Mobilisation de sources du XIXe siècle dans les études contemporaines de systématique des plantes cultivées

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Floral morphology to discriminate taxa between and within Cytisus sect. Alburnoides, sect. Spartopsis and sect. Verzinum (Genisteae, Fabaceae)

Delimitation of sections is controversial within the genus Cytisus L. (Fabaceae, Genisteae). A morphological study has been conducted on 19 taxa from sections Alburnoides, Spartopsis and Verzinum to clarify their discrimination. Thirty-five quantitative and qualitative characters were recorded on a maximum of 15 dry or living flowers per taxon. Three multiple correspondence factor analyses (MCFA) were performed on a matrix based on 22 of the 35 recorded morphological characters to (1) compare the variability within and between individuals and (2) distinguish groups among the studied taxa. MCFA showed that both flowers sampled from the same plant or different individuals could represent the morphological variability of a taxon. MCFA also clustered the 19 taxa into three groups corresponding to sections Alburnoides, Spartopsis and Verzinum as defined by Cristofolini and Troia (Taxon 44:733–746, 2006). However, floral morphology has not been sufficient to discriminate taxa within sections. A key of the three studied sections based on floral characters is given

Names, collections, and molecular data of cultivated plant taxonomy

Like taxonomy of wild taxa, taxonomy of cultivated plants deals at least with three kinds of information: names, collections and molecules. However, in the case of cultivated plants, some complications occur, such as lost names of cultivated plants which have been missed from indexing by large databases. Herbaria with large sets of old cultivated material are excessively rare and a good number of cultivars has been lost due to lack of cultivation. In contrast, it is easier to establish living collections of and get molecular data from cultivated plants than wild taxa. Unraveling the history of plant selection using molecular tools is complicated as most cultivated groups are subject to artificial hybridization. Using samples from various woody angiosperm genera, we will consider some of these points to highlight specificities of the taxonomy of cultivated plant, including sparse source of information and reticulated history

Typification of names in genus Hieracium based on original herbarium material of Alexis Jordan and Alexandre Boreau

181 names of Hieracium species going back to original herbarium material of Alexis Jordan or Alexandre Boreau are lectotypified, 27 are neotypified. The study is based on herbarium specimens of the Université Catholique de Lyon (LY) and Ville d’Angers (ANG), Martrin-Donos’s herbarium at the Institut Botanique de Montpellier (MPUTarn) and Arvet-Touvet’s herbarium at the Musée d’Histoire Naturelle de Grenoble (GRM-AT). The type specimens are illustrated by photographs of the entire herbarium sheets with some detail views of flower heads and leaves. Usual nomenclatural synonyms are given for each taxon

Revised lectotypification of Spartium scoparium L. (Fabaceae)

The currently accepted lectotype of the Linnaean species Spartium scoparium is a specimen of Cytisus arboreus (Desf.) DC. This lectotype is here superseded in favour of another specimen in the Linnaean collection on the grounds of conflict with the protologue. The current name for the species known as Cytisus scoparius (L.) Link can therefore be maintained

A revision of Cytisus sections Alburnoides, Spartopsis and Verzinum (Genisteae, Fabaceae)

Cytisus sections Alburnoides DC., Spartopsis Dumort. and Verzinum (Raf.) Talavera (tribe Genisteae, Fabaceae) are revised. These comprise 10 species of the genus, of which two species are recognised in Cytisus section Alburnoides, four in Cytisus section Spartopsis (of which two species are divided into subspecies), and four in Cytisus section Verzinum (one with two subspecies). Three new combinations are made: Cytisus ardoinoi subsp. sauzeanus, C. grandiflorus subsp. maurus and C. scoparius subsp. insularis. Keys to the sections and to the species within each section are given. All taxa are described. Conservation assessments are made

A monograph of Octoknema (Octoknemaceae — Olacaceae s.l.)

A revision of Octoknema Pierre is provided, based on morphological data gathered from a study of herbarium specimens and observations in the field. Fourteen species of Octoknema are recognised including six new species: O. bakossiensis Gosline & Malécot, O. belingensis Gosline & Malécot, O. chailluensis Malécot & Gosline, O. kivuensis Gosline & Malécot, O. mokoko Gosline & Malécot and O. ogoouensis Malécot & Gosline. Data are given for four additional poorly known taxa (Octoknema species A, B, C and D)

Isolation-by-Distance and Outbreeding Depression Are Sufficient to Drive Parapatric Speciation in the Absence of Environmental Influences

A commonly held view in evolutionary biology is that speciation (the emergence of genetically distinct and reproductively incompatible subpopulations) is driven by external environmental constraints, such as localized barriers to dispersal or habitat-based variation in selection pressures. We have developed a spatially explicit model of a biological population to study the emergence of spatial and temporal patterns of genetic diversity in the absence of predetermined subpopulation boundaries. We propose a 2-D cellular automata model showing that an initially homogeneous population might spontaneously subdivide into reproductively incompatible species through sheer isolation-by-distance when the viability of offspring decreases as the genomes of parental gametes become increasingly different. This simple implementation of the Dobzhansky-Muller model provides the basis for assessing the process and completion of speciation, which is deemed to occur when there is complete postzygotic isolation between two subpopulations. The model shows an inherent tendency toward spatial self-organization, as has been the case with other spatially explicit models of evolution. A well-mixed version of the model exhibits a relatively stable and unimodal distribution of genetic differences as has been shown with previous models. A much more interesting pattern of temporal waves, however, emerges when the dispersal of individuals is limited to short distances. Each wave represents a subset of comparisons between members of emergent subpopulations diverging from one another, and a subset of these divergences proceeds to the point of speciation. The long-term persistence of diverging subpopulations is the essence of speciation in biological populations, so the rhythmic diversity waves that we have observed suggest an inherent disposition for a population experiencing isolation-by-distance to generate new species