The evolution of hymenopteran wings: the importance of size

The allometric relationships between body size and several aspects of wing morphology in the insect order Hymenoptera were investigated using multivariate morphometric techniques. The study focused primarily on wing allometry in five monophyletic genera of bees ( Perdila, Halictus, Ceratina, Trigona and Apis ), but the patterns of size-related evolutionary change found within each of these genera are also found to exist in numerous other hymenopteran taxa. Increased body size in hymenopteran lineages is correlated with the following changes in wing morphology: (1) decreased relative stigma area, (2) distal extension of wing vein elements, (3) increased aspect ratio and (4) proximal shift in the centroid of wing area. The reverse is true for decreased size. The widespread allometric trends most likely result from adaptive change in wing morphology due to size-related changes in the physical properties impinging on the organism–principally the quality and magnitude of drag. The fact that similar wing morphologies among distantly related species can result from similarity in body size has important implications for the study of hymenopteran phylogeny, especially at lower taxonomic levels and when a high proportion of wing characters are employed.     

The pale brown allele in Cepaea nemoralis

The pale brown colour morph in Cepaea nemoralis appears to be determined by an allele at the C (colour) locus ( C ^{P B}). Pale brown is dominant to yellow, codominant with pink and recessive to dark brown. It is linked to the B locus (which controls the presence or absence of banding on the shell), but not to the U locus, which determines whether there is one band or five. In segregations of pale brown and yellow there is a significant deficiency of pale brown, suggesting that there are differences in viability between the morphs.     

Effects of low-chloride solutions on action potentials of sheep cadiac purkinje fibers

The rapid repolarization during phase 1 of the action potential of sheep cardiac purkinje fibers has been attributed to a time- and voltage-dependent chloride current. In part, this conclusion was based on experiments that showed a substantial slowing of phase 1 when larger, presumably impermeant, anions were substituted for chloride in tyrode’s solution. We have re- examined the electrical effects of low-chloride solutions. We recorded action potentials of sheep cardiac purkinje fibers in normal tyrode’s solution and in low-chloride solutions made by substituting sodium propionate, acetylglycinate, methylsulfate, or methanesulfonate for the NaCl of Tyrode’s solution. Total calcium was adjusted to keep calcium ion activity of test solutions equal to that of control solutions. Propionate gave qualitatively variable results in preliminary experiments; it was not tested further. Low-chloride solutions made with the other anions gave much more consistent results: phase 1 and the notch that often occurs between phases 1 and 2 were usually unaffected, and the action potential duration usually increased. The only apparent change in the resting potential was a transient 3-6 mV depolarization when low-chloride solution was first admitted to the chamber, and a symmetrical transient hyperpolarization when chloride was returned to normal. If a time- and voltage-dependent chloride current exists in sheep cardiac purkinje fibers, our results suggest that it plays little role in generating phase 1 of the action potential.     

Requirement of Ethylene for Growth of Callus and Somatic Embryogenesis in Medicago sativa L.

The role of ethylene in the growth of callus and somatic embryogenesisin Medicago sativa was examined. The application of 2,5-norbornadiene,a competitive inhibitor of ethylene action, during a 10 d inductionperiod to medium containing 2,4-D and kinetin inhibited thegrowth of callus but did not affect somatic embryogenesis, nordid it affect ethylene production during the induction stage.The exposure of tissue, incubated on differentiation medium,without hormones, to an atmosphere of 2,5-norbornadiene, inhibitedboth growth and embryo maturation and stimulated pigmentation.The inhibition of embryo maturation was observed even in thepresence of norbornadiene at a concentration which did not affectgrowth of tissue. It is suggested that the action of endogenous ethylene is necessaryfor the growth of the callus and embryo maturation. Key words: Medicago sativa, ethylene, callus growth, somatic embryogenesis     

A trap for capturing planktonic chironomid larvae

This paper describes the construction and field operation of a trap designed to investigate the movements of larval Chironomidae in the open water of lakes. Although the trap was designed to be multidirectional, with six trapping bottles, only two directional components, vertical and horizontal, could be distinguished. This led to examination of three bottles only during later field studies, namely bottle 1 facing into the current, bottle 5 facing the substrate and bottle 6 facing the surface of the lake. Some results are presented and trap operation and sampling efficiency discussed. A major advantage of the trap is its use as a long term accumulator of planktonic organisms as opposed to traditional spot sampling techniques which tend to miss the less numerous plankters.     

Parallel evolution in Marquesan partulid land snails

Partulid land snails of the genus Samoana inhabiting the Marquesas Islands of French Polynesia exist as two distinct types, the 'thick-shelled' and 'thin-shelled' species. The two types differ in size, shell-thickness, pigmentation of the shell and mantle, stickiness of the mucus, and length of the tentacles. A study of variation in allozymes indicates that the species form a monophyletic group, within which the differences between the two types have twice evolved independendy, once in the northern islands and at least once in the south. In the Society Islands the two suites of characters are found in both Partula and Samoana , where there is evidence of at least four other independent derivations of the two types. The thin-shelled species consistendy tend to occur at the higher altitudes (above 200 m). These cases of parallel evolution argue strongly that the complexes of associated characters have arisen through natural selection.     

A bioregional analysis of the distribution of rainforest cover,deforestation and degradation in Papua New Guinea

Papua New Guinea (PNG) is an extensively forested country. Recent research suggests that despite commencing a trajectory of deforestation and degradation later than many counties in the Asia–Pacific region, PNG is now undergoing comparable rates of forest change. Here we explore the bioregional distribution of changes in the forest estate over the period 1972–2002 and examine their implications for forest protection. This is undertaken through the development of a novel bioregional classification of the country based on biogeographic regions and climatic zones, and its application to existing forest cover and forest‐cover change data. We found that degradation and deforestation varied considerably across the 11 defined biogeographic regions. We report that the majority of deforestation and degradation has occurred within all the lowland forests, and that it is these forests that have the greatest potential for further losses in the near term. The largest percentage of total change occurred in the east of PNG, in the islands and lowlands of the Bismarck, D'Entrecasteaux, East Papuan Islands and in the South‐East Papua–Oro region. The only region with a significant highlands component to undergo deforestation at a comparable magnitude to the islands and lowland regions was the Huon Peninsula and Adelbert region. Significant changes have also occurred at higher elevations, especially at the interface of subalpine grasslands and upper montane forests. Lower montane forests have experienced proportionally less change, yet it is these forests that constitute the majority of forests enclosed within the protected area system. We find that protected areas are not convincingly protecting either representative areas of PNG's ecosystems, nor the forests within their borders. We conclude by suggesting a more expansive and integrated approach to managing the national forest estate.     

Using co-occurrence network structure to extract synonymous gene and protein names from MEDLINE abstracts

Background  

Text-mining can assist biomedical researchers in reducing information overload by extracting useful knowledge from large collections of text. We developed a novel text-mining method based on analyzing the network structure created by symbol co-occurrences as a way to extend the capabilities of knowledge extraction. The method was applied to the task of automatic gene and protein name synonym extraction.