Nesting activity,breeding success and colony size for the Wedge-tailed Shearwater Puffinus pacificus on Heron Island

Abstract The Capricorn Group of islands in Australia's Great Barrier Reef Marine Park sustains one of the world's largest breeding populations of the Wedge-tailed Shearwater Puffinus pacificus. Heron Island, a 13.5 ha coral cay which supports tourist and research station leases as well as a national park, is the third largest nesting island in the group. Sample censuses of breeding burrows were conducted each year between 1985 and 1990 and a further survey was completed in 1993. These returned estimates of between 13 264±1387 and 16 337±1545 active burrows (Y±SE). Burrow densities within each of the habitats monitored showed no significant trends between years, although there were large differences in burrow density between habitats. There were roughly the same number of burrows in the developed (west) and national park (east) halves of the cay. A miniature video camera system (burrowscope), which allowed nesting chambers at the ends of burrows to be inspected, was used in 1989, 1990 and 1993. This demonstrated that around half the burrows were occupied by incubating birds. Variations were found in the distribution of incubating birds between habitats, although this did not remain constant between the years. In the 1993 season, breeding activity was traced from the burrow establishment to fledging stage. Fifty-one per cent of burrows were used for breeding (eggs laid), 77% of eggs hatched and 80% of chicks produced a fledgling. Overall breeding success for the island was estimated at 61%. In 1993 the area designated as Buildings was found to have significantly lower hatching success compared with natural habitats. Most mortality occurred at the egg stage; however, in the Fringe habitat, mortality was highest at the chick stage. Previous surveys have estimated the breeding population from burrow counts. It now appears that only about 30% of such burrows produce fledglings.     

THE CONTROL OF SEXUAL MORPHOGENESIS IN THE ASCOMYCOTINA

(1) A series of factors controls sexual morphogenesis in the Ascomycotina, a process involving the formation of novel structures such as ascocarps (fruit bodies) and asci (sacs containing spores) during sexual reproduction. (2) Environmental and genetic factors must be correct before Ascomycetes may sexually reproduce. Compatibility in many heterothallic species is under polygenic control, with the mating type loci and also other genetic factors determining the productivity of sexual crosses. (3) Classical genetic studies have shown that sexual morphogenesis involves the expression of a series of developmentally regulated genes, and this has been confirmed by recent molecular studies which have demonstrated changes in patterns of mRNA and protein synthesis during ascocarp formation. (4) Hyphal differentiation leading to the formation of mature fruit bodies occurs in response to a series of signals, which include various physical and chemical factors. (5) Chemical sex factors have been identified which are believed to have important regulatory or nutritional roles in sexual morphogenesis. These include the following. (a) Diffusible sex hormones which may regulate developmental switching between asexual and sexual modes of reproduction, including (i) pheromones involved with the induction of gametangia and gamete attraction, and (ii) sex morphogens involved with triggering particular stages of fruit body formation. (b) Sexual growth substances which are required as nutrients, and may be precursors for the production of sex hormones, or metabolites used in the synthesis of novel sexual structures. Most of these sex factors are lipids. (6) Certain sex morphogens and sexual growth substances have been shown to exhibit activity in a variety of fungal species, suggesting that fungi of related phylogenetic descent may utilize similar metabolites or signalling factors during sexual reproduction. (7) Phenoloxidase enzymes may catalyse hyphal aggregation in developing fruit bodies. (8) Initial stages of ascocarp development may occur independently of the events of the sexual cycle. However, a link(s) with the functional ascogenous hyphae is needed for the formation of morphologically mature ascocarps. (9) Suitable environmental conditions are sufficient to trigger sexual morphogenesis in homothallic Ascomycetes. However, an extra level of control is present in heterothallic species, with a compatible partner required to complete sexual reproduction. This may be partly because novel regulatory products, formed by the combined action of the mating type loci of different partners, are required for further ascocarp development. (10) Further research is required to identify more fungal chemical sex factors and to determine the role of environmental stress in controlling sexual morphogenesis, and how this may be related to temporal patterns in the expression of mating type genes.     

The expression of resistance to powdery mildew infection in winter wheat cultivars. II. Adult plant resistance

Resistance to powdery mildew infection was compared in 18 winter wheat cultivars under field conditions in three seasons, 1977 to 1979. In each year, natural infection occurred from populations of Erysiphe graminis f. sp. tritici containing host-specific pathogenicity characters matching identified cultivar resistance. Leaves, ears and stems were assessed separately. The expression of resistance in leaves appeared to be independent of that in ears. There were few consistent differences between cultivars in stem infection. Resistance in adult leaves did not necessarily correspond with that in seedling leaves; resistance in ears did not appear to be correlated with plant height. Quantitative differences between cultivars having the same identified resistance characters occurred in both leaves and ears; Flinor, Avalon and Bounty were most resistant on leaves whereas Iona, Wizard and Bounty were most resistant on ears. Differences in background resistance were considered to be responsible for these observations.     

Diet segregation between two colonies of little penguins Eudyptula minor in southeast Australia

We studied foraging segregation between two different sized colonies of little penguins Eudyptula minor with overlapping foraging areas in pre‐laying and incubation. We used stomach contents and stable isotope measurements of nitrogen (δ¹⁵N) and carbon (δ¹³C) in blood to examine differences in trophic position, prey‐size and nutritional values between the two colonies. Diet of little penguins at St Kilda (small colony) relied heavily on anchovy while at Phillip Island (large colony), the diet was more diverse and anchovies were larger than those consumed by St Kilda penguins. Higher δ¹⁵N values at St Kilda, differences in δ¹³C values and the prey composition provided further evidence of diet segregation between colonies. Penguins from each colony took anchovies from different cohorts and probably different stocks, although these sites are only 70 km apart. Differences in diet were not reflected in protein levels in the blood of penguins, suggesting that variation in prey between colonies was not related to differences in nutritional value of the diet. Anchovy is currently the only available prey to penguins throughout the year and its absence could have a negative impact on penguin food supply, particularly at St Kilda where the diet is dominated by this species. While it is difficult to establish whether diet segregation is caused by inter‐ or intra‐colony competition or spatial differences in foraging areas, we have shown that colonies with broadly overlapping foraging ranges could have significant differences in trophic position, diet composition and prey size while maintaining a diet of similar nutritional value.     

Assessment of long-term changes in habitat availability for Arctic charr (Salvelinus alpinus) in a temperate lake using oxygen profiles and hydroacoustic surveys

1. Hydroacoustics (2002–04) and long‐term oxygen data (1969–2004) have been used in conjunction to examine the habitat of Arctic charr in the north and south basins of Windermere, U.K., a temperate lake subjected to cultural eutrophication and subsequent nutrient management. 2. Since 1969 there has been a gradual decline in the oxygen concentration in the bottom waters of both basins of 0.03–0.04 mg L^?1year^?1, resulting in up to 43% of the volume of the south basin having an oxygen concentration <5 mg L^?1 in the early autumn. 3. Hydroacoustic data indicate that most Arctic charr routinely avoid the upper 10 m of the water column irrespective of temperature, with the implication that an observed gradual warming of the lake has not yet directly impacted upon their habitat. 4. In recent years there has been a behavioural response of the Arctic charr population to migrate vertically to avoid oxygen concentrations <2.3–3.1 mg L^?1. Further, the depth of the lower bound of the Arctic charr population is shown to be highly correlated with the deep water oxygen concentration throughout the year prior to autumnal overturn.     

Plasticity in photosynthetic response to nutrient supply of seedlings from a mixed conifer‐angiosperm forest

Abstract We measured the plasticity of the response of photosynthesis to nutrient supply in seedlings of the dominant four conifer and broadleaved angiosperm tree species from an indigenous forest in South‐westland, New Zealand. We hypothesized that the response of conifers to differing nutrient supply would be less than the response for the angiosperms because of greater adaptation to low fertility conditions. In Prumnopitys ferruginea (D. Don) de Laub. the maximum velocity of electron transport, J_max, doubled with a 10‐fold increase in concentration of nitrogen supply. In Dacrydium cupressinum Lamb. the maximum velocity of carboxylation, V_cmax, doubled with a 10‐fold increase in phosphorus supply. In contrast, photosynthetic capacity for the angiosperm species Weinmannia racemosa L.f. was affected only by the interaction of nitrogen and phosphorus and photosynthetic capacity of Metrosideros umbellata Cav. was not affected by nutrient supply. The response of the conifers to increasing availability of nutrient suggests greater plasticity in photosynthetic capacity, a characteristic not generally associated with adaptation to soil infertility, thus invalidating our hypothesis. Our data suggest that photosynthetic response to nutrient supply cannot be broadly generalized between the two functional groups.     

NEW CRINOIDS (ECHINODERMATA) FROM THE LLANDOVERY (LOWER SILURIAN) OF THE BRITISH ISLES

Abstract:  British Llandovery crinoids remain poorly known. Three species are documented herein that were originally described, but not published, by W. H. C. Ramsbottom. Clematocrinus ramsbottomi Fearnhead sp. nov. (Tortworth Inlier, Gloucestershire; Telychian) has a heteromorphic column, N434243414342434, radices directed away from the crown, and ten long, uniserial arms with a pustular aboral sculpture and long, slender pinnules. Clematocrinus spp. are widely distributed in the Silurian of England. Ptychocrinus mullochillensis Fearnhead and Donovan sp. nov. (Girvan district, Strathclyde; Rhuddanian) is the second report of this Upper Ordovician–Lower Silurian genus from outside North America. Although incompletely known, this species is distinguished by its hidden infrabasals, 20 arms and sunken interbrachial plates with a strongly stellate sculpture. Petalocrinus bifidus (Bather MS) Donovan and Fearnhead sp. nov. (Woolhope Inlier, Herefordshire; Telychian) is locally common enough to give its name to a mappable lithostratigraphic unit, the Petalocrinus Limestone. Unlike other Petalocrinus species known from the Silurian of China, northern Europe and North America, the fused arms of P. bifidus are divided in two by a proximal adoral ridge and an associated distal notch. Unlike extant crinoids, Petalocrinus probably lived as a rheophobe; the fused arms may have acted to deter predators.     

Post-hatching environment contributes greatly to phenotypic variation between two populations of the Australian garden skink, Lampropholis guichenoti

While recent experimental work on a variety of reptile species has demonstrated that incubation temperature influences hatchling phenotypes, the biological significance of such phenotypic variation remains unclear. Incubation temperature may exert significant long-term phenotypic effects. Alternatively, such influences may be temporary, or negligible relative to effects induced by genetic factors, or by the environmental conditions experienced after hatching. Even if incubation temperature exerts long-term effects on phenotype, this might occur indirectly (by influencing hatching dates) rather than by direct modifications of developmental processes. We quantified the influences of the source population, incubation temperature and rearing environment, on the phenotype of the Australian garden skink (Lampropholis guichenoti) from populations that differ in nest temperature and phenotype. Intcrpopulation differences in the phenotypes of young lizards were found to be a product of all three factors. However, the long-term effects of both population and incubation temperature operated indirectly (through variation in the date of hatching) rather than directly (through genetic or developmental factors). That is, once all temporal effects were removed, the only discernible influence on juvenile phenotypes was their rearing environment. Thus, some of the most important influences on lizard phenotypes may operate via modifications of hatching date.     

Plant 5.8S RNA is a Component of 80S but not 70S Ribosomes

LIVING organisms contain two classes of ribosomes that can be distinguished by differences in their size, the molecular weights of their constituent high molecular weight RNAs and their sensitivity to certain inhibitors of protein synthesis. The ribosomes of one type occur in bacteria, blue-green algae and chloroplasts. They have sedimentation coefficients of approximately 70S^1,2, contain RNA with molecular weights of about 1.1 × 10⁶ (23S) and 0.56 × 10⁶ (16S)³ and their activity is inhibited by chloramphenicol^4,5, lincomycin and spectinomycin⁶. The ribosomes of the other type are found in the cytoplasm of animal and plant cells, have sedimentation coefficients of 80S^1,2, contain RNA with molecular weights of 1.3?1.75 × 10⁶ (25–28S) and 0.7 × 10⁶ (18S)³ and are prevented from functioning by cycloheximide⁴.     

Aspects of crinoid palaeontology of the North Esk Inlier,Scotland (Silurian,Llandovery, Telychian)

Abstract: The described fauna of well‐preserved Llandovery (Telychian) echinoderms from the North Esk Inlier, including six crinoids, one echinoid and seven starfish species, is mainly allochthonous. Most of these taxa are known only from starfish beds, channel fill deposits probably representing submarine mass flows and preserving a biota probably derived from elsewhere, presumably shallower water. Only one crinoid species, Pisocrinus cf. campana Miller, is recognized as a common fossil away from the starfish beds and is a biostratigraphic marker for the base of the Wether Law Linn Formation, forming part of the Skenidioides‐Cyrtia Association. Crinoid columnals preserved perpendicular to bedding (that is, in putative life position) in Lamont’s bivalve bed, Deerhope Formation, are tentatively interpreted as being in situ by comparison with a similar occurrence in the Silurian of Arisaig, Nova Scotia. Two new species of crinoid are described, the cladid Dendrocrinus? sp. and the columnal morphospecies Pentagonocyclicus (col.) lamonti sp. nov.