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CASANDRA J. LLOYD ANDREW P. NORTON RUTH A. HUFBAUER STEVEN M. BOGDANOWICZ SCOTT J. NISSEN 《Molecular ecology resources》2004,4(4):605-607
Spurgia capitigena is a gall midge that has been released as a biological control agent of leafy spurge (Euphorbia esula), a noxious rangeland weed in North America. We isolated 15 microsatellite loci from S. capitigena with from two to 27 alleles at each locus. These markers will allow us to examine the structure and levels of neutral genetic variation in native and introduced populations. 相似文献
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JAMES FARLOW RUTH ELSEY 《Lethaia: An International Journal of Palaeontology and Stratigraphy》2004,37(4):401-405
The mid-thigh circumference of the intact hindlimb in Alligator mississippiensis is tightly correlated with transverse dimensions of the proximal and distal articular surfaces of the femur, and with minimum midshaft femoral circumference. Maximum diameter of the proximal articular end, width across the distal articular end, and midshaft circumference are the best femoral predictors of circumference of the intact thigh. Regression equations of mid-thigh circumference against these femoral dimensions can be used to estimate the transverse dimensions of the intact hindlimb in extinct crocodylian-like archosaurs. 相似文献
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GEMMA WOLDENDORP † MICHAEL J. HILL † RUTH DORAN † MARILYN C. BALL† 《Global Change Biology》2008,14(2):294-308
Although plants are more susceptible to frost damage under elevated atmospheric [CO2], the importance of frost damage under future, warmer climate scenarios is unknown. Accordingly, we used a model to examine the incidence and severity of frost damage to snow gum (Eucalyptus pauciflora) in a sub‐alpine region of Australia for current and future conditions using the A2 IPCC elevated CO2 and climate change scenario. An existing model for predicting frost effects on E. pauciflora seedlings was adapted to include effects of elevated [CO2] on acclimation to freezing temperatures, calibrated with field data, and applied to a study region in Victoria using climate scenario data from CSIRO's Global Climate Model C‐CAM for current (1975–2004) and future (2035–2064) 30 years climate sequences. Temperatures below 0 °C were predicted to occur less frequently while the coldest temperatures (i.e. those below ?8 °C) were almost as common in the future as in the current climate. Both elevated [CO2] and climate warming affected the timing and rates of acclimation and de‐acclimation of snow gum to freezing temperatures, potentially reducing the length of time that plants are fully frost tolerant and increasing the length of the growing season. Despite fewer days when temperatures fall below 0 °C in the future, with consequently fewer damaging frosts with lower average levels of impact, individual weather sequences resulting in widespread plant mortality may still occur. Furthermore, delayed acclimation due to either warming or rising [CO2] combined with an early severe frost could lead to more frost damage and higher mortality than would occur in current conditions. Effects of elevated [CO2] on frost damage were greater in autumn, while warming had more effect in spring. Thus, frost damage will continue to be a management issue for plantation and forest management in regions where frosts persist. 相似文献
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MÁRCIO R. VELOSO FRANCELINO ADRIANA DE LIMA MENDONÇA RUTH R. DO NASCIMENTO FERNANDO A. C. DE MENDONÇA EDLEIDE L. DA SILVA MARIA DO ROSÁRIO T. DE FREITAS CYRO R. CABRAL JR CARLOS EDUARDO DA SILVA JOSÉ H. S. RIBEIRO ANTÔNIO EUZÉBIO G. SANTANA 《Physiological Entomology》2008,33(1):37-42
Abstract. Ethological studies are conducted under laboratory conditions using workers of Atta sexdens sexdens and Atta opaciceps collected from field colonies to investigate the mechanisms involved in the alarm response and intra-specific recognition in leaf-cutting ants. Hexane extracts from the heads of gardeners and generalist workers elicit higher levels of alarm response in foragers from the same colony than do mandibular gland extracts from foragers and soldiers, indicating that gardeners, generalists and foragers are primarily responsible for the production of alarm pheromone. Foragers subjected to extracts from non-nestmates exhibit significantly greater alarm responses than are induced by similar extracts derived from nestmate workers, suggesting that the alarm pheromone may have a role in nestmate recognition. 相似文献
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STEPHEN C. MCKILLUP RUTH V. MCKILLUP 《Biological journal of the Linnean Society. Linnean Society of London》2008,95(1):62-71
The marine snail, Littoraria filosa, is polymorphic for shell colour, with yellow, brown, and pink morphs that correspond in both appearance and frequency to the predominant background colours of its habitat. Previous research on this polymorphism has found indirect evidence of apostatic selection and selection for crypsis by unknown agents, probably crabs, and direct evidence of selection for crypsis by the parasitoid fly Sarcophaga megafilosia. In the present study, we report on field experiments to investigate whether S. megafilosia and shell‐crushing predators exert apostatic selection on L. filosa. For S. megafilosia, seven experimental treatments containing yellow and brown snails in the proportions of 0.1, 0.2, 0.4, 0.5, 0.6, 0.8, and 0.9 of each colour were established on mangrove trees and used to separately quantify the proportions of each colour attacked on grey/brown trunks and yellow/green leaves. The results obtained confirmed an earlier finding of selection for crypsis, but only showed slight, but significant, anti‐apostatic selection by S. megafilosia. For shell‐crushing predators, seven experimental treatments containing yellow and brown snails in the proportions of 0.08, 0.17, 0.33, 0.50, 0.66, 0.83, and 0.92 were established on two types of trees that differed in their background proportions of brown and green: (1) trees which had been pruned of approximately 90% of their foliage and (2) unpruned trees. The results obtained showed both selection for crypsis and apostatic selection. Furthermore, a selectively neutral frequency for yellow L. filosa was found for each background, and was less on pruned trees than unpruned ones (and vice versa for brown L. filosa), which can therefore account for the maintenance of a colour polymorphism where the proportions of each morph tend to resemble and correspond in frequency to the colours of the background. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 62–71. 相似文献
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DIPLOID-TETRAPLOID SYMPATRY IN DACTYLIS(GRAMINEAE) 总被引:4,自引:4,他引:0
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Compartmental analyses of intact roots of barley (Hordeum vulgareL. cv. Klondike) plants, grown with different levels of NO3(up to 1·0 mol m3) in the external media, wereundertaken using 13NO3. Two additional treatments, namelysodium dodecyl sulphate (SDS) or brief exposure to high temperature,designed to investigate the identity of the three NO3compartments revealed by compartmental analyses, provided supportfor the identification of the latter as corresponding to superficialsolution, apoplasm, and cytoplasm. Half-lives for exchange ofthese compartments, 3 s, 30 s, and 7 mm, were unaffected bythe level of NO3 provided during growth. Independentestimates of 13NO3 fluxes obtained by direct methodsagreed well with values of fluxes calculated from the compartmentalanalyses. Cytoplasmic [NO3], estimated from the compartmental analyses,were in the range from 137 mol m3, and increasedwith increasing [NO3] of the medium. Such values forcytoplasmic [NO3] are inconsistent with an earlier proposal(Siddiqi, Glass, Ruth, and Rufty, 1990; Glass, Siddiqi, Ruth,and Rufty, 1990) of passive NO3 uptake in the concentrationrange above 10 mol m3. A model, based upon localizeddistribution of nitrate reductase activity in epidermal cells,is proposed in which the proposed passive low affinity NO uptakeat high external [NO3] is restricted to epidermal cells. During loading periods with 13NO3, significant amountsof 13N were translocated to the shoot. Two pools of 13N, onebeing the root symplasm, appear to participate in the transferof labelled N to the shoot. Key words: Barley, compartmentation, nitrate, nitrate reductase, 13N 相似文献