scholarly journals Evolution under pH stress and high population densities leads to increased density‐dependent fitness in the protist Tetrahymena thermophila

Evolution ◽  
2020 ◽  
Vol 74 (3) ◽  
pp. 573-586 ◽  
Author(s):  
Felix Moerman ◽  
Angelina Arquint ◽  
Stefanie Merkli ◽  
Andreas Wagner ◽  
Florian Altermatt ◽  
...  
Keyword(s):  
Tetrahymena Thermophila ◽  
High Population ◽  
Population Densities ◽  
Density Dependent ◽  
Ph Stress

scholarly journals Evolution under pH stress and high population densities leads to increased density-dependent fitness in the protist Tetrahymena thermophila

2019 ◽  
Author(s):  
Felix Moerman ◽  
Angelina Arquint ◽  
Stefanie Merkli ◽  
Andreas Wagner ◽  
Florian Altermatt ◽  
...  
Keyword(s):  
Abiotic Stress ◽  
Tetrahymena Thermophila ◽  
Low Ph ◽  
High Population ◽  
Population Densities ◽  
Density Dependent ◽  
Ph Stress ◽  
Evolutionary Changes ◽  
Ph Conditions ◽  
Protist Species

AbstractAbiotic stress is a major force of selection that organisms are constantly facing. While the evolutionary effects of various stressors have been broadly studied, it is only more recently that the relevance of interactions between evolution and underlying ecological conditions, that is, eco-evolutionary feedbacks, have been highlighted. Here, we experimentally investigated how populations adapt to pH-stress under high population densities. Using the protist species Tetrahymena thermophila, we studied how four different genotypes evolved in response to stressfully low pH conditions and high population densities. We found that genotypes underwent evolutionary changes, some shifting up and others shifting down their intrinsic rates of increase (r0). Overall, evolution at low pH led to the convergence of r0 and intraspecific competitive ability (α) across the four genotypes. Given the strong correlation between r0 and α, we argue that this convergence was a consequence of selection for increased density-dependent fitness at low pH under the experienced high density conditions. Increased density-dependent fitness was either attained through increase in r0, or decrease of α, depending on the genetic background. In conclusion, we show that demography can influence the direction of evolution under abiotic stress.

scholarly journals A Two-Component Regulator Mediates Population-Density-Dependent Expression of the Bradyrhizobium japonicum Nodulation Genes

2002 ◽  
Vol 184 (6) ◽  
pp. 1759-1766 ◽  
Author(s):  
John Loh ◽  
Dasharath P. Lohar ◽  
Brett Andersen ◽  
Gary Stacey
Keyword(s):  
Gene Expression ◽  
Population Density ◽  
Conditioned Medium ◽  
Bradyrhizobium Japonicum ◽  
Response Regulator ◽  
High Population ◽  
Wild Type ◽  
Population Densities ◽  
Density Dependent ◽  
Culture Density

ABSTRACT Bradyrhizobium japonicum nod gene expression was previously shown to be population density dependent. Induction of the nod genes is highest at low culture density and repressed at high population densities. This repression involves both NolA and NodD2 and is mediated by an extracellular factor found in B. japonicum conditioned medium. NolA and NodD2 expression is maximal at high population densities. We demonstrate here that a response regulator, encoded by nwsB, is required for the full expression of the B. japonicum nodYABC operon. In addition, NwsB is also required for the population-density-dependent expression of both nolA and nodD2. Expression of nolA and nodD2 in the nwsB mutant remained at a basal level, even at high culture densities. The nwsB defect could be complemented by overexpression of a second response regulator, NodW. Consistent with the fact that NolA and NodD2 repress nod gene expression, the expression of a nodY-lacZ fusion in the nwsB mutant was unaffected by culture density. In plant assays with GUS fusions, nodules infected with the wild type showed no nodY-GUS expression. In contrast, nodY-GUS expression was not repressed in nodules infected with the nwsB mutant. Nodule competition assays between the wild type and the nwsB mutant revealed that the addition of conditioned medium resulted in a competitive advantage for the nwsB mutant.

Maternal Inhibition of Hatching at High Population Densities inTigriopus japonicus(Copepoda, Crustacea)

1988 ◽  
Vol 174 (2) ◽  
pp. 139-144 ◽  
Author(s):  
DAVID KAHAN ◽  
YEHUDA BERMAN ◽  
THEODORA BAR-EL
Keyword(s):  
High Population ◽  
Population Densities

scholarly journals The significance of biomass allocation to population growth of the invasive species Ambrosia artemisiifolia and Ambrosia trifida with different densities

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Wenxuan Zhao ◽  
Tong Liu ◽  
Yan Liu ◽  
Hanyue Wang ◽  
Ruili Wang ◽  
...  
Keyword(s):  
Cluster Formation ◽  
Ambrosia Artemisiifolia ◽  
High Density ◽  
High Population ◽  
Leaf Biomass ◽  
Total Biomass ◽  
Low Density ◽  
Population Densities ◽  
Ambrosia Trifida ◽  
Short Period

Abstract Background Ambrosia artemisiifolia and Ambrosia trifida are globally distributed harmful and invasive weeds. High density clusters play an important role in their invasion. For these two species, the early settled populations are distributed at low densities, but they can rapidly achieve high population densities in a short period of time. However, their response to intraspecific competition to improve the fitness for rapid growth and maintenance of high population densities remains unclear. Therefore, to determine how these species form and maintain high population densities, individual biomass allocations patterns between different population densities (low and high), and plasticity during seedling, vegetative, breeding and mature stages were compared. In 2019, we harvested seeds at different population densities and compared them, and in 2020, we compared the number of regenerated plants across the two population densities. Results Most biomass was invested in the stems of both species. Ambrosia trifida had the highest stem biomass distribution, of up to 78%, and the phenotypic plasticity of the stem was the highest. Path analysis demonstrated that at low-density, total biomass was the biggest contributor to seed production, but stem and leaf biomass was the biggest contributors to high-density populations. The number of seeds produced per plant was high in low-density populations, while the seed number per unit area was huge in high-density populations. In the second year, the number of low-density populations increased significantly. A. artemisiifolia and A. trifida accounted for 75.6% and 68.4% of the mature populations, respectively. Conclusions High input to the stem is an important means to regulate the growth of the two species to cope with different densities. These two species can ensure reproductive success and produce appropriate seed numbers. Therefore, they can maintain a stable population over time and quickly form cluster advantages. In the management, early detection of both species and prevention of successful reproduction by chemical and mechanical means are necessary to stop cluster formation and spread.

High population densities of Macrolophus pygmaeus on tomato plants can cause economic fruit damage: interaction with Pepino mosaic virus ?

2015 ◽  
Vol 72 (7) ◽  
pp. 1350-1358 ◽  
Author(s):  
Rob Moerkens ◽  
Els Berckmoes ◽  
Veerle Van Damme ◽  
Nelia Ortega-Parra ◽  
Inge Hanssen ◽  
...  
Keyword(s):  
Mosaic Virus ◽  
High Population ◽  
Population Densities ◽  
Pepino Mosaic Virus ◽  
Tomato Plants ◽  
Macrolophus Pygmaeus ◽  
Fruit Damage

Life Cycle of Carpophilus humeralis F. (Coleoptera: Nitidulidae) in Puerto Rico

1969 ◽  
Vol 68 (1) ◽  
pp. 53-57
Author(s):  
Fernando Gallardo-Covas
Keyword(s):  
Puerto Rico ◽  
Life Cycle ◽  
Reproductive Potential ◽  
Larval Period ◽  
High Population ◽  
Population Densities ◽  
Ripe Fruit ◽  
Laboratory Conditions ◽  
Carpophilus Humeralis

Carpophilus humeralis F. is one of the main pests on pineapple in Puerto Rico. This insect has high population densities because of a high reproductive potential, each female under laboratory conditions, lays about 542 eggs over a two month period, averaging 9 eggs per day; short larval period (18 days); longevity of adults (2.5 months); and abundance of ripe fruit in pineapple fields as sites for constant reproduction.

scholarly journals Variation in space and time: a long-term examination of density-dependent dispersal in a woodland rodent

2019 ◽  
Author(s):  
Simon T. Denomme-Brown ◽  
Karl Cottenie ◽  
J. Bruce Falls ◽  
E. Ann Falls ◽  
Ronald J. Brooks ◽  
...  
Keyword(s):  
Time Series ◽  
Population Density ◽  
Local Density ◽  
Spatial Scales ◽  
Deer Mice ◽  
Population Densities ◽  
Density Dependent ◽  
Regional Population ◽  
The Relationship ◽  
Density Dependent Dispersal

AbstractDispersal is a fundamental ecological process that can be affected by population density, yet studies report contrasting effects of density on propensity to disperse. Additionally, the relationship between dispersal and density is seldom examined using densities measured at different spatial scales or over extensive time-series. We used 51-years of trapping data to examine how dispersal by wild deer mice (Peromyscus maniculatus) was affected by changes in both local and regional population densities. We examined these patterns over both the entire time-series and also in ten-year shifting windows to determine whether the nature and strength of the relationship changed through time. Probability of dispersal decreased with increased local and regional population density, and the negative effect of local density on dispersal was more pronounced in years with low regional densities. Additionally, the strength of negative density-dependent dispersal changed through time, ranging from very strong in some decades to absent in other periods of the study. Finally, while females were less likely to disperse, female dispersal was more density-dependent than male dispersal. Our study shows that the relationship between density and dispersal is not temporally static and that investigations of density-dependent dispersal should consider both local and regional population densities.

scholarly journals Neolithic Priorities: Ritual and Visual Preferences within Burials and Corporeality in the Balkans

2014 ◽  
Vol 17 (2) ◽  
pp. 184-207
Author(s):  
Goce Naumov
Keyword(s):  
Case Studies ◽  
Social Hierarchy ◽  
High Population ◽  
Body Parts ◽  
Population Densities ◽  
Funerary Practices ◽  
The Balkans ◽  
Select Group ◽  
Visual Preferences ◽  
Geographical Context

Neolithic bodies are not only manifestations of subjective principles. Social and symbolic norms are also incorporated within the bodies of both actual and represented individuals. These norms often relate to economic and religious notions of society, as well as to effigies. Owing to high population densities in Neolithic villages, only a select group of the inhabitants were buried within settlements or represented in images. This generated a category of privileged individuals and body features, which were related to symbolic principles rather than social hierarchy. Such practices among Neolithic societies in the Balkans are evident within burials and human representations. Individuals buried inside settlements, anthropomorphic house models, and figurines from several sites in Ovče Pole, Pelagonia, and the Skopje Valley are used as case studies in this paper. Placing these sites into a wider geographical context, it is argued that gender, age and body parts were significant criteria in funerary practices and features of corporeality.

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