Taxonomic notes on the Australian skyhopper genus Kosciuscola Sjstedt (Orthoptera: Acrididae: Oxyinae).

The Australian skyhopper genus Kosciuscola Sjstedt consists of brachypterous species that inhabit the Australian alpine and subalpine region. The genus used to include 5 species and 1 subspecies, but according to a recent phylogenomic study, there could be as many as 14 species in the genus, that are genetically and geographically isolated from each other. This study represents the first step in describing and documenting the diversity of this interesting genus.

How is adaptive potential distributed within species ranges?

Quantitative genetic variation (QGV) represents a major component of adaptive potential and, if reduced toward range-edge populations, could prevent a species' expansion or adaptive response to rapid ecological change. It has been hypothesized that QGV will be lower at the range edge due to small populations-often the result of poor habitat quality-and potentially decreased gene flow. However, whether central populations are higher in QGV is unknown.

Predicting species and community responses to global change using structured expert judgement: An Australian mountain ecosystems case study.

Conservation managers are under increasing pressure to make decisions about the allocation of finite resources to protect biodiversity under a changing climate. However, the impacts of climate and global change drivers on species are outpacing our capacity to collect the empirical data necessary to inform these decisions. This is particularly the case in the Australian Alps which have already undergone recent changes in climate and experienced more frequent large-scale bushfires.

Ecological responses to variation in seasonal snow cover.

Seasonal snow is among the most important factors governing the ecology of many terrestrial ecosystems, but rising global temperatures are changing snow regimes and driving widespread declines in the depth and duration of snow cover. Loss of the insulating snow layer will fundamentally change the environment. Understanding how individuals, populations, and communities respond to different snow conditions is thus essential for predicting and managing future ecosystem change.

Do different rates of gene flow underlie variation in phenotypic and phenological clines in a montane grasshopper community?

Species responses to environmental change are likely to depend on existing genetic and phenotypic variation, as well as evolutionary potential. A key challenge is to determine whether gene flow might facilitate or impede genomic divergence among populations responding to environmental change, and if emergent phenotypic variation is dependent on gene flow rates. A general expectation is that patterns of genetic differentiation in a set of codistributed species reflect differences in dispersal ability.

Physiological Limits along an Elevational Gradient in a Radiation of Montane Ground Beetles.

A central challenge in ecology and biogeography is to determine the extent to which physiological constraints govern the geographic ranges of species along environmental gradients. This study tests the hypothesis that temperature and desiccation tolerance are associated with the elevational ranges of 12 ground beetle species (genus Nebria) occurring on Mt. Rainier, Washington, U.

Conserved and narrow temperature limits in alpine insects: Thermal tolerance and supercooling points of the ice-crawlers, Grylloblatta (Insecta: Grylloblattodea: Grylloblattidae).

For many terrestrial species, habitat associations and range size are dependent on physiological limits, which in turn may influence large-scale patterns of species diversity. The temperature range experienced by individuals is considered to shape the breadth of the thermal niche, with species occupying temporally and/or geographically stable climates tolerating a narrow temperature range. High-elevation environments experience large temperature fluctuations, with frequent periods below 0 °C, but Grylloblatta (Grylloblattodea: Grylloblattidae) occupy climatically stable microhabitats within this region.

Strong genetic structure corresponds to small-scale geographic breaks in the Australian alpine grasshopper Kosciuscola tristis.

Background: Mountain landscapes are topographically complex, creating discontinuous 'islands' of alpine and sub-alpine habitat with a dynamic history. Changing climatic conditions drive their expansion and contraction, leaving signatures on the genetic structure of their flora and fauna. Australia's high country covers a small, highly fragmented area.

Niche breadth predicts geographical range size: a general ecological pattern.

The range of resources that a species uses (i.e. its niche breadth) might determine the geographical area it can occupy, but consensus on whether a niche breadth-range size relationship generally exists among species has been slow to emerge.

Estimating genetic benefits of polyandry from experimental studies: a meta-analysis.

The consequences of polyandry for female fitness are controversial. Sexual conflict studies and a meta-analysis of mating rates in insects suggest that there is a longevity cost when females mate repeatedly. Even so, compensatory material benefits can elevate egg production and fertility, partly because polyandry ensures an adequate sperm supply.

Why do fiddler crabs build chimneys?

Chimneys are mud mounds built by fiddler crabs that encircle the entrance to their burrow. Their function in many species is unknown. In Uca capricornis, crabs of both sexes and all sizes build chimneys, but females do so disproportionately more often.

Water relations of Eucalyptus pauciflora near the alpine tree line in winter.

Water potential measurements were made, over three winter seasons, on Eucalyptus pauciflora Sieb. ex Spreng. at four elevations extending up to 200 m above the natural tree line in the Snowy Mountains area of southeastern Australia.

Factors influencing germination and establishment of Eucalyptus pauciflora near the alpine tree line.

Factors affecting seed germination, seedling establishment and growth to reproductive maturity in Eucalyptus pauciflora Sieb. ex Spreng. at the tree line in southeastern Australia were investigated.

Photosynthetic capacity and carbon allocation patterns in diverse growth forms of Eucalyptus.

Eucalytptus species originating in Australian habitats differing in moisture regimes were examined under uniform growth conditions for their photosynthetic characteristics and allocation patterns. Species from the driest environments, the 'mallee' types, had the smallest leaf sizes and the highest leaf specific weights; and forest species, from moist coastal sites, had the largest and thinnest leaves. Photosynthetic rates on a dry weight basis were highly correlated with leaf nitrogen content in all species.

Water deficits in timberline trees in the Snowy Mountains of South-Eastern Australia.

Leaf water potential (Ψ), leaf diffusion resistance (r ) and net photosynthesis of leaves of Eucalyptus pauciflora Sieb at timberline (2,040 m) were measured in winter and spring in the Snowy Mountains area of southeastern Australia. Four treatments were established in a 2×2 factorial design involving exposure to direct sunlight, screening to reduce solar radiation by approximately 50%, exposure to direct radiant cooling at night, and screening to reduce radiant cooling. A less comprehensive set of measurements was also made in summer.

Effects of water stress and differential hardening treatments on photosynthetic characteristics of a xeromorphic shrub,Eucalyptus socialis, F. Muell.

The influence of water stress on photosynthesis of drought hardened, and non-hardened,Eucalyptus socialis plants was examined. Particular attention was given to the effects of low leaf water potential on stomatal and intracellular resistance to CO transport and on the CO compensation point. Though the hardening treatment had a pronounced influence on leaf morphology, there was no apparent difference in the photosynthetic response to drought stress between hardened and non-hardened treatments, or with repeated drought cycles.

Temperature dependence of photosynthesis in cotton.

Cotton plants (Gossypium hirsutum L., var. Deltapine Smooth Leaf) were grown under controlled environmental conditions over a range of day/night temperatures from 20/15 to 40/35 C.

Estimation of the transport and carboxylation components of the intracellular limitation to leaf photosynthesis.

A model is presented which enables gas exchange data to be used to partition the intracellular resistance to leaf photosynthesis into carboxylation and transport components. A basic assumption is that the over-all kinetics of the carboxylation reaction fit the Michaelis-Menten equation.The model was tested for cotton (Gossypium hirsutum L.

Leaf temperature effects on measurements of diffusive resistance to water vapor transfer.

Substantial errors can be introduced to estimates of leaf resistance (r(l)) obtained from diffusion porometers unless precautions are taken to reduce the leaf-cup temperature difference (T(leaf) - T(cup)) to acceptable levels prior to measurement. When T(leaf) > T(cup), underestimation of leaf resistance occurs; the reverse applies when T(leaf) < T(cup).The effect is most pronounced under open-stomata conditions and declines as stomatal resistance increases.

Variation in levels of some leaf enzymes.

Several procedures were compared for efficiency in the extraction of certain leaf enzymes (phosphoenolpyruvate carboxylase, ribulose 1,5-diphosphate carboxylase and malate dehydrogenase) in Atriplex hastata (a "C3" species exhibiting conventional photosynthetic metabolism), and in A. spongiosa (a "C4" species in which the initial photosynthetic products are C4 dicarboxylic acids). Glycolate oxidase was also assayed in some cases, and Atriplex nummularia and Sorghum bicolor were also used as test material.

Effect of Errors in Measuring Leaf Temperature and Ambient Gas Concentration on Calculated Resistances to CO(2) and Water Vapor Exchanges in Plant Leaves.

Errors as small as 1 C in the measurement of leaf temperature (T(leaf)) are shown to cause significant changes in the estimated value of the stomatal resistance (expressed in terms of total resistance to water vapor transfer, summation operatorrH(2)O). The effect increases as T(leaf) increases and as ambient relative humidity increases, if other conditions are maintained constant. The effect on the key CO(2) exchange parameter, the intracellular (or mesophyll) resistance, r(int), tends to be small under open stomata conditions but increases rapidly as stomatal closure occurs, particularly if the true value of r(int) is relatively small.

The role of the mesophyll cell wall in leaf transpiration.

Evidence is presented which suggests that the mesophyll cell walls of cotton leaves may influence observed rates of transpiration.The net diffusive flux of water vapour, from the upper and lower surfaces of a leaf, was compared with the flux of nitrous oxide through a leaf and evidence obtained of an extra resistance in the water-vapour pathway associated with water transport in the mesophyll cell walls.This extra resistance appeared to be insignificant at low transpiration rates and in turgid leaves, but increased with transpiration rate and dehydration.

Comparative photosynthesis, growth and transpiration of two species of Atriplex.

Throughout a period of 23 days, during which the photosynthesis, growth and transpiration of two species of Atriplex were compared, A. spongiosa, a "C4" species (first products of photosynthesis = 4-C dicarboxylic acids), maintained net rates of leaf photosynthesis as high as, or higher than, those of A. hastata, a "C3" species (photosynthesis exhibiting the Calvin-type characteristics).