THE GEOTROPIC RESPONSE IN ASTERINA

Upon a surface inclined at angle α Asterina gibbosa orients upward during negatively geotropic creeping until the average angle (θ) of the path is such that Δ sin θ/Δ sin α = const. This is true also in positively geotropic movement. The direction of orientation may be temporarily reversed by mechanical disturbance. The variation of θ is greater at low slopes. Tests with directed impressed pulls, due to an attached cork float, show that the pull upon the tube feet is of primary consequence for the determination of θ. When the component of gravitational pull in the direction of movement reaches a fraction of the total pull which is proportional to the gravitational vector parallel to the surface, the laterally acting component is ineffective. On this basis, it follows that Δ sin θ/Δ sin α = const.     

INTERPOPULATION KARYOTYPE DIFFERENCES IN AUSTRALIAN IRIDOMYRMEX OF THE "DETECTUS" GROUP (HYMENOPTERA: FORMICIDAE: DOLICHODERINAE)

i
A haploid number of nine was found in each of three population samples of the " detectus" group of the ant genus Iridomyrmex, but differences occurred in the morphology of the three smallest chromosomes, the remaining six large metacentrics being similar throughout.     

EVIDENCE FOR SEVERAL SIBLING BIOLOGICAL SPECIES CENTRED ON MYRMECZA PZLOSULA (F. SMITH) (HYMENOPTERA: FORMICIDAE)

Abstract
The behaviour in laboratory bioassays of male codling moth, Cydia pomonella (L.), when presented with various mixtures of ( E, E )-8, 10-dodecadienol and the 2 saturated alcohols, dodecanol and tetradeconol, shows that the presence of all 3 compounds is necessary in order to obtain a response equivalent to that elicited by the natural pheromone.     

Meta-population structure in a coral reef fish demonstrated by genetic data on patterns of migration,extinction and re-colonisation

Background  

Management strategies for coral reefs are dependant on information about the spatial population structure and connectivity of reef organisms. Genetic tools can reveal important information about population structure, however, this information is lacking for many reef species. We used a mitochondrial molecular marker to examine the population genetic structure and the potential for meta-population dynamics in a direct developing coral reef fish using 283 individuals from 15 reefs on the Great Barrier Reef, Australia. We employed a hierarchical sampling design to test genetic models of population structure at multiple geographical scales including among regions, among shelf position and reefs within regions. Predictions from island, isolation-by-distance and meta-population models, including the potential for asymmetric migration, local extinction and patterns of re-colonisation were examined.     

Atrial natriuretic peptides in man

Research on the physiological role of atrial peptides in man is limited, and the potential for these peptides, or more stable analogues, in therapeutics is uncertain. It is clear, however, that plasma levels of immunoreactive atrial natriuretic peptide (IR-ANP) are increased in volunteers taking a high sodium diet, and are elevated in patients with heart failure, chronic renal failure, and primary aldosteronism. There is suggestive evidence that IR-ANP levels are increased also in essential hypertension, although overlap with normotensives is considerable. Injection or infusion of atrial peptides into man results in a diuresis, an increased output of urine electrolytes, a fall in blood pressure and a rise in heart rate, suppression of aldosterone and sometimes of renin also, and stimulation of norepinephrine. In essential hypertensives, urinary effects may be greater than in normotensives. Heart failure patients show a rise in cardiac output and falls in both systemic and pulmonary arterial pressure. Over the next few years and especially if specific antagonists can be developed, the physiologic and pathophysiologic roles of atrial peptides in normal man and in clinical disorders should be clarified. It is possible that stable analogues of atrial peptides will find a place in the treatment of cardiac failure, renal failure, and perhaps hypertension.     

Hierarchical genetic structure of the introduced wasp Vespula germanica in Australia

The wasp Vespula germanica is a highly successful invasive pest. This study examined the population genetic structure of V. germanica in its introduced range in Australia. We sampled 1320 workers and 376 males from 141 nests obtained from three widely separated geographical areas on the Australian mainland and one on the island of Tasmania. The genotypes of all wasps were assayed at three polymorphic DNA microsatellite markers. Our analyses uncovered significant allelic differentiation among all four V. germanica populations. Pairwise estimates of genetic divergence between populations agreed with the results of a model-based clustering algorithm which indicated that the Tasmanian population was particularly distinct from the other populations. Within-population analyses revealed that genetic similarity declined with spatial distance, indicating that wasps from nests separated by more than approximately 25 km belonged to separate mating pools. We suggest that the observed genetic patterns resulted from frequent bottlenecks experienced by the V. germanica populations during their colonization of Australia.     

Purification of plant hormone extracts by gel permeation chromatography

Gel permeation chromatography on porous polystyrene beads has been adapted for the purification of plant extracts prior to analysis for plant hormones. The retention characteristics of gibberellins, indoleacetic acid, cytokinins and abscisic acid are presented along with chromatograms of some typical plant extracts.     

A formal investigation of Cultural Selection Theory: acoustic adaptation in bird song

The greatest challenge for Cultural Selection Theory lies is the paucity of evidence for structural mechanisms in cultural systems that are sufficient for adaptation by natural selection. In part, clarification is required with respect to the interaction between cultural systems and their purported selective environments. Edmonds et al. have argued that Cultural Selection Theory requires simple, conclusive, unambiguous case studies in order to meet this challenge. To that end, this paper examines the songs of the Rufous-collared Sparrow, which seem to exhibit cultural adaptations minimizing signal degradation relative to local environments. Specifically, the more forested the habitat, the more the tail end of the song resembles a whistle rather than a trill; yet, variation in song is uncorrelated with genetic variation. This paper explores the mechanisms responsible for these putative acoustic adaptations through a series of computer simulations. The main point of this research is not to test this model, but to demonstrate that models of this type have the resources to meet the in-principle objections that have been raised against Cultural Selection Theory. This research lends much-needed empirical support to Cultural Selection Theory by clarifying the nature of the interaction between culture and environment. It also contributes to evolutionary theory by clarifying the scope and limits of adaptation by natural selection.