Morphometric Evidence of Hybrid Swarms in Mixed Populations of Polystichum munitum and P. imbricans (Dryopteridaceae)

1993 ◽  
Vol 18 (2) ◽  
pp. 248 ◽  
Author(s):  
Michael S. Mayer ◽  
Michael R. Mesler
Keyword(s):  
Hybrid Swarms ◽  
Mixed Populations ◽  
Polystichum Munitum

The Evolution of Helping Behavior in Large, Randomly Mixed Populations

1986 ◽  
Vol 127 (2) ◽  
pp. 209-221 ◽  
Author(s):  
Joel R. Peck ◽  
Marcus W. Feldman
Keyword(s):  
Helping Behavior ◽  
Mixed Populations

Population Dynamics and Regeneration of a Hybrid Zone Between Eucalyptus risdonii Hook-F and E amygdalina Labill

1986 ◽  
Vol 34 (3) ◽  
pp. 305 ◽  
Author(s):  
BM Potts
Keyword(s):  
Hybrid Zone ◽  
Null Point ◽  
Asymmetric Distribution ◽  
Hybrid Swarm ◽  
Population Response ◽  
Pure Species ◽  
Seed Migration ◽  
Hybrid Swarms ◽  
Population Turnover ◽  
Phenotypic Fitness

Regeneration of a hybrid zone between E. amygdalina and E. risdonii and pure species stands following wildfire is reported, as well as the reproductive and vegetative fitness of parental and hybrid phenotypes. E. risdonii phenotypes dominated the seed rain and seedling cohort and there was clearly a marked fitness differential between E. amygdalina and E. risdonii at their boundary. When the F1 type hybrid is in competition with both parental types it is generally reproductively the least fit, although frequently vegetatively vigorous. Reduced fitness appears to extend to advanced generations as hybrid phenotypes tending.toward either species are, on average, less fit than the corresponding parental type. The pattern of phenotypic fitness suggests that the species' boundary is in disequilibrium and it is argued that E. risdonii is invading the range of E. amygdalina by both pollen and seed migration. There is an asymmetric distribution of F1 type hybrids across the boundary and the hybrid swarm examined is being invaded by E. risdonii genes. It is suggested that hybridization may be associated with natural disequilibrium and, where seed migration is limited, boundary movements may be preceded by a wave of hybridization due partly to pollen swamping of the least fit species. Hybrid swarms may develop but, at the boundary of large stands, are probably transitory. There is a marked inertia in the population response to the prevailing selective regime due to the extremely slow population turnover and limited dispersal potential. This is discussed in the broader context of non-equilibrium models where it is argued that dispersal may be the factor limiting population response to perturbation of a shallow environmental gradient. This is due to large geographical shifts in the position of the null point and would be accentuated in a patchy environment where migration as a front is prevented.

scholarly journals From Hybrid Swarms to Swarms of Hybrids

2014 ◽  
Vol 2 (8) ◽  
pp. 311-318 ◽  
Author(s):  
Thomas J. Stohlgren ◽  
Allen L. Szalanski ◽  
John Gaskin ◽  
Nicholas Young ◽  
Amanda West ◽  
...  
Keyword(s):  
Hybrid Swarms

scholarly journals ASSOCIATION OF IL-8 -251T>A (RS4073) POLYMORPHISM WITH SUSCEPTIBILITY TO GASTRIC CANCER: A SYSTEMATIC REVIEW AND META-ANALYSIS BASED ON 33 CASE-CONTROL STUDIES

2020 ◽  
Vol 57 (1) ◽  
pp. 91-99
Author(s):  
Mansour MOGHIMI ◽  
Seyed Alireza DASTGHEIB ◽  
Naeimeh HEIRANIZADEH ◽  
Mohammad ZARE ◽  
Elnaz SHEIKHPOUR ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Meta Analysis ◽  
Random Effect ◽  
Random Effect Model ◽  
Case Control ◽  
Case Control Studies ◽  
Effect Model ◽  
Increased Risk ◽  
Mixed Populations ◽  
Stratified Analysis

ABSTRACT BACKGROUND: The role of -251A>T polymorphism in the anti-inflammatory cytokine interleukin-8 (IL-8) gene in gastric cancer was intensively evaluated, but the results of these studies were inconsistent. OBJECTIVE: Therefore, we performed a meta-analysis to provide a comprehensive data on the association of IL-8 -251T>A polymorphism with gastric cancer. METHODS: All eligible studies were identified in PubMed, Web of Science, EMBASE, Wanfang and CNKI databases before September 01, 2019. The pooled odds ratios (ORs) with 95% confidence intervals (CIs) were derived from a fixed effect or random effect model. RESULTS: A total of 33 case-control studies with 6,192 cases and 9,567 controls were selected. Overall, pooled data showed that IL-8 -251T>A polymorphism was significantly associated with an increased risk of gastric cancer under all five genetic models, i.e., allele (A vs T: OR=1.189, 95% CI 1.027-1.378, P=0.021), homozygote (AA vs TT: OR=1.307, 95% CI 1.111-1.536, P=0.001), heterozygote (AT vs TT: OR=1.188, 95% CI 1.061-1.330, P=0.003), dominant (AA+AT vs TT: OR=1.337, 95% CI 1.115-1.602, P=0.002) and recessive (AA vs AT+TT: OR=1.241, 95% CI 1.045-1.474, P=0.014). The stratified analysis by ethnicity revealed an increased risk of gastric cancer in Asians and mixed populations, but not in Caucasians. Moreover, stratified by country found a significant association in Chinese, Korean and Brazilian, but not among Japanese. CONCLUSION: This meta-analysis suggests that the IL-8 -251T>A polymorphism is associated with an increased risk of gastric cancer, especially by ethnicity (Asian and mixed populations) and country (Chinese, Korean and Brazilian).

scholarly journals Efficacy of different formulations of Bromodiolone-based rodenticides against rodent pests in alfalfa

2010 ◽  
Vol 25 (3) ◽  
pp. 277-282
Author(s):  
Goran Jokic ◽  
Marina Vuksa ◽  
Ibrahim Elezovic ◽  
Bojan Stojnic ◽  
Suzana Djedovic
Keyword(s):  
Common Vole ◽  
Field Mouse ◽  
Microtus Arvalis ◽  
Small Rodents ◽  
Striped Field Mouse ◽  
Significant Difference ◽  
Plot Area ◽  
Main Plot ◽  
Mixed Populations ◽  
Abundance And Distribution

In order to compare the efficacy of different formulations of Bromodiolone-based rodenticides against mixed populations of common vole (Microtus arvalis Pall) and striped field mouse (Apodemus agrarius) in alfalfa, the testing was conducted using the standard EPPO method at the locations of Belegis and Putinci, in summer of 2010. The experimental design consisted of a completely randomized block with four replicates and with the main plot area of 400 m2. The abundance and distribution of small rodents populations at the experimental plots were determined on the basis of appearance and spatial distribution of active holes. The efficacy of different rodenticide formulations was evaluated according to the number of active holes 7, 14, and 28 days after treatment (DAT), using the Henderson- Tilton?s formula. The testing was done with the commercially available rodenticide formulations: (grain-based baits), RB (ready-to-use baits - pouches) and PT (pellets), containing 0.005% of active ingredient Bromodiolone. The monofactoral analysing of variance did not result in any statistically significant difference in efficacy of rodenticide formulations 7 DAT at the Belegis locality and 7 and 14 DAT at the Putinci locality. But, the statistically significant difference in efficacy of rodenticide formulations was observed at Belegis locality on the 14th day of the experiment. Also, at the end of experiment, the efficacy of rodenticide formulations significantly varied at both locations. Nominally, the lowest efficacy of 72.5% was exhibited by formulation, while the average efficacy of RB and PT formulations against mixed populations of common vole and striped field mouse in alfalfa was 88.3% and 77.7%, respectively. It is concluded that the use of RB formulation of Bromodiolone-based rodenticides can improve the control of rodent pests in alfalfa.

Applicability of the case-parent design in the etiological research of Type 1 diabetes in Chile and other genetically mixed populations

1999 ◽  
Vol 43 (2) ◽  
pp. 143-146 ◽  
Author(s):  
J.L. Santos ◽  
D. Schaid ◽  
F. Pérez-Bravo ◽  
E. Carrasco ◽  
M. Calvillán ◽  
...  
Keyword(s):  
Type 1 Diabetes ◽  
Mixed Populations

Geographic Patterns of Interspecific Hybridization between Spotted Knapweed (Centaurea stoebe) and Diffuse Knapweed (C. diffusa)

2009 ◽  
Vol 2 (1) ◽  
pp. 55-69 ◽  
Author(s):  
Amy C. Blair ◽  
Ruth A. Hufbauer
Keyword(s):  
North America ◽  
North American ◽  
Management Strategies ◽  
Spotted Knapweed ◽  
The North ◽  
Hybrid Swarms ◽  
Hybrid Plants ◽  
Introduced Range ◽  
Diffuse Knapweed ◽  
A Site

AbstractHybridization between species has the potential to change invasion dynamics. Field observations suggest that spotted knapweed and diffuse knapweed, two ecologically and economically destructive invasive plants, hybridize in their introduced range. As a first step towards understanding whether hybridization has affected the dynamics of the invasion of these species, we conducted field surveys in the introduced (North American) and native (European) ranges to discern patterns of hybridization and measured fitness-related traits among field hybrids and parental species. In North America we detected plants with hybrid morphology in 97% of the diffuse knapweed sites (n= 40); such hybrid plants were taller and more often exhibited polycarpy than plants with typical diffuse knapweed morphology. Hybrids were not detected in North American spotted knapweed sites (n= 22). In most regions surveyed in Europe, diffuse knapweed and spotted knapweed were isolated from each other and existed as distinct, nonhybridizing species. However, in Ukraine, the two species frequently coexisted within a site, resulting in hybrid swarms. On average, the plants from the North American diffuse knapweed sites (including plants with both diffuse and hybrid morphology), were larger than the apparently pure diffuse knapweed in the native range. The cross-continental patterns of hybridization likely are explained by differences in cytology. It recently has been confirmed that the spotted knapweed in North America is tetraploid whereas the diffuse knapweed is diploid. Genetic incompatibilities associated with these two cytotypes likely prevent ongoing hybridization. We hypothesize that hybrid individuals were introduced to North America along with diffuse knapweed. Because plants with hybrid morphology are found in nearly all North American diffuse knapweed sites, the introduction of hybrids likely occurred early in the invasion of diffuse knapweed. Thus, although the presence of hybrids might facilitate the ongoing invasion of diffuse knapweed into North America, elevated concern regarding their presence might not be warranted. Because such individuals are not likely to represent a new hybridization event, currently effective management strategies used in diffuse knapweed sites should not need alteration.

scholarly journals FACTORIAL PRODUCTIVITY EXPERIMENTS IN A SHALLOW ESTUARY: ENERGETICS OF INDIVIDUAL PLANKTON SPECIES IN MIXED POPULATIONS

1968 ◽  
Vol 13 (2) ◽  
pp. 309-314 ◽  
Author(s):  
Bernard C. Patten ◽  
George M. Van Dyne
Keyword(s):  
Shallow Estuary ◽  
Mixed Populations ◽  
Plankton Species

Differential isolation of Pythium species from soil by means of selective media, temperature, and pH

1975 ◽  
Vol 21 (5) ◽  
pp. 606-612 ◽  
Author(s):  
R. D. Lumsden ◽  
W. A. Ayers ◽  
R. L. Dow
Keyword(s):  
Gallic Acid ◽  
Acid Medium ◽  
Inoculum Potential ◽  
Pythium Species ◽  
Optimum Temperature ◽  
Isolation Method ◽  
Frequency Method ◽  
Plate Method ◽  
Selective Media ◽  
Mixed Populations

Pythium aphanidermatum, with an optimum temperature for growth at 35C, grew well and was readily isolated from soil on pimaricin–vancomycin medium (MPVM) when incubated for24 h at 38–40C. The pH of the medium affected recovery; maximum numbers developed above pH 6.0. Other Pythium spp. were recovered on MPVM at 20–25C, but were excluded by incubation at 38–40C. These Pythium spp. included P. ultimum, P. paroecandrum, P. irregulare, P. mamillatum, and an unidentified Pythium sp. These species grew well and were readily isolated from soil on gallic acid medium (GAM) when incubated for 24–48 h at 20C. P. aphanidermatum and P. myriotylum grew from mycelium on GAM, but their oospores did not germinate nor could they be isolated from soil on this medium. P. myriotylum grew well on MPVM, but was only rarely isolated, even from soils with known high potential for disease caused by P. myriotylum. Propagules of Pythium were enumerated by a plate-dilution frequency method or by a smear-plate method in serial dilutions of soil in 0.3% water agar. This differential isolation method is valuable for studies on the ecology, survival, and inoculum potential in soils with mixed populations of P. aphanidermatum and other Pythium spp.

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