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Divergence Rates (divergence + rate)
Selected AbstractsThe genetic population structure of Buthus occitanus (Scorpiones: Buthidae) across the Strait of Gibraltar: calibrating a molecular clock using nuclear allozyme variationBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2004BENJAMIN GANTENBEIN I assess here the importance of the Strait of Gibraltar as a barrier to gene flow for populations of the scorpion Buthus occitanus. This polytypic buthid scorpion occurs in Europe and in North Africa where it is morphologically more diverse. The phylogenetic relationship between B. occitanus populations across the Strait of Gibraltar is investigated by nuclear allozymes analysis (15 loci scored). Phylogenetic analysis based on estimated gene frequency data results in a tree topology that divides the populations into three clades, i.e. a European, an Atlas (= Morocco samples) and a Tell-Atlas clade (= Tunisian samples). The Tell-Atlas clade grouped with the European clade with a rather high bootstrap support of 70%. Within these clades low levels of genetic variability are observed. Calibrating a molecular clock under the assumption that the European populations are autochthonous and have been isolated from the North African for at least 5.33 Myr reveals a divergence rate of 0.060 genetic distance (D) per Myr estimated between European and Moroccan samples and 0.036D Myr,1 between European and Tunisian samples, respectively. © 2004 The Linnean Society of London, Biological Journal of the Linnean Society, 2004, 81, 519,534. [source] An AFLP clock for the absolute dating of shallow-time evolutionary history based on the intraspecific divergence of southwestern European alpine plant speciesMOLECULAR ECOLOGY, Issue 4 2009MATTHIAS KROPF Abstract The dating of recent events in the history of organisms needs divergence rates based on molecular fingerprint markers. Here, we used amplified fragment length polymorphisms (AFLPs) of three distantly related alpine plant species co-occurring in the Spanish Sierra Nevada, the Pyrenees and the southwestern Alps/Massif Central to establish divergence rates. Within each of these species (Gentiana alpina, Kernera saxatilis and Silene rupestris), we found that the degree of AFLP divergence (DN72) between mountain phylogroups was significantly correlated with their time of divergence (as inferred from palaeoclimatic/palynological data), indicating constant AFLP divergence rates. As these rates did not differ significantly among species, a regression analysis based on the pooled data was utilized to generate a general AFLP rate. The application of this latter rate to AFLP data from other herbaceous plant species (Minuartia biflora: Schönswetter et al. 2006; Nigella degenii: Comes et al. 2008) resulted in a plausible timing of the recolonization of the Svalbard Islands and the separation of populations from the Alps and Scandinavia (Minuartia), and of island population separation in the Aegean Archipelago (Nigella). Furthermore, the AFLP mutation rate obtained in our study is of the same magnitude as AFLP mutation rates published previously. The temporal limits of our AFLP rate, which is based on intraspecific vicariance events at shallow (i.e. late glacial/Early Holocene) time scales, remains to be tested. [source] Description and Phylogenetic Relationships of Spumochlamys perforata n. sp. and Spumochlamys bryora n. sp. (Amoebozoa, Arcellinida)THE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 6 2009ALEXANDER KUDRYAVTSEV ABSTRACT. Spumochlamys perforata n. sp. and Spumochlamys bryora n. sp. were isolated and described from dry epiphytic moss. The morphology and ultrastructure of both species clearly demonstrate that they belong to the genus Spumochlamys (family Microchlamyiidae). They differ from its only described member, Spumochlamys iliensis (as well as from species of Microchlamys), in the relief of the dorsal surface of the test, revealed by scanning electron microscopy, which can represent a good characteristic for species identification. They also differ in the structure of the dorsal part of the test wall (especially S. perforata). Small subunit ribosomal DNA-based molecular phylogenetic analyses show that Spumochlamys is a deeply branching lineage of the Arcellinida, without any close affinities. Actin gene sequence analysis places this genus within the Tubulinea, close to two other arcellinid lineages but without forming a monophyletic group with them. These data together strongly suggest that the lack of resolution in the arcellinid molecular phylogenies is due to serious undersampling of taxa, a limited number of sequence data, and high divergence rates in most of the species. [source] |