scholarly journals Relationship Between Phyllosphere Population Sizes of Xanthomonas translucens pv. translucens and Bacterial Leaf Streak Severity on Wheat Seedlings

1999 ◽  
Vol 89 (2) ◽  
pp. 131-135 ◽  
Author(s):  
Kurt D. Stromberg ◽  
Linda L. Kinkel ◽  
Kurt J. Leonard
Keyword(s):  
Disease Control ◽  
Population Size ◽  
Logistic Model ◽  
Bacterial Leaf Streak ◽  
Pathogen Population ◽  
Wheat Seedlings ◽  
Xanthomonas Translucens ◽  
Population Sizes ◽  
The Relationship ◽  
Disease Severity Level

The relationship between leaf-associated population sizes of Xanthomonas translucens pv. translucens on asymptomatic leaves and subsequent bacterial leaf streak (BLS) severity was investigated. In three experiments, X. translucens pv. translucens was spray-inoculated onto 10-day-old wheat seedlings over a range of inoculum densities (104, 105, 106, 107, and 108 CFU/ml). Lesions developed most rapidly on plants inoculated with higher densities of X. translucens pv. translucens. Leaf-associated pathogen population sizes recovered 48 h after inoculation were highly predictive of BLS severity 7 days after inoculation (R2 = 0.970, P < 0.0001). The relationship between pathogen population size on leaves and subsequent BLS severity was best described by the logistic model. Leaf-associated X. translucens pv. translucens population size and BLS severity from a particular pathogen inoculum density often varied among experiments; however, the disease severity level caused by a particular leaf-associated X. translucens pv. translucens population size was not significantly different among experiments. Biological and disease control implications of the X. translucens pv. translucens population size-BLS severity relationship are discussed.

scholarly journals Mitochondrial DNA Sequence Diversity in Mammals: A Correlation between the Effective and Census Population Sizes

2020 ◽  
Vol 12 (12) ◽  
pp. 2441-2449
Author(s):  
Jennifer James ◽  
Adam Eyre-Walker
Keyword(s):  
Mitochondrial Dna ◽  
Metabolic Rate ◽  
Population Size ◽  
Effective Population Size ◽  
Dna Sequence ◽  
Range Size ◽  
Effective Population ◽  
Population Sizes ◽  
Census Population Size ◽  
The Relationship

Abstract What determines the level of genetic diversity of a species remains one of the enduring problems of population genetics. Because neutral diversity depends upon the product of the effective population size and mutation rate, there is an expectation that diversity should be correlated to measures of census population size. This correlation is often observed for nuclear but not for mitochondrial DNA. Here, we revisit the question of whether mitochondrial DNA sequence diversity is correlated to census population size by compiling the largest data set to date, using 639 mammalian species. In a multiple regression, we find that nucleotide diversity is significantly correlated to both range size and mass-specific metabolic rate, but not a variety of other factors. We also find that a measure of the effective population size, the ratio of nonsynonymous to synonymous diversity, is also significantly negatively correlated to both range size and mass-specific metabolic rate. These results together suggest that species with larger ranges have larger effective population sizes. The slope of the relationship between diversity and range is such that doubling the range increases diversity by 12–20%, providing one of the first quantifications of the relationship between diversity and the census population size.

scholarly journals Quantifying the relationship between genetic diversity and population size suggests natural selection cannot explain Lewontin's paradox

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Vince Buffalo
Keyword(s):  
Genetic Diversity ◽  
Population Size ◽  
Phylogenetic Signal ◽  
Neutral Theory ◽  
Negative Relationship ◽  
Abundant Species ◽  
Census Size ◽  
Population Sizes ◽  
The Relationship ◽  
Linked Selection

Neutral theory predicts that genetic diversity increases with population size, yet observed levels of diversity across metazoans vary only two orders of magnitude while population sizes vary over several. This unexpectedly narrow range of diversity is known as Lewontin’s Paradox of Variation (1974). While some have suggested selection constrains diversity, tests of this hypothesis seem to fall short. Here, I revisit Lewontin’s Paradox to assess whether current models of linked selection are capable of reducing diversity to this extent. To quantify the discrepancy between pairwise diversity and census population sizes across species, I combine previously-published estimates of pairwise diversity from 172 metazoan taxa with newly derived estimates of census sizes. Using phylogenetic comparative methods, I show this relationship is significant accounting for phylogeny, but with high phylogenetic signal and evidence that some lineages experience shifts in the evolutionary rate of diversity deep in the past. Additionally, I find a negative relationship between recombination map length and census size, suggesting abundant species have less recombination and experience greater reductions in diversity due to linked selection. However, I show that even assuming strong and abundant selection, models of linked selection are unlikely to explain the observed relationship between diversity and census sizes across species.

scholarly journals Mitochondrial DNA Sequence Diversity in Mammals: a Correlation Between the Effective and Census Population Sizes

2020 ◽  
Author(s):  
Jennifer James ◽  
Adam Eyre-Walker
Keyword(s):  
Mitochondrial Dna ◽  
Metabolic Rate ◽  
Population Size ◽  
Effective Population Size ◽  
Dna Sequence ◽  
Sequence Diversity ◽  
Effective Population ◽  
Population Sizes ◽  
Census Population Size ◽  
The Relationship

AbstractWhat determines the level of genetic diversity of a species remains one of the enduring problems of population genetics. Since, neutral diversity depends upon the product of the effective population size and mutation rate there is an expectation that diversity should be correlated to measures of census population size. This correlation is often observed for nuclear but not for mitochondrial DNA. Here we revisit the question of whether mitochondrial DNA sequence diversity is correlated to census population size by compiling the largest dataset to date from 639 mammalian species. In a multiple regression we find that nucleotide diversity is significantly correlated to both range size and mass-specific metabolic rate, but not a variety of other factors. We also find that a measure of the effective population size, the ratio of non-synonymous to synonymous diversity, is also significantly negatively correlated to both range and mass-specific metabolic rate. These results together suggest that species with larger ranges have larger effective population sizes. The slope of the relationship between diversity and range is such that doubling the range increases diversity by 12 to 20%, providing one of the first quantifications of the relationship between effective and census population sizes.

scholarly journals Effects of copper-based compounds, antibiotics and a plant activator on population sizes and spread of Clavibacter michiganensis subsp. michiganensis in greenhouse tomato seedlings

2009 ◽  
Vol 24 (1) ◽  
pp. 19-27 ◽  
Author(s):  
Svetlana Milijasevic ◽  
Biljana Todorovic ◽  
Ivana Potocnik ◽  
Emil Rekanovic ◽  
Milos Stepanovic
Keyword(s):  
Population Size ◽  
The Other ◽  
Copper Oxychloride ◽  
Copper Hydroxide ◽  
Clavibacter Michiganensis ◽  
Pathogen Population ◽  
Tomato Seedlings ◽  
Clavibacter Michiganensis Subsp ◽  
Population Sizes ◽  
Plant Activator

Three copper-based compounds (copper hydroxide, copper oxychloride, copper sulphate), two antibiotics (streptomycin and kasugamycin) and a plant activator (ASM) significantly reduced population sizes and spread of C. michiganensis subsp. michiganensis among tomato seedlings in the greenhouse. Streptomycin had the best effect in reducing pathogen population size in all sampling regions. Moreover, this antibiotic completely stopped the spread of C. michiganensis subsp. michiganensis in the region most distant from the inoculum focus. Copper hydroxide mixed with streptomycin significantly limited the pathogen population, compared with copper hydroxide alone, the other copper-based compounds, ASM and kasugamycin. However, combining streptomycin with copper hydroxide did not contribute to its greater efficacy against the pathogen population. Copper-based compounds, in general, were less effective in limiting pathogen population sizes than the other treatments in all three sampling regions, primarily copper oxychloride and the combination of copper hydroxide and mannose. Among copper compounds, copper hydroxide was the most prominent in reducing the bacterial population, especially in the region closest to the inoculums focus, while its combination with mannose did not improve the effects. Kasugamycin significantly limited pathogen population size, compared to copper bactericides, but it was less effective than the other antibiotic compound, i.e. streptomycin. The plant activator ASM significantly reduced population density, and it was more effective when used three days prior to inoculation than six days before inoculation.

scholarly journals Effect of Pheromone Blend Components, Sex Ratio, and Population Size on the Mating of Cadra cautella (Lepidoptera: Pyralidae)

2020 ◽  
Vol 20 (6) ◽  
Author(s):  
Abeysinghe Mudiyanselage Prabodha Sammani ◽  
Dissanayaka Mudiyanselage Saman Kumara Dissanayaka ◽  
Leanage Kanaka Wolly Wijayaratne ◽  
William Robert Morrison
Keyword(s):  
Sex Ratio ◽  
Population Size ◽  
Management Practices ◽  
Mating Disruption ◽  
Current Knowledge ◽  
Mating Status ◽  
Cadra Cautella ◽  
Synthetic Chemicals ◽  
Population Sizes ◽  
Lepidoptera Pyralidae

Abstract The almond moth Cadra cautella (Walker), a key pest of storage facilities, is difficult to manage using synthetic chemicals. Pheromone-based management methods remain a high priority due to advantages over conventional management practices, which typically use insecticides. Cadra cautella females release a blend of pheromone including (Z, E)-9,12-tetradecadienyl acetate (ZETA) and (Z)-9-tetradecadien-1-yl acetate (ZTA). The effect of these components on mating of C. cautella and how response varies with the population density and sex ratio remain unknown. In this study, the mating status of C. cautella was studied inside mating cages under different ratios of ZETA and ZTA diluted in hexane and at different population sizes either with equal or unequal sex ratio. The lowest percentage of mated females (highest mating disruption [MD] effects), corresponding to roughly 12.5%, was produced by a 5:1 and 3.3:1 ratio of ZETA:ZTA. Populations with equal sex ratio showed the lowest percentage of mated females, at 20% and 12.5% under lower and higher density, respectively. The next lowest percentage of mated females was produced when the sex ratio was set to 1: 2 and 2:1 male:female, with just 25% and 22.5% of moths mated, respectively. This study shows that mating status of C. cautella is influenced by ZETA:ZTA ratio, sex ratio, and population size. This current knowledge would have useful implications for mating disruption programs.

scholarly journals EFFECTS OF POPULATION SIZE AND SELECTION INTENSITY ON SHORT-TERM RESPONSE TO SELECTION FOR POSTWEANING GAIN IN MICE

Genetics ◽  
1973 ◽  
Vol 73 (3) ◽  
pp. 513-530
Author(s):  
J P Hanrahan ◽  
E J Eisen ◽  
J E Legates
Keyword(s):  
Population Size ◽  
Selection Response ◽  
Selection Intensity ◽  
Realized Heritability ◽  
Family Selection ◽  
Effective Population ◽  
Population Sizes ◽  
Selection For ◽  
Selection Intensities ◽  
Term Response

ABSTRACT The effects of population size and selection intensity on the mean response was examined after 14 generations of within full-sib family selection for postweaning gain in mice. Population sizes of 1, 2, 4, 8 and 16 pair matings were each evaluated at selection intensities of 100% (control), 50% and 25% in a replicated experiment. Selection response per generation increased as selection intensity increased. Selection response and realized heritability tended to increase with increasing population size. Replicate variability in realized heritability was large at population sizes of 1, 2 and 4 pairs. Genetic drift was implicated as the primary factor causing the reduced response and lowered repeatability at the smaller population sizes. Lines with intended effective population sizes of 62 yielded larger selection responses per unit selection differential than lines with effective population sizes of 30 or less.

Estimation of Catchabilities and Population Sizes of Lobsters

1963 ◽  
Vol 20 (1) ◽  
pp. 59-88 ◽  
Author(s):  
J. E. Paloheimo
Keyword(s):  
Environmental Factors ◽  
Population Size ◽  
Atlantic Coast ◽  
Temperature Data ◽  
New Method ◽  
Bottom Temperature ◽  
Population Size Estimates ◽  
Population Sizes ◽  
Estimate Population Size ◽  
Size Estimates

Techniques of estimating population size, level of fishing, and the degree of dependence of fishing success on environmental factors are examined on the basis of tagging, catch and effort data. A new method is developed to estimate population size from catch, effort, and temperature data when the catchability varies with temperature.The methods of estimation discussed are applied to data collected from a number of lobster fisheries on Canada's Atlantic coast. Analysis confirms a relationship between the catchability of lobsters and bottom temperature. Differences in this relationship are found between areas and between tagged and untagged lobsters within areas. It is suggested that these differences are attributable to the differences in densities as well as to aggregations of lobsters and fishing. The effect of these aggregations on population size estimates is considered.Calculated average catchabilities at comparable temperatures are different for different areas. These differences are correlated with the numbers of trap hauls per day per square miles fished. It is suggested that the differences in the catchabilities might be due to interactions between units of gear not predicted by the customary relationship between catch and effort.

Influence of Inoculation Method, Spot Inoculation Site, and Inoculation Size on the Efficacy of Acidic Electrolyzed Water against Pathogens on Lettuce

2003 ◽  
Vol 66 (11) ◽  
pp. 2010-2016 ◽  
Author(s):  
SHIGENOBU KOSEKI ◽  
KYOICHIRO YOSHIDA ◽  
YOSHINORI KAMITANI ◽  
KAZUHIKO ITOH
Keyword(s):  
Population Size ◽  
Room Temperature ◽  
Escherichia Coli O157 ◽  
Bacterial Inoculation ◽  
Pathogen Population ◽  
Salmonella Spp ◽  
Electrolyzed Water ◽  
Inoculation Methods ◽  
E Coli ◽  
Inoculation Site

The influence of bacterial inoculation methods on the efficacy of sanitizers against pathogens was examined. Dip and spot inoculation methods were employed in this study to evaluate the effectiveness of acidic electrolyzed water (AcEW) and chlorinated water (200 ppm free available chlorine) against Escherichia coli O157:H7 and Salmonella spp. Ten pieces of lettuce leaf (5 by 5 cm) were inoculated by each method then immersed in 1.5 liters of AcEW, chlorinated water, or sterile distilled water for 1 min with agitation (150 rpm) at room temperature. The outer (abaxial) and inner (adaxial) surfaces of the lettuce leaf were distinguished in the spot inoculation. Initial inoculated pathogen population was in the range 7.3 to 7.8 log CFU/g. Treatment with AcEW and chlorinated water resulted in a 1 log CFU/g or less reduction of E. coli O157:H7 and Salmonella populations inoculated with the dip method. Spot inoculation of the inner surface of the lettuce leaf with AcEW and chlorinated water reduced the number of E. coli O157:H7 and Salmonella by approximately 2.7 and 2.5 log CFU/g, respectively. Spot inoculation of the outer surface of the lettuce leaf with both sanitizers resulted in approximately 4.6 and 4.4 log CFU/g reductions of E. coli O157:H7 and Salmonella, respectively. The influence of inoculation population size was also examined. Each sanitizer could not completely eliminate the pathogens when E. coli O157:H7 and Salmonella cells inoculated on the lettuce were of low population size (103 to 104 CFU/g), regardless of the inoculation technique.

scholarly journals DO LANGUAGE CHANGE RATES DEPEND ON POPULATION SIZE?

2008 ◽  
Vol 11 (03) ◽  
pp. 357-369 ◽  
Author(s):  
SØREN WICHMANN ◽  
DIETRICH STAUFFER ◽  
CHRISTIAN SCHULZE ◽  
ERIC W. HOLMAN
Keyword(s):  
Population Size ◽  
Computer Simulations ◽  
Empirical Data ◽  
Language Change ◽  
Strong Dependence ◽  
Language Model ◽  
Population Sizes

An earlier study [24] concluded, based on computer simulations and some inferences from empirical data, that languages will change the more slowly the larger the population gets. We replicate this study using a more complete language model for simulations (the Schulze model combined with a Barabási–Albert network) and a richer empirical dataset [12]. Our simulations show either a negligible or a strong dependence of language change on population sizes, depending on the parameter settings; while empirical data, like some of the simulations, show a negligible dependence.

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