DENSITY FLUCTUATIONS, GROWTH AND DRY TISSUE PRODUCTION OF HYDROCOCCUS BRAZIERI (TENISON WOODS, 1876) AND ARTHRITICA SEMEN (MENKE, 1843) IN PEEL INLET, WESTERN AUSTRALIA

Hydrococcus brazieri and Arthritica semen on a sandflat at Coodanup,Peel Inlet, Western Australia, accounted for 89.5% of totalmollusc numbers. The mean density of H. brazieri was 9487 m^–2and A. semen averaged 8105 m^–2. H. brazieri grew at 0.5mm month^–1 and reached maturity in 4 months; A. semengrew at 0.3 mm month^–1 and reached maturity in 6 months.Somatic production in the Peel-Harvey estuarine system was estimatedto be 0.5 g m^–2yr^–1for H. brazieri and 4.1 g m^–2yr^–1for A. semen. The positions of these two species in the estuarinefoodweb is discussed. (Received 26 June 1981;     

Neuroendocrinology of Osmoregulation in Decapod Crustacea

Experimental evidences for neuroendocrine control of osmoreregulationin decapod crustaceans are mounting. The eyestalk system, brainand thoracic ganglionic centers, and the pericardial organ appearto be involved in this control. Evidences based on experimentationwith eyestalk removal and the injection of extracts of neuroendocrinecenters are presented. Neuroendocrine extracts affect the movementsof salts and water in the gills, stomach, intestine and antennalglands. The pericardial organ material may affect osmoregulationby increasing rate of circulation and influencing salt movement. Three factors have been partially separated from CNS tissues.A factor of the freshwater crayfish, and other freshwater decapods,increases the influx of salt. Two factors from an estuarinecrab influence the movement of water, an acetone-soluble factorincreasing its influx and a water-soluble factor decreasinginflux and increasing efflux. The factors may be involved inthe adaptation of the animals to their osmotic environments. None of the factors have yet been identified in circulationnor in effector tissues. Future research must place specialemphasis on the identification of the CNS factors in circulationas well as in secretory cells and effector tissues to establishtheir true hormonal nature.     

Increasing tolerance to Cry1Ac cotton from cotton bollworm, Helicoverpa armigera, was confirmed in Bt cotton farming area of China

Abstract.  1. Changes in the frequency of Cry1Ac resistance genes and shifts in tolerance of cotton bollworm, Helicoverpa armigera , to the Cry1Ac toxin were assessed using bioassays of F₁ and F₂ offspring of isofemale lines from Anci County of Hebei Province (a multiple-crop system including corn, soybean, peanut, and Bt cotton) and Xiajin County of Shandong Province (an intensive Bt cotton planting area) in Northern China during 2002–2005.
2. A conservative analysis of the overall results indicated that there was a small increase in the frequency of major, non-recessive resistance genes over time.
3. The relative average development ratings [RADR – growth rate of a line on a Bt diet in proportion to the growth rate on a non-Bt (NBT) diet] of the bollworm larvae in F₁ tests increased significantly from year to year, indicating a gradual trend towards higher tolerance to Cry1Ac in the field populations.
4. There were also significant positive correlations between RADR of the lines in the F₁ generation and the RADR of their F₂ offspring, indicating that the tolerance was genetically based.
5. Quantitative genetic simulation analysis showed that resistance of H . armigera to Bt cotton in Xiajin could evolve to a high level in 11–15 years if no effective resistance management measures are carried out.     

Where are the glacial refugia in Europe? Evidence from pteridophytes

In this paper we demonstrate that, by investigating polyploid complexes in Asplenium, it is possible to locate the areas in Europe that are southern glacial rcfugia, and arc likely to have been so since the beginning of the Pleistocene during the consecutive cold and warm periods in Europe. Identification and conservation of these specific areas that serve as safe havens for plants, and perhaps animals, is of paramount importance for the maintenance of European biodiversity because Man's activities arc resulting in an ever-increasing loss of natural habitats and putting diversity at risk. The genus Asplenium in Europe comprises some 50 taxa: half of these are diploid while the other half arc polyploids derived from the diploids. All aspleniums in Europe are (small) rock ferns with high substrate specificity. Today, most of mainland Europe, Scandinavia and the British Isles has been colonized by polyploid Asplenium species, while the diploids that gave rise to these polyploids are distributed around (and more or less confined to) the Mediterranean Basin. In the tetraploids genetic variation is partitioned mostly between sites, whereas diploids show a high degree of genetic variation both within and between sites. The tctraploid taxa seem capable of single spore colonization via intragametophytic selfing, but the diploid taxa appear to be predominantly outbreeding. For most diploids at least two gametophytes, produced by different spores, have to be present to achieve fertilization and subsequent sporophyte formation for the successful colonization of a new site. This results in a slower rate of colonization. The formation of auto- and allopolyploid taxa from diploid communities appears to have been a recurrent and common feature in Europe. Minority cytotypc exclusion is likely to prevent the establishment of tetraploids within the diploid communities, but spores from tetraploids can establish populations outside the diploid communities. The differences between colonization abilities of tctraploid and ancestral diploid taxa, resulting from their different breeding systems, has prevented the merging and mingling of their ranges and led to the establishment of contact/ hybrid zones. This has resulted in the restriction of diploid populations to ancient glacial rcfugia and the colonization of the rest of Europe by polyploids. Mapping the current distribution of these diploid communities and comparing the genetic diversity within and between outbreeding diploid Asplenium taxa allows us to define the area, age and historical biogcography of these rcfugia and to assess their importance for present day genetic and species diversity in Europe.     

REPRODUCTION BY NORTHERN BOBWHITES IN WESTERN OKLAHOMA

Abstract: We studied northern bobwhites (Colinus virginianus) in western Oklahoma, USA, during the nesting seasons of 1992–2001. We obtained latitude-specific information on nesting biology and tested hypotheses on the cause of declines in clutch size with progression of the nesting season and on the phenological relation of first, second, and third nesting attempts. For pooled data on bobwhites alive during 15 April-15 September, 64 ± 6.5% of juvenile females (n = 56), 90 ± 10.0% of adult females (n = 9), 13 ± 4.1% of juveniles males (n = 68), and 41 ± 10.7% of adult males (n = 22) incubated ≥ 1 nest. Bobwhites that entered the reproduction period starting on 15 April (n = 229) accumulated 203 nesting attempts (male and female incubations), which translated to 1.7 attempts/hen for all hens that entered (n = 117) and 3.1 attempts/hen for hens that survived to 15 September (n = 65). Overall success for incubated nests (48 ± 2.8%, n = 331) was independent of sex-age class and nesting attempt (1, 2, 3), but it declined at a rate of 2.37%/year (95% CL = 1.10–3.64%/year) during the study. Clutch size declined by 1 egg for every 14–20 elapsed days in the nesting season and the rate of decline was independent of incubation attempt (1 or 2); this result suggests that lower clutch sizes later in the nest season were not necessarily a function of re-nesting. Ending of nest-incubation attempts (1, 2, 3) occurred within an 8-day period from 26 August-2 September. Our results implied that early-season nesting cover is a management concern and that high nest success is possible in the absence of nest predator suppression where abundant nest sites occur across the landscape.     

Habitat-Suitability Bounds for Nesting Cover of Northern Bobwhites on Semiarid Rangelands

ABSTRACT Northern bobwhite (Colinus virginianus) is a species for which extensive knowledge exists regarding its ecology, life history, and habitat. Although the qualitative aspects of bobwhite habitat have been described and known for many decades, researchers have neglected to characterize bobwhite habitat quantitatively (i.e., habitat selection). Thus, biologists have been capable of identifying components that compose bobwhite habitat but have only been able to speculate on how much of each component was necessary. We documented selection-avoidance behavior of nesting bobwhites in Brooks County, Texas, USA, during May-August, 2004–2005. We measured 5 vegetation features (i.e., nesting-substrate ht and width, suitable nest clump density, herbaceous canopy coverage, and radius of complete visual obstruction) at nest sites (n = 105) and at random points (n = 204). We used continuous selection functions to assess habitat use and identify bounds of suitability. Selection domains for nesting-substrate height and radius of complete visual obstruction were 16.9–31.2 cm and 1.05-4.35 m, respectively. Across all measurements, bobwhites selected for nest sites with a nesting-substrate width ≥22.4 cm, suitable nest-clump density ≥730 nest clumps/ha, and herbaceous canopy coverage ≥36.7%. This knowledge will provide an important foundation for managers to evaluate current nesting conditions on semiarid rangelands and provide a basis for habitat management aimed at creating suitable nesting habitat for bobwhites.     

THE LIMPET PATELLOIDA NIGROSULCATA ON INTERTIDAL PLATFORMS IN THE PERTH AREA, WESTERN AUSTRALIA

Patelloida nigrosulcata on intertidal platforms in the Perthmetropolitan area live on the backs of shells of living abalone,Haliotis roei. Over 95% of abalone 30 mm have one or more limpets,and there is a close relationship between abalone and limpetdensity. Sexes are usually separate in P. nigrosulcata, butabout 4% of the population in hermaphroditic. The animals spawntwice annually in winter (May–June) and spring (October–November).The reproductive periodicity of P. nigrosulata is compared toother published data on acmaeids. ^*Present address: Australian Institute of Marine Science, PMBNo. 3, Townsville, Queensland 4810, Australia (Received 23 March 1987;     

Genetic modelling: an analysis of a colour polymorphism in the Snow Goose (Anser caerulescens)

Previous studies of colour polymorphism in the Snow Goose [ Anser caerulescens ; failed to consider and reject alternative hypotheses to that of a single locus with incomplete dominance. Utilizing data from a long-term study of a wild population, we test the validity of these earlier results by considering two alternatives: (1) a single locus with multiple allelism and (2) a threshold polygenic system. Our analyses corroborate the original model, but emphasize the importance of testing all plausible hypotheses.     

Comparative Aspects of Energy Metabolism in Plant Trypanosomatids

ABSTRACT. The energy metabolism was compared among four different representatives of the genus Phytomonas isolated from different plants and localities: the sieve tubes of the hartrot-infected coconut palm in French Guyana, the latex fluid of Euphorbia hyssopifolia in French Guyana and the fruits of tomato and cherimoya in Spain. All four isolates produced acetate, ethanol, glycerol and glycine as metabolic end-products. In addition, small amount of succinate and pyruvate were excreted. Only minor quantitative differences were observed in the four isolates. Glycosomes, harboring the glycolytic enzymes, were present in all isolates. No evidence was found for an active involvement of the mitochondrion in metabolism. Respiration was insensitive to the classical inhibitors of the respiratory chain, such as antimycin and potassium cyanide, but inhibited by salicylhydroxamic acid. No evidence was found for the functioning of a citric-acid cycle. It is concluded that representative of this genus share the same highly active carbohydrate metabolism combined with a complete suppression of mitochondrial activity.     

Mathematical treatment of water movement in plant cells and tissue: a review

Abstract. Over the past three decades, many contributions have been made to the development of a mathematical basis for describing water transport in plant cells and tissue. This review paper attempts to summarize the more significant contributions and to outline the concepts upon which the various mathematical analyses are founded.
The paper itself is divided into three major sections. Section I deals with the quantitative water relations of single plant cells. Basic equations are developed which describe the water statics and water dynamics of such cells. Included is a discussion of the theory and methods for measuring the various parameters (permeabilities, cell wall elastic moduli, etc.) which enter into the development. The section closes with a presentation of circuit analog models for single plant cells.
Section II is devoted to a review and development of the water relations of plant tissues which contain numerous cells in series. Following a historical overview, various existing models are derived and physical tissue properties which enter the derivation are identified. The concept of 'local equilibrium' is discussed and circuit analog models for single cells are generalized and applied to several cells in series.
The final section contains two example applications of water transport theory as it applies to plant tissue. One application involves radial water movement in a soybean hypocotyl while the other deals with water transport in a growing root tip. A summary at the end of the section is largely devoted to a discussion of the limitations of mathematical models dial are presently available.