Australia's marine biogeography revisited: Back to the future?

The recognition of broad biogeographic provinces provides an important framework for ecological and conservation biological research. Marine biologists have long recognized distinct biogeographic provinces in southern Australia, primarily on the basis of qualitative differences in intertidal species assemblages. Here we provide an a priori test for these traditional eastern (Peronian), western (Flindersian) and south‐eastern (Maugean) provinces. Specifically, we analyse distributional data for approximately 1500 algal species using the newly available Australian Virtual Herbarium, an online database of herbarium specimens. Our quantitative algal analyses across southern Australia identify three distinct biogeographic assemblages, consistent with traditional qualitative provinces. We argue that these broad provinces provide a highly effective framework for understanding and managing Australia's marine biodiversity. In particular, biogeographic provinces provide a regional framework for integrating the ongoing discovery of biological variation at finer scales. More broadly therefore we recommend that biologists undertake quantitative analyses to test provincial biogeographic boundaries around the globe.     

Characterization of the Germination Responses to Temperature of Lettuce (Lactuca sativa L.) Achenes

Germination tests were done on 23 cultivars of lettuce (Lactucasativa L.) comprising a variety of different morphological formsselected for cultivation at various seasons. Significant differences at the upper limit of temperature tolerancewere found between different cultivars: maximum temperaturesfor 50 per cent germination ranged from 23 to 32 °C, andsusceptibility to the induction of secondary dormancy by hightemperatures varied widely from one cultivar to another. Nocorrelations were established between germination responsesand heading type, achene colour or growing season The germination responses of all cultivars at temperatures fromjust above 0 to 20 °C were closely similar and results froma large number of experiments were used to produce a standardgermination reference curve foti culvars of L. sativa. Departfuresrom this curve were found to arise predominantly from variationsin seed quality or test conditions rather than from the genotypeof the cultivar. Detailed comparisons of germination at all possible combinationsof alternate and constant day/night temperatures are presentedfor two cultivars. One with relatively high tolerance to high-temperatureinducedinhibition, the other with low tolerance. The results are discussed in relation to the original distributionof the species as a wild plant and its history of cultivationby man. Lactuca sativa L., Lettuce, achene germination, temperature response     

Incidence, importance and virulence of Puccinia hordei on barley in New Zealand

Brown rust of barley (Puccinia hordei) is widespread in New Zealand and causes crop losses in some years. The cultivars presently grown lack adequate genetic resistance but a highly resistant line has been produced. Twelve different virulence combinations were identified in the pathogen population using the Welsh differential lines; there were differences between North Island and South Island isolates; and no virulence was observed for resistance conferred by factors Pa 3 and Pa 7.     

The influence of stream invertebrate composition at neighbouring sites on local assemblage composition

1. The composition of freshwater invertebrate assemblages at a location is determined by a range of physico‐chemical and biotic factors in the local environment, as well as larger‐scale spatial factors such as sources of recruits. We assessed the relative importance of the species composition of local neighbourhoods and proximal environmental factors on the composition of invertebrate assemblages. 2. Macroinvertebrate assemblages were sampled at 188 running‐water sites in the catchment of the River Rede, north‐east England. A total of 176 species were recorded. 3. Environmental data, in the form of 13 biotic and abiotic measurements that described stream physical structure, aquatic vegetation and water characteristics, were recorded for each site. Detrended correspondence analysis was then used to simplify nine of these stream environmental variables to create an index of stream structure. 4. The species composition of the invertebrate assemblages was related to the environmental variables, using an information theoretic approach. The impact of the species composition of neighbouring sites on each site was determined using Moran's I and autoregressive modelling techniques. 5. Species composition was primarily associated with water pH and stream structure. The importance of the species composition of neighbouring sites in determining local species assemblages differed markedly between taxa. The autoregressive component was low for Coleoptera, intermediate for Trichoptera and Plecoptera, and high for Ephemeroptera. 6. We hypothesise that the observed differences in the autoregressive component amongst these orders reflects variation in their dispersal abilities from neighbouring sites.     

The Uptake of Inorganic Ions by Plant Leaves

A technique for estimating the gross uptake of ions by plantleaves is described. Uptake of strontium-89 and caesium-137from droplets applied to plant leaves was greatly affected bythe humidity of the air, the effect being markedly dependenton the initial concentration of the solution. Uptake was greaterin light than in darkness; the effect of temperature was relativelysmall. The percentage uptake of the nuclides was reduced only to arelatively small extent as the concentration of carrier ionwas increased. This was in marked contrast to the situationwhen leaves were fully immersed in solution. ¹³⁷Cs was takenup to a greater extent than iodine, phosphate, or sulphate.The role of exchange and of fixed negative charges in uptakeis discussed.