Initial Population Density its Effect on the Pathogenic Potential and Population Growth of Rotylenchulus reniformis on Cowpea (Vigna unguiculata L.)

2013 ◽  
Vol 01 (03) ◽  
Author(s):  
Archana U Singh
Keyword(s):  
Population Density ◽  
Population Growth ◽  
Vigna Unguiculata ◽  
Initial Population ◽  
Rotylenchulus Reniformis ◽  
Pathogenic Potential ◽  
Initial Population Density

scholarly journals A theoretical framework for multi-species range expansion in spatially heterogeneous landscapes

2021 ◽  
Author(s):  
Lukas Eigentler ◽  
Nicola R Stanley-Wall ◽  
Fordyce A Davidson
Keyword(s):  
Population Density ◽  
Range Expansion ◽  
Theoretical Framework ◽  
Dominant Mode ◽  
Bacterial Biofilm ◽  
Time Interval ◽  
Initial Population ◽  
Initial Population Density ◽  
Competitive Outcome ◽  
The Impact

Range expansion is the spatial spread of a population into previously unoccupied regions. Understanding range expansion is important for the study and successful manipulation and management of ecosystems, with applications ranging from controlling bacterial biofilm formation in industrial and medical environments to large scale conservation programmes for species undergoing climate-change induced habitat disruption. During range expansion, species typically encounter competitors. Moreover, the environment into which expansion takes place is almost always heterogeneous when considered at the scale of the individual. Despite the ubiquitous nature of these features, the impact of competition and spatial landscape heterogeneities on range expansion remains understudied. In this paper we present a theoretical framework comprising two competing generic species undergoing range expansion and use it to investigate the impact of spatial landscape heterogeneities on range expansion with a particular focus on its effect on competition dynamics. We reveal that the area covered by range expansion during a fixed time interval is highly variable due to the fixed landscape heterogeneities. Moreover, we report significant variability in competitive outcome (relative abundance of a focal species) but determine that this is induced by low initial population densities, independent of landscape heterogeneities. We further show that both area covered by range expansion and competitive outcome can be accurately predicted by a Voronoi tessellation with respect to an appropriate metric, which only requires information on the spatial landscape and the response of each species to that landscape. Finally, we reveal that if species interact antagonistically during range expansion, the dominant mode of competition depends on the initial population density. Antagonistic actions determine competitive outcome if the initial population density is high, but competition for space is the dominant mode of competition if the initial population density is low.

scholarly journals A Population of Meloidogyne javanica in Spain Virulent to the Mi Resistance Gene in Tomato

Plant Disease ◽  
2001 ◽  
Vol 85 (3) ◽  
pp. 271-276 ◽  
Author(s):  
C. Ornat ◽  
S. Verdejo-Lucas ◽  
F. J. Sorribas
Keyword(s):  
Population Density ◽  
Negative Correlation ◽  
Meloidogyne Javanica ◽  
Initial Population ◽  
Initial Population Density ◽  
Tomato Yield ◽  
Final Population ◽  
Tomato Cultivars ◽  
Mi Gene ◽  
Susceptible Tomato

A population of Meloidogyne javanica virulent to Mi-gene in tomato was identified in Spain. It reproduced similarly on resistant and susceptible tomato cultivars in the greenhouse, microplots, and in the field. In monoxenic cultures, reproduction of the virulent M. javanica was higher than that of an avirulent population on resistant but not on susceptible tomatoes. The virulent population suppressed tomato yield of both resistant and susceptible tomatoes by 29% in microplots. Initial population density (Pi) was inversely correlated with Pf (final population density)/Pi on both resistant and susceptible tomatoes in the field. A negative correlation was found between Pi and tomato yield for the susceptible but not for the resistant cultivar.

Experiment on obtaining an algologically pure culture of Tetraselmis viridis in non-sterile conditions

2020 ◽  
pp. 94-100
Author(s):  
Svetlana Yu. Gorbunova ◽  
Rudolf P. Trenkenshu
Keyword(s):  
Population Density ◽  
Pure Culture ◽  
Sea Water ◽  
The Black Sea ◽  
Initial Population ◽  
Green Microalgae ◽  
Infected Culture ◽  
Initial Population Density ◽  
Mechanical Removal ◽  
Tetraselmis Viridis

The possibility of obtaining an algologically pure culture of Tetraselmis viridis, grown on the Black Sea water in non-sterile conditions, was shown experimentally. Our experiments showed that at low initial population density of the culture after 1–3 days, there was an infection of the culture with blue-green species of microalgae (Oscillatoria sp.). Thrice repeated mechanical removal of blue-green microalgae cells by filtering the infected culture allowed obtaining an algologically pure culture of T. viridis. Under similar conditions of T. viridis cultivation, but with the initial addition of NaCl (15 g/l) to the nutrient medium aimed at increasing salinity to the Mediterranean level, there was no contamination of the culture.

scholarly journals Modelling the effect of demographic traits and connectivity on the genetic structuration of marine metapopulations of sedentary benthic invertebrates

2015 ◽  
Vol 73 (7) ◽  
pp. 1935-1945 ◽  
Author(s):  
Mariana Padrón ◽  
Katell Guizien
Keyword(s):  
Genetic Diversity ◽  
Genetic Structure ◽  
Population Density ◽  
Genetic Drift ◽  
Benthic Invertebrates ◽  
Spatial Planning ◽  
Marine Spatial Planning ◽  
Initial Population ◽  
Initial Population Density ◽  
Demographic Fluctuations

Abstract Accounting for connectivity is essential in marine spatial planning and the proper design and management of marine protected areas, given that their effectiveness depends on the patterns of dispersal and colonization between protected and non-protected areas. The genetic structure of populations is commonly used to infer connectivity among distant populations. Here, we explore how population genetic structure is affected by pre- and settlement limitations with a spatially explicit coupled metapopulation-gene flow model that simulates the effect of demographic fluctuations on the allele frequencies of a set of populations. We show that in closed populations, regardless of population growth rate, the maintenance of genetic diversity at saturating initial population density increases with species life expectancy as a result of density-dependent recruitment control. Correlatively, at low initial population density, the time at which a population begins to lose its genetic diversity is driven larval and post-settlement mortality (comprised in the recruitment success parameter)—the larger the recruitment success, the stronger the genetic drift. Different spatial structures of connectivity established for soft bottom benthic invertebrates in the Gulf of Lions (NW Mediterranean, France) lead to very different results in the spatial patterns of genetic structuration of the metapopulation, with high genetic drift in sites where the local retention rate was larger than 2%. The effect of recruitment failure and the loss of key source populations on heterozygosity confirm that transient demographic fluctuations help maintain genetic diversity in a metapopulation. This study highlights the role of intraspecific settlement limitations due to lack of space when the effective number of breeders approaches saturating capacity, causing a strong reduction in effective reproduction. The present model allows to: (i) disentangle the relative contribution of local demography and environmental connectivity in shaping seascape genetics, and (ii) perform in silico evaluations of different scenarios for marine spatial planning.

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