1,720,985 research outputs found
Settling the identity and phylogenetic position of the psychrotolerant green algal genus Coleochlamys (Trebouxiophyceae)
No full textGrantová Agentura České Republiky http://dx.doi.org/10.13039/50110000182
Overlooked diversity with terrestrial lifestyle in the predominantly freshwater and snow phylogroup Chloromonadinia (Volvocales, Chlorophyceae)
No full textMendelian segregation of leaf phenotypes in experimental F 2 hybrids elucidates origin of morphological diversity of the apomictic Ranunculus auricomus complex
No full text: A new trebouxiophyte lineage (Chlorophyta) inhabiting low pH environments from Europe to South America
No full textMolecular Evidence for the Wide Distribution of Two Lineages of Terrestrial Green Algae (Chlorophyta) over Tropics to Temperate Zone
No full textPhylogenetic analyses of 18S rDNA sequences from environmental clones and culture strains revealed a widespread distribution of two subaerial green algal lineages, Jenufa and Xylochloris, recently described from rainforests in southeast Asia. A new lineage of Jenufa (Chlorophyceae), most closely related to or even conspecific with J. minuta, was formed by sequences of European origin. Two more lineages of Jenufa were formed by three additional sequences from Ecuador and Panama. The other lineage was a close relative of Xylochloris irregularis (Trebouxiophyceae), probably representing a new species of the genus and distinct from the only so far described species, X. irregularis. It comprised two distinct clades each containing almost identical sequences from Germany and Ecuador. Analyses of the new sequences for both genera allowed to presume a preference of J. minuta to subaerial growth on rock or artificial hard substrates combined with a remarkable adaptation to extended periods of darkness, whereas Xylochloris may preferably occur on tree bark or in the soil
<i>Lunachloris lukesovae</i> gen. et sp. nov. (Trebouxiophyceae, Chlorophyta), a novel coccoid green alga isolated from soil in South Bohemia, Czech Republic
No full textChloromonas arctica sp. nov., a psychrotolerant alga from snow in the High Arctic (Chlamydomonadales, Chlorophyta)
No full text<i>Chloromonas svalbardensis</i> n. sp. with Insights into the Phylogroup <i>Chloromonadinia</i> (Chlorophyceae)
No full textspecies complex
No full textAbstract The time frame and geographical patterns of diversification processes in European temperate‐montane herbs are still not well understood. We used the sexual species of the Ranunculus auricomus complex as a model system to understand how vicariance versus dispersal processes in the context of Pleistocene climatic fluctuations have triggered speciation in temperate‐montane plant species. We used target enrichment sequence data from about 600 nuclear genes and coalescent‐based species tree inference methods to resolve phylogenetic relationships among the sexual taxa of the complex. We estimated absolute divergence times and, using ancestral range reconstruction, we tested if speciation was enhanced by vicariance or by dispersal processes. Phylogenetic relationships among taxa were fully resolved with some incongruence in the position of the tetraploid R. marsicus. Speciation events took place in a very short time at the end of the Mid‐Pleistocene Transition (830–580 thousand years ago [ka]). A second wave of intraspecific geographical differentiation occurred at the end of the Riss glaciation or during the Eemian interglacial between 200 and 100 ka. Ancestral range reconstruction suggests a widespread European ancestor of the R. auricomus complex. Vicariance has triggered allopatric speciation in temperate‐montane plant species during the climatic deterioration that occurred during the last phase of the Mid‐Pleistocene Transition. Vegetation restructuring from forest into tundra could have confined these forest species into isolated glacial macro‐ and microrefugia. During subsequent warming periods, range expansions of these species could have been hampered by apomictic derivatives and by other congeneric competitors in the same habitat.German Research Foundation http://dx.doi.org/10.13039/50110000165
complex and its role in a geographical parthenogenesis scenario
No full textAbstract The larger distribution area of asexuals compared with their sexual relatives in geographical parthenogenesis (GP) scenarios has been widely attributed to the advantages of uniparental reproduction and polyploidy. However, potential disadvantages of sexuals due to their breeding system have received little attention so far. Here, we study the breeding system of five narrowly distributed sexual lineages of Ranunculus notabilis s.l. (R. auricomus complex) and its effects on outcrossing, inbreeding, female fitness, and heterozygosity. We performed selfing and intra‐ and interlineage crossings by bagging 481 flowers (59 garden individuals) followed by germination experiments. We compared seed set and germination rates, and related them to genetic distance and genome‐wide heterozygosity (thousands of RADseq loci). Selfings (2.5%) unveiled a significantly lower seed set compared with intra‐ (69.0%) and interlineage crossings (69.5%). Seed set of intra‐ (65%) compared to interpopulation crossings (78%) was significantly lower. In contrast, all treatments showed comparable germination rates (32%–43%). Generalized linear regressions between seed set and genetic distance revealed positive relationships in general and between lineages, and a negative one within lineages. Seed set was the main decisive factor for female fitness. Germination rates were not related to genetic distance at any level, but were positively associated with heterozygosity in interlineage crossings. Experiments confirmed full crossability and predominant outcrossing among sexual R. notabilis s.l. lineages. However, up to 5% (outliers 15%–31%) of seeds were formed by selfing, probably due to semi‐self‐compatibility in a multi‐locus gametophytic SI system. Less seed set in intrapopulation crossings, and higher seed set and germination rates from crossings of genetically more distant and heterozygous lineages (interlineage) indicate negative inbreeding and positive outbreeding effects. In GP scenarios, sexual species with small and/or isolated populations can suffer from decreased female fitness due to their breeding system. This factor, among others, probably limits range expansion of sexuals.Potential disadvantages of sexual plant species due to their breeding system have received little attention in geographical parthenogenesis (GP) scenarios so far. We compared seed set and germination rates of five sexual lineages of Ranunculus notabilis s.l (R. auricomus complex) and related them to genetic distance and genome‐wide heterozygosity. Results suggest that inbreeding depression particularly affects intrapopulation (intralineage) crossings, and that positive outbreeding effects particularly influence interlineage crossings. In GP scenarios, sexual species with small and/or isolated populations can suffer from decreased female fitness due to their breeding system. imageOpen-Access-Publikationsfonds 202
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