A cladistic analysis of the genus Lopezia (Onagraceae)

Lopezia, a genus of 22 species largely restricted to Mexico, forms a monophyletic group defined by the possession of two stamens in tetramerous flowerS. A cladistic analysis of the genus was performed using 16 characters from morphology, anatomy and embryology. Twenty of the 22 species were considered the terminal taxa. Polarity of the characters was based on the outgroup comparison method, using three alternative outgroups: the genus Fuchsia, Onagraceae excluding Ludwigia, and Epilobieae-Onagreae. Using Fuchsia as outgroup, 29 equally parsimonious cladograms were produced, each with 24 steps and a consistency index of 0.75. A successive weighting procedure was applied, resulting in 15 cladograms with consistency index of 0.85. The strict consensus cladogram defines eight monophyletic groups and supports most of the current sectional classification of Lopezia, with the exception that no synapomorphy defines section Jehlia. The larger sections Lopezia and Pelozia, although well-defined as clades, are not fully resolved internally. All cladograms support section Riesenbachia as monophyletic. The two alternative hypotheses for outgroups produced similar results: 61 most parsimonious trees, reduced after the successive weighting procedure to 15, which are identical to those produced with Fuchsia as outgroup. These results are discussed in the context of data on cytology and pollination biology.     

PRECISE MEASUREMENT OF THE CHANGE OF STATISTICAL DISTRIBUTION OF CELL SIZE OCCURRING DURING THE SYNCHRONOUS CULTURE OF CHLORELLA

Change of statistical distribution of cell size occurring inthe synchronous culture of Chlorella ellipsoidea was followedby using a COULTER counter. The culture was started using apopulation of D-cells which showed a sharp distribution of cellsize. During the growth phase, there occurred characteristicchanges in the height and shape of the distribution curve; namely,the height first decreased with broadening of the distributionand then increased to the level even higher than the originalpeak. The broadening of the curves, which indicates the loweringof degree of homogeneity of population, occurred during theperiod of most active growth, and the homogeneity was restoredat later stages of ripening where the growth became sluggish.When the ripened cells (L₃) were transferred to the darknesstheir volume decreased to some extent before the occurrenceof cellular division. It was assumed that the shrinkage of cellsobserved may be partly due to exudation of water from the cellsand partly to the consumption of fuel material caused by enhancedrespiration, both having been shown to occur at the stage ofcell maturation. (Received June 12, 1964; )     

Molecular phylogeny of the subfamily Exoristinae (Diptera,Tachinidae), with discussions on the evolutionary history of female oviposition strategy

Abstract. Phylogenetic relationships among tribes in the tachinid subfamily Exoristinae (Diptera, Tachinidae) are inferred from four genes, namely white, 18S, 28S and 16S rDNA. For phylogenetic inferences, maximum parsimony, maximum likelihood and Bayesian Markov chain Monte Carlo analyses were performed. The resultant, very similar, trees are nearly concordant with the traditional classification based on morphological characters. Our results suggest that the Tachinidae are monophyletic and sister to the Sarcophagidae. The tribal relationships within Exoristinae are supported in part with high reliabilities and are similar to those inferred by Stireman. Based on the resultant trees, the phylogenetic relationships and possible morphological synapomorphies were investigated. In addition, we evaluated the transformation of female reproductive habits in the Exoristinae, finding support for the hypothesis that ovolarviparity evolved independently from oviparity in several clades, and obtaining different results concerning the evolutionary history of micro‐ovolarviparity depending on character optimization.     

A NEW ACOUSTIC SIGNAL OF THE FRUIT-FLIES DROSOPHILA SIMULANS AND D. MELANOGASTER

ABSTRACT

We found a new acoustic signal in Drosophila simulans (si) and D. melanogaster (me). It is a ‘rejection signal’ (RS) produced by adult males and young males and females in response to the courting behaviour of mature males who emit ‘pulse songs’ (i.e. love song: LS). It occurs most frequently in si, less in adults me except if the interacting males belong to different chemical morphs (i.e. temperate or equatorial population). There are no differences in the LS characteristics directed to various sexes and ages. The RSs produced by adult males or by young animals do not differ significantly either. They are emitted by neither virgin nor fecundated adult me females but a few times by virgin adult si females. The RS (like the LS) is a multipulse signal but intervals between pulses are about twice those of LS, around 90 ms for si and 80 ms for me. They are very irregular, as is the distribution of energy along the bandwidth mainly between 300 and 800 Hz for si and 200 and 600 Hz for me. The sound level of the RS is from 10 to 20 dB less than the LS. The RS seems to be linked to the ‘flicking’ behaviour produced by both wings, while the LS always corresponds to the so-called ‘wing vibration’.     

Structural Associations Between Mitochondria and Chloroplasts in the Bundle Sheath Cells of Portulaca oleracea

Mitochondria and chloroplasts are structurally associated inthe bundle sheath cells of Portulaca oleracea L., an NAD malicenzyme type C₄ plant. These associations occur in some restrictedregions where the mitochondrial cristae extend inwards. Exposureof plants to 1.0 µ11^–1 SO₂ for 3 h induced shrinkageof mitochondria of the bundle sheath cells, which further visualizedthe structural association between the organelles. C₄ plant, chloroplast, mitochondrion, Portulaca oleracea, sulphur dioxide     

Measurement of vulnerability to water stress‐induced cavitation in grapevine: a comparison of four techniques applied to a long‐vesseled species

Among woody plants, grapevines are often described as highly vulnerable to water‐stress induced cavitation with emboli forming at slight tensions. However, we found native embolism never exceeded 30% despite low xylem water potentials (Ψ_x) for stems of field grown vines. The discrepancy between native embolism measurements and those of previous reports led us to assess vulnerability curve generation using four separate methods and alterations (i.e. segment length and with/without flushing to remove embolism prior to measurement) of each. Centrifuge, dehydration and air‐injection methods, which rely on measurement of percentage loss of hydraulic conductivity (PLC) in detached stems, were compared against non‐invasive monitoring of xylem cavitation with nuclear magnetic resonance (NMR) imaging. Short segment air‐injection and flushed centrifuge stems reached >90 PLC at Ψ_x of‐0.5 and ?1.5 MPa, respectively, whereas dehydration and long‐segment air‐injection measurements indicated no significant embolism at Ψ_x > ?2.0 MPa. Observations from NMR agreed with the dehydration and long segment air‐injection methods, showing the majority of vessels were still water‐filled at Ψ_x > ?1.5 MPa. Our findings show V. vinifera stems are far less vulnerable to water stress‐induced cavitation than previously reported, and dehydration and long segment air‐injection techniques are more appropriate for long‐vesseled species and organs.     

Phylogenetic Relationships Among Microsporidia Based on rDNA Sequence Data, With Particular Reference to Fish-Infecting Microsporidium Balbiani 1884 Species.

Recently, large discrepancies have been identified between microsporidian systematics based on molecular and traditional characteristics. In the current study the 530f-580r region of the rRNA gene of eight microsporidian species was cloned and sequenced. Included were two unclassified species of Microsporidium Balbiani, 1884 and an unidentified microsporidian that infects the musculature of different sea bream species. Sequence identities in excess of 98% indicated that these three species almost certainly are members of the same genus. Phylogenetic analyses of all microsporidian sequence data available for this region of the gene (20 species) and for partial small subunit sequences (51 species of 21 genera) revealed these species to be distinct from the family Pleistophoridae Doflein, 1901 and closely related them to the genus Sproguea Weissenberg, 1976. This clade was found to comprise a sister taxon to that containing the vast majority of fish-infecting species. Broad cladistic divisions were found between terrestrial insect-infecting and fish-infecting species, which together are distant from the aquatic insect-infecting microsporidia. The rRNA gene of certain fish-infecting genera was found to be more highly conserved than previously reported. This has implications for its utility in diagnostic assays and phylogenetic studies at, or close to, the species level.