Molecular systematics of the suborder Trogiomorpha (Insecta: Psocodea: 'Psocoptera')

Phylogenetic relationships among extant families in the suborder Trogiomorpha (Insecta: Psocodea: 'Psocoptera') were inferred from partial sequences of the nuclear 18S rDNA and Histone 3 and mitochondrial 16S rDNA genes. Analyses of these data produced trees that largely supported the traditional classification; however, monophyly of the infraorder Psocathropetae (= Psyllipsocidae + Prionoglarididae) was not recovered. Instead, the family Psyllipsocidae was recovered as the sister taxon to the infraorder Atropetae (= Lepidopsocidae + Trogiidae + Psoquillidae), and the Prionoglarididae was recovered as sister to all other families in the suborder. Character states previously used to diagnose Psocathropetae are shown to be plesiomorphic. The sister group relationship between Psyllipsocidae and Atropetae was supported by two morphological apomorphies: the presence of a paraproctal anal spine and an anteriorly opened phallosome. Based on these sequence data and morphological observations, we propose a new classification scheme for the Trogiomorpha as follows: infraorder Prionoglaridetae (Prionoglarididae), infraorder Psyllipsocetae (Psyllipsocidae), infraorder Atropetae (Lepidopsocidae, Trogiidae, Psoquillidae).  © 2006 The Linnean Society of London, Zoological Journal of the Linnean Society , 2006, 146 , 287–299.     

Growth and development of Avena fatua (Wild-oat) in the field

The growth and development of field-grown Avena fatua plants were studied for autumn and spring sowings in two consecutive years. The duration of various growth stages from sowing until anthesis was quantified in terms of thermal time (accumulated degree days) or photothermal time (degree days modified by photoperiod). Base temperatures and photoperiods for developmental phases were estimated as those which minimised the coefficient of variation among sowing dates. Relationships were derived between leaf emergence, canopy height, plant leaf area, and photothermal time. Stem extension and flowering occurred earlier in autumn-sown plants than spring-sown plants. Autumn-sown plants produced more leaves on the main stem, and had greater leaf area and above-ground biomass at anthesis than spring-sown plants.     

Size and shape distribution of level-bottom tabulate corals and stromatoporoids (Silurian)

Baarli, B. G., Johnson, M. E. & Keilen, H. B. 1992 07 15: Size and shape distribution of level-bottom tabulate corals and stromatoporoids (Silurian).
Size and shape distribution of tabulate coral and stromatoporoid faunas were studied at two Lower Silurian sections in Norway on the Baltic platform and one section in eastern Iowa on the Laurentian platform. All the sections are dominated by storm beds with predominantly shallowing upward features; they differ from one another in clastic content and proximity to land. Most of the fauna lived below normal wave-base, but within the photic zone, on fine grained and firm bottoms. In all three localities, size clearly increases up-section for stromatoporoids, favositids, and heliolitids but it decreases for halysitids in the Oslo region. Sediment influx worked negatively on size but generally not so much as to affect average size. lurbulence in combination with decreasing sediment influx affected the size decrease in heliolitids up section. Nutrients and turbidity were of minor importance as growth controlling factors. Light intensity is the only factor that shows a pattern consistent with increased size up-section. Sediment influx alfected fauna composition and shape: heliolitids had the highest sediment tolerance and stromatoporoids had the lowest. Ragged skeletons were linked to tempestites. Corals and stromatoporoids reveal a population-specific response to environmental change, largely independent of benthic assemblage zones or communities. Tabulate corals, stromaroporaids, bathymetry, size variation. clastic input, benthic assemblages .     

Molecular phylogeny and ecological diversification in a clade of New World songbirds (genus Vireo)

We constructed a molecular phylogeny for a clade of eye-ringed vireos ( Vireo flavifrons and the V . solitarius complex) to examine existing hypotheses of speciation and ecological diversification. Complete sequences of the mtDNA cytochrome b gene were obtained from 47 individuals of this group plus four vireonid outgroups. Mean levels of sequence divergence in the clade varied from 0.29% to 5.7%. Differences were greatest between V . flavifrons and four taxa of ' V . solitarius '. The latter separated into three taxonomic, geographical and ecological groups: V . plumbeus plumbeus, V . cassinii cassinii , and V . solitarius solitarius plus V . solitarius alticola . These differed by an average of 2.6–3.2%. Populations within each group revealed low levels of sequence variation ( x- = 0.20%) and little geographical structuring. The mtDNA data generally corroborate results from allozymes. V. plumbeus shows a loss of yellow-green carotenoid pigmentation from the ancestral condition. The occupancy of relatively dry habitats by this species and V . cassinii represents a derived ecological shift from more-humid environments occupied by other species of vireonids. Ecological divergence in this clade occurred in allopatry and is associated with generic-level stability in morphometrics and foraging styles. Migratory behaviour and seasonal habitat shifts apparently evolved multiple times in vireos breeding in temperate environments. Present geographical and ecological distributions, and low levels of intrataxon genetic divergence, are hypothesized to be the result of postglacial regionalization of climate–plant associations and rapid northward expansion of breeding ranges.     

The breeding system of Ramosmania heterophylla–dioecy or heterostyly?

OWENS, S.J., JACKSON, A., MAUNDER, M., RUDALL, P.JOHNSON, M.A.T., 1993. The breeding system of Ramosmania heterophylla– dioecy or heterostyly?Ramosmania heterophylla (Cafe Marron), endemic to Rodrigues, Mauritius, is now almost extinct, since it appears to exist in the wild as a single plant, but has recently been successfully established at Kew by means of vegetative cuttings. Despite plenty of flowers on the Kew plants, attempts to set seed by manual pollination for seed banking purposes have failed. This investigation showed that pollen is viable and that embryo sacs appear fully developed. Lack of seed set is a result of the non-functional stigmas on short styles. The most likely explanation is that the last-known plant is male, although heterostyly or a mutant stylar developmental gene cannot be ruled out. The plant has a chromosome number of 2n= 22.     

Laboratory studies of non-preference resistance to cabbage root fly in radish

First generation progenies selected from four radish cultivars on the basis of their attractiveness to ovipositing cabbage root fly in the laboratory were compared in the same environment. There were significant differences between and within cultivars in their attractiveness for egg-laying, indicating that genetic variation existed and that selection had effected a heritable change. However, inconsistencies between experiments indicated that other, as yet unquantified, factors were compounded with the heritable component of non-preference resistance. There was no evidence to suggest that seed weight, leaf area, or hypocotyl size affected the attractiveness of the plants. The effects of eliminating any choice between selections was investigated in the laboratory by exposing 4-wk-old ‘high’ and ‘low’ preference selections of cv. Asmer Tip Top to the pest for 6 days. Three times as many eggs were laid on ‘high’ than on ‘low’ preference selections, indicating that the heritable non-preference resistance to cabbage root fly in Asmer Tip Top was maintained when no choice was offered to the flies, an essential requirement for ‘resistant’ cultivars in the field.     

Herbicide toxicities in some Australian anurans and the effect of subacute dosages on temperature tolerance

Tadpoles of the anurans, Adelotus brevis, Limnodynastes peroni, and Bufo marinus were exposed to a range of concentrations of up to ten different herbicides. The Median Tolerance Limit (TL₅₀) was calculated for each toxicant from data obtained by static bioassay. Some adult frogs (Litoria ewingi and Limnodynastes tasmaniensis) were subjected to greater concentrations of several of the toxicants. Toxicity varied greatly among the tadpoles exposed to various toxicants with fenoprop being the most toxic chemical tested, while no differences were observed in behaviour or activity between the exposed and control adult frogs. A significant reduction occurred in the thermal tolerance of one to two week old A. brevis exposed to subacute dosages of amitrole-T, picloram, and 2,2-DPA.     

Regional integration of evidence for evolution in the Silurian Pentamerus-Pentameroides lineage

Under ideal conditions, the stratophenetic test for phyletic gradualism in fossil lineages requires nearly continuous samples of time-specific populations through rock sequences representing geologically significant periods of time. Shifting environments account for one source of 'imperfection' in the local rock record. Few species are sufficiently eurytopic to survive changing environments in a given region over a long time span. Where marine fossils are involved, independently correlated sea-level curves may be used to patch together segments of stratigraphic sections from different regions that collectively encompass the uninterrupted environment of the target species. In the Lower Silurian of Iowa, stratigraphic gaps among test samples for phyletic gradualism in pentamerid brachiopods occur wherever pentamerid communities are succeeded by deeper water stricklandiid communities or by shallower-water coral-algal communities. Correlation of sea-level curves indicates that water depth was consistently shallower in the northern Great Lakes area. Usually when stricklandiid communities replaced a pentamerid community in Iowan seas, contemporaneous pentamerid communities replaced a coral-algal community in Michigan or Ontario seas. Temporal meshing of samples from Iowa and the northern Great Lakes area (based on congruent Stricklandia and Eocoelia lineage zones) supports the hypothesis that Pentamerus oblongus evolved to Pentameroides subrectus through a gradual narrowing and loss of divergence in its outer plates. A transitional morphotype between the two genera (from the Lower Silurian of Alabama) is illustrated. □ Phyletic gradualism, punctuated equilibria, Brachiopoda, Pentamerida, Silurian, North America.