Population variation in Plantago major from southern Ontario

1982 ◽  
Vol 60 (12) ◽  
pp. 2846-2856 ◽  
Author(s):  
S. I. Warwick ◽  
J. McNeill
Keyword(s):  
Reproductive Effort ◽  
Growth Form ◽  
Distinct Group ◽  
Population Variation ◽  
Plantago Major ◽  
Southern Ontario ◽  
Climatic Regions ◽  
Canonical Variates ◽  
Growth Features ◽  
Number Of Seeds

The morphological variation and growth and flowering responses in 15 populations of Plantago major collected from different climatic regions and habitat types in southern Ontario were examined. Both within- and between-population differences were assessed using canonical variates analyses. These were carried out on data obtained from field-collected specimens, and from plants grown from seed for a 2-year period in a standard garden trial. Four groupings of the 15 population samples were recognized in the field data. These included the two lawn populations, 8 and 15; population 14, collected from a cultivated field; population 9, originating from a nonmown wasteground site; and the remaining populations collected from a range of trampled roadside – waste ground sites. Analyses of the garden trial data indicated similar groupings. Population 14 remained a distinct group containing individuals characterized by long narrow leaves, a semiprostrate growth form, earlier flowering, greater reproductive effort, reduced rosette production, a larger number of seeds per capsule, and smaller seeds. These individuals would appear to correspond to ssp. pleiosperma. The remaining population samples were characterized by a smaller number of seeds per capsule, larger seeds, a smaller reproductive effort, and later flowering and they would appear to be referable to ssp. major. The two lawn populations, 8 and 15, contained the largest number of prostrate individuals, which were smaller in size and produced less biomass than individuals in the remaining populations. The latter group consisted of large erect plants which produced considerable floral and vegetative growth. There was no evidence for clinal patterns of variation in flowering behaviour and growth features in relation to the climatic gradients in southern Ontario among the 15 populations of P. major.

scholarly journals Evaluation of Seven Complex Pennisetum Hybrids for Container and Landscape Performance in the Pacific Northwestern United States

2013 ◽  
Vol 23 (4) ◽  
pp. 525-528 ◽  
Author(s):  
Ryan N. Contreras ◽  
Jim Owen ◽  
Wayne Hanna ◽  
Brian Schwartz
Keyword(s):  
United States ◽  
Growth Form ◽  
Field Performance ◽  
Eastern United States ◽  
Randomized Experiments ◽  
Climatic Regions ◽  
The Pacific ◽  
Wide Range ◽  
Complex Hybrid ◽  
Market Preference

Ornamental grasses such as fountaingrass or napiergrass, collectively called pennisetums, belong to the genus Pennisetum, which is a diverse genus with over 80 species adapted to a wide range of climatic regions and known for its drought tolerance. Breeding efforts have led to improvements such as more intense purple foliage color, disease resistance, and apparent sterility. These improved forms have been developed and tested in the eastern United States. The objective of this research was to evaluate container and field performance of seven new complex hybrid pennisetums in the Pacific northwestern United States. Two completely randomized experiments with three replications were conducted over 2 years (2010 and 2011) at two locations. We selected seven trispecific hybrid pennisetums resulting from interploid and interspecific crossing that were given accessions Tift 5, Tift 6, Tift 10, Tift 11, Tift, 13, Tift 15, and Tift 26. Experiment 1 evaluated container performance in Corvallis, OR, while Expt. 2 evaluated field performance in Aurora, OR. Size index (SI), growth form rating, and color rating were collected and analyzed separately by location. In the container study, significant differences were observed among selections for growth form in 2010 and color ratings in both 2010 and 2011. In 2010, Tift 6, Tift 11, Tift 13, and Tift 15 had the highest growth form rating. For color rating, Tift 5, Tift 10, and Tift 26 were among the four highest rated selections in both years. In the field study, Tift 5, Tift 10, Tift 11, and Tift 26 had the highest SI when data were pooled over the 2 years, but all selections reached acceptable size for landscape use during both years of the study. Similarly, there were color differences among selections with Tift 5, Tift 10, Tift 15, and Tift 26 being highest rated. None of the selections survived below winter temperatures of −5 °C at either location during either year of the study. Our evaluations indicate that these selections have potential in the Pacific northwestern United States as annuals. Differences in complex hybrid pennisetums were observed in SI, growth form rating, and color rating. These differences demonstrated the variation among selections and will allow producers to choose desired traits based on market preference.

Growth Form and Reproductive Effort in Goldenrods (Solidago, Compositae)

1973 ◽  
Vol 107 (957) ◽  
pp. 651-661 ◽  
Author(s):  
Warren G. Abrahamson ◽  
Madhav Gadgil
Keyword(s):  
Reproductive Effort ◽  
Growth Form

Dry weight and resource allocation patterns among individuals in populations of Plantago major and P. rugelii

1982 ◽  
Vol 60 (11) ◽  
pp. 2424-2439 ◽  
Author(s):  
W. R. Hawthorn ◽  
P. B. Cavers
Keyword(s):  
Frequency Distribution ◽  
Reproductive Effort ◽  
Natural Populations ◽  
Dry Weight ◽  
Life History Trait ◽  
Plantago Major ◽  
Allocation Pattern ◽  
Plant Weight ◽  
Frequency Distributions ◽  
Allocation Patterns

The frequency distributions of log plant weight in 1st-year plants of Plantago major L. and P. rugelii Decne. were studied in greenhouse experiments, including an investigation of associated differences in allocation patterns to plant parts between individuals in various weight classes. The frequency distributions of log plant weight of both plantains were strongly negatively skewed (many large plants and few small ones) at the lowest sowing density, where little or no mortality occurred during the course of the study. At two higher sowing densities significant mortality was noted and the frequency distributions tended to "log normality" or to a significant platykurtosis. The presence of bromegrass (Bromus inermis Leyss.) reduced the weight of individual plantains and resulted in frequency distributions that were essentially "log normal." Growing the two plantains together did not alter the shapes of the frequency distributions achieved in monocultures with and without grass. A possible pattern of changes in the frequency distribution of log plant weight with the passage of time is briefly discussed. Significant differences were observed in the allocation patterns of individuals of P. major within a population to roots, caudices, leaves, supporting reproductive structures, and seeds. The allocation patterns were not normally distributed according to plant weight; thus the use of average values of allocation pattern for the population as a whole should be viewed with caution. The proportional allocation to seeds (reproductive effort) by individuals of P. major from increasingly larger weight classes generally increased at an exponential rate, and more rapidly than simultaneous decreases in root and caudex allocation. The greatest reproductive effort and the greatest number of seeds per plant of P. major were associated with the strongest negative skewness of frequency distribution of log plant weight. First-year plants of P. rugelii exhibited a different response. Very few flowered during the study. However, in a variety of treatments the allocation to root and caudex by individuals which differed in biomass by as much as two orders of magnitude was remarkably constant at about 23%. In contrast, the allocation to belowground structures was much more variable among individuals of P. major, ranging from 50% or more by the smallest individuals to less than 5% by the largest plants. This life-history trait could partly account for the greater survival over winter and longevity observed in natural populations of P. rugelii compared with those of P. major.

Reproductive effort and phenology of seed production of savanna grasses with different growth form and life history

Vegetatio ◽  
1996 ◽  
Vol 123 (1) ◽  
pp. 91-100 ◽  
Author(s):  
E. M. Veenendaal ◽  
W. H. O. Ernst ◽  
G. S. Modise
Keyword(s):  
Life History ◽  
Seed Production ◽  
Reproductive Effort ◽  
Growth Form

Geographical variation in populations of Chenopodium album resistant and susceptible to atrazine. I. Between- and within-population variation in growth and response to atrazine

1982 ◽  
Vol 60 (4) ◽  
pp. 483-493 ◽  
Author(s):  
S. I. Warwick ◽  
P. B. Marriage
Keyword(s):  
Chenopodium Album ◽  
Geographical Location ◽  
Growth Characteristics ◽  
Population Variation ◽  
Population Differences ◽  
Differential Growth ◽  
Electrophoretic Patterns ◽  
Susceptible Populations ◽  
Growth Features ◽  
Lower Biomass

Between- and within-population variation in growth characteristics, isoenzyme patterns, and response to atrazine were studied in individuals from four atrazine-resistant (R) and four susceptible (S) populations of Chenopodium album L. collected from sites of contrasting climate in southern Ontario. In both the R and S types, population differences in growth characteristics were correlated with geographical location and climatic differences. The more northerly R and S populations had a greater rate of development, earlier maturation, lower biomass at maturity, and greater reproductive effort compared, respectively, with the more southerly R and S populations.Estimates of within-population variation were obtained statistically for a number of growth characters and from the electrophoretic patterns of five enzyme systems (PGM, PGI, GOT, MPI, and LAP). These indicated marked homogeneity in the four R populations as compared with the more variable S populations. Populations from the two disjunct areas of resistance were different for two of the enzymes studied and would appear to represent two different genotypes. This would suggest that mutation for resistance in populations of C. album has occurred independently in the two areas. Coupled with the evidence for differential growth characteristics of these two genotypes in response to climate, we would suggest that resistance has developed in individuals already established in each of the two separate areas, rather than spreading from a single recent introduction of the R type in Ontario.As expected, distinct differences between the R and S types were obtained in response to postemergence treatments with atrazine. The four R populations either showed no effect or exhibited increased growth. S populations all showed marked decreases in growth and production of biomass. Significant between-population differences in growth features were apparent for both types in the control and were maintained in the presence of atrazine. Although small differences in relative susceptibility were obtained for the susceptible populations, statistically significant population by treatment interactions were not evident.

Variation and climatic adaptation in northern populations of Datura stramonium

1985 ◽  
Vol 63 (7) ◽  
pp. 1303-1308 ◽  
Author(s):  
Susan E. Weaver ◽  
Victor A. Dirks ◽  
Suzanne I. Warwick
Keyword(s):  
Seed Weight ◽  
Dry Weight ◽  
Datura Stramonium ◽  
Population Variation ◽  
Strongly Correlated ◽  
Mean Values ◽  
Percent Germination ◽  
Canonical Variates ◽  
The Mean ◽  
Initial Seed

Between- and within-population variation for 21 quantitative characters was estimated for five populations of Datura stramonium originating along a climatic gradient ranging from southern Ohio, U.S.A., to Elgin County, Ont., Canada. Datura stramonium is a predominantly inbreeding, annual species with a distribution which is expanding northward in Ontario. Plants were grown from seed to maturity in the greenhouse under uniform conditions. The five populations differed significantly in the mean values of all measured characters. Canonical variates analyses were used to distinguish the populations on the basis of combined groups of characters. Canonical means of the five populations differed significantly for both seedling and mature plant characters, but the relative distance between populations varied for the two character sets. Levels of between- and within-family variation differed significantly among populations and from one character to another. Percent germination, seedling dry weight, and leaf area were strongly correlated with initial seed weight. Seed weight and cotyledon length increased and days to anthesis decreased with a decreasing length of the growing season.

Aging, Life History, and Human Evolution

2020 ◽  
Vol 49 (1) ◽  
pp. 101-121 ◽  
Author(s):  
Richard G. Bribiescas
Keyword(s):  
Life History ◽  
Comparative Research ◽  
Reproductive Effort ◽  
Great Apes ◽  
Population Variation ◽  
Trade Offs ◽  
Evolution Of Aging ◽  
Physical Degradation ◽  
Shed Light ◽  
Over Time

Aging occurs in all sexually reproducing organisms. That is, physical degradation over time occurs from conception until death. While the life span of a species is often viewed as a benchmark of aging, the pace and intensity of physical degradation over time varies owing to environmental influences, genetics, allocation of energetic investment, and phylogenetic history. Significant variation in aging within mammals, primates, and great apes, including humans, is therefore common across species. The evolution of aging in the hominin lineage is poorly known; however, clues can be derived from the fossil record. Ongoing advances continue to shed light on the interactions between life-history variables such as reproductive effort and aging. This review presents our current understanding of the evolution of aging in humans, drawing on population variation, comparative research, trade-offs, and sex differences, as well as tissue-specific patterns of physical degradation. Implications for contemporary health challenges and the future of human evolutionary anthropology research are also discussed.

Biomass-allocation patterns in populations of Trillium erectum and T. grandiflorum in southern Ontario

1987 ◽  
Vol 65 (8) ◽  
pp. 1671-1675 ◽  
Author(s):  
Jerry G. Chmielewski ◽  
Gordon S. Ringius
Keyword(s):  
Biomass Allocation ◽  
Reproductive Effort ◽  
Total Biomass ◽  
Southern Ontario ◽  
Allocation Patterns

Biomass-allocation patterns to aerial tissues were examined among six populations for each of Trillium erectum L. and T. grandiflorum (Michx.) Salisb. in southern Ontario. Total biomass did not differ among populations of T. erectum, but androecial proportions and reproductive effort generally decreased from southwest to northeast. Total biomass of T. grandiflorum varied significantly among populations and its pattern of reproductive effort was the reverse of that of T. erectum. Androecium–gynoecium ratios decreased across southern Ontario from southwest to northeast for both species. These results suggest that there may be a shift from allogamy to autogamy in a northeasterly direction across southern Ontario.

scholarly journals Seed dormancy varies widely among Arabidopsis thaliana populations both between and within Fennoscandia and Italy

2021 ◽  
Author(s):  
Giulia Zacchello ◽  
Svenja Bomers ◽  
Cecilia Böhme ◽  
Froukje Postma ◽  
Jon Agren
Keyword(s):  
Climate Change ◽  
Arabidopsis Thaliana ◽  
Seed Dormancy ◽  
Climatic Factors ◽  
Summer Temperature ◽  
Population Variation ◽  
Life History Trait ◽  
Adaptive Potential ◽  
Climatic Regions ◽  
The Relationship

The timing of germination is a key life-history trait in plants, which is strongly affected by the strength of seed dormancy. Continental-wide variation in seed dormancy has been related to differences in climate and the timing of conditions suitable for seedling establishment. However, for predictions of adaptive potential and consequences of climatic change, information is needed regarding the extent to which seed dormancy varies within climatic regions and the factors driving such variation We planted 17 Italian and 28 Fennoscandian populations of Arabidopsis thaliana in the greenhouse and at two field sites in Italy and Sweden. To identify possible drivers of among-population variation in seed dormancy, we examined the relationship between seed dormancy and climate at the sites where populations were originally sampled. Seed dormancy was on average stronger in the Italian compared to the Fennoscandian populations, but also varied widely within both regions. Estimates of seed dormancy in the three maternal environments were positively correlated, but seeds had on average stronger dormancy when produced in the greenhouse than at the two field sites. Among Fennoscandian populations, seed dormancy tended to increase with increasing summer temperature and decreasing precipitation at the site of origin. In the smaller sample of Italian populations, no significant association was detected between mean seed dormancy and climate at the site of origin. The correlation between seed dormancy and climatic factors in Fennoscandia suggests that at least some of the among-population variation is adaptive and that climate change will affect selection on this trait.

EFFECTS OF AGRICULTURAL LAND USE ON POTENTIAL SHEET EROSION LOSSES IN SOUTHERN ONTARIO

1976 ◽  
Vol 56 (4) ◽  
pp. 443-451 ◽  
Author(s):  
L. J. P. VAN VLIET ◽  
G. J. WALL ◽  
W. T. DICKINSON
Keyword(s):  
Land Use ◽  
Agricultural Land ◽  
Cropping Systems ◽  
Agricultural Land Use ◽  
Agricultural Watersheds ◽  
Row Crops ◽  
Southern Ontario ◽  
Climatic Regions ◽  
Permanent Pasture ◽  
Sheet Erosion

Potential sheet erosion losses from 13 agricultural watersheds were investigated to assess the effects of agricultural land use on soil erosion levels. The agricultural watersheds, ranging in size from 19 to 54 km2, were representative of the predominant livestock and cropping management systems in the major physiographic and climatic regions of Southern Ontario. Average annual sheet erosion losses were estimated on a field basis using the universal soil loss equation. Rainfall intensity and soil and topographic variability were considered in deriving mean annual soil losses for a range of field crops. Crops yielding the highest annual sheet erosion loss estimates were row crops, such as horticultural cash crops (9.1 ton/ha/yr), beans (7.6 ton/ha/yr), and continuous corn (6.7 ton/ha/yr). Erosion losses from crops in rotations with grasses or legumes (corn, small grains, meadow) and from tobacco were determined to be approximately one half of values obtained for continuous row cropping systems. Lowest sheet erosion losses occurred on permanent pasture and woodlands (<0.5 ton/ha/yr). Results of this study suggest that on a regional basis, the intensively farmed cash crop areas have higher erosion potentials than areas with rotational cropping systems. Watersheds with a low potential for sheet erosion often are dominated by livestock operations, where a large percentage of the area is represented by grasses or legumes and permanent pasture.

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