Marie-Catherine Boisselier-Dubayle

Genetic structure of the saxicole Pitcairnia geyskesii (Bromeliaceae) on inselbergs in French Guiana

South American inselbergs constitute singular and fragmented habitats in the tropical rain forest. Pitcairnia geyskesii is restricted to these habitats and exhibits both sexual and asexual reproduction. The genetic structure of populations on three inselbergs in French Guiana is examined by analysis of ten isozyme loci. All analyzed populations show high levels of genetic variation. On average, 63.3% of loci per population were polymorphic, with a mean number of 2.21 alleles per polymorphic locus, and mean observed and expected heterozygosities of 0.185 and 0.183, respectively. The analyses of genetic variability displayed at different levels (inselbergs, subpopulations, and mats) give different but complementary information. A significant multilocus disequilibrium was detected in one subpopulation, whereas none was observed within the whole populations sampled on the three inselbergs. Tests on spatial genetic structure indicate a patchy distribution of genotypes on two inselbergs. The data give some insights on the reproductive behavior of P. geyskesii. (1) Efficient sexual reproduction leads to seed recruitment at the level of the inselberg. (2) Both clonality and seed recruitment occur within mats. (3) Vegetative spread by fragmentation is involved in the establishment of new mats. There is substantial differentiation (F(ST) = 0.322) and low gene flow among inselbergs (Nm = 0.234). High genetic diversity within inselbergs appears as a consequence of the association of genet longevity induced by clonal replication and recruitment of new genets produced by sexual reproduction.

The leafy liverwortPorella baueri (Porellaceae) is an allopolyploid

Porella platyphylla andP. cordaeana are genetically well differentiated in Europe (I = 0.486). Isozyme data from 156 European colonies reveal thatP. baueri is polyploid and could be an interspecific hybrid between these two species. It is characterized by large lobe cells, toothed margins of the female bracts, and ciliate perianth mouth. Correspondence analysis using morphological characters revealed that its colonies cluster into two geographicallý separated groups, similar to one or other of the putative parental species. These results agree with the genetic analysis, that also revealed two main allelic associations, each with a distinct geographical range. We hypothesize that this pattern was produced by introgression subsequent to hybridization, or by gene silencing. The discovery of this new, allopolyploid species suggests that hybridization is an important evolutionary process in liverworts.

Barcoding type specimens helps to identify synonyms and an unnamed new species in Eumunida Smith, 1883 (Decapoda:Eumunididae)

TheprimarypurposeofDNA-barcodingprojectsistogenerateanefficientexpertiseandidentificationtool.This is an important challenge to the taxonomy of the 21st century, as the demand increases and the expert capacity does not. However,identifyingspecimensusingDNA-barcodesrequiresapreliminaryanalysistorelatemolecularclusterstoavailable scientific names. Through a case study of the genus Eumunida (Decapoda:Eumunididae), we illustrate how naming molecule-based units, and thus providing an accurate DNA-based identification tool, is facilitated by sequencing type specimens. Using both morphological and unlinked molecular markers (COI and 28S genes), we analysed 230 specimens from 12 geographic areas, covering two-thirds of the known diversity of the genus, including type specimens of 13 species. Most hypotheses of species delimitation are validated, as they correspond to molecular units linked to only one taxonomic name (and vice versa). However, a putative cryptic species is also revealed and three entities previously named as distinct speciesmayinfactbelongtoasingleone,andthusneedtobesynonymised.Ouranalyses,whichintegratethecurrentnaming rules, enhance the a-taxonomy of the genus and provide an effective identification tool based on DNA-barcodes. They illustratetheabilityofDNA-barcodes,especiallywhentypespecimensareincluded,topinpointwhereataxonomicrevision is needed.

Species Delimitation In The Genus Bythinella (Mollusca: Caenogastropoda: Rissooidea): A First Attempt Combining Molecular And Morphometrical Data

Within the springsnail genus Bythinella, few discontinuous morphological characters allow to unambiguously delineate species-level taxa. Opinions on the alpha-taxonomy of the group are divergent, with some authors recognizing every morphologically distinct local form as a species, while others interpreting such geographical forms as intraspecific variation. Because the value of morphological characters was rarely contrasted with molecular data, such opinions remained untested. In this work, variation between populations was studied through genetics isozymes, phylogeny (DNA), and morphometrics. Eleven populations representing five putative species were sampled from the French Pyrenees, a region where a high number of nominal species are classically recognized. Based on genetic and phylogenetic analyses, the material clusters into three groups, of which one consists of several nominal species. Environmental factors, sexual dimorphism, and genetic factors contribute to the significant morphological variation observed within the genetic groups. Thus, the number of species of Bythinella recognized in the Pyrenees appears probably overestimated, and the characters traditionally used for species delimitation should be re-evaluated.

Enzyme polymorphism inPreissia quadrata (Hepaticae, Marchantiaceae)

Preissia quadrata has a high habitat specificity and a reproductive system including frequent sexual reproduction and absence of specialized asexual propagules. Fertilization is aquatic. Colonies collected in Europe, Asia, eastern and western Canada show the species to be polymorphic at the eleven isozyme loci studied. Most often, thalli of the same colony appeared genetically identical. Partitioning of genetic variation was among rather than within colonies, suggesting a clonal structure of the colonies and a species structure consisting of a series of small populations reproductively isolated from each other. Little genetic exchange between colonies growing nearby was present, but the species does not appear to consist of regionally circumscribed genetically cohesive entities. Some European and Canadian colonies had identical electrophoretic patterns. The problem of understanding the phenomena holding liverwort species together, both morphologically and genetically, remains an open question. The genetic structure of the species might be due to its past history. It might have had a continuous distribution in the northern part of the Northern Hemisphere. If so, little subsequent genetic diversification, perhaps linked to its haploid-dominant life cycle, must be supposed.