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11.
Counts of Steller sea lion ( Eumetopias jubatus ) pups and non-pups (adults and juveniles) from aerial photographs of rookeries at Año Nuevo Island between 1990 and 1993 were significantly higher than those made on the ground. Based on regression of natural logs of photographic counts versus year, the number of pups declined at a rate of −0.099yr while non-pup numbers declined at −0.315/yr. Examination of ground count data for the same period revealed a significant decline in non-pups (−0.139/yr), but no trend was detected in the ground counts of pups. The regression coefficients from photographic and ground counts of non-pups did not differ significantly. Power analyses using the program TRENDS indicated that detectable rates of change in abundance from four annual surveys were much lower for counts of pups than counts of non-pups where sampling precision was based on fits to linear models. 相似文献
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《植物生态学报》2015,39(8):816
Aims Fractal root system is phenotypic plasticity result of plant root architecture to respond to environmental heterogeneity, may reflect the growth strategy of plants to adapt to environmental conditions. Our objective was to explore the relationship between root fractal dimension and fractal abundance of fractal root system of Melica przewalskyi population in response to aspect variation in the northwest of China. Methods The study site was located in a degraded alpine grassland on the northern slope in Qilian Mountains, Gansu Province, China. Survey and sampling were carried out at 40 plots which were set up along four slope aspects transects with 20 m distance between adjacent plots. Handheld GPS was used to determine the elevation, longitude and latitude of each plot. ArcGIS was used to set up digital elevation model (DEM). Community traits were investigated and six individuals roots of M. przewalskyi were collected randomly at each plot. The samples were cleaned and divided into different organs, then scanning the root with the Win-RHIZO for measurements of fractal dimension and fractal abundance in laboratory, and their biomass were then measured after being dried at 80 °C in an oven. Important findings With the slope aspect turned from north to east, west, and south, the density, height and soil moisture content of the plant community displayed a pattern of initial decline, the height, density, root fractal abundance of M. przewalskyi increased and the root fractal dimension decreased. The root fractal dimension was negatively associated with the fractal abundance in all aspects, but the relationship varied along the slope aspects gradient; there was a highly significant negative correlation (p < 0.01) between the root fractal dimension and fractal abundance at north slope and south slope aspect, whereas the correlation only reached a significant level (p < 0.05) at the east slope aspect and west slope aspect; indicating that there is a trade-off between the root fractal dimension and fractal abundance. In addition, when the slope aspect changed from north to east, west and south, the standardized major axis (SMA) slope of the regression equation in the scaling relationships between root fractal dimension and fractal abundance increased (p < 0.05), indicating that the roots of M. przewalskyi at the droughty southern slope have less branch and more sparse in the same soil volume of root exploitation and utilization. Consequently, the resource allocation pattern on reasonable trade-off between root fractal dimension and fractal abundance in different slope aspect of M. przewalskyi, reflects the relationship between the income and the cost of construction of plant root architecture. 相似文献
16.
Summary Feeding the secondary plant compound 6-Methoxybenzoxazolinone (6-MBOA) during winter to a free living population of Microtus townsendii accelerated breeding in females. Both the recruitment of young and sexual maturation of these young were advanced by four weeks in comparison with a control population. Overwintered females supplied with 6-MBOA matured at a lower body weight than control females. But there was no such weightat-maturity difference between the grids for males. During April and May 72% of all juveniles captured came from the experimental population. Winter reproduction and early recruitment of young stimulated by 6-MBOA could have important population consequences for these voles. 相似文献
17.
Inbreeding under a cyclical mating system 总被引:1,自引:0,他引:1
A. Farid M. Makarechian C. Strobeck 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1987,73(4):506-515
Summary General recursion formulae for the coefficient of inbreeding under a cyclical mating system were derived in which one male and one female are selected from each of the n families per generation (population size N = 2 n). Each male is given the family number of his sire in each generation, while his mate comes from another family, varying systematically in different generations. Males of the r-th family in generations 1, 2, 3,..., t = n–1 within each cycle mate with females from families r+1, r+2, r+3,..., r+t to produce generations 2, 3, 4,..., t+1=1, respectively. The change in heterozygosity shows a cyclical pattern of rises and falls, repeating in cycles of n–1 generations. The rate of inbreeding oscillates between <-3% to >6% in different generations within each cycle, irrespective of the population size. The average rate of inbreeding per generation is approximately 1/[4 N-(Log2N+1)], which is the rate for the maximum avoidance of inbreeding. The average inbreeding effective population size is approximately 2 N–2. 相似文献
18.
Repeated observations are made on species and numbers of individuals in some islets. The changes after 14 years are reported for 11 islets. They include several extinctions and invasions. Great changes in numbers of individuals were found, especially for many of the annuals, in some of them as great as between 0–10 and over 10 000 individuals. The greatest constancy was found in a few dominant and subdominant perennials.Dedicated to Prof.K. H. Rechinger on the occasion of his 80th birthday. 相似文献
19.
G. Modiano G. Cermele C. Santolamazza S. Biagioni G. Scarsella L. E. Pacifici G. Toschi 《International Journal of Anthropology》1987,2(1):61-73
392 random patients treated with SCC prior to surgery were assayed for pseudocholinesterase activity and electrophoretic pattern.
The estimate of the percent frequencies of theE
1
a
allele were 1.16±0.38 and of the C5 (+) phenotype 9.7±1.5, both typical of Caucasian populations. By combining the presentE
1
a
gene frequency estimate with that from another sample of the same population (Cermele
et al., 1987) a better estimate with smaller confidence limits was obtained, that is: 1,14±0,27. One subject interpreted asE
1
a
E
1
a
on phenotypic grounds was also found (expected 0,05) in this random sample.
A correlation coefficient of −0.521 was found between E activity and myorelaxation time in the whole sample. High correlation
values (r=−0.55 and r=−0.46) were found forE
1
u
E
1
u
; C5 (−) andE
1
u
E
1
u
; C5 (+) individuals, respectively, showing a strong dependence of the latter variable on the former one even within apparently
homogeneous classes. The use of the product of these two variables as a classification criterion allowed the identification
of a subject with very long myorelaxation time but normal activity. 相似文献
20.
Cell wall mannoproteins during the population growth phases in Saccharomyces cerevisiae 总被引:2,自引:0,他引:2
E. Valentín E. Herrero H. Rico F. Miragall R. Sentandreu 《Archives of microbiology》1987,148(2):88-94
Mannoproteins from cell walls of Saccharomyces cerevisiae synthesized at successive stages of the population growth cycle have been solubilized with Zymolyase and subsequently analyzed. The major change along the population cycle concerned a large size mannoprotein material; the size of the newly-synthesized molecules varied from 120,000–500,000 (mean of about 200,000) at early exponential phase to 250,000–350,000 (mean of about 300,000) at late exponential phase. These differences are due to modifications in the amount of N-glycosidically linked mannose residues, since the size of the peptide moiety was 90,000–100,000 at all growth stages and the level of O-glycosylation changed only slightly. After, incubation of the purified walls with concanavalin A-ferritin and subsequent analysis by electron microscopy, labelling was localized at the external and internal faces of the walls. The middle space of these was labelled after digestion of the glucan network with Zymolyase, which demonstrate the presence of mannoproteins in close contact with the structural glucan molecules throughout the wall.Abbreviations BSA
bovine serum albumin
- Con A
concanavalin A
- SDS
sodium dodecyl sulphate 相似文献