Accuracy,Precision, and Observation Rates of Global Positioning System Telemetry Collars

ABSTRACT We addressed concerns regarding performance of various Global Positioning System (GPS) collar configurations for describing habitat use by Rocky Mountain elk (Cervus elaphus) in rugged, forested terrain. We tested 8 GPS collars (Lotek Wireless, Newmarket, ON, Canada) in 4 different model and equipment configurations at 2 reference points (an open hilltop and a forested ravine) to determine habitat-specific differences in performance among collar configurations. We then placed individual collars at 60 additional points that were stratified randomly among 4 canopy-cover classes and 3 classes of available sky. All collars exhibited a locational bias of 4 m horizontally west and of 10 m vertically below a reference standard established by position-averaging with a handheld receiver (Garmin 12MAP) calibrated at National Geodetic Survey benchmarks. The GPS collar models that were programmed for longer satellite-acquisition times provided greater location precision than models that had been programmed for short acquisition times to preserve battery power. Canopy cover and available sky had a greater effect on collar location precision and observation rates than slope, slope position, aspect, conifer basal area, tree height, canopy depth, or elevation. Researchers should test collars at known reference points to confirm that location precision and rates of observation are adequate for their particular study objectives. Manufacturers of GPS collars should inform clients of their programming criteria for acquisition time so that customers can make informed decisions regarding trade-offs between precision of locations, data quantity, and battery life.     

Topophysis affects the Potential of Axillary Bud Growth, Fresh Biomass Accumulation and Specific Fresh Weight in Single-stem Roses (Rosa hybrida L.)

Topophysis, the effect on growth and differentiation of positionof axillary buds along the shoot, was studied by propagatingfive-leaflet-leaf single-node cuttings which were excised fromseven stem positions and grown as single stemmed plants. InRosahybrida ‘Korokis’ Kiss®, ‘Tanettahn’Manhattan Blue®, and ‘Sweet Promise’ Sonia®,following release of the buds from apical dominance by excision,morphogenetic development was studied until anthesis. The timefrom excision/planting until onset of bud growth, visible flowerbud appearance, and anthesis was generally shorter in plantsoriginating from apical bud positions than from basipetal positions.Topophysis mainly affected the onset of axillary bud growth;the earliest growth and development was found in cuttings fromthe second uppermost node position. This node tended to havethe lowest plastochron value, which indicated the existenceof a transition between sylleptic and proleptic buds. Stem lengthat visible flower bud and at anthesis generally increased asthe cutting position changed basipetally until the second lowestposition, and the number of five-leaflet-leaves at anthesisand the total number of nodes generally increased basipetally.For internode length, growth rate, and fresh biomass efficiencythe cuttings taken from the uppermost and lowermost positionsgenerally had significantly lower values than cuttings fromall medial positions. At anthesis, plants originating from cuttingsexcised from lower medial positions generally had a higher freshweight, greater flower stem diameter, and a significantly higherspecific fresh weight than those plants originating from apicalor basal positions. Among the cultivars, Sonia was the mostefficient in increasing fresh biomass and had the highest growthrate, whereas Manhattan Blue possessed the highest specificfresh weight, indicating a higher plant quality. It is suggestedthat topophysis inRosa is an independent phenomenon intrinsicto the axillary bud. apical dominance; axillary bud growth; fresh biomass accumulation; cut rose; flowering; Rosaceae; Rosa hybrida L.; rose; shoot growth; single-stem roses; specific fresh weight; topophysis; quality     

CONSUMER INVOLVEMENT AND EVALUATION OF GREEN PEAS1

This paper reports the effect of consumer involvement on overall acceptance of frozen peas used in green salad and the effect of consumer involvement on the consumer's ability to perceive variations in a set of physical/chemical characteristics such as AIS (Alcohol Insoluble Solids) and color. The results reveal that consumers with high involvement evaluate 16 experimentally varied pea samples more in accordance with quality indicators used in the industry than consumers with low involvement. In our study 61% of the consumers were highly involved. For low involved consumers there was no relation between average acceptance and the quality indicators used by producer/retailer and retailer/consumer. High involved consumers could identify more of the physical/chemical variation in the pea samples than the low involved consumers. The results stress the importance of a preliminary segmentation of consumers. The low involved consumers do not seem to have any specific preferences for any of the samples included in the study although samples are varied considerably with respect to size, color and amount of sucrose. It may be considered as indifference. An obvious conclusion to draw from the results of this study is to concentrate on the highly involved consumers in further product development.     

Population genetic analysis reveals a long-term decline of a threatened endemic Australian marsupial

Since European colonization, Leadbeater's possum ( Gymnobelideus leadbeateri ) has declined across its range to the point where it is now only patchily distributed within the montane ash forests of the Central Highlands of Victoria. The loss of large hollow-bearing trees coupled with inadequate recruitment of mature ash forest has been predicted to result in a reduction in population size of up to 90% by 2020. Furthermore, bioclimatic analyses have suggested additional reductions in the species' distribution under a variety of climate change scenarios. Using a panel of 15 highly resolving microsatellite markers and mitochondrial control region sequence data, we infer past and present gene flow. Populations in the northern part of the core range were highly admixed, and showed no signs of either current or historical barriers to gene flow. A marginal, isolated and inbred population at Yellingbo was highly genetically differentiated, both in terms of current and historic genetic structure. Sequence data confirmed the conclusions from earlier genetic simulation studies that the Yellingbo population has been isolated from the rest of the species range since before European-induced changes to the montane landscape, and formed part of a larger genetic unit that is now otherwise extinct. Historic loss of maternal lineages in the Central Highlands of Victoria was detected despite signals of immigration, indicating population declines that most probably coincided with changes in climate at the end of the Pleistocene. Given ongoing habitat loss and the recent (February 2009) wildfire in the Central Highlands, we forecast (potentially extensive) demographic declines, in line with predicted range reductions under climate change scenarios.     

Pleistocene refugia and polytopic replacement of diploids by tetraploids in the Patagonian and Subantarctic plant Hypochaeris incana (Asteraceae, Cichorieae)

We report the phylogeographic pattern of the Patagonian and Subantarctic plant Hypochaeris incana endemic to southeastern South America. We applied amplified fragment length polymorphism (AFLP) and chloroplast DNA (cpDNA) analysis to 28 and 32 populations, respectively, throughout its distributional range and assessed ploidy levels using flow cytometry. While cpDNA data suggest repeated or simultaneous parallel colonization of Patagonia and Tierra del Fuego by several haplotypes and/or hybridization, AFLPs reveal three clusters corresponding to geographic regions. The central and northern Patagonian clusters (∼38–51° S), which are closer to the outgroup, contain mainly tetraploid, isolated and highly differentiated populations with low genetic diversity. To the contrary, the southern Patagonian and Fuegian cluster (∼51–55° S) contains mainly diploid populations with high genetic diversity and connected by high levels of gene flow. The data suggest that H. incana originated at the diploid level in central or northern Patagonia, from where it migrated south. All three areas, northern, central and southern, have similar levels of rare and private AFLP bands, suggesting that all three served as refugia for H. incana during glacial times. In southern Patagonia and Tierra del Fuego, the species seems to have expanded its populational system in postglacial times, when the climate became warmer and more humid. In central and northern Patagonia, the populations seem to have become restricted to favourable sites with increasing temperature and decreasing moisture and there was a parallel replacement of diploids by tetraploids in local populations.     

Non-interactive effects of habitat complexity and adult crayfish on survival and growth of juvenile crayfish (Pacifastacus leniusculus)

1.  In a 1-month outdoor stream channel experiment, we investigated the relative importance of habitat complexity (i.e. cobbled area) and the presence of adult signal crayfish ( Pacifastacus leniusculus ) males on the survival and growth of juveniles.
2.  In treatments with high habitat complexity, more juveniles survived, more were newly moulted and they had a higher specific growth rate (SGR) at the end of the experiment than juveniles in treatments with low habitat complexity. The presence of adult males did not affect survival, moulting stage or growth of the juveniles.
3.  The presence of adult males decreased juvenile activity during night. Juveniles in treatments with low habitat complexity were more active than juveniles in high habitat complexity during both day and night.
4.  There was no difference in total invertebrate biomass between treatments. However, some invertebrate taxa, such as Chironomidae larvae, were affected by habitat complexity or the presence of adult crayfish. Juvenile crayfish in all channels had consumed detritus, algae and Chironomidae larvae and there were no differences in gut contents or stable isotope signals (carbon and nitrogen) between treatments, indicating a similar diet among the juveniles across treatments. However, the biomass of chironomids was significantly higher in channels with adult crayfish present, indicating a decreased consumption of chironomids by juveniles in the presence of adults.
5.  Our results suggest that the recruitment of juvenile crayfish is mostly affected by habitat complexity. The competition for food and shelter and aggressive interactions between the juveniles were most pronounced in low habitat complexity, indicating that habitats with a good access to shelter will enhance recruitment of juvenile crayfish in streams.     

Water relations of compound leaves and phyllodes in Acacia koa var. latifolia

Abstract Moisture release characteristics and field measurements of physiological parameters (conductance and water potential) and environmental parameters (ambient temperature, water vapour saturation deficit and photosynthetic photon flux density) were measured for phyllodes and compound leaves of Acacia koa over a 2 month period at Hawaii Volcanoes National Park, Hawaii, to determine what differences in water relations might occur between leaf types. The phyllodes were found to contain more water at full turgor, use less water in turgor control and have stomatal conductances more closely associated with bulk leaf water status and environmental variables. These results suggest that the phyllodes are more drought adapted, whereas the compound leaves probably promote more rapid early growth during periods of high moisture availability.     

Root Formation of Pea Cuttings in Relation to the Irradiance of the Stock Plants

Pea plants were grown at different irradiances for eleven days. At this stage they were used for cuttings. The irradiance during the rooting period (155 mW · dm^?2) was the same in all the experiments, Cuttings from stock plants cultivated at the weakest irradiance obtained the highest number of roots, and the poorest rooting appeared in cuttings from stock plants grown at the highest irradiance. The results indicate that the nutritional status of the stock plant is an important factor for root formation in the cutting. Light may influence the production of inhibitors which directly or indirectly affect root formation. The possible role of carbohydrates and growth promoters in the process of root formation is discussed.     

14CO2 Pulse-Chase Labelling in Clusia minor L.

Conditions and maintenance of growth were chosen so that plantsof Clusia minor L. were obtained which showed the C₃- and CAM-modes of CO₂-exchange, respectively. C. minor is known to accumulateconsiderable amounts of citric acid in addition to malic acidduring the dark-phase of CAM. ¹⁴CO₂-pulse-chase experiments were performed with these plants.Patterns of labelling during the pulse and redistribution oflabel during the chase in the C₃-mode were as expected for C₃-photosynthesis.Pulse-labelling in the CAM-mode during the last hour of thelight period, during the first part of the dark period and duringthe last hour of the dark period always led to an almost exclusiveincorporation of label into malate. Redistribution of labelfrom malate after the pulse at the end of the dark period duringthe chase in the subsequent light period followed the patternexpected for light-dependent reassimilation of CO₂ remobilizedfrom malate in CAM during the light period. During the chasesin the dark period, label was transferred from ^l4C-malate tocitrate. This suggests that during accumulation of citric acidin the dark period of CAM in C. minor, citrate is synthesizedin the mitochondria from malate or oxaloacetate after formationof malate via phosphoenolpyruvate carboxylase. The experiment also showed that no labelled compounds are exportedfrom leaves in the CAM-mode during the dark period. In plantsof the C₃-mode the roots proved to be strong sinks. Key words: Clusia minor, labelling, pulse-chase, ¹⁴CO₂