Fossil biotas from the Okanagan Highlands, southern British Columbia and northeastern Washington State: climates and ecosystems across an Eocene landscape

The late Early to early Middle Eocene Okanagan Highlands fossil sites, spanning -1000 km north-south (northeastern Washington State, southern British Columbia) provide an opportunity to reconstruct biotic communities across a broad upland landscape during the warmest part of the Cenozoic. Plant taxa from these fossil sites are characteristic of the modern eastern North American deciduous forest zone, principally the mixed mesophytic forest, but also include extinct taxa, taxa known only from eastern Asian mesothermal forests, and a small number of taxa restricted to the present-day North American west coast coniferous biome. In this preliminary report, paleoclimates and forest types are reconstructed using collections from Republic in Washington State, USA., and Princeton, Quilchena, Falkland, McAbee, Hat Creek, Horsefly, and Driftwood Canyon in British Columbia, Canada. Both leaf margin analysis (LMA) and quantitative bioclimatic analysis of identified nearest living relatives of megaflora indicated upper microthermal to lower mesothermal moist environments (MAT -10-15 degrees C, CMMT > 0 degrees C, MAP > 100 cm/year). Some taxa common to most sites suggest cool conditions (e.g., Abies, other Pinaceae; Alnus, other Betulaceae). However, all floras contain a substantive broadleaf deciduous element (e.g., Fagaceae, Juglandaceae) and conifers (e.g., Metasequoia) with the bioclimatic analysis yielding slightly higher MAT than LMA. Thermophilic (principally mesothermal) taxa include various insects, the aquatic fern Azolla, palms, the banana relative Ensete, taxodiaceous conifers, Eucommia and Gordonia, taxa which may have occurred near their climatic limits. The mixture of thermophilic and temperate insect and plant taxa indicates low-temperature seasonality (i.e., highly equable climate).

Variation in cervical cancer screening by region, socio-economic, migrant and Indigenous status in women in New South Wales

The purpose of this study was to estimate the extent of association of cervical screening in NSW women with socio-economic status (SES), rurality, and proportions of non-English speaking background (NESB) and Indigenous status. Data on women who had at least one Pap test over two years (January 1998-December 1999) were obtained from the NSW Pap test Register. Each local government area (LGA) was allocated to categories of population proportions of NESB and Indigenous status, a rurality classification based on population density and remoteness, and to an SES quintile. The odds ratios (OR) of having a Pap test were estimated and confounding adjusted by multiple logistic regression analysis. Implied Pap test rates in urban NESB and in rural Indigenous women were estimated from the modelled estimates. The adjusted OR for a Pap test in large rural centres (1.14) was significantly higher than those for metropolitan or capital city residents (0.9 and 1.0 respectively). Adjusted OR for a Pap test in other rural centres (0.73) and other remote areas (0.64) were significantly lower than those for metropolitan or capital city residents. In urban populations the lowest OR were in areas with both low SES and high proportion of NESB. The lowest OR for Pap screening in rural populations occurred in the most remote areas with the highest proportion of Indigenous women. For urban NESB women the biennial Pap test rate was estimated as 50%, and for rural Indigenous women 29%, compared with the NSW average of 59%.

Fossil trees in ancient fluvial channel deposits: evidence of seasonal and longer-term climatic variability

It has been established that large numbers of certain trees can survive in the beds of rivers of northeastern Australia where a strongly seasonal distribution of precipitation causes extreme variations in flow on both a yearly and longer-term basis. In these rivers, minimal flow occurs throughout much of any year and for periods of up to several years, allowing the trees to become established and to adapt their form in order to facilitate their survival in environments that experience periodic inundation by fast-flowing, debris-laden water. Such trees (notably paperbark trees of the angiosperm genus Melaleuca) adopt a reclined to prostrate, downstream-trailing habit, have a multiple-stemmed form, modified crown with weeping foliage, development of thick, spongy bark, anchoring of roots into firm to lithified substrates beneath the channel floor, root regeneration, and develop in flow-parallel, linear groves. Individuals from within flow-parallel, linear groves are preserved in situ within the alluvial deposit of the river following burial and death. Four examples of in situ tree fossils within alluvial channel deposits in the Permian of eastern Australia demonstrate that specialised riverbed plant communities also existed at times in the geological past. These examples, from the Lower Permian Carmila Beds, Upper Permian Moranbah Coal Measures and Baralaba Coal Measures of central Queensland and the Upper Permian Newcastle Coal Measures of central New South Wales, show several of the characteristics of trees described from modern rivers in northeastern Australia, including preservation in closely-spaced groups. These properties, together with independent sedimentological evidence, suggest that the Permian trees were adapted to an environment affected by highly variable runoff, albeit in a more temperate climatic situation than the modem Australian examples. It is proposed that occurrences of fossil trees preserved in situ within alluvial channel deposits may be diagnostic of environments controlled by seasonal and longer-term variability in fluvial runoff, and hence may have value in interpreting aspects of palaeoclimate from ancient alluvial successions. (C) 2001 Elsevier Science B.V. All rights reserved.

The application of electron microscopy and microanalysis in conjunction with organic petrology to further the understanding of organic-mineral association: examples from Mount Isa and McArthur Basins, Australia

Organic petrology supported by electron microscopical and micro-analytical techniques was applied to organic matter in Proterozoic sediments to better understand hydrothermal processes responsible for ore-grade mineralisation. It was shown that organic maturation was not only closely linked to the geological history of the sediments, but also highlighted heat transfer by convection as differentiated from conduction solely through sediment burial and step-wise subsidence. Water-rock ratios effect organic maturation in hydrothermal systems, and erratic reflectance profiles are indicators of convective heat transfer. Identification and characterisation of organic materials in terms of source rock and migrated hydrocarbons was shown to be a powerful tool in reconstructing the thermal history of sediments, identifying hydrothermal episodes, fluid pathways and heat source in the northern Australian Proterozoic basins. Higher reflectance of organic matter towards the central parts of the Mount Isa Basin and some of the most northerly parts point to proximity to higher heat flow at times, in contrast to relatively low temperatures prevailing in the western parts of the basin, next to the Murphy Inlier. A close correlation shown between peak organic reflectance values and super-sequence boundaries farther highlighted the valuable information to be gained from organic petrology, by allowing the separation of processes responsible for metal dissolution and transportation from those inducing precipitation. (C) 2001 Elsevier Science B.V All rights reserved.

Adaptation of rainbow fish to lake and stream habitats

Fish occupy a range of hydrological habitats that exert different demands on locomotor performance. We examined replicate natural populations of the rainbow fishes Melanotaenia eachamensis and M. duboulayi to determine if colonization of low-velocity (lake) habitats by fish from high-velocity (stream) habitats resulted in adaptation of locomotor morphology and performance. Relative to stream conspecifics, lake fish had more posteriorly positioned first dorsal and pelvic fins, and shorter second dorsal fin bases. Habitat dimorphism observed between wild-caught fish was determined to be heritable as it was retained in M. eachamensis offspring raised in a common garden. Repeated evolution of the same heritable phenotype in independently derived populations indicated body shape divergence was a consequence of natural selection. Morphological divergence between hydrological habitats did not support a priori expectations of deeper bodies and caudal peduncles in lake fish. However, observed divergence in fin positioning was consistent with a family-wide association between habitat and morphology, and with empirical studies on other fish species. As predicted, decreased demand for sustained swimming in takes resulted in a reduction in caudal red muscle area of lake fish relative to their stream counterparts. Melanotaenia duboulayi lake fish also had slower sustained swimming speeds (U-crit) than stream conspecifics. In M. eachamensis, habitat affected U-crit of males and females differently. Specifically, females exhibited the pattern observed in M. duboulayi (lake fish had faster U-crit than stream fish), but the opposite association was observed in males (stream males had slower Ucrit than lake males). Stream M. eachamensis also exhibited a reversed pattern of sexual dimorphism in U-crit (males slower than females) relative to all other groups (males faster than females). We suggest that M. eachamensis males from streams responded to factors other than water velocity. Although replication of muscle and U,,it phenotypes across same habitat populations within and/or among species was suggestive of adaptation, the common garden experiment did not confirm a genetic basis to these associations. Kinematic studies should consider the effect of the position and base length of dorsal fins.

The coincidence of thrips and dispersed pollen in PNRSV-infected stonefruit orchards - a precondition for thrips-mediated transmission via infected pollen

Recent laboratory studies have demonstrated that Prunus necrotic ringspot virus (PNRSV) (family Bromoviridae) can be readily transmitted when thrips and virus-bearing pollen are placed together on to test plants. For this transmission mechanism to result in stonefruit tree infection in the field, PNRSV-bearing pollen must be deposited onto surfaces of stonefruit trees on which thrips also occur. In a previous paper, we demonstrated that almost all pollen in a PNRSV-infected Japanese plum orchard in southeastern Queensland was deposited onto flowers, whereas few grains occurred on leaves and none on stems. Here, we present results of our investigation of thrips species composition, distribution and abundance on stonefruit trees in the same study area as our previous pollen deposition study. We collected a total of 2010 adult thrips from 13 orchards during the 1989, 1991 and 1992 flowering seasons of which all but 14 were in the suborder Terebrantia. Most (97.4%) terebrantian thrips were of three species, Thrips imaginis, Thrips australis and Thrips tabaci. Thrips tabaci as well as species mixtures that included T imaginis, T australis and T tabaci have been shown to transmit PNRSV via infected pollen in laboratory tests. Adult thrips were frequently collected from flowers but rarely from leaves and never from stems. Large and significant differences in numbers of T imaginis, T australis and T tabaci adults in flowers occurred among orchards and between seasons. No factor was conclusively related to thrips numbers but flowers of late-flowering stonefruit varieties tended to hold more thrips than those of early-flowering varieties. Our results indicate that the common thrips species present on stonefruit trees in the Granite Belt are also ones previously shown to transmit PNRSV via infected pollen in the laboratory and that these thrips are concentrated in stonefruit flowers where most stonefruit pollen is deposited. These results contribute to mounting circumstantial evidence that stonefruit flowers may be inoculated with PNRSV via an interaction of thrips with virus-bearing pollen and that this transmission mechanism may be an important cause of new tree infections in the field.

Broadening conceptions of curriculum for young people: Reports from three student-teachers on exchange

Research reports prepared by three Australian preservice teachers--Paula Shaw, Chris Sharp and Scott McDonald--undertaking their teacher education practicum in Canada, form the basis of this paper. The reports provide critical insights into three aspects of education for young people in both Canada and Australia. They also provide critical insight into the ways in which a practicum research project, along with the opportunities afforded through an international experience, enabled the preservice teachers to broaden their understanding of the curriculum for young people, of issues relevant to the diverse needs of young people, and of themselves and their priorities as teachers. The preservice teachers investigated three topics: attempts to reduce homophobia in schools; the presence or absence of Aboriginal content in the school curricula in British Columbia and Queensland; and "schools-within-schools" as a means to meet the needs of diverse student populations. Linda Farr Darling from the University of British Columbia provides a response to the three reports.

Bajo de la Alumbrera copper-gold deposit: Stable isotope evidence for a porphyry-related hydrothermal system dominated by magmatic aqueous fluids

Alteration zones at the gold-rich Bajo de la Alumbrera porphyry copper deposit in northwestern Argentina are centered on several porphyritic intrusions. They are zoned from a central copper-iron sulfide and gold-mineralized potassic (biotite-K-feldspar +/- quartz) core outward to propylitic (chlorite-illite-epidote-calcite) assemblages. A mineralized intermediate argillic alteration assemblage (chlorite-illite +/- pyrite) has overprinted the potassic alteration zone across the top and sides of the deposit and is itself zoned outward into phyllic (quartzinuscovite-illite +/- pyrite) alteration. This study contributes new data to previously reported delta(18)O and delta D compositions of fluids responsible for the alteration at Bajo de la Alumbrera, and the data are used to infer likely ore-forming processes. Measured and calculated delta(18)O and delta D values of fluids (+8.3 to +10.2 and -33 to -81 parts per thousand, respectively) confirm a primary magmatic origin for the earliest potassic alteration phase. Lower temperature potassic alteration formed from magmatic fluids with lower delta D values (down to -123 parts per thousand). These depleted compositions are distinct from meteoric water and consistent with degassing and volatile exsolution of magmatic fluids derived from an underlying magma. Variability in the calculated composition of fluid associated with potassic alteration is explained in terms of phase separation (or boiling). if copper-iron sulfide deposition occurred during cooling (as proposed elsewhere), this cooling was largely a result of phase separation. Magmatic water was directly involved in the formation of overprinting intermediate argillic alteration assemblages at Bajo de la Alumbrera. Calculated delta(18)O and delta D values of fluids associated with this alteration range from +4.8 to +8.1 and -31 to -71 per mil, respectively Compositions determined for fluids associated with phyllic alteration (-0.8 to +10.2 and -31 to -119 parts per thousand) overlap with the values determined for the intermediate argillic alteration. We infer that phyllic alteration assemblages developed during two stages; the first was a high-temperature (400 degrees-300 degrees C) stage with D-depleted water (delta D = -66 to -119 parts per thousand). This compositional range may have resulted from magma degassing and/or the injection of new magmatic water into a compositionally evolved hydrothermal system. The isotopic variations also can be explained by increased fluid-rock interaction. The second stage of phyllic alteration occurred at a lower temperature (similar to 200 degrees C), and variations in the modeled isotopic compositions imply mixing of magmatic and meteoric waters. Ore deposition that occurred late in the evolution of the hydrothermal system was probably associated with further cooling of the magmatic fluid, in part caused by fluid-rock interaction and phase separation. Changing pH and/or oxygen fuoracity may have caused additional ore deposition. The ingress of meteoric water appears to postdate the bulk of mineralization and occurred as the system at Bajo de la Alumbrera waned.

Habitat selection and breeding success in a forest-nesting Alcid, the marbled murrelet, in two landscapes with different degrees of forest fragmentation

We studied habitat selection and breeding success in marked populations of a protected seabird (family Alcidae), the marbled murrelet (Brachyramphus marmoratus), in a relatively intact and a heavily logged old-growth forest landscape in south-western Canada. Murrelets used old-growth fragments either proportionately to their size frequency distribution (intact) or they tended to nest in disproportionately smaller fragments (logged). Multiple regression modelling showed that murrelet distribution could be explained by proximity of nests to landscape features producing biotic and abiotic edge effects. Streams, steeper slopes and lower elevations were selected in both landscapes, probably due to good nesting habitat conditions and easier access to nest sites. In the logged landscape, the murrelets nested closer to recent clearcuts than would be expected. Proximity to the ocean was favoured in the intact area. The models of habitat selection had satisfactory discriminatory ability in both landscapes. Breeding success (probability of nest survival to the middle of the chick rearing period), inferred from nest attendance patterns by radio-tagged parents, was modelled in the logged landscape. Survivorship was greater in areas with recent clearcuts and lower in areas with much regrowth, i.e. it was positively correlated with recent habitat fragmentation. We conclude that marbled murrelets can successfully breed in old-growth forests fragmented by logging.

Ecological factors associated with the breeding and migratory phenology of high-latitude breeding western sandpipers

Environmental conditions influence the breeding and migratory patterns of many avian species and may have particularly dramatic effects on long-distance migrants that breed at northern latitudes. Environment, however, is only one of the ecological variables affecting avian phenology, and recent work shows that migration tactics may be strongly affected by changes in predator populations. We used long-term data from 1978 to 2000 to examine the interactions between snowmelt in western Alaska in relation to the breeding or migration phenologies of small shorebirds and their raptor predators. Although the sandpipers' time of arrival at Alaskan breeding sites corresponded with mean snowmelt, late snowmelts did delay breeding. These delays, however, did not persist to southward migration through British Columbia, likely due to the birds' ability to compensate for variance in the length of the breeding season. Raptor phenology at an early stopover site in British Columbia was strongly related to snowmelt, so that in years of early snowmelt falcons appeared earlier during the sandpipers' southbound migration. These differential effects indicate that earlier snowmelt due to climate change may alter the ecological dynamics of the predator-prey system.

Fossil trees in ancient fluvial channel deposits: evidence of seasonal and longer-term climatic variability

It has been established that large numbers of certain trees can survive in the beds of rivers of northeastern Australia where a strongly seasonal distribution of precipitation causes extreme variations in flow on both a yearly and longer-term basis. In these rivers, minimal flow occurs throughout much of any year and for periods of up to several years, allowing the trees to become established and to adapt their form in order to facilitate their survival in environments that experience periodic inundation by fast-flowing, debris-laden water. Such trees (notably paperbark trees of the angiosperm genus Melaleuca) adopt a reclined to prostrate, downstream-trailing habit, have a multiple-stemmed form, modified crown with weeping foliage, development of thick, spongy bark, anchoring of roots into firm to lithified substrates beneath the channel floor, root regeneration, and develop in flow-parallel, linear groves. Individuals from within flow-parallel, linear groves are preserved in situ within the alluvial deposit of the river following burial and death. Four examples of in situ tree fossils within alluvial channel deposits in the Permian of eastern Australia demonstrate that specialised riverbed plant communities also existed at times in the geological past. These examples, from the Lower Permian Carmila Beds, Upper Permian Moranbah Coal Measures and Baralaba Coal Measures of central Queensland and the Upper Permian Newcastle Coal Measures of central New South Wales, show several of the characteristics of trees described from modern rivers in northeastern Australia, including preservation in closely-spaced groups. These properties, together with independent sedimentological evidence, suggest that the Permian trees were adapted to an environment affected by highly variable runoff, albeit in a more temperate climatic situation than the modem Australian examples. It is proposed that occurrences of fossil trees preserved in situ within alluvial channel deposits may be diagnostic of environments controlled by seasonal and longer-term variability in fluvial runoff, and hence may have value in interpreting aspects of palaeoclimate from ancient alluvial successions. (C) 2001 Elsevier Science B.V. All rights reserved.