Genus

About: Genus is a research topic. Over the lifetime, 68921 publications have been published within this topic receiving 590966 citations. The topic is also known as: monospecies genus & genus (zoology).

Phylogenetic relationships in Lupinus (Fabaceae: Papilionoideae) based on internal transcribed spacer sequences (ITS) of nuclear ribosomal DNA.

Abstract: ¨Internal transcribed spacer (ITS) sequences of nuclear ribosomal DNA from 44 taxa of the genus Lupinus and five outgroup taxa were used for phylogenetic analysis. Lupinus appears as a strongly supported monophyletic genus, which is unambiguously part of the Genisteae. The lupines are distributed into five main clades in general accordance with their geographical origin. In the Old World, almost all the recognized taxonomic units are well resolved. The ITS data reveal an unexpectedly close relationship between the diverse sections Angustifoli and Lutei. The ITS results suggest a geographical division between the western New World lupines and the eastern ones. They also indicate the presence of some moderately to strongly supported groups of taxa, such as the Microcarpi‐Pusilli group, the L. spariflorus‐L. arizonicusgroup, the L. mexicanus‐ L. elegans group in the western New World, and the notable L. multiflorus‐L. paraguariensisgroup in the eastern New World. The latter group strongly suggests that the eastern South American compound- and simple-leaved perennial lupines derive from a common ancestor. However, apart from some exceptions, relationships within the genus still remain largely unresolved based on ITS data. The lack of resolution at the base of the genus is suggestive of a rapid initial radiation of the lupines subsequent to the dispersal of their common ancestor. Relative rate tests demonstrate the presence of rate heterogeneity of ITS sequences within Lupinus. In many pairwise comparisons between taxa, substitution rate inequalities are correlated with the habit (annual, perennial), suggesting some role for the generation time effects in the evolutionary history of lupines. Lupinus L. (Fabaceae) is a large and diverse genus comprising 200‐500 (Dunn and Gillett, 1966) annual and perennial herbaceous species, as well as a few soft-woody shrubs and small trees (Dunn, 1984; Turner, 1995), which occur in a wide range of ecogeographical conditions in both the New and the Old World. Lupines are more diverse in the New World with over 90% of the species in 1

A Century of Research on the Amoeboflagellate Genus Naegleria

Abstract: Summary. The amoeboflagellate genus Naegleria contains pathogenic and nonpathogenic species. As most species are morphologically indistinguishable, species are defined and identified by molecular methods. For routine identification, isoenzyme analyses are performed. For the description of a new species, sequences of ribosomal DNA are increasingly used and the analyses of these sequences also allow us to define the phylogenetic relationships between species and strains. In the present monograph 27 Naegleria lineages are discussed and identified as separate species. Using molecular methods, Naegleria spp. have been identified which either form dividing flagellates or which do not form flagellates at all, thus contradicting the accepted definition of the genus. Willaertia, which forms dividing flagellates, is the genus that is the closest relative of the genus Naegleria. The genus Naegleria has some particularities in its molecular biology, such as circular ribosomal DNA plasmids, group I introns in the small and large subunit ribosomal DNA, and an unusual pyrophosphate-dependant phosphofructokinase. The phylogeny of the Naegleria spp. is compared to the situation concerning the other genera of the familyVahlkampfiidae. Also discussed is the state of affairs concerning species designation based on phylogeny in the genus Acanthamoeba, another free-living amoeba with species pathogenic to man.