2003

2003

Title: Origin and evolution of the genera Pleodorina and Volvox (Volvocales)

Source: BIOLOGIA 58 (4): 425-431 JUL 2003

Abstract: The previous molecular phylogenetic study using 6021 base pairs from five chloroplast genes suggested that two species of Pleodorina (P. californica, P. japonica) might have evolved from a Volvox-like alga by the decrease in colony cell number and size. However, number of species of the genus Volvox was very limited especially in the section Merrillosphaera.

In the present study, 6021 base pairs of the concatenated five chloroplast genes from 10 strains representing seven taxa of the genus Volvox were added to the previous data matrix. The sequence data resolved two anisogamous/oogamous clades within a large monophyletic group comprising five advanced genera of the Volvocaceae (Yamagishiella, Platydorina, Eudorina, Pleodorina and Volvox), one containing Volvox sect. Volvox and the anisogamous genus Platydorina (32-celled flattened colony), and the other (Eudorina group) composed of three other sections of Volvox, Pleodorina and Eudorina. The isogamous genus Yamagishiella (32-celled colony) was positioned basally to the Eudorina group. Therefore, evolution of anisogamy with sperm packets from isogamy might have occurred twice within the Volvocaceae. Based on the present molecular phylogenetic analysis, species of Volvox and Pleodorina within the Eudorina group represented three and two, respectively, separate lineages. One the three Volvox lineages [composed of V (sect. Merrillosphaera) carteri, V (sect. Merrillosphaera) obversus, V. (sect. Merrillosphaera) tertius, V. (sect. Merrillosphaera) africanus and V (sect. Copelandosphaera) dissipatrix] was sister to the monophyletic group consisting of one of the two Pleodorina lineages (P. californica and P. japonica) and V (sect. Janetosphaera) aureus. In addition, species of Eudorina were basal to the two lineages of Pleodorina and three Volvox lineages within the Eudorina group, representing the ancestral situation of Pleodorina/Volvox (excluding sect. Volvox). Thus, reverse evolution from a Volvox-like alga to Pleodorina suggested previously appears unlikely.

Strojsova A, Vrba J, Nedoma N, et al.

Seasonal study of extracellular phosphatase expression in the phytoplankton of a eutrophic reservoir
EUR J PHYCOL 38 (4): 295-306 NOV 2003

Abstract:
Many phosphorus-deficient algae and cyanobacteria produce extracellular, mostly cell-attached, phosphatases, presumably to make ambient organically bound phosphorus available. The distribution of phosphatase activity among natural phytoplankton populations and its ecological significance is largely unknown. Bulk extracellular phosphatase activity of plankton (using a standard fluorometric assay) and expression of phosphatases at the level of single phytoplankton cells were studied in the eutrophic Rimov reservoir during three consecutive seasons. The new enzyme labelled fluorescence (ELF) technique was modified by introducing (i) fixation with HgCl2 to preserve fragile species and (ii) use of polycarbonate filters to concentrate the phytoplankton. After enzymatic hydrolysis of artificial substrate (ELF(R)97 phosphate), the fluorescent product (ELF(R)97 alcohol, ELFA) formed insoluble precipitates at the site of phosphatase activity. Inhibition experiments suggested that both the standard assay and the ELF technique detected the same group of phosphatases. Weak ELFA formation and/or stability at pH > 8 might prevent sufficient detection of alkaline phosphatases using the ELF technique. ELFA labelling was detected in most algal classes, except for Euglenophyceae and the majority of Cryptophyceae and Chrysophyceae. Surprisingly, phosphatase activity was almost absent in the dominant populations. No ELFA labelling occurred in the phytoplankton in early spring 2000 and during the clear-water phases in all sampling years. Species of Cyanobacteria, Chlorophyceae and Conjugatophyceae showed phosphatase activity mainly in summer and at the beginning of autumn, while one species of Chrysophyceae (Synura petersenii) and three diatoms (Aulacoseira italica, Cyclotella spp., and Stephanodiscus hantzschii) produced phosphatases in spring. Several green algae (Ankyra ancora, Ankyra judayi, Coelastrum pseudomicroporum, Eudorina elegans, and Pediastrum spp.) were ELFA-labelled whenever present in the phytoplankton. Some species produced the ectoenzyme only in one season, such as Aphanizomenon flos-aquae (Cyanobacteria), Elakatothrix genevensis (Chlorophyceae), or Cryptomonas spp. On the other hand, one third of the 56 species studied never expressed any ELFA labelling. Large variability of phosphatase production was found not only among different algal species, but also within the population of one species. Not all cells of the population were equally ELFA-labelled and also the level of ELFA fluorescence was different. In particular cases, ELFA labelling on algal cells could be produced by bacterial rather than algal ectoenzymes. In comparison to standard methods, the ELF method provided more specific information about the variability of phosphatase activity (i.e. phosphorus stress) within the whole phytoplankton community as well as within one species populations.

Rengefors K, Ruttenberg KC, Haupert CL, et al.

Experimental investigation of taxon-specific response of alkaline phosphatase activity in natural freshwater phytoplankton
LIMNOL OCEANOGR 48 (3): 1167-1175 MAY 2003

Abstract:
It is widely accepted that alkaline phosphatase activity (APA) is an efficient indicator of phosphate limitation in freshwater phytoplankton communities. In this study, we investigated whether the response in APA to phosphate limitation differs among the taxa in a mixed phytoplankton assemblage. We used the new enzyme-labeled fluorescence (ELF) technique, which allows microscopic detection of phosphate limitation in individual cells of multiple species. The most prominent findings of this study were that alkaline phosphatase (AP) was induced in many, but not all taxa and that different taxa, as well as different cells within a single taxon, experienced different degrees of phosphate stress under the same environmental conditions. Our approach was to manipulate the limiting nutrient in a natural freshwater phytoplankton community by incubating lake water in the laboratory. We induced nitrogen (N) or phosphate limitation through additions of inorganic nutrients. Both the ELF assay and bulk APA indicated that the lake phytoplankton were not phosphate limited at the start of the experiment. During the experiment, several chlorophyte taxa (e.g., Eudorina and an unidentified solitary spiny coccoid) were driven to phosphate limitation when inorganic N was added, as evidenced by a higher percentage of ELF-labeled cells relative to controls, whereas other chlorophyte taxa such as Actinastrum and Dicryosphaerium were not phosphate stressed under these conditions. In the phosphate-limited treatments, little or no ELF labeling was observed in any cyanobacterial taxa. Furthermore, all taxa observed after the ELF labeling procedure (>10-mum fraction) were labeled with ELF at least on one occasion, demonstrating the wide applicability of the ELF method. By using ELF labeling in tandem with bulk APA, the resolution and analysis of phosphate limitation was increased, allowing the identification of specific phosphate-stressed taxa.

2002

Coleman AW

Comparison of Eudorina/Pleodorina ITS sequences of isolates from nature with those from experimental hybrids
AM J BOT 89 (9): 1523-1530 SEP 2002

Abstract:
Internal transcribed spacer (ITS) regions of nuclear ribosomal repeats were compared among 50 Eudorina and Pleodorina isolates and two Volvox species known to clade with Eudorina species. Of the six major subclades found, four containing Eudorina and Pleodorina illinoisensis isolates, one containing Eudorina and Pleodorina indica, and one containing Volvox gigas and V. powersii, the basal branching order remains uncertain, but the positioning of isolates known to mate was always as nearest neighbors on the terminal branches of the tree. Four hybrid clones from a cross of E. elegans with P. illinoisensis, known from chromosome counts to be products of the failure of meiosis at zygote germination, contain both parental ITS repeat regions, as expected. However, they have in addition both crossover and other variant ITS cistrons among their many repeats of ITS. Such variation is limited to terminal regions of helices, as recognized from knowledge of RNA transcript secondary structure. Proper alignment then utilizes all of the nucleotide positions; the hybrid variants appear in positions intermediate between their parents in the tree. In fact, such variants seem to be hallmarks of recent hybridization events, since they were not found in any of the other 50 isolates.

Tien CJ, Krivtsov V, Levado E, et al.

Occurrence of cell-associated mucilage and soluble extracellular polysaccharides in Rostherne Mere and their possible significance
HYDROBIOLOGIA 485 (1-3): 245-252 OCT 2002

Abstract:
The cell-associated mucilage and soluble extracellular polysaccharides (EPS) were investigated in a eutrophic freshwater lake (Rostherne Mere, Cheshire, U. K.) over up to 2 year annual cycles. Five particular lake algae (Anabaena spiroides Klebahn, Anabaena flos-aquae Brebisson ex Bornet & Flahault, Anabaena circinalis Rabenhorst, Microcystis aeruginosa Kutzing emend. Elenkin and Eudorina elegans Ehrenberg) were found to be the major contributors to cell-associated mucilage, particularly M. aeruginosa. Calculation of the total amount of cell-associated mucilage in the phytoplankton samples showed that it occupied 0.0001-0.007% (the latter during a bloom of Microcystis) of lake water volume within the epilimnion. Seasonal changes in the total volume of associated mucilage reflected the succession of mucilage-producing algal species in Rostherne Mere, which was closely correlated with the physico-chemical (temperature, oxygen, pH, nutrients) and biological (Secchi depth, phytoplankton) parameters within the lake. High levels of cell-associated mucilage present in the lake may have potential for binding metals or other ions in the aquatic environment. Colourimetric determination of the concentration of soluble EPS revealed concentrations of between 2.5 and 60 mg l(-1), with peak levels during the bacillariophyceaen bloom and late clear water phase. The second phase did not appear to relate directly to changes in algal population, and may result from bacterial activity, algal lysis or zooplankton activity. As soluble EPS forms a major component of the total amount of dissolved carbon in lakes, the study of the soluble EPS is important to understand the carbon cycle in freshwaters. No direct correlation occurred between algal-associated mucilage and soluble EPS over a single annual cycle.

Tien CJ

Biosorption of metal ions by freshwater algae with different surface characteristics
PROCESS BIOCHEM 38 (4): 605-613 DEC 2 2002

Abstract:
Four freshwater algae with different cell surface characteristic, Oscillatoria limnetica, Anabaena spiroides, Eudorina elegans and Chlorella vulgaris, were chosen to examine their copper(II), cadmium(II) and lead(II) (copper, cadmium, and lead cations with a charge of 2+) sorption activity using the Freundlich model, in terms of the surface area/dry weight ratios, and the presence of other metal ions. Experimental data obeyed the Freundlich model, indicating multiple functional binding sites on algal surfaces. All four algae showed the highest sorption capacity for Pb among three metals. Their sorption activity varied with initial metal concentrations. The surface area/dry weight ratio was demonstrated to be a major parameter determining the sorption activities and mechanisms of algae. However, no apparent relationship occurred between metal-binding ability and, the presence and amount of mucilage. Competition of metal ions on algal surface binding sites was found differed with algal species and metal ions. The high and significantly different sorption activities for three metals by four algae suggested the suitability and good selectivity for treatment of different kinds of industrial effluents. (C) 2002 Elsevier Science Ltd. All rights reserved.

2001

Richardot M, Debroas D, Thouvenot A, et al.

Influence of cladoceran grazing activity on dissolved organic matter, enzymatic hydrolysis and bacterial growth
J PLANKTON RES 23 (11): 1249-1261 NOV 2001

Abstract:
To assess the influence of grazing by cladocerans on dissolved organic matter (DOM), glycolytic and proteolytic activities and bacterial growth were measured by in situ incubation of lake water from the epilimnion of an oligotrophic reservoir in three different treatments: in absence of zooplankton, and in presence of zooplankton (natural abundance and concentrated four-fold). These experiments were conducted at two periods in the succession of plankton populations (May and June 1998), that differed in the quality of the prey ingested (Eudorina sp. compared to Cryptomonas sp. and Rhodomonas sp.) and their grazing intensity (31.8 +/- 2.2 mug C l(-1) day(-1) compared to 10.2 +/- 0.5 mug C l(-1) day(-1)). A systematic increase in bacterial biomass was measured in the treatments containing the highest zooplankton concentrations. The DOM concentrations produced in situ showed few significant differences between the three treatments, but the assimilation of DOM was higher in the presence of zooplankton than in their absence. These results show that the influence of cladocerans on the DOM was more of a qualitative than a quantitative nature. The protein compounds derived from the grazing activities of metazoans seem to be a major nutrient source for growth for bacteria (r = 0.81, P < 0.05). In this study, the highest hydrolytic activities were recorded in the presence of high concentrations of metazoan zooplankton. However, the processes that regulated these activities differed between the two experimental dates (repression compared to enzyme stimulation). Grazing activities could lead to an increase in phytoplanktonic excretion during the growth phase, and therefore the production of low molecular weight compounds that are easily assimilated by the bacterial plankton.

Coleman AW

Biogeography and speciation in the Pandorina/Volvulina (Chlorophyta) superclade
J PHYCOL 37 (5): 836-851 OCT 2001

Abstract:
Mating affinity, nuclear rDNA internal transcribed spacer (ITS) sequence, and geographic distribution of more than 100 isolates of Pandorina,Volvulina, and Yamagishiella were determined. Comparative analysis of ITS sequences reaffirmed the unity of Pandorina morum and its separation from all other species of Volvocaceae except those of Volvulina. This latter genus, represented by four species, appears to represent only morphological variants of several P. morum subclades. The P. morum clade (including also additional species such as P. smithii and P. colemaniae) encompasses an evolutionary span, as determined by comparison of ITS, greater than either of the multispecies genera Gonium or Eudorina. There are at least 30 Pandorina/Volvulina syngens, sexually isolated groups, so far as can be determined, among the current collection of strains. In addition, as in other volvocacaean genera, two clones are homothallic, capable of forming zygotes within a genetic clone. The existence of so many syngens suggests that considerable evolutionary diversification of the genes controlling gamete compatibility and intercross survival has occurred, unaccompanied by significant morphological change. Within each syngen, genetic distance increases with geographic distance between collection sites. At least half of the isolates studied must have been introduced northward since the Pleistocene. Although we probably know more about characters in this group of algae than any other algal group, in part because they are so easy to culture, we are still largely ignorant of what circumscribes their niche in nature. The study of all these organisms, distributed throughout the world presumably by the activities of shorebirds, emphasizes the evolutionary role of mating genes in the inevitable formation of new genetically isolated subclades in these eukaryotes and provides initial data on their rate of appearance versus their rate of distribution over the earth.

Nozaki H, Krienitz L

Morphology and phylogeny of Eudorina minodii (Chodat) Nozaki et Krienitz, comb. nov (Volvocales, Chlorophyta) from Germany
EUR J PHYCOL 36 (1): 23-28 FEB 2001

Abstract:
Morphology, sexual reproduction and phylogeny of a colonial green alga collected from Germany were studied in culture. Light and electron microscopy of the gelatinous (extracellular) matrix of vegetative colonies, the absence of obligately somatic cells, and the anisogamous sexual reproduction with sperm packets in this alga indicated that if: is assignable to the genus Eudorina. This German alga was similar to E. elegans Ehrenberg in its multiple pyrenoids of nearly identical size and almost identical sized vegetative cells in the colony, but differed from it in having a prominent tubular structure (flagellar sheath) surrounding each flagellum in the gelatinous matrix of the vegetative colonies. Sexual reproduction was homothallic and dioecious. On the other hand, the vegetative morphology agreed well with that of Pandorina minodii Chodat with regard to multiple pyrenoids and the prominent flagellar sheaths. Thus, a new combination, Eudorina minodii (Chodat) Nozaki et Krienitz, is proposed. Molecular phylogenetic analyses of the rbcL-atpB gene sequences from the colonial Volvocales reserved that E. minodii and several heterothallic strains of E, elegans constituted a robust clade. Therefore, prominent flagellar sheaths and homothallic sexual reproduction in E. minodii may be derived characters that evolved recently within the clade.

2000

Fabbro LD, Duivenvoorden LJ

A two-part model linking multidimensional environmental gradients and seasonal succession of phytoplankton assemblages
HYDROBIOLOGIA 438 (1-3): 13-24 NOV 2000

Abstract:
Algal assemblages and their respective niches are analysed for a large riverine impoundment in semi-arid Australia. The extreme variability of the flow regime and the extensive period of low or no flow produced conditions including prolonged stratification akin to those of a lake during the dry season. Hierarchical agglomerative clustering of phytoplankton data and comparison with a principal component analysis of corresponding environmental data are used to demonstrate the linkage between steep environmental gradients and variations in the phytoplankton assemblages. The factor score plots separate the algal assemblages according to key environmental parameters including increasing clarity of the water column, temperature and modification of water chemistry. Assemblages normally contained cyanoprokaryotes (Oscillatoriales), euglenophytes or non-flagellated chlorophytes during flows followed by flagellated chlorophytes and cyanoprokaryotes (Nostocales) during the dry season. Species present during the period of reduced flow occupied conditions similar to those presented in the literature for temperate and/or tropical lakes. Common species included Pandorina morum, Eudorina elegans, Anabaena circinalis, Aphanizomenon issatschenkoi, Aphanizomenon aphanizomenioides and Cylindrospermopsis raciborskii. A two-part model is proposed which predicts the most likely genera of phytoplankton with respect to multidimensional environmental gradients.

Nozaki H, Misawa K, Kajita T, et al.

Origin and evolution of the colonial Volvocales (Chlorophyceae) as inferred from multiple, chloroplast gene sequences
MOL PHYLOGENET EVOL 17 (2): 256-268 NOV 2000

Abstract:
A combined data set of DNA sequences (6021 bp) from five protein-coding genes of the chloroplast genome (rbcL, atpB, psaA, psaB, and psbC genes) were analyzed for 42 strains representing 30 species of the colonial Volvocales (Volvox and its relatives) and 5 related species of green algae to deduce robust phylogenetic relationships within the colonial green flagellates. The 4-celled family Tetrabaenaceae was robustly resolved as the most basal group within the colonial Volvocales. The sequence data also suggested that all five volvocacean genera with 32 or more cells in a vegetative colony (all four of the anisogamous/oogamous genera, Eudorina, Platydorina, Pleodorina, and Volvox, plus the isogamous genus Yamagishiella) constituted a large monophyletic group, in which 2 Pleodorina species were positioned distally to 3 species of Volvox. Therefore, most of the evolution of the colonial Volvocales appears to constitute a gradual progression in colonial complexity and in types of sexual reproduction, as in the traditional volvocine lineage hypothesis, although reverse evolution must be considered for the origin of certain species of Pleodorina. Data presented here also provide robust support for a monophyletic family Goniaceae consisting of two genera: Gonium and Astrephomene. (C) 2000 Academic Press.

1999

Coleman AW

Phylogenetic analysis of "Volvocacae" for comparative genetic studies
P NATL ACAD SCI USA 96 (24): 13892-13897 NOV 23 1999

Abstract:
Sequence analysis based on multiple isolates representing essentially all genera and species of the classic family Volvocaeae has clarified their phylogenetic relationships. Cloned internal transcribed spacer sequences (ITS-1. and ITS-2, flanking the 5.8S gene of the nuclear ribosomal gene cistrons) were aligned, guided by ITS transcript secondary structural features, and subjected to parsimony and neighbor joining distance analysis. Results confirm the notion of a single common ancestor, and Chlamydomonas reinharditii alone among all sequenced green unicells is most similar. interbreeding isolates were nearest neighbors on the evolutionary tree in all cases. Some taxa, at whatever level, prove to be clades by sequence comparisons, but others provide striking exceptions. The morphological species Pandorina morum, known to be widespread and diverse in mating pairs, was found to encompass all of the isolates of the four species of Volvulina. Platydorina appears to have originated early and not to fall within the genus Eudorina, with which it can sometimes be confused by morphology. The four species of Pleodorina appear variously associated with Eudorina examples. Although the species of Volvox are each clades, the genus Volvox is not The conclusions confirm and extend prior, more limited, studies on nuclear SSU and LSU rDNA genes and plastid-encoded rbcL and atpB. The phylogenetic tree suggests which classical taxonomic characters are most misleading and provides a framework for molecular studies of the cell cycle-related and other alterations that have engendered diversity in both vegetative and sexual colony patterns in this classical family.

Angeler DG, Schagerl M, Coleman AW

Phylogenetic relationships among isolates of Eudorina species (Volvocales, Chlorophyta) inferred from molecular and biochemical data
J PHYCOL 35 (4): 815-823 AUG 1999

Abstract:
Phylogenetic analyses of 19 strains representing five species of Eudorina, one strain of Pleodorina indica, and seven strains of Yamagishiella unicocca were carried out by sequencing the internal transcribed spacer region (ITS 1 and ITS 2) of the nuclear ribosomal DNA (rDNA) repeats. The sequence data resolved five phylogenetic groups, one consisting of Y. unicocca and the other four encompassing all the Eudorina species. Two isolates, Eudorina sp, (ASW 05157) and Pleodorina indica (ASW 05153), were of uncertain affiliation, Whereas one monophyletic group included strains of E. elegans only, the other strains of E. elegans appeared alongside E. cylindrica, E. illinoisensis, and E. unicocca var. unicocca in the other Eudorina clades. The distribution pattern of the carotenoid loroxanthin ([3R,3'R,6'R]beta,epsilon-carotene-3,19,3'-triol), a systematically useful biochemical marker within chlorophycean flagellates, was shown to match the evaluated molecular data. Whereas it was either totally absent or universally present in six of the deduced phylogenetic lines, it occurred randomly in the E. elegans clade containing only E, elegans isolates. The results substantiated the current hypothesis that the unique vegetative morphology of E. elegans has independently arisen at various times during evolution and that it is not a marker of a monophyletic group.

Nozaki H, Ohta N, Takano H, et al.

Reexamination of phylogenetic relationships within the colonial Volvocales (Chlorophyta): An analysis of atpB and rbcL gene sequences
J PHYCOL 35 (1): 104-112 FEB 1999

Abstract:
The chloroplast-encoded atpB gene was sequenced from 33 strains representing 28 species of the colonial Volvocales (the Volvocaceae and its relatives) to reexamine phylogenetic relationships as previously deduced by morphological data and rbcL gene sequence data.1128 base pairs in the coding regions of the atpB gene were analyzed by MP, NJ, and ML analyses, Although supported with relatively low bootstrap values (75% and 65% in the NJ and ML analyses, respectively), three anisogamous/oogamous volvocacean genera-Eudorina, Pleodorina, and Volvox, excluding the section Volvox(= Euvolvox, illegitimate name), constituted a large monophyletic group (Eudorina group), Outside the Eudorina group, a robust Lineage composed of three species of Volvox sect, Volvox was resolved as in the rbcL gene trees, rejecting the hypothesis of the previous cladistic analysis based on morphological data that the genus Volvox is monophyletic, In addition, the NJ and ML trees suggested that Eudorina is a non-monophyletic genus as inferred from the morphological data and rbcL gene sequences. Although phylogenetic status of the genus Gonium is ambiguous in the rbcL gene trees and the paraphyly of this genus is resolved in the cladistic analysis based on morphological data, the atpB gene sequence data suggest monophyly of Gonium with relatively low bootstrap values (56-61%) in the NJ and ML trees. On the basis of the combined sequence data (2256 base pairs) from atpB and rbcL genes, Gonium was resolved as a robust monophyletic genus in the NJ and ML trees (with 68-86% bootstrap values), and Eudorina elegans Ehrenberg represented a paraphyletic species positioned most basally within the Eudorina group, However, phylogenetic status and relationships of the families of the colonial Volvocales were still almost ambiguous even in the combined analysis.

1998

Angeler DG

Life-cycle studies and culture experiments for identification of doubtful volvocacean organisms - observations on Pandorina and Eudorina
HYDROBIOLOGIA 370: 269-275 1998

Abstract:
Traditionally, the volvocacean genera Pandorina and Eudorina are distinguished by vegetative morphology: Eudorina has hollow coenobia with loosely arranged spherical to ovoid cells, whereas Pandorina coenobia are compact with pear- to keystoneshaped cells contiguous in the centre. However, sometimes intermediate forms are found which cannot be identified to genus by traditional morphological characters. Especially the degree of compactness of Pandorina coenobia may be highly variable. Such abberant forms must be taken into culture in order to establish their identity, by studying (1) their lift: cycles, both sexual and asexual processes, and (2) the influence of varied culture conditions (temperature, daylenght, nutrients) on their morphology. In these ways, the taxonomic position may be clarified.

Cvijan M, Lausevic R

The significance of green algae in Vlasinsko Jezero reservoir phytoplankton (Serbia)
BIOLOGIA 53 (4): 519-527 AUG 1998

Abstract:
The paper highlights the importance of green algae in phytoplankton community formation and primary production of the dimictic, mesotrophic Vlasinsko Jezero reservoir. Green algae from plankton samples are presented by 87 taxa, with predominance of desmids. The highest floristical diversity has been established in the shallow bays and between aquatic macrophytes, especially in the southern part of the reservoir at the edge of peat bog. In the terms of biomass, green algae play the most important role in building up phytoplankton community. Chlorophyll-a maxima corresponded with the development of Chlorophyta populations composed mainly of Planktosphaeria sp., Eudorina elegans and Pandorina morum.

Ott I, Laugaste R

Organic matter and the composition of Volvocales and Chlorococcales in Estonian small lakes
BIOLOGIA 53 (4): 529-535 AUG 1998

Abstract:
The limnological data gathered mainly between 1951 and 1995 were summarized from the point of view of relationships between organic substances and chlorococcalean and volvocalean species in summer. During the last forty years the role of Chlorococcales (including the biomass values) rose in all lake groups as well as the content of organic compounds. Chlorococcales and Volvocales are especially important (abundance and number of species) in the investigated lakes where the amount of easily degradable allochthonous organic compounds has risen. Simple correlations between the different characteristics of organic compounds, biomass, and the number of species are generally weak. Correlations are stronger with BOD values. Heavy allochthonous organic load from different sources may cause water bloom by Chlorococcales and Volvocales. The highest Values were recorded from Lake Harku in Tallinn because of sewage water from the city (biomass 46.1 g/m(3), Scenedesmus quadricauda (TURPIN) BREB. sensu CHODAT, Pediastrum boryanum (TURPIN) MENEGHINI; Partsi Kortsijarv (dairy industry, 32.1 g/m(3), Tetraedron minimum (A. BRAUN) HANSG., Scenedesmus quadricauda); Kooraste Linajarv (flax retting, 15 g/m(3), Dictyosphaerium pulchellum Wood); L. Ruusmae (manure, 14.5 g/m(3), Coelastrum microporum NAGELI and Eudorina elegans EHRENB.). The most common alga in the lakes with a high content of easily degradable organic matter is Phacotus coccifer KORSHIKOV. In some cases, allochthonous DOM could be the factor that control the development of phytoplankton. During the last four decades the number of species and abundance of Volvocales and Chlorococcales has increased, and lakes have become more similar to ponds and sewage treatment pools.

Schagerl M, Angeler DG

The distribution of the xanthophyll loroxanthin and its systematic significance in the colonial Volvocales (Chlorophyta)
PHYCOLOGIA 37 (2): 79-83 MAR 1998

Abstract:
The distribution of the xanthophyll loroxanthin [(3R,3'R,6'R)- beta,epsilon-carotene-3,19,3'-triol] within colonial volvocalean families was analyzed by reversed-phase high pressure Liquid chromatography (rP-HPLC). The results demonstrate that loroxanthin is a physiological marker delineating the families Tetrabaenaceae Nozaki et Itoh and Goniaceae (Pascher) Pascher. Thus loroxanthin may be considered to be of systematic significance within the Volvocales, and its use as a marker supports recent ideas on phylogenetic relationships. Within the Volvocaceae Ehrenberg, its infraspecific disjunct distribution indicates that it is not useful systematically in this family and that it varies even within a morphologically defined species. The pattern of loroxanthin distribution was compared with molecular data and traditional characters.

1997

Nozaki H, Ito M, Uchida H, et al.

Phylogenetic analysis of Eudorina species (Valvocaceae, Chlorophyta) based on rbcL gene sequences
J PHYCOL 33 (5): 859-863 OCT 1997

Abstract:
Species and varieties in the genus Eudorina Ehrenberg (Volvocaceae, Chlorophyta) were evaluated on the basis of phylogenetic analyses of the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (rbcL) gene sequence from 14 strains of four Eudorina species, as well as from nine species of Pleodorina and Volvox. The sequence data suggested that 10 of the 14 Eudorina strains form three separate and robust monophyletic groups within the nonmonophyletic genus Eudorina. The first group comprises ail three strains off. unicocca G. M. Smith; the second group consists of one of the E, elegans Ehrenberg var elegans strains, the E. cylindrica Korshikov strain, and both E. illinoisensis (Kofoid) Pascher strains; and the third group consists of two monoecious varieties off, elegans [two strains of E. elegans var synoica Goldstein and one strain of E. elegans var. carteri (G. hi. Smith) Goldstein]. In addition, E. illinoisensis represents a poly- or paraphyletic species within the second group. The remaining four strains, all of which are assigned to E. elegans var. elegans, are nonmonophyletic. Although their position in the phylogenetic trees is more or less ambiguous, they are ancestral to other taxa ill the large anisogamous/oogamous monophyletic group including Eudorina, Pleodorina, and Volvox (except for sect. Volvox). Thus, the four Eudorina groups resolved in the present molecular phylogeny do not correspond with the species concepts of Eudorina based on vegetative morphology, but they do reflect the results Of the previous intercrossing experiments and modes of monoecious and dioecious sexual reproduction.

Angeler DG, Schagerl M

Distribution of the xanthophyll loroxanthin in selected members of the Chlamydomonadales and Volvocales (Chlorophyta)
PHYTON-ANN REI BOT A 37 (1): 119-132 1997

Abstract:
The distribution of the xanthophyll loroxanthin in selected members of the chlorophycean flagellate orders Chlamydomonadales and Volvocales (Chlamydophyceae) was established by rp-HPLC. The newly found facts of our study are: (1) the absence of loroxanthin in the Tetrabaenaceae and (2) the presence of loroxanthin in members of the Volvocaceae: Pandorina morum and Eudorina elegans exhibit an intraspecific disjunct occurence of this pigment. This is in contrast to previous studies where loroxanthin was found to be absent within this family. The consequences of our data on the recently proposed usefulness as phylogenetical marker within chlorophycean flagellates are discussed.

Nozaki H, Ito M, Sano R, et al.

Phylogenetic analysis of Yamagishiella and Platydorina (Volvocaceae, Chlorophyta) based on rbcL gene sequences
J PHYCOL 33 (2): 272-278 APR 1997

Abstract:
Yamagishiella, based on Pandorina unicocca Rayburn et Starr is distinguished from Eudorina by its isogamous sexual reproduction, whereas Platydorina exhibits anisogamous sexual reproduction. In the present study, rue sequenced the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (rbcL) genes from five Japanese and North American strains of Y. unicocca (Rayburn et Stair) Nozaki, true Platydorina caudata Kofoid strains, and two strains of Eudorina unicocca G. M. Smith, as well as eight related colonial and unicellular species. Phylogenetic trees were constructed based on these sequence data and on previously published rbcL gene sequences from 23 volvocalean species in order to deduce phylogenetic relationships within the colonial Volvocales, with particular regard to the phylogenetic positions and status of the genera Yamagishiella and Platydorina. Two robust monophyletic groups of the anisogamous/oogamous volvocacean species were resolved in the maximum-parsimony tree as well as in the neighbor-joining distance tree. One of the two groups comprises three species of Volvox section Volvox, whereas the other is composed of other sections of Volvox as well as of all the species of Eudorina and Pleodorina. Platydorina, however, was positioned outside these two monophyletic groups. Therefore, derivation of the Platydorina lineage may be earlier than that of such anisogamous/oogamous groups, or origin of ''anisogamy with sperm, packets'' in Platydorina may De independent of sperm packet evolution in Eudorina, Pleodorina, and Volvox. It was also resolved with high bootstrap values that all of the Y. unicocca strains form a monophyletic group positioned outside the large monophyletic group including Eudorina and Pleodorina. These reject the possibility of the reverse evolution of isogamy from anisogamy to give rise to Yamagishiella within the lineage of Eudorina.

Liss M, Kirk DL, Beyser K, et al.

Intron sequences provide a tool for high-resolution phylogenetic analysis of volvocine algae
CURR GENET 31 (3): 214-227 MAR 1997

Abstract:
Three nuclear spliceosomal introns in conserved locations were amplified and sequenced from 28 strains representing 14 species and 4 genera of volvocalean green algae. Data derived from the three different introns yielded congruent results in nearly all cases. In pairwise comparisons, a spectrum of taxon-specific sequence differences ranging from complete identity to no significant similarity was observed, with the most distantly related organisms lacking any conserved elements apart from exon-intron boundaries and a pyrimidine-rich stretch near the 3' splice site. A metric (SI50), providing a measure of the degree of similarity of any pair of intron sequences, was defined and used to calculate phylogenetic distances between organisms whose introns displayed statistically significant similarities. The rate of sequences divergence in the introns was great enough to provide useful information about relationships among different geographical isolates of a single species, but in most cases was too great to provide reliable guides to relationships above the species level. A substitution rate of approximately 3 x 10(-8) per intron position per year was estimated, which is about 150-fold higher than in nuclear genes encoding rRNA and about 10-fold higher than the synonymous substitution rate in protein-coding regions. Thus, these homologous introns not only provide useful information about intraspecific phylogenetic relationships, but also illustrate the concept that different parts of a gene may be subject to extremely different intensities of selection. The intron data generated here (1) reliably resolve for the first;time the relationships among the five most extensively studied strains of Volvox, (2) reveal that two other Volvox species may be more closely related than had previously been suspected, (3) confirm prior evidence that particular isolates of Eudorina elegans and Pleodorina illinoisensis appear to be sibling taxa, and (4) contribute to the resolution of several hitherto unsettled issues in Chlamydomonas taxonomy.

1996

Nozaki H

Morphology and evolution of sexual reproduction in the Volvocaceae (Chlorophyta)
J PLANT RES 109 (1095): 353-361 SEP 1996

Abstract:
Morphological features of sexual reproduction in the Volvocaceae are reviewed, focusing particularly on gametic union and zygote germination. Both of the two conjugating gametes of the isogamous genera Pandorina, Volvulina and Yamagishiella bear a tubular mating structure (mating papilla), and plasmogamy is initiated by union of the papillae tips. On zygote germination, a single biflagellate gone cell is released from the zygote

wall. Although all the anisogamous and oogamous genera of the Volvocaceae produce ''sperm packets'' during gametogenesis and a single gone cell at zygote germination, some difference can be recognized in the male gametes. The male gametes of Eudorina bear a tubular cytoplasmic protuberance (putative mating papilla) near the base of the flagella, whereas such a structure recognized at the light microscopic level is not evident in Pleodorina and Volvox, Evolution of the sexual reproduction characteristics of volvocacean algae is discussed on the basis of recent cladistic analysis of morphological data as well as of the ribosomal (r) RNA phylogeny and large subunit of the ribulose-1,5-biphosphate carboxylase/oxygenase(rbcL) gene trees.

Holomuzki JR, Hemphill N

Snail-tadpole interactions in streamside pools
AM MIDL NAT 136 (2): 315-327 OCT 1996

Abstract:
We studied competitive interactions and grazing effects of the snail Physella integra and the American toad Bufo americanus in ephemeral streamside pools in W-central Kentucky. Snails and tadpoles reared alone and combined at ambient densities in artificial pools revealed that costs of coexisting differed between taxa. Snails invested resources into growth and survival at the expense of reproduction when with anuran competitors, whereas tadpoles exhibited slowed development and decreased biomass per pool in combined-species treatments. These negative effects were likely a result of food limitation, considering that herbivory by both taxa significantly reduced algal abundance relative to ungrazed controls. Herbivory by both species also affected the assemblage of benthic algae. Diatoms, particularly Nitzschia spp. were the predominant algae in both single-species treatments, whereas the green algae Eudorina and Oedogonium comprised most of the community biovolume in combined-species treatments. The filamentous green algae Cladophora was dominant in ungrazed controls.

A survey of 16 isolated pools along three third-ol der streams revealed patterns of snail egg production and benthic algal assemblage similar to treatment effects in the artificial pool experiment. The survey also indicated that snails and tadpoles seldom co-occur in these pools; thus competition between them may be infrequent. Linkages between phosphate availability predation and habitat persistence seem particularly important in mediating competitive interactions between these taxa.

1995

Nozaki H, Itoh M, Sano R, et al.

Phylogenetic relationships within the colonial volvocales (Chlorophyta) inferred from rbcL gene sequence data
J PHYCOL 31 (6): 970-979 DEC 1995

Abstract:
The chloroplast-encoded large subunit of the ribulose-1, 5-bisphosphate carboxylase/oxygenase (rbcL) gene was sequenced from 20 species of the colonial Volvocales (the Volvacaceae, Goniaceae, and Tetrabaenaceae) in order to elucidate phylogenetic relationships within the colonial Volvocales. Eleven hundred twenty-eight base pairs In the coding regions of the (rbcL) gene were analyzed by the neighbor-joining (NJ) method using three kinds of distance estimations, as well as by the maximum parsimony (MP) method. A large group comprising all the anisogamous and oogamous volvocacean species was resolved in the MP tree as well as in the NJ trees based on overall and synonymous substitutions. In all the trees constructed, Basichlamys and Tetrabaena (Tetrabaenaceae) constituted a very robust phylogenetic group. Although not supported by high bootstrap values, the MP tree and the NJ tree based on nonsynonymous substitutions indicated that the Tetrabaenaceae is the sister group to the large group comprising the Volvocaceae and the Goniaceae. In addition, the present analysis strongly suggested that Pandorina and Astrephomene are monophyletic genera whereas Eudorina is nonmonophyletic. These results are essentially consistent with the results of the recent cladistic analyses of morphological data. However, the monophyly of the Volvocaceae previously supported by four morphological synapomorphies is found only in the NJ tree based on nonsynonymous substitutions (with very low bootstrap values). The genus Volvox was clearly resolved as a polyphyletic group with V. rousseletii Pocock separated from other species of volvox in the rbcL gene comparisons, although this genus represents a monophyletic group in the previous morphological analyses. Furthermore, none of the rbcL gene trees supported the monophyly of the Goniaceae; Astrephomene was placed in various phylogenetic positions.

DEMOTT WR

THE INFLUENCE OF PREY HARDNESS ON DAPHNIAS SELECTIVITY FOR LARGE PREY
HYDROBIOLOGIA 307 (1-3): 127-138 JUL 7 1995

Abstract:
Two comparable methods were used to study the feeding of four species of Daphnia on large spherical particles which differed in size and hardness. The first method used gut analysis to estimate the selectivities of daphnids feeding in a broad size range of a single particle type, including polystyrene beads (4-60 mu m diameter) in the laboratory and Eudorina colonies (10-90 mu m) in the field. In the second method, Daphnia of different sizes fed in a mixture of 6.5 mu m Chlamydomonas and one of eight test particles. Smaller daphnids were less effective in feeding on large test particles. Nonlinear regression was therefore used to estimate the Daphnia body size at which the clearance rate on a test particle was reduced to 50% of that for Chlamydomonas. The results of both methods show that prey size and hardness are both very important in determining daphnid feeding selectivity. For a given particle size, 'soft' algae(naked and gelatinous flagellates) are more readily ingested than 'hard' algae (diatoms and dinoflagellates), and 'hard' algae are more readily ingested than polystyrene beads. Daphnia can feed effectively on algae that are 2-5 times larger than the largest ingestible bead.

DALDORPH PWG, THOMAS JD

FACTORS INFLUENCING THE STABILITY OF NUTRIENT-ENRICHED FRESH-WATER MACROPHYTE COMMUNITIES - THE ROLE OF STICKLEBACKS PUNGITIUS-PUNGITIUS AND FRESH-WATER SNAILS
FRESHWATER BIOL 33 (2): 271-289 APR 1995

Abstract:
1. Enclosures, with the following characteristics, were used to investigate the effects of increased nutrient (nitrate and phosphate) loading on freshwater communities: (a) controls with normal densities of invertebrates, and including macrophytes, molluscs and fish (sticklebacks), and communities similar to the controls but with (b) much reduced snail densities and (c) increased fish densities.

2. The addition of nutrients resulted in increases in the biomass of phytoplankton and epiphyton, as well as zooplankton counts, in all the experimental enclosures.

3. A reduction in the snail population density resulted in a significant decrease in phytoplankton density and an increase, compared to controls, in the density of epiphytic algae growing on the leaves of the submerged macrophytes, Potamogeton crispus and Groenlandia densa. It also resulted in a significant increase (3.5 times that in the controls) in chlorophyll-a values of epilithic algae growing on glass slides, an increase in senescent tissue in macrophytes and a decline in the mass of Groenlandia densa by the end of the experiment

4. An increase in the fish population resulted in a significant decline, compared to the controls, in the densities of zooplankton (including Chydorus sphaericus and copepods), Lymnaea peregra (from May to mid-June), Asellus meridianus, Crangonyx pseudogracilis, Culex (P.) molestus and Physa fontinalis. It also resulted in a change in the composition of the phytoplankton, with an increase in the large colonial Eudorina elegans and a decline in smaller planktonic algae, including Ankistrodesmus and Cryptomonas spp.

5. The possible mechanisms responsible for the effects are evaluated and their relevance to conservation and management of freshwater macrophyte communities are discussed.

1994

OFARRELL I

COMPARATIVE-ANALYSIS OF THE PHYTOPLANKTON OF 15 LOWLAND FLUVIAL SYSTEMS OF THE RIVER PLATE BASIN (ARGENTINA)
HYDROBIOLOGIA 289 (1-3): 109-117 SEP 9 1994

Abstract:
The phytoplankton of fifteen lowland courses of the River Plate Basin is compared and characterized by means of multivariate analyses.

The cluster analysis performed with the more abundant species of each fluvial system reveals three main groups. Rivers with a high discharge and a large floodplain are grouped on the basis of the dominance of several Aulacoseira species. An eutrophic flora typified by Cyclotella meneghiniana, Synedra ulna and several green algae occurs in the smaller rivers with high conductivity, low transparency and important discharge variations. A third group comprises the Uruguay River and its tributaries, characterized by the presence of several pennatae diatoms and flagellates: Amphipleura pellucida, Surirella tenera, Terpsinoe musica, Navicula cuspidata, Eudorina elegans, Pandorina morum and Peridinium gatunense.

The Principal Component Analysis based on a data matrix of physical, chemical and hydrological parameters revealed similar results. The ordination according to the first two components reflects the geographic location of these systems in the River Plate Basin, responding to a decreasing gradient of conductivity, pH and solids and an increasing minimum temperature. The rivers were ordinated by means of a Correspondence Analysis based on the main algal groups.

BARONE R, FLORES LN

PHYTOPLANKTON DYNAMICS IN A SHALLOW, HYPERTROPHIC RESERVOIR (LAKE ARANCIO, SICILY)
HYDROBIOLOGIA 289 (1-3): 199-214 SEP 9 1994

Abstract:
Phytoplankton abundance and composition in the hypertrophic man-made Lake Arancio was analyzed, based on a programme of weekly sampling from May 1990 to November 1991 and supported by measurements of limnological parameters. The highest value of phytoplankton biomass (78 mg l(-1)) was observed in October 1990, during a bloom of the desmid Closterium limneticum var. fallax, while the lowest (0.15 mg l(-1)) was measured in April 1991. During spring, autumn and winter 1990, species of the genus Closterium dominated the community, in the sequence: C. aciculare, C. limneticum var. fallax, C. limneticum. The summer community was more diverse with the predominance of organisms belonging to Chlorophyceae (Chlamydomonas, Eudorina, Coelastrum) and Cyanophyceae (Microcystis, Anabaena). In spring 1991, there was a long clear-water phase during which small green algae (Ankyra, Oocystis) and cryptomonads dominated. Subsequently, the summer season was characterized by a clear sequence of dominants, drawn, in turns, from species belonging to: Bacillariophyceae, Dinophyceae, Cyanophyceae, Euglenophyceae. The physics of the reservoir and its depth, owing to filling/draining constraints in a summer-arid climate, appeared to play a key role in the dynamics of phytoplankton community.

HOOPS HJ, LONG JJ, HILE ES

FLAGELLAR APPARATUS STRUCTURE IS SIMILAR BUT NOT IDENTICAL IN VOLVULINA-STEINII, EUDORINA-ELEGANS, AND PLEODORINA-ILLINOISENSIS (CHLOROPHYTA) - IMPLICATIONS FOR THE VOLVOCINE EVOLUTIONARY LINEAGE
J PHYCOL 30 (4): 679-689 AUG 1994

Abstract:
The colonial and multicellular members of the Volvocales can be arranged in order of increasing size and complexity as the ''volvocine series.'' This series is often assumed to reflect an evolutionary progression. The flagellar apparatuses of previously examined algae are not consistent with a simple lineage. The flagellar apparatuses of Astrephomene gubernaculifera Pocock, Gonium pectorale Muller, Platydorina caudata Kofoid, Volvox rousseletii G. S. West, and V. carteri f. weismannia (Powers) Iyengar differ from one another, and there is no apparent progression in flagellar apparatus features from the simple to complex colonial forms. We examined the flagellar apparatuses of Volvulina steinii Playfair, Eudorina elegans Ehr., and Pleodorina illinoisensis Kofoid and found then to be similar to one another. The basal bodies ave connected by a distal fiber that is offset to the anti side of the cell. Two microtubular rootlets originate on the inside of the basal bodies and extend toward the syn side. The other two rootlets are oriented perpendicular to the first two and are anti-parallel to each other. A coarsely striated component underlies the four-membered rootlets and extends to the basal bodies. A proximal fiber complex connects the two basal bodies. This complex consists of a branched striated component on the cis side of each basal body. One part extends toward the anti side of the cell, while the other extends into a fibrous component that runs between basal bodies. An additional structure extends in the anti direction from the trans side of each basal body. A fibrous component extends past one basal body in all four species. This component goes past the trans basal body in Volvulina steinii and the cis basal body in E. elegans and P. illinoisensis. The flagellar apparatuses of these organisms are similar to those of G. pectorale and Volvox carteri but different from the other colonial volvocalean algae examined. The algae examined in this study plus G. pectorale and V. carteri probably share a common evolutionary history that postdates the transition from the unicellular to colonial habit. Such a shared evolutionary history is a requirement of the volvocine hypothesis. However, we have not observed progressive changes in the flagellar apparatus correlated with increasing cell number, differentiation, and sexual specialization. Thus, it is possible, but not certain, that G. pectorale, Volvulina steinii, E. elegans, P. illinoisensis, and Volvox carteri may form part of a volvocine lineage.

NOZAKI H, ITOH M

PHYLOGENETIC-RELATIONSHIPS WITHIN THE COLONIAL VOLVOCALES (CHLOROPHYTA) INFERRED FROM CLADISTIC-ANALYSIS BASED ON MORPHOLOGICAL DATA
J PHYCOL 30 (2): 353-365 APR 1994

Abstract:
A cladistic analysis was used to deduce the phylogenetic relationships within the colonial Volvocales. Forty-one pairs of characters related to gross morphology and ultrastructure of vegetative colonies as well as asexual and sexual reproduction were analyzed based on parsimony, using the PAUP 3.0 computer program, for 25 species belonging to nine volvocacean and goniacean genera of the colonial Volvocales. Chlamydomonas reinhardtii Dangeard was the outgroup. The strict consensus tree indicated the presence of two monophyletic groups, one composed of all the volvocacean species analyzed in this study and the other containing the goniacean species except for the four-celled species Gonium sociale (Dujardin) Warming. In addition, these two groups constitute a large monophyletic group, to which G. sociale is a sister group. A new combination Tetrabaena socialis (Dujardin) Nozaki et Itoh and a new family Tetrabaenaceae Nozaki et Itoh are thus proposed for G. sociale. In addition, the analysis suggests that the volvocacean genera Eudorina and Pleodorina are paraphyletic groups, respectively, and that the monotypic genus Yamagishiella has no autapomorphic characters and represents primitive features of the anisogamous and oogamous genera of the Volvocaceae. Phylogenetic relationships within the Volvocaceae and the Goniaceae, as well as the various modes of sexual reproduction exhibited by these organisms, are discussed on the basis of the analysis.

1992

NOZAKI H, KUROIWA T

ULTRASTRUCTURE OF THE EXTRACELLULAR-MATRIX AND TAXONOMY OF EUDORINA, PLEODORINA AND YAMAGISHIELLA GEN-NOV (VOLVOCACEAE, CHLOROPHYTA)
PHYCOLOGIA 31 (6): 529-541 NOV 1992

Abstract:
Vegetative colonies of Pandorina unicocca Rayburn et Starr, four taxa of Eudorina [E. elegans Ehrenberg (type species), E. illinoisensis (Kofoid) Pascher, E. unicocca G.M. Smith var. unicocca and E. unicocca var. peripheralis Goldstein] and two species of Pleodorina [P. californica Shaw (type species) and P. indica (Iyengar) Nozaki] were examined with electron microscopy in order to characterize the structure of the extracellular matrix. Each cell of the colonies of all the taxa examined was tightly enclosed by a dense fibrillar zone of the extracellular matrix (cellular envelope) with sparse fibrillar material filling the space outside the cellular envelopes within the tripartite colonial boundary of the matrix. This arrangement is essentially different from that of Pandorina morum (O.F. Muller) Bory (type species) and P. colemaniae Nozaki. As Eudorina and Pleodorina both have anisogamous sexual reproduction with sperm packets (bundles of male gametes), a new genus, Yamagishiella Nozaki, is proposed for encompassing the isogamous species Yamagishiella unicocca (Rayburn et Starr) Nozaki comb. nov. [Pandorina unicocca].

BUCHHEIM MA, CHAPMAN RL

PHYLOGENY OF CARTERIA (CHLOROPHYCEAE) INFERRED FROM MOLECULAR AND ORGANISMAL DATA
J PHYCOL 28 (3): 362-374 JUN 1992

Abstract:
Comparative ultrastructural data have shown that at least two distinct groups exist within Carteria. Similarly, interpretations of variation in gross morphological features have led to the discovery of morphologically distinct groups within the genus. Partial sequences from the nuclear-encoded small- and large-subunit ribosomal RNA molecules of selected Carteria taxa were studied as a means of 1) testing hypotheses that distinct groups of species exist within the genus and 2) assessing monophyly of the genus. Parsimony analysis of the sequence data suggests that three Carteria species, C. lunzensis, C. crucifera, and C. olivieri, form a monopkyletic group that is the basal sister group to all other ingroup flagellate taxa (including species of Chlamydomonas, Haematococcus, Stephanosphaera, Volvox, and Eudorina). Two other Carteria taxa, C. radiosa and Carteria sp. (UTEX isolate LB 762), form a clade that is the sister group to a clade that includes Haematococcus spp., Chlamydomonas spp., and Stephanosphaera. Thus, the sequence data support the interpretations of ultrastructural evidence that described two distinct Carteria lineages. Moreover, the sequence data suggest that these two Carteria groups do not form a monophyletic assemblage. Parsimony analysis of a suite of organismal (morphological, ultrastructural, life history, and biochemical) character data also suggest two distinct lineages among the five Carteria taxa; however, the organismal data are ambiguous regarding monophyly of these Carteria taxa. When the two independent data sets are pooled, monophyly of Carteria is not supported; therefore, the weight of available evidence, both molecular and organismal, fails to support the concept of Carteria as a natural genus.

1989

NOZAKI H, KUROIWA H, MITA T, et al.

PLEODORINA-JAPONICA SP-NOV (VOLVOCALES, CHLOROPHYTA) WITH BACTERIA-LIKE ENDOSYMBIONTS
PHYCOLOGIA 28 (2): 252-267 JUN 1989

1984

PATEL RJ, MANOHAR KV

EUDORINA-PLUSICOCCA SMITH,G.M. - A NEW RECORD FOR INDIA
CURR SCI INDIA 53 (8): 432-433 1984

1983

REYNOLDS CS, RODGERS MW

CELL-DIVISION AND COLONY-DIVISION IN EUDORINA (CHLOROPHYTA, VOLVOCALES) AND SOME ECOLOGICAL IMPLICATIONS
BRIT PHYCOL J 18 (2): 111-119 1983

NOZAKI H

SEXUAL REPRODUCTION IN EUDORINA-ELEGANS (CHLOROPHYTA, VOLVOCALES)
BOT MAG TOKYO 96 (1042): 103-110 1983

1982