Studies on lichen-dominated systems. XIII. Seasonal and geographical variation of net CO2 exchange of Alectoria ochroleuca

1975 ◽  
Vol 53 (22) ◽  
pp. 2598-2607 ◽  
Author(s):  
D. W. Larson ◽  
K. A. Kershaw
Keyword(s):  
Light Intensity ◽  
Intraspecific Variation ◽  
Seasonal Changes ◽  
Net Photosynthesis ◽  
Co2 Exchange ◽  
Ecological Significance ◽  
Beach Ridge ◽  
Exchange Method ◽  
Geographical Locations ◽  
Seasonal Acclimation

By using a new gas-exchange method, the seasonal changes in net photosynthetic rates of Alectoria ochroleuca were examined in relation to thallus moisture content, thallus temperature, and light intensity. These experiments were run using samples collected from both the top and bottom positions of a raised-beach ridge and showed very little intraspecific variation. Collections made from other geographical locations, however, showed that considerable intraspecific variation was possible within this species.At the Pen Island site, A. ochroleuca shows patterns of net photosynthesis adapted to the xeric ridge-top environments on which it is most abundant.Rapid seasonal acclimation to temperature and changes in the response to light intensity were found for both ridge-top and ridge-bottom collections of A. ochroleuca. The ecological significance of these findings is discussed.

Studies on lichen-dominated systems. XVI. Comparative patterns of net CO2 exchange in Cetraria nivalis and Alectoria ochroleuca collected from a raised-beach ridge

1975 ◽  
Vol 53 (23) ◽  
pp. 2884-2892 ◽  
Author(s):  
D. W. Larson ◽  
K. A. Kershaw
Keyword(s):  
Species Distribution ◽  
Net Photosynthesis ◽  
Co2 Exchange ◽  
Physiological Data ◽  
Seasonal Patterns ◽  
Beach Ridge ◽  
Bottom Position ◽  
Intraspecific Difference ◽  
Seasonal Acclimation ◽  
Data Matrices

Seasonal patterns of net photosynthesis in Cetraria nivalis that was collected from the top and bottom positions of a raised-beach ridge were examined in relation to those for Alectoria ochroleuca from the same site. While seasonal acclimation is pronounced in C. nivalis to an extent equal to that found in A. ochroleuca, C. nivalis showed significant intraspecific difference in these patterns. Cetraria nivalis that was collected from the bottom position of the beach ridge is more active metabolically than the ridge-top collections. Cetraria nivalis is most abundant on the lower slopes of these ridges. A comparison of the physiological data matrices for both ridge-top and ridge-bottom collections of A. ochroleuca and C. nivalis partly explains the patterns of species distribution that are observed in the field.

Comparative CO2 exchange patterns in mosses from two tundra habitats at Barrow, Alaska

1976 ◽  
Vol 54 (12) ◽  
pp. 1355-1369 ◽  
Author(s):  
Walter C. Oechel ◽  
Nigel J. Collins
Keyword(s):  
Light Intensity ◽  
Water Content ◽  
Dark Respiration ◽  
Net Photosynthesis ◽  
Dry Weight ◽  
Co2 Exchange ◽  
Polar Regions ◽  
Light Intensities ◽  
Matter Production ◽  
Exchange Patterns

The effects of variation in light intensity, temperature, and water content on rates of net photosynthesis and dark respiration have been investigated in two common tundra mosses, Polytrichum alpinum from drier habitats and Calliergon sarmentosum from wetter habitats at Barrow, Alaska. Optimum temperatures for net photosynthesis of 10–15 °C for both species and saturating light intensities (photosynthetically active radiation (PhAR), 400–700 nm) of about 0.12 cal cm−2 min−1 for P. alpinum and 0.15 cal cm−2 min−1 for C. sarmentosum correlate well with measurements of light intensity and moss tissue temperatures made over the season at the collection site. It is suggested that depressions in net photosynthetic rates around midday might be caused by supraoptimal temperatures and possibly supraoptimal light intensities. Calliergon sarmentosum, a semiaquatic species required a higher water content (about 450% dry weight) than P. alpinum (about 200%) to reach maximal rates of net photosynthesis. Mean maximal rates of net photosynthesis ranged from about 2.6 to 4.4 mg CO2 g−1 dry weight h−1 for P. alpinum and from about 1.5 to 3.0 mg CO2 g−1 dry weight h−1 for C. sarmentosum. Predictions of net annual production have been made for both species. Predicted levels of 171 g C m−2 per 50-day season for C. sarmentosum compare well with results obtained for species of similar growth form elsewhere in polar regions. For P. alpinum the predicted level of 38.5 g C m−2 per 50-day season compares with observed dry matter production at the same site of 43 g m−2 per season.

Influence of temperature on net CO2 exchange in roses

1991 ◽  
Vol 71 (1) ◽  
pp. 235-243 ◽  
Author(s):  
J. Jiao ◽  
M. J. Tsujita ◽  
B. Grodzinski
Keyword(s):  
Dark Respiration ◽  
Net Photosynthesis ◽  
Co2 Exchange ◽  
Effect Of Temperature ◽  
Flower Bud ◽  
Temperature Range ◽  
Whole Plant ◽  
Optimal Temperature Range ◽  
Influence Of Temperature On ◽  
Whole Plants

The effect of temperature on net CO2 exchange of source and sink tissues of the flowering shoots and of whole plants was examined using single-stemmed Samantha roses. At all stages of shoot development, the optimal temperature range for whole-plant carbon (C) gain at saturating irradiance and ambient CO2 level was between 20° and 25 °C, narrower than the temperature range for optimal leaf net photosynthesis. Dark respiration increased more dramatically than photosynthesis with temperatures between 15 and 35 °C. At 25 °C, C loss due to respiration from the flower bud at colour bud stage accounted for 45% of the C loss of the flowering shoot. At low irradiance levels (e.g. 200 μmol m−2 s−1) whole-plant net photosynthesis was greater at 16° than at 22 °C because of a greater reduction in respiration. Lowering the night temperature from 27 to 17 °C also increased daily C gain due to a reduction in the C lost at night. Whole-plant net photosynthesis of plants grown and measured at enriched (1000 ± 100 μL L−1) CO2 was greater than that of plants grown and measured at ambient (350 ± 50 μL L−1) level at temperatures between 15° and 35 °C. Furthermore, the optimal temperatures for whole-plant net photosynthesis in CO2 enrichment was higher than at ambient CO2 level. Key words: Dark respiration, net photosynthesis, Rosa hybrida, temperature

The ecology of Ramalina menziesii. VI. Laboratory responses of net CO2 exchange to moisture, temperature, and light

1987 ◽  
Vol 65 (1) ◽  
pp. 182-191 ◽  
Author(s):  
U. Matthes-Sears ◽  
T. H. Nash III ◽  
D. W. Larson
Keyword(s):  
Dark Respiration ◽  
Net Photosynthesis ◽  
Co2 Exchange ◽  
Response Curves ◽  
Central California ◽  
Photosynthetic Rates ◽  
Chlorophyll Contents ◽  
The Mean ◽  
The Difference ◽  
Thallus Water Content

The response of net CO2 exchange to thallus water content, thallus temperature, and photosynthetically active radiation was measured in the laboratory for two morphologically different forms of Ramalina menziesii collected from a coastal and an inland habitat in central California. Equations describing the response curves are fitted to the data and compared statistically for the two sites during two seasons. Significant differences were present for all responses both in summer and winter but were more pronounced for net photosynthesis than for dark respiration. The main differences between the two forms were in the absolute rates of net photosynthesis; a maximum of 6.2 was measured for the inland form but only 3.6 mg∙g−1∙h−1 for the coastal form. Chlorophyll contents were also different between the two forms, indicating that chlorophyll is the likely cause for the difference in net photosynthetic rates. Net photosynthetic rates were higher at low temperatures during winter than during summer, but otherwise seasonal variations in the gas exchange responses were relatively minor. Both forms of the lichen are light saturated at quantum fluxes greater than 200 μE∙m−2∙s−1. Both show an optimum temperature for maximum CO2 exchange at 25 °C, well above the mean operating temperature of R. menziesii in the field.

scholarly journals Intraspecific variation in seed size and light intensity affect seed germination and initial seedling growth of a tropical shrub

2017 ◽  
Vol 31 (4) ◽  
pp. 736-741 ◽  
Author(s):  
Aniele C. R. Veloso ◽  
Priscila S. Silva ◽  
Wallison K. Siqueira ◽  
Karen L.R. Duarte ◽  
Ingrid L. V. Gomes ◽  
...  
Keyword(s):  
Seed Germination ◽  
Light Intensity ◽  
Intraspecific Variation ◽  
Seed Size ◽  
Seedling Growth

Intraspecific variation between the ITS sequences of Toxocara canis, Toxocara cati and Toxascaris leonina from different host species in south-western Poland

2012 ◽  
Vol 87 (4) ◽  
pp. 432-442 ◽  
Author(s):  
R. Fogt-Wyrwas ◽  
H. Mizgajska-Wiktor ◽  
J. Pacoń ◽  
W. Jarosz
Keyword(s):  
Intraspecific Variation ◽  
Intraspecific Variability ◽  
Toxocara Canis ◽  
Point Of View ◽  
Its Sequences ◽  
Parasitic Nematodes ◽  
Toxocara Cati ◽  
Evolutionary Point ◽  
Geographical Locations ◽  
Toxascaris Leonina

AbstractSome parasitic nematodes can inhabit different definitive hosts, which raises the question of the intraspecific variability of the nematode genotype affecting their preferences to choose particular species as hosts. Additionally, the issue of a possible intraspecific DNA microheterogeneity in specimens from different parts of the world seems to be interesting, especially from the evolutionary point of view. The problem was analysed in three related species – Toxocara canis, Toxocara cati and Toxascaris leonina – specimens originating from Central Europe (Poland). Using specific primers for species identification, internal transcribed spacer (ITS)-1 and ITS-2 regions were amplified and then sequenced. The sequences obtained were compared with sequences previously described for specimens originating from other geographical locations. No differences in nucleotide sequences were established in T. canis isolated from two different hosts (dogs and foxes). A comparison of ITS sequences of T. canis from Poland with sequences deposited in GenBank showed that the scope of intraspecific variability of the species did not exceed 0.4%, while in T. cati the differences did not exceed 2%. Significant differences were found in T. leonina, where ITS-1 differed by 3% and ITS-2 by as much as 7.4% in specimens collected from foxes in Poland and dogs in Australia. Such scope of differences in the nucleotide sequence seems to exceed the intraspecific variation of the species.

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