C. contraria cluster can be clearly separated from each other using chloroplast genes. ...
A Chara exhibiting extreme morphological features including stipulodes, spine cells, and bracteoles is described and subjected to barcoding procedures to determine whether it belongs to the Chara contraria group or the C. hispida group. MatK barcoding clearly placed it in the C. contraria clade which was consistent with gametangial morphology, but not stipulode, spine cell and bracteole morphology. The specimen was determined to be included in the Chara contraria var. hispidula taxon, not previously reported or described for Newfoundland, Canada, or the USA.
... Blaženčić 30.09.1983 and17.07.1984). However, in June 2017, it was discovered at the new site of Dulin pond, a shallow, permanent freshwater body, situated in the Deliblato Sands Nature Reserve (Trbojević et al. 2020). The finding in Slatina, near Baranda, is hence the third record for Serbia. ...
... In terms of species ecology, the Slatina locality could be considered the only one typical for C. connivens in Serbia. Specimens found in the explicitly freshwater Dulin pond turned out to be genetically specific (Trbojević et al. 2020), hence, further findings of C. connivens specimens in various localities are needed in order to resolve the status of the unusual specimens from Dulin pond. Dicranum polysetum is a calcifuge species which usually grows on the ground in forests and plantations, especially under pines and birches, in boreal and continental climates (Blockeel et al. 2014). ...
This paper presents new records and noteworthy data on the following taxa in SE Europe and adjacent regions: cyanobacteria Anagnostidinema amphibium, mycorrhizal fungus Tricholoma frondosae, stonewort Chara connivens, mosses Dicranum polysetum and Ulota intermedia, and dicots Eclipta prostrata, Paeonia daurica subsp. daurica, Ruta graveolens and Sorbus bosniaca.
... Specimens with isostichous triplostichous cortex, inconspicuous spines and reduced stipulodes (Online Resource 1, Fig. S1a-d) could be representing C. globularis, but also C. connivens (clear difference between these species is that C. globularis is monoecious, and C. connivens dioecious). Bearing in mind the proximity of Dulin pond (about 1.5 km air distance from researched locality) where we formerly reported C. connivens (Trbojević et al. 2020a), we could not make safe decision. Similarly, the plants from the Chara spp. group with clearly tylacanthous triplostichous cortex, reduced/small solitary spines and acute upper stipulodes correspond to the C. virgata description, but as plants were sterile and many intermediate forms has been seen in this material (Online Resource 1, Fig. S1e-h), and the fact that this species and C. globularis are hard to disitinguish particularly when they live together , again we could not make safe decision. ...
Many charophytes are rare and endangered algae species. All charophyte species significantly contribute to the stability and health of the ecosystems they inhabit. Charophytes survive in their habitats thanks to the longevity of the diaspores (oospores and gyrogonites) in the sediment. Many charophyte species have a specific phenology and can sometimes be overlooked in surveys of macrophyte vegetation. We monitored vegetation for three years and collected sediment from a small water body in Serbia to test the hypotheses that (a) Extant charophyte diaspores have promising, yet currently limited application as taxonomic markers, (b) Vegetation data on charophyte diversity may provide different information than data obtained by extracting diaspores from sediments and (c) parallel surveys of vegetation and sediments can provide a more comprehensive view of charophyte diversity compared to traditional annual vegetation monitoring. Diaspores proved to be promising taxonomic characters for charophyte identification. In our study, six taxa could be identified on a species level based on diaspores alone, while one species group (Chara spp.) requires further investigation as it could consist of up to four species. Compared to vegetation, the sediment survey provided different information on charophyte diversity and confirmed the presence of the species Sphaerochara intricata and Sphaerochara prolifera, which were never detected during the vegetation survey. Sediment studies conducted in parallel with vegetation studies provide important insight into the diversity of charophytes and the prospects for their habitat conservation.
... The taxonomy by Wood (1965) is the most recent one covering the whole charophyte flora. The obvious incongruence of morphological and phylogenetic affinity within some species groups from the genus Chara L. has already been described (Meiers et al. 1999;Schneider et al. 2016;Trbojević et al. 2020), highlighting the importance of genetic studies for each new species. Here we describe a new species from Israel using a polyphasic approach and outline some implications for the taxonomy of the genus Chara. ...
A new species, Chara lipkinii, was described based on specimens from the Mediterranean, Israel. Dioecy, 10-13 branchlets in a whorl, complete tylacanthous to isostichous displostichous axial cortex with very short solitary spine cells, hardly visible diplostephanous bistipulate short obtuse stipulodes, frequently appearing as haplostephanous, in combination with completely ecorticate branchlets without cortex initials and with 1-3, mainly two nodes with unilateral bract cells distinguish it from species of Chara described to date. Its morphological traits, which are most important in the infrageneric taxonomy described by Wood, point towards its placement in the subsection Chara, rather than its distant clustering with both Chara and Grovesia. The oospore surface of C. lipkinii showed no features allowing identification based on oospore morphology only, but could be useful to distinguish it from some species. According to our analyses, the genetic affinity of species based on rbcL and ITS1 mostly does not support infrageneric division of the genus Chara based on morphological traits. Chara lipkinii is a freshwater and brackish water species, growing in small shallow inland water bodies and streams in the Eastern Mediterranean, i.e., in one of the most threatened water bodies of the region. The species faces a very high risk of extinction in the wild. It has disappeared from all previously discovered localities, which no longer support charophyte populations. The gradual decline and disappearance of living plants from one recently discovered locality of C. lipkinii were observed as a result of heavy sediment accumulation and eutrophication. Urgent action to restore the habitat needs to be taken.
... We predict that C. globata might be recorded in the future in the other Maghreb countries, particularly by applying combined morphological and phylogenetic approaches. Accordingly, it has been established that subtle species identification of members of the charophytes at the species and intraspecific level has nowadays become much easier thanks to the integrative polyphasic approaches, irrespective of the occurrence of populations showing marked phenotypic variability and developing so-called "phenoecodemes" as a result of the environmental and/or culture conditions [22,29,44]. ...
Present-day information available on the charophyte macroalgae in Egypt, including their phylogenetic affinities, remains largely incomplete. In this study, nine charophyte populations were collected from different aquatic biotopes across the Egyptian Western-Desert Oases and Sinai Peninsula. All populations were investigated using an integrative polyphasic approach including phylogenetic analyses inferred from the chloroplast-encoded gene (rbcL) and the internal transcribed spacer (ITS1) regions, in parallel with morphotaxonomic assignment, ultrastructure of the oospore walls, and autecology. The specimens identified belonged to the genera Chara, Nitella, and Tolypella, with predominance of the first genus to which five species were assigned though they presented some interesting aberrant taxonomic features: C. aspera, C. contraria, C. globata, C. tomentosa, and C. vulgaris. Based on our integrative study, the globally rare species C. globata was reported for the second time for the whole African continent. The genus Nitella was only represented by N. flagellifera, and based on the available literature, it is a new record for North Africa. Noteworthy, an interesting Tolypella sp., morphologically very similar to T. glomerata, was collected and characterized and finally designated with the working name ‘Tolypella sp. PBA–1704 from a desert, freshwater wetland’, mainly based on its concatenated rbcL+ITS1 phylogenetic position. This study not only improved our understanding on the diversity, biogeography and autecological preferences of charophytes in Egypt, but it also broadened our knowledge on this vulnerable algal group in North Africa, emphasizing the need of more in-depth research work in the future, particularly in the less–impacted desert habitats.
... Urbaniak and Gąbka [6] remarked the irregularity of the cortex, which was also noted in this study. It was already shown that the number of cortex cell rows may be variable within a genetically homogeneous Chara group [22], which may be the case in C. baueri as well. ...
Chara baueri is one of the rarest charophytes worldwide. It had been considered extinct in Europe for more than a century, from the 1870s to 2006, when it was rediscovered in Germany. The current distribution of this species is limited to a few localities in Europe (Germany, Poland and Russia), and one locality in Asia (Kazakhstan). We present a new finding of Chara baueri, to be a significant contribution to the species ecology and biogeography, and helping to review and update the current scarce knowledge. Chara baueri was discovered in Serbia and monitored for two vegetative seasons in 2018 and 2019, along with the associated macrophyte vegetation and water quality parameters. The morphology and ecology data of the species are presented comparatively with the literature data and the biogeography is critically reviewed. The population in Serbia is the first verified record of Chara baueri in southern Europe. Considering the recent findings and the knowledge accumulated in these records, Chara baueri was very possibly never extinct at all, but overlooked in Europe for the entire 20th century. We suggest that waterfowl migrating from the northern parts of Europe should be considered as the important spreading agent of Chara baueri in southern regions.
The charophytes in many regions of the world are still poorly understood. This hampers the synthesis of distributional and ecological datasets at worldwide and continental scales, as well as complicates the generalization of species concepts for widely distributed and local taxa. To fill in the blanks for charophytes in the Caucasus and to improve our knowledge of species distribution areas in Eurasia, a field survey and study of available specimens from Dagestan (North Caucasus, Russia) was conducted based on morphological observation using light and scanning electron microscopy and molecular genetic analyses allowing for the precise identification and testing of the presence of cryptic and undescribed taxa. Nineteen new localities for seven Chara species and one Tolypella species, seven new species, and one new genus were identified in the studied region, and one new species in the Caspian Sea region was found. Some species records changed the outline or filled in the gaps in species distribution data. The presence of species distributed mainly in central Eurasia (C. globata, C. neglecta) with mainly Mediterranean–Middle Eastern species (C. gymnophylla) is notable for this region, as well as for other studied regions of the Caucasus characterized by a mixture combination of species with different distribution patterns. Chara gymnophylla was frequent in Dagestan, similar to the Mediterranean and Middle Eastern regions. Small brackish waterbodies on the coast of the Caspian Sea, freshwater mountain rivers, small associated waterbodies, and water reservoirs are the main habitats of charophytes in the studied region. Based on habitat preference and distribution in the Caucasus, recommendations for the protection of some species were suggested. The lack of endemic species among charophytes from Dagestan and Caucasus contrasts with the flora of terrestrial magnoliophytes that is rich in species endemism.
Citation: Marković, A.; Blaženčić, J.; Tanasković, A.; Šinžar-Sekulić, J. Diversity and Ecology of Charophytes from Vojvodina (Serbia) in Relation to Physico-Chemical and Bioclimatic Habitat Properties. Diversity 2023, 15, 342. https:// Abstract: In Serbia, almost all charophyte species belong to one of the IUCN categories. This study aimed to gather more knowledge about their floristic richness, distribution and ecology. During the survey, 262 localities were investigated in the Vojvodina province, northern Serbia. Seventeen charophyte species were found, out of which 16 were included in the analyses. The environmental matrix included 38 localities, each characterized by habitat type and 35 environmental parameters. The canonical correspondence analysis (CCA) showed six parameters as being statistically significant: substrate, altitude, depth, water temperature, temperature annual range and precipitation of the driest month. Together, these explain the 32.34% variability in the species composition and abundance data. Altitude and substrate contributed the most to this. Two main types of habitats were outlined by the analysis. Small and shallow temporary habitats in the river floodplains, at lower altitudes, with muddy and clayish substrate, belong to one type. These areas are inhabited by either very tolerant species, such as Chara vulgaris and C. globularis, or the so-called "spring" species of the genera Tolypella and Nitella. Habitats which are located at higher altitudes, when deeper and more permanent with a sandy substrate, such as sandpits and river habitats, belong to the second one. These areas are inhabited by species like Chara papillosa, C. hispida, and Nitellopsis obtusa.
The precise determination of charophytes to the species level is important for many reasons, but the common morphological taxonomic characteristics, particularly between morphologically similar taxa can be insufficient or misleading. The aim of our study was to create a comparative analysis of the oospore’s morphometric parameters in morphologically similar taxa such as Chara globularis Thuil., C. “connivens” P.Salzmann ex A.Braun, C. braunii C.C.Gmel. and C. baueri A.Braun (from Serbia). The potential for applying oospore features in species delineation was assessed, along with the interpopulation variability of oospore parameters in geographically remote populations of C. globularis and C. braunii. Common oospore parameters (height, width, number of ridges, width of fossa, and distance between the apical pole of the oospore and its widest part) were measured and the isopolarity index and anisopolarity index indices were calculated. Both interpopulation variability and interspecific differences were confirmed using oospore morphology for the selected charophyte species. Although interpopulation variability does in fact exist, oospore parameters clearly differ between morphologically similar taxa. These results are important from a taxonomic perspective, but also from the aspect of diaspore bank characterization and its potential application in restoration projects. The results also justify the need for the development of oospore identification keys at the local and regional level, particularly in the regions where they are completely lacking (e.g. Balkans). Collecting more data on oospore morphometry is necessary for our results to be widely used.
The first record of a species belonging to the genus Chara L. subgenus Chara R.D.Wood section Grovesia R.D.Wood subsect. Willdenowia R.D.Wood from Europe is presented here, thus challenging the interpretation of its distribution pattern as an intertropical group of charophytes. The morphological characters of the specimens, as well as the results of a phylogenetic analysis, clearly identified them as Chara zeylanica J.G.Klein ex Willd. Although the subsection Willdenowia has yet to receive a thorough taxonomic treatment, a discussion of its relationship to other taxa of this subsection is provided despite the lack of a commonly agreed upon taxonomic concept. The ecological conditions of the Sardinian site of C. zeylanica are presented. Moreover, the status of and threats to this taxon, and hypotheses regarding potential pathways through which it reached Europe, are discussed.
We present the latest version of the Molecular Evolutionary Genetics Analysis (MEGA) software, which contains many sophisticated
methods and tools for phylogenomics and phylomedicine. In this major upgrade, MEGA has been optimized for use on 64-bit computing
systems for analyzing bigger datasets. Researchers can now explore and analyze tens of thousands of sequences in MEGA. The
new version also provides an advanced wizard for building timetrees and includes a new functionality to automatically predict
gene duplication events in gene family trees. The 64-bit MEGA is made available in two interfaces: graphical and command line.
The graphical user interface (GUI) is a native Microsoft Windows application that can also be used on Mac OSX. The command
line MEGA is available as native applications for Windows, Linux, and Mac OSX. They are intended for use in high-throughput
and scripted analysis. Both versions are available from www.megasoftware.net free of charge.
The Troll springs are warm springs on Svalbard (Spitsbergen). Charophytes were collected in the years 1910, 1912, 1958, 1992/1993, and 2018. However, since the Chara samples showed unusual morphological traits, there were doubts with respect to species identity. We here use DNA barcoding to show that there occur two Chara species in the Troll springs: Chara aspera and C. canescens.
The stonewort Chara connivens was rediscovered in the Vistula Lagoon in 2011, almost 35 years after its last record. In 2012, the species was recorded for the first time in the Szczecin Lagoon. Chara connivens occurred at shallow (0.5–1.2 m) sandy-muddy and muddy bottoms of small embayments. In the Vistula Lagoon, the stonewort was represented by single small specimens, while in the Szczecin Lagoon, it formed dense and extensive patches.
The objective of this study was to analyze the temporal variability of biometric features and the carbonate production of two charophytes: Chara polyacantha A. Braun and Chara rudis A. Braun against the background of the physical-chemical properties of water. The investigation was carried out in a small, mid-forest Lake Jasne (western Poland). It is a polymictic, mesotrophic, hardwater ecosystemdominated by charophyte vegetation. Eachmonth, 10 individuals of each specieswere characterized in terms of morphometric features, fresh and dry weight, and the percentage of calciumcarbonate. Additionally, physical chemical parameters of the water were studied. The results of physical-chemical analyses indicated similar habitat conditions for both species. Despite smaller dry weight C. polyacantha was characterized by greatermorphological variability and higher rates of growth and percentage share of calcium carbonate in dry mass than C. rudis.The percentage of calcium carbonates in dry mass did not differ significantly between the species and exceeded 60%, reaching the maximum (76% in C. polyacantha) in July and August. For both species, distinct correlations between the structure of biomass and morphological features were found. The obtained results show the great importance of charophyte vegetation in carbon cycling and functioning of lake ecosystems.
Chara altaica A. Braun (Charales, Charophyceae), a monoecious species of the section
Desvauxia, was newly found in Japan and studied by light and scanning electron microscopy (SEM)
as well as gene sequence analysis of the large subunit of Rubisco (rbcL). Our first SEM observations
of C. altaica oospores revealed that small papillae were scattered on the fossa wall, an SEM oospore
wall ornamentation that is essentially different from that of the monoecious species C. (sect.
Desvauxia) evoluta T. F. Allen. Phylogenetic analysis demonstrated that C. altaica and 10 European
samples of the dioecious species C. (sect. Desvauxia) canescens Desvaux & Loiseleur-
Deslongchamps formed a robust monophyletic group, in which the rbcL gene sequence from C.
altaica is identical to those from 4 parthenogenetic samples, but different from 6 other bisexual and
parthenogenetic samples of C. canescens.
Genetic variation of five species belonging to the section Hartmania – Chara baltica, C. intermedia, C. hispida, C. polyacantha and C. rudis – was investigated using Amplified Fragment Length Polymorphism (AFLP) techniques. Chara intermedia can be distinguished from the others by the presence or absence of numerous morphological characters. However, probably because of the high variability of the morphological features and common occurrence of apparently transitional forms, more than 80 specimens of the five species were collected and analysed. The specimens were collected from a total of 24 sites, including freshwater localities and sites in the Baltic Sea, initially classified into the five species based on morphological features, and then analysed using AFLP; as an outgroup we used C. globularis. The specimens formed two groups, the first group comprising C. intermedia and C. baltica, the second C. hispida, C. rudis and C. polyacantha. No consistent genetic differences were found between species within each of the two groups. Transitional forms of C. hispida/C. rudis were placed in a clade between individuals of C. hispida and C. rudis. Local populations of some charophytes differ morphologically from one another, possibly as a result of local adaptation.
Since its introduction in 2001, MrBayes has grown in popularity as a software package for Bayesian phylogenetic inference using Markov chain Monte Carlo (MCMC) methods. With this note, we announce the release of version 3.2, a major upgrade to the latest official release presented in 2003. The new version provides convergence diagnostics and allows multiple analyses to be run in parallel with convergence progress monitored on the fly. The introduction of new proposals and automatic optimization of tuning parameters has improved convergence for many problems. The new version also sports significantly faster likelihood calculations through streaming single-instruction-multiple-data extensions (SSE) and support of the BEAGLE library, allowing likelihood calculations to be delegated to graphics processing units (GPUs) on compatible hardware. Speedup factors range from around 2 with SSE code to more than 50 with BEAGLE for codon problems. Checkpointing across all models allows long runs to be completed even when an analysis is prematurely terminated. New models include relaxed clocks, dating, model averaging across time-reversible substitution models, and support for hard, negative, and partial (backbone) tree constraints. Inference of species trees from gene trees is supported by full incorporation of the Bayesian estimation of species trees (BEST) algorithms. Marginal model likelihoods for Bayes factor tests can be estimated accurately across the entire model space using the stepping stone method. The new version provides more output options than previously, including samples of ancestral states, site rates, site d(N)/d(S) rations, branch rates, and node dates. A wide range of statistics on tree parameters can also be output for visualization in FigTree and compatible software.
DNA barcoding involves sequencing a standard region of DNA as a tool for species identification. However, there has been no agreement on which region(s) should be used for barcoding land plants. To provide a community recommendation on a standard plant barcode, we have compared the performance of 7 leading candidate plastid DNA regions (atpF–atpH spacer, matK gene, rbcL gene, rpoB gene, rpoC1 gene, psbK–psbI spacer, and trnH–psbA spacer). Based on assessments of recoverability, sequence quality, and levels of species discrimination, we recommend the 2-locus combination of rbcL+matK as the plant barcode. This core 2-locus barcode will provide a universal framework for the routine use of DNA sequence data to identify specimens and contribute toward the discovery of overlooked species of land plants.
Characeae is a family of freshwater green algal macrophytes found on every continent except Antarctica. Although some species are thought to be cosmopolitan, others appear to be restricted to relatively small geographic areas. Chara brittonii is a North American endemic previously reported from eight scattered populations in Indiana, Michigan, New Jersey, and Ohio. Given that few extant populations were known, basic questions about its distribution, habitat preference, morphology, and phylogenetic placement remained unanswered. We have surveyed every reported locality for C. brittonii except the New Jersey locality, because the collection details are vague, and also surveyed numerous additional waterbodies in Indiana, Michigan, and Wisconsin. We have found extant populations in nine localities in three states. These include one newly reported site in Indiana and five newly reported sites in Wisconsin, the first known populations in that state. Chara brittonii seems to have been extirpated from several historical sites in recent decades. We expanded both the range and the number of known extant populations for C. brittonii and hypothesize that C. brittonii may be more widespread in the Midwest than previously thought. Factors contributing to the actual and apparent rarity of this species are discussed including its preferred habitat and small size. We observed that the number of antheridial scute cells of C. brittonii varied from 4–8 with both triangular and elongate scutes produced on the same thallus, an unusual condition for the family. Phylogenetic analyses using three plastid-encoded markers placed C. brittonii among a paraphyletic grade of C. foliolosa sensu lato strains in the monophyletic subsection Willdenowia. We propose that C. foliolosa, as currently recognized, represents a species complex of several phylogenetically distinct lineages, and conclude that C. brittonii is a structurally and phylogenetically distinct species worthy of conservation.
Charophytes are aquatic macrophytes with a complex morphology that belong to the Streptophytina phylum. The high degree of morphological plasticity in the genus Chara has led researchers to propose two competing species concepts, a micro- and macrospecies concept, the relevance of which we tested by phylogenetic analyses. We conducted a phylogenetic survey based on the phylogenetic relationships between 14 species of the genus Chara using molecular data from two nuclear (18S rDNA, nrITS-1) and three chloroplast (rbcL, atpB, matK) markers. As the combined molecular data indicated that the overall level of genetic divergence between the investigated species was, at ≤3%, relatively low, a robust species delineation was difficult to achieve. The sequence dataset of 6214 base pairs did not separate individuals of closely related taxa with distinct morphological characters; e.g., the interspecific genetic variability for C. contraria and C. filiformis or C. rudis and C. hispida was zero. In contrast, the molecular data revealed clear differences between C. vulgaris and C. contraria; species that are distinguished only by their relative levels of development of primary and secondary cortex cell rows. The low levels of genetic variability between as well as within the taxa studied here suggest that there has been a relatively recent, but still incomplete, speciation of Chara species.
Charophytes are benthic algae with a complex morphology and high phenotypic plasticity. This has led to ambiguities in species delineation. However, until now genetic studies on Chara have been based on samples collected from a restricted geographic range or only included a restricted number of taxa. This may have hindered a general interpretation of the results. We applied barcoding of matK, a rapidly evolving coding section of the plastid genome, in 324 Chara samples collected from 19 countries, in order to test whether the distribution of barcode haplotypes among individuals was consistent with species boundaries as they are currently understood. The phylogenetic tree grouped the 324 Chara individuals, which according to commonly used identification keys represented 29 species, into 12 well-defined groups (i.e. monophyletic morphospecies or groups of morphospecies). Considerable morphological variation occurred within genetically homogeneous groups. This included traits which are commonly used for Chara species determination, such as the length and number of spine cells, the length of stipulodes and bract cells, cortication (tylacanthous, isostichous, aulacanthous and absent cortication), as well as sex differentiation. However, there were also substantial genetic differences among morphologically similar species (e.g. C. virgata – C. globularis – C. connivens). No morphological trait consistently reflected genetic differences. This indicates that morphological traits for specific taxa may serve as diagnostic tools for species delimitation, but that they are not generally suitable for inferring genetic differentiation or phylogenetic relationships. We propose that (i) C. virgata and C. strigosa, (ii) C. liljebladii, C. horrida and C. baltica, and (iii) C. hispida, C. rudis and C. polyacantha are conspecific. Our data also indicate that C. gymnophylla should be divided into tylacanthous forms (which are closely related to C. contraria) and aulacanthous forms (which are related to C. vulgaris).
Charophytes (Charales) are benthic algae with a complex morphology. They are vulnerable to ecosystem changes, such as eutrophication, and are red-listed in many countries. Accurate identification of Chara species is critical for understanding their diversity and for documenting changes in species distribution. Species delineation is, however, complicated, because of high phenotypic plasticity. We used barcodes of the ITS2, matK and rbcL regions to test if the distribution of barcode haplotypes among individuals is consistent with species boundaries as they are currently understood. The study included freshly collected and herbarium material of 91 specimens from 10 European countries, Canada and Argentina.Results show that herbarium specimens also for aquatic plants like Chara are useful as a source of material for genetic analyses. rbcL and matK had highest sequence recoverability, but rbcL had a somewhat lower discriminatory power than ITS2 and matK. The tree resulting from the concatenated data matrix grouped the samples that according to a traditional morphological approach consisted of 12 different taxa, into six main groups. A large unresolved group consisted of C. intermedia, C. hispida, C. horrida, C. baltica, C. polyacantha, C. rudis, C. aculeolata, and C. corfuensis. A second unresolved group consisted of C. virgata and C. strigosa. The taxa within each of the unresolved groups shared identical barcode sequences on the 977 positions of the concatenated data matrix. The morphological differences of taxa within both unresolved groups include the number and length of spine cells, stipulodes, and bract cells. We suggest that these morphological traits have less taxonomic relevance than hitherto assumed.This article is protected by copyright. All rights reserved.
Most charophyte species are threatened across Europe. Understanding their current and future distribution is a challenge for their conservation. We looked for species distribution models (SDM) and for increasing or decreasing species occurrence under a future climate scenario in Switzerland. Firstly, we modeled the occurrence of charophyte species in 1402 Swiss localities using presence-absence data and environmental variables (waterbody size, mean July temperature, July precipitation, soil calcium carbonate content and proportions of land used by agriculture and forest cover in the catchment area and in the surroundings). We used Generalized Additive Models (GAM) to analyze the data. Secondly, based on the models, we predicted the occurrence of the species in 21,092 localities listed in Switzerland. Thirdly, we applied a climate scenario to our models (2 °C mean July temperature increase and 15% reduction in July precipitation) and predicted species occurrence under these new conditions. Twelve charophyte species were modeled successfully. The major driver of species distribution was the waterbody size, followed by climate and land-use variables. We detected predicted impacts of climate changes on the species occurrence and identified the potential winners and losers. About half of the species are predicted to become losers; they colonize the littoral zone of lakes. Other charophytes are potential winners; the majority of them colonize small waterbodies
A complex of freshwater plants known collectively as Chara globularis exists through most temperate to subarctic regions of the world. This study focuses on the extent of reproductive isolation existing between various populations that differ with respect to geographical separation and external morphological features. Widespread isolation was encountered ranging from progeny of reduced vigor, through nongerminative oospores, to the complete absence of gametic exchange. There is no evidence to support the view that charophytes are ever truly cosmopolitan in the sense that local populations throughout the world are even potentially interfertile. Most "spccics" or even microspecies appear to consist of complexes of partially to completely genetically isolated local populations.
A significant portion of calcium carbonate is deposited in lake sediments as a
result of biological processes related to the photosynthetic activity of phytoplankton
in the pelagic realm and, in addition, macrophytes in the littoral
zone. Lake Wigry, one of the largest lakes in Poland (north-east Poland), is
characterized by: (i) carbonate sediments with a CaCO3 content exceeding
80% within the littoral zone; and (ii) large areas of submerged vegetation
dominated by charophytes (macroscopic green algae, Characeae family). It is
claimed that charophytes are highly effective in utilizing HCO3
�
and forming
thick CaCO3 encrustations. Thus, this study was aimed at evaluating the
CaCO3 production by dense Chara stands overgrowing the lake bottom reaching
a depth of 4 m. In late July 2009, the fresh and dry mass of plants, the percentage
contribution of calcium carbonate and the production of CaCO3 per
1 m2 were investigated along three transects at three depths (1 m, 2 m and
3 m, with each sample area equal to 0�0625 m2) per transect. The composition
and structure of phytoplankton and the physico-chemical properties of the
water analysed in both the littoral and pelagic zones served as the environmental
background and demonstrated moderately low fertility in the lake.
The greatest dry plant mass exceeded 1000 g m
�2 and CaCO3 encrustations
constituted from 59% to over 76% of the charophyte dry weight. Thus, the
maximum and average values of carbonates precipitated by charophytes were
685�5 and 438 g m
�2, respectively, which exceeded previously reported
results. A correlation of carbonate production with the depth of Chara stands
was detected, and intermediate depths offered the most favourable conditions
for carbonate precipitation (589 g m
�2 on average). As precipitated carbonates
are ultimately stored in bottom deposits, the results highlight the significance
of charophytes in lacustrine CaCO3 sedimentation.
1. Charophytes have disappeared from several enriched lakes in Scania (southern Sweden) since the 1940s. Poor light conditions, rather than a toxic effect of phosphorus or negative impact of fish, are the most probable reason for this decline.
2. Small species of charophytes (shoot diameter 0.5–1.0 mm), which are able to form dense, low mats, still occur in eutrophic lakes with high phosphorus concentrations, but are restricted to areas of shallow water. In contrast, large species (shoot diameter
1–4 mm) have totally disappeared from the most turbid lakes. I suggest that these species are unable to grow in very shallow water because of damage by ice and wave action.
3. Maximum depth distribution (ze) and Secchi depth (D) were measured in Scanian lakes for both charophytes and angiosperms and combined with data obtained from Chambers & Kalff (1985). According to the combined data, zc and D are closely correlated with each other for both angiosperms and charophytes.
4. The zc of charophytes is higher than zc of angiosperms in clear lakes but lower in turbid lakes. Higher zc of angiosperms in the most turbid lakes is explained by special adaptations of these species to poor light availability (shoot elongation, canopy formation, rapid growth during spring).
Aquatic macrophytes can serve as useful indicators of water pollution along the littoral of lakes. In Bavaria, the submerged vegetation of about 100 lakes has been investigated by SCUBA diving over the past decade to evaluate the state of nutrient pollution. All lakes are marl lakes located in the northern calcareous alps and the prealpine region. The lakes differ in size, morphology, water residence time, nutrient loading, trophic status, recreational activities, and other characteristics. In all cases the entire shoreline of the lakes has been investigated. Among the investigated lakes are the three biggest Bavarian lakes, i.e. Lake Chiemsee, Lake Starnberg and Lake Ammersee. Mapping of the submerged vegetation occurred in four different depth zones, and variable shoreline sections. The length of each section was determined by the uniformity of the vegetation; as it changed, a new section was designated. Within each section and zone species were recorded and abundance of all observed macrophytes was estimated semi-quantitatively on a five-point scale. Nine different groups of macrophytes were recognised, including, in total, 45 different species of macrophytes. On the basis of this catalogue of indicator species, in combination with the abundance of the species, a macrophyte index was devised, which ranges from 1 (unpolluted) to 5 (heavily polluted). Six groups of values of the macrophyte index, each represented by a different colour or grey-scale (in this publication), are presented to allow a clear illustration of the results. Important information for the successful restoration of lakes in Upper Bavaria has been obtained from the distribution patterns of the submerged vegetation. Many unknown waste water inflows or diffuse sources could be detected due to abrupt changes in the macrophyte index. Furthermore, the success of waste water removal by ring canalisation, resulting in a re-oligotrophication of many Bavarian lakes can be followed by changes in the macrophyte index.
Charophytes are macrophytic green algae, occurring in standing and running waters throughout the world. Species descriptions
of charophytes are contradictive and different determination keys use various morphologic characters for species discrimination.
Chara intermedia Braun, C. baltica Bruzelius and C. hispida Hartman are treated as three species by most existing determination keys, though their morphologic differentiation is based
on different characteristics. Amplified fragment length polymorphism (AFLP) was used to detect genetically homogenous groups
within the C. intermedia-C. baltica-C. hispida-cluster, by the analysis of 122 C. intermedia, C. baltica and C. hispida individuals from central and northern Europe. C. hispida clustered in a distinct genetic group in the AFLP analysis and could be determined morphologically by its aulacanthous cortification.
However, for C. intermedia and C. baltica no single morphologic character was found that differentiated the two genetic groups, thus C. intermedia and C. baltica are considered as cryptic species. All C. intermedia specimen examined came from freshwater habitats, whereas the second group, C. baltica, grew in brackish water. We conclude that the species differentiation between C. intermedia and C. baltica, which is assumed to be reflected by the genetic discrimination groups, corresponds more with ecological (salinity preference)
than morphologic characteristics.
Based on the genetic analysis three differing colonization models of the Baltic Sea and the Swedish lakes with C. baltica and C. intermedia were discussed. As samples of C. intermedia and C. baltica have approximately the same Jaccard coefficient for genetic similarity, we suggest that C. baltica colonized the Baltic Sea after the last glacial maximum from refugia along the Atlantic and North Sea coasts. Based on the
similarity of C. intermedia intermediate individuals of Central Europe and Sweden we assume a colonization of the Swedish lakes from central Europe.
Species separation in charophytes is primarily based on vegetative morphology, but the taxonomic delineation at species level worldwide is inconsistent. Here we compare ecophysiological characteristics of selected Chara species with vegetative morphological traits and genetic data. Four populations of the Chara baltica–Chara intermedia species cluster from locations along a north-south gradient through Europe were investigated. Physiological differences indicate habitat-specific adaptations. The Baltic Sea population from Hiddensee was found to be separated from a freshwater river population close to Munich with respect to light and salinity acclimation capabilities. However, a population from a brackish Mediterranean pool near Montpellier and one from the continental brackish water lake “Salziger See” near Halle, Germany, show intermediate ecophysiological characteristics, suggesting a continuum. Genetic analyses using AFLP (amplified fragment length polymorphism) match the results of the physiological analyses. The individuals of the Mediterranean and the Salziger See neither cluster to the typical C. baltica from the Baltic Sea nor to the C. intermedia from the freshwater habitat, but instead take an intermediate position. These results are stable against the background of a larger AFLP dataset on charophytes. Morphological analysis revealed no distinct groups and we therefore conclude that the C. baltica–C. intermedia cluster forms a physiological, morphological and genetic continuum.
The capability of Chara beds to act as nutrient sinks in shallow lakes is reviewed. Under favorable conditions charophytes form dense meadows. Biomass and nutrient content in such beds are comparable or even higher than in beds of vascular aquatic macrophytes. As some Chara species are capable of overwintering, the nutrient storage in plant biomass may extend beyond the growing season. Some commonly observed phenomena in vascular plants (nutrient uptake and mobilization of nutrients from the sediment) appear to be unlikely or negligible in Characeae. Charophytes have been reported to decompose slower than their vascular counterparts prolonging nutrient storage in plant biomass.Charophytes may also indirectly affect nutrient cycling in lakes. Utilization of bicarbonate is accompanied by precipitation of calcite during periods of intensive photosynthesis, favoring immobilization of P by binding in the crystal structure or sorption on sedimenting mineral particles. Charophytes are able to deliver oxygen to the sediment, thus potentially enhancing nitrification/denitrification processes and preventing iron-bound sediment phosphorus from being released to the overlying water. Furthermore, dense Chara meadows restrict sediment resuspension, consequently blocking an important internal source of nutrients to planktonic algae. We conclude that Chara meadows probably are an efficient nutrient trap in shallow lakes.