The influence of plant spacing on density-dependent versus frequency-dependent spore transmission of the anther smut Microbotryum violaceum

Oecologia ◽  
1999 ◽  
Vol 119 (1) ◽  
pp. 55-62 ◽  
Author(s):  
Erika Bucheli ◽  
Jacqui A. Shykoff
Keyword(s):  
Plant Spacing ◽  
Microbotryum Violaceum ◽  
Frequency Dependent ◽  
Density Dependent ◽  
Anther Smut ◽  
Spore Transmission

scholarly journals Frequency-dependent interactions determine outcome of competition between two breast cancer cell lines

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Audrey R. Freischel ◽  
Mehdi Damaghi ◽  
Jessica J. Cunningham ◽  
Arig Ibrahim-Hashim ◽  
Robert J. Gillies ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cancer Cell ◽  
Critical Density ◽  
Low Ph ◽  
Breast Cancer Cell Lines ◽  
Frequency Dependent ◽  
Density Dependent ◽  
Low Glucose ◽  
Competition Assays ◽  
Mcf 7

AbstractTumors are highly dynamic ecosystems in which diverse cancer cell subpopulations compete for space and resources. These complex, often non-linear interactions govern continuous spatial and temporal changes in the size and phenotypic properties of these subpopulations. Because intra-tumoral blood flow is often chaotic, competition for resources may be a critical selection factor in progression and prognosis. Here, we quantify resource competition using 3D spheroid cultures with MDA-MB-231 and MCF-7 breast cancer cells. We hypothesized that MCF-7 cells, which primarily rely on efficient aerobic glucose metabolism, would dominate the population under normal pH and low glucose conditions; and MDA-MB-231 cells, which exhibit high levels of glycolytic metabolism, would dominate under low pH and high glucose conditions. In spheroids with single populations, MCF-7 cells exhibited equal or superior intrinsic growth rates (density-independent measure of success) and carrying capacities (density-dependent measure of success) when compared to MDA-MB-231 cells under all pH and nutrient conditions. Despite these advantages, when grown together, MCF-7 cells do not always outcompete MDA-MB-231 cells. MDA-MB-231 cells outcompete MCF-7 cells in low glucose conditions and coexistence is achieved in low pH conditions. Under all conditions, MDA-MB-231 has a stronger competitive effect (frequency-dependent interaction) on MCF-7 cells than vice-versa. This, and the inability of growth rate or carrying capacity when grown individually to predict the outcome of competition, suggests a reliance on frequency-dependent interactions and the need for competition assays. We frame these results in a game-theoretic (frequency-dependent) model of cancer cell interactions and conclude that competition assays can demonstrate critical density-independent, density-dependent and frequency-dependent interactions that likely contribute to in vivo outcomes.

scholarly journals Social fluidity mobilizes contagion in human and animal populations

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Ewan Colman ◽  
Vittoria Colizza ◽  
Ephraim M Hanks ◽  
David P Hughes ◽  
Shweta Bansal
Keyword(s):  
Social Bonds ◽  
Group Living ◽  
Basic Reproductive Number ◽  
Reproductive Number ◽  
Frequency Dependent ◽  
Density Dependent ◽  
Gregarious Behavior ◽  
Animal Populations ◽  
Group Members ◽  
Social Fluidity

Humans and other group-living animals tend to distribute their social effort disproportionately. Individuals predominantly interact with a small number of close companions while maintaining weaker social bonds with less familiar group members. By incorporating this behavior into a mathematical model, we find that a single parameter, which we refer to as social fluidity, controls the rate of social mixing within the group. Large values of social fluidity correspond to gregarious behavior, whereas small values signify the existence of persistent bonds between individuals. We compare the social fluidity of 13 species by applying the model to empirical human and animal social interaction data. To investigate how social behavior influences the likelihood of an epidemic outbreak, we derive an analytical expression of the relationship between social fluidity and the basic reproductive number of an infectious disease. For species that form more stable social bonds, the model describes frequency-dependent transmission that is sensitive to changes in social fluidity. As social fluidity increases, animal-disease systems become increasingly density-dependent. Finally, we demonstrate that social fluidity is a stronger predictor of disease outcomes than both group size and connectivity, and it provides an integrated framework for both density-dependent and frequency-dependent transmission.

scholarly journals Mating System of the Anther Smut Fungus Microbotryum violaceum: Selfing under Heterothallism

2008 ◽  
Vol 7 (5) ◽  
pp. 765-775 ◽  
Author(s):  
Tatiana Giraud ◽  
Roxana Yockteng ◽  
Manuela López-Villavicencio ◽  
Guislaine Refrégier ◽  
Michael E. Hood
Keyword(s):  
Mating System ◽  
Smut Fungus ◽  
Microbotryum Violaceum ◽  
Anther Smut

scholarly journals First Report of Anther Smut Caused by Microbotryum violaceum on Forked Catchfly (Silene dichotoma) in Turkey

Plant Disease ◽  
2008 ◽  
Vol 92 (2) ◽  
pp. 315-315
Author(s):  
D. Berner ◽  
B. Tunali
Keyword(s):  
North America ◽  
Evolutionary Biology ◽  
Science Research ◽  
Internal Transcribed Spacers ◽  
Smut Fungi ◽  
Native Plant ◽  
Microbotryum Violaceum ◽  
Voucher Specimen ◽  
First Report ◽  
Anther Smut

Forked catchfly (Silene dichotoma Ehrh.), family Caryophyllaceae, is a common and native plant in rangelands and pastures in Turkey. It is also an introduced plant that is widely distributed in North America. In May of 2007, approximately 20 forked catchfly plants on the campus of Ondokuz Mayis University in Samsun, Turkey were found diseased with the anther smut fungus Microbotryum violaceum (Pers.:pers.) G. Deml & Oberw. (Basidiomycota, Microbotryomycetes, Microbotryales [3], Microbotryaceae). All anthers in all flowers of diseased plants were smutted. Diseased flowers were collected, air dried, and sent to the quarantine facility of the Foreign Disease-Weed Science Research Unit (FDWSRU), USDA/ARS, Fort Detrick, MD. Teliospores within the flowers were extracted and observed microscopically. Teliospores were globose, 6 to 9 μm (mean 6.5 μm) in diameter, pale violet, with reticulate walls, and matching the description of M. violaceum (4). Nucleotide sequences for the internal transcribed spacers (ITS 1 and 2) and 5.8S ribosomal region (GenBank Accession No. EU122308) were aligned with other sequences in GenBank with the BLAST algorithm. Sequences of this isolate aligned 99% with sequences of other isolates of M. violaceum, M. lychnidis-dioicae (A.P. de Candolle ex J.I. Liro) G. Deml & F. Oberwinkler, and M. silenes-inflatae (A.P. de Candolle ex J.I. Liro) G. Deml & F. Oberwinkler and clustered with other M. violaceum isolates. M. violaceum is an obligate parasite of many plant species in the Caryophyllaceae family, and the fungus has been widely studied as a model for population genetics and evolutionary biology (2). To our knowledge, this is the first report of M. violaceum parasitizing forked catchfly in Turkey, and is the only report of this fungus-plant interaction in Asia Minor (1). The fungus has not been reported from this plant in North America (1). A voucher specimen has been deposited with the U.S. National Fungus Collections (BPI 878235) and living spores are being maintained at FDWSRU. References: (1) D. F. Farr et al. Fungal Databases. Systematic Botany and Mycology Laboratory. Online publication. ARS, USDA, 2007. (2) T. Giraud. Heredity 93:559, 2004. (3) D. S. Hibbett et al. Mycol. Res. 111:509, 2007. (4) K. Vánky. European Smut Fungi. Gustav Fischer Verlag, Stuttgart, Germany, 1994.

scholarly journals Can't live with them, can't live without them? Balancing mating and competition in two-sex populations

2017 ◽  
Vol 284 (1865) ◽  
pp. 20171999 ◽  
Author(s):  
Aldo Compagnoni ◽  
Kenneth Steigman ◽  
Tom E. X. Miller
Keyword(s):  
Sex Ratio ◽  
Mating Success ◽  
Sex Ratios ◽  
Structured Populations ◽  
Allee Effects ◽  
Mate Finding ◽  
Frequency Dependent ◽  
Density Dependent ◽  
Positive Effects ◽  
Demographic Processes

Two-sex populations are usually studied through frequency-dependent models that describe how sex ratio affects mating, recruitment and population growth. However, in two-sex populations, mating and recruitment should also be affected by density and by its interactions with the sex ratio. Density may have positive effects on mating (Allee effects) but negative effects on other demographic processes. In this study, we quantified how positive and negative inter-sexual interactions balance in two-sex populations. Using a dioecious grass ( Poa arachnifera ), we established experimental field populations that varied in density and sex ratio. We then quantified mating success (seed fertilization) and non-mating demographic performance, and integrated these responses to project population-level recruitment. Female mating success was positively density-dependent, especially at female-biased sex ratios. Other demographic processes were negatively density-dependent and, in some cases, frequency-dependent. Integrating our experimental results showed that mate-finding Allee effects dominated other types of density-dependence, giving rise to recruitment that increased with increasing density and peaked at intermediate sex ratios, reflecting tension between seed initiation (greater with more females) and seed viability (greater with more males). Our results reveal, for the first time, the balance of positive and negative inter-sexual interactions in sex-structured populations. Models that account for both density- and sex ratio dependence, particularly in mating, may be necessary for understanding and predicting two-sex population dynamics.

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