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ALEXANDER G. VOLKOV JUSTIN C. FOSTER TALITHA A. ASHBY RONALD K. WALKER JON A. JOHNSON VLADISLAV S. MARKIN 《Plant, cell & environment》2010,33(2):163-173
Thigmonastic movements in the sensitive plant Mimosa pudica L., associated with fast responses to environmental stimuli, appear to be regulated through electrical and chemical signal transductions. The thigmonastic responses of M. pudica can be considered in three stages: stimulus perception, electrical signal transmission and induction of mechanical, hydrodynamical and biochemical responses. We investigated the mechanical movements of the pinnae and petioles in M. pudica induced by the electrical stimulation of a pulvinus, petiole, secondary pulvinus or pinna by a low electrical voltage and charge. The threshold value was 1.3–1.5 V of applied voltage and 2 to 10 µC of charge for the closing of the pinnules. Both voltage and electrical charge are responsible for the electro‐stimulated closing of a leaf. The mechanism behind closing the leaf in M. pudica is discussed. The hydroelastic curvature mechanism closely describes the kinetics of M. pudica leaf movements. 相似文献
83.
JON E. BROMMER HANNU PIETIÄINEN KARI AHOLA PATRIK KARELL TEUVO KARSTINEN HEIKKI KOLUNEN 《Global Change Biology》2010,16(2):577-586
Multiannual cycles in the abundance of voles and other animals have been collapsing in the last decades. It has been proposed that this phenomenon is ‘climatically forced’ by milder winters. We here consider the dynamics of bank and field voles during more than two decades in two localities (170 km apart) in southern Finland. Using wavelet analysis, we show that a clear 3‐year cycle disappeared in the mid 1990s. However, the vole cycle returned in both localities after about 5 years despite winters becoming increasingly milder. In both localities, vole cycles were mainly determined by bank voles after the period of noncyclic dynamics, whereas field voles were dominant before this irregularity. Wavelet coherency analysis shows that spatial synchrony temporarily broke down during the period of noncyclic dynamics, but was fully restored afterwards. The return of the cycle despite ongoing rapid climate change argues against ‘climatic forcing’ as a general explanation for loss of cycles. Rather, the population‐dynamical consequences of climate change may be dependent on the local species composition and mechanism of delayed density dependence. 相似文献
84.
MELISSA R. GUNN DEBORAH A. DAWSON ANDREW LEVISTON KATIE HARTNUP COREY S. DAVIS CURTIS STROBECK JON SLATE DAVID W. COLTMAN 《Molecular ecology resources》2005,5(3):650-653
We isolated 18 polymorphic microsatellite loci to be used for pedigree analysis in a wild population of North American red squirrels, Tamiasciurus hudsonicus. Allelic diversity and observed heterozygosity ranged from six to 13 and 0.39 to 0.89, respectively, in a sample of 93 individuals. Up to 13 sets of primers also amplify in other rodent species. 相似文献
85.
TANYA J. BLAKELY JON S. HARDING ANGUS R. MCINTOSH MICHAEL J. WINTERBOURN 《Freshwater Biology》2006,51(9):1634-1645
1. Worldwide, increasing numbers of stream restoration projects are being initiated to rehabilitate waterways modified by urbanisation. However, many of these projects have limited success in restoring stream communities. Prompted by this, we investigated previously unrecognised barriers to aquatic insect colonisation in urban streams. 2. To investigate whether the availability of suitable substrata for oviposition limited the longitudinal distribution of caddisflies, large boulders were added to the upstream reaches of one stream. Prior to the addition, more egg masses were observed downstream and this longitudinal pattern persisted subsequently. 3. Malaise trapping revealed that adult caddisfly diversity and abundance was greater downstream than upstream. Furthermore, in a previous study the authors found larval caddisflies reflected the longitudinal distribution of adults. 4. The only obvious potential obstructions between reaches were roads beneath which the stream flowed through culverted crossings. Malaise trapping was used to examine the effect of road culverts and bridges on caddisfly dispersal. Numbers of caddisflies caught declined upstream and about 2.5 × more individuals were taken in traps immediately below than above five culverts. 4. Bridges, which had a more open structure than culverts, had no significant effect on the size of catches made above and below them. 5. Road culverts could act as partial barriers to upstream flight, with consequences for larval recruitment in urban streams. We recommend that urban planners and designers of restoration projects consider possible synergistic effects of poor oviposition habitat and barriers to aquatic insect dispersal, which may be critical for the colonisation of urban headwater streams and for the maintenance of stream insect populations. 相似文献
86.
Fluxes of carbon dioxide and water vapour over an undisturbed tropical forest in south-west Amazonia 总被引:9,自引:0,他引:9
JOHN GRACE JON LLOYD JOHN MCINTYRE ANTONIO MIRANDA PATRICK MEIR HELOISA MIRANDA JOHN MONCRIEFF JON MASSHEDER IVAN WRIGHT JOHN GASH 《Global Change Biology》1995,1(1):1-12
- 1 Carbon dioxide and water vapour fluxes were measured for 55 days by eddy covariance over an undisturbed tropical rain forest in Rondonia, Brazil. Profiles of CO2 inside the canopy were also measured.
- 2 During the night, CO2 concentration frequently built up to 500 ppm throughout the canopy as a result of low rates of exchange with the atmosphere. In the early morning hours, ventilation of the canopy occurred.
- 3 Ecosystem gas exchange was calculated from a knowledge of fluxes above the canopy and changes of CO2 stored inside the canopy. Typically, uptake by the canopy was 15 μmol m?2 s?1 in bright sunlight and dark respiration was 6-7 μmol m?2 s?1 The quantum requirement at low irradiance was: 40 mol photons per mol of CO2.
- 4 Bulk stomatal conductance of the ecosystem was maximal in the early morning (0.4-1.0 mol m?2 s?1) and declined over the course of the day as leaf-to-air vapour pressure difference increased.
87.
LI WEI JON R. FLANDERS STEPHEN J. ROSSITER CASSANDRA M. MILLER‐BUTTERWORTH LI B. ZHANG SHUYI Y. ZHANG 《Biological journal of the Linnean Society. Linnean Society of London》2010,99(3):582-594
The influence of Pleistocene climatic oscillations on shaping the genetic structure of Asian biota is poorly known. The Japanese pipistrelle bat occurs over a wide range in eastern Asia, from Siberia to Japan. To test the relative impact of ancient and more recent events on genetic structure in this species, we combined mitochondrial (cytochrome b) and microsatellite markers to reconstruct its phylogeographic and demographic history on continental China and its offshore islands, Hainan Island and the Zhoushan Archipelago. Our mitochondrial DNA tree recovered two divergent geographical clades, indicating multiple glacial refugia in the region. The first clade was mainly confined to Hainan Island, indicating that gene flow between this population and the continent has been restricted, despite being repeatedly connected to the mainland during repeated glacial episodes. By contrast, haplotypes sampled on the Zhoushan Archipelago were mixed with those from the mainland, suggesting a recent shared history of expansion. Although microsatellite allele frequencies showed clear discontinuities across the sampling range, supporting the current isolation of both Hainan Island and the Zhoushan Archipelago, we also found clear evidence of more recent back colonization, probably via post‐glacial expansion or, in the latter case, occasional long distance dispersal. The results obtained highlight the importance of using multiple sets of markers for teasing apart the roles of ancient and more recent events on population genetic structure. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 582–594. 相似文献
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89.
Here we describe the complete nucleotide sequence of the mitochondrial genome (16 583/4 bp) of the zebra finch (Taeniopygia guttata). Primers were designed based on highly conserved regions of an alignment of three passerine complete mitochondrial DNA (mtDNA) sequences. A combination of overlapping long polymerase chain reaction (PCR) purification, followed by fully nested PCR and sequencing was used to determine the complete mtDNA genome. Six birds, from distinct maternal lineages of a pedigreed population were sequenced. Five novel haplotypes were identified. These sequences provide the first data for sequence variation across the whole mitochondrial genome of a passerine bird species. 相似文献
90.