scholarly journals Evolution of populations expanding on curved surfaces

2018 ◽  
Author(s):  
Daniel A. Beller ◽  
Kim M. J. Alards ◽  
Francesca Tesser ◽  
Ricardo A. Mosna ◽  
Federico Toschi ◽  
...  
Keyword(s):  
Range Expansion ◽  
Evolutionary Dynamics ◽  
Flat Surface ◽  
Analytical Description ◽  
Relative Increase ◽  
Curved Surfaces ◽  
Complex Environments ◽  
Neutral Genetic Diversity ◽  
Expanding Population ◽  
Dynamics Of Populations

AbstractThe expansion of a population into new habitat is a transient process that leaves its footprints in the genetic composition of the expanding population. How the structure: of the environment shapes the population front and the evolutionary dynamics during such a range expansion is little understood. Here, we investigate the evolutionary dynamics of populations consisting of many selectively neutral genotypes expanding on curved surfaces. Using a combination of individual-based off-lattice simulations, geometrical arguments, and lattice-based stepping-stone simulations, we characterise the effect of individual bumps on an otherwise flat surface. Compared to the case of a range expansion on a flat surface:, we observe a transient relative increase, followed by a decrease, in neutral genetic diversity at the population front. Ill addition, we find that individuals at the sides of the bump have a dramatically increased expected number of descendants, while their neighbours closer to the bump’s centre are far less lucky. Both observations can be explained using an analytical description of straight paths (geodesics) on the curved surface, Complementing previous studies of heterogeneous flat environments, the findings here build our understanding of how complex environments shape the evolutionary dynamics of expanding populations.

scholarly journals Discrete and continuum phenotype-structured models for the evolution of cancer cell populations under chemotherapy

2020 ◽  
Vol 15 ◽  
pp. 14 ◽  
Author(s):  
Rebecca E.A. Stace ◽  
Thomas Stiehl ◽  
Mark A.J. Chaplain ◽  
Anna Marciniak-Czochra ◽  
Tommaso Lorenzi
Keyword(s):  
Cancer Cell ◽  
Cell Population ◽  
Evolutionary Dynamics ◽  
Analytical Description ◽  
Chemotherapeutic Agents ◽  
Cell Populations ◽  
Theoretical Ground ◽  
Individual Based Model ◽  
Nonlocal Parabolic Equation ◽  
Epigenetic Drug

We present a stochastic individual-based model for the phenotypic evolution of cancer cell populations under chemotherapy. In particular, we consider the case of combination cancer therapy whereby a chemotherapeutic agent is administered as the primary treatment and an epigenetic drug is used as an adjuvant treatment. The cell population is structured by the expression level of a gene that controls cell proliferation and chemoresistance. In order to obtain an analytical description of evolutionary dynamics, we formally derive a deterministic continuum counterpart of this discrete model, which is given by a nonlocal parabolic equation for the cell population density function. Integrating computational simulations of the individual-based model with analysis of the corresponding continuum model, we perform a complete exploration of the model parameter space. We show that harsher environmental conditions and higher probabilities of spontaneous epimutation can lead to more effective chemotherapy, and we demonstrate the existence of an inverse relationship between the efficacy of the epigenetic drug and the probability of spontaneous epimutation. Taken together, the outcomes of the model provide theoretical ground for the development of anticancer protocols that use lower concentrations of chemotherapeutic agents in combination with epigenetic drugs capable of promoting the re-expression of epigenetically regulated genes.

scholarly journals Fragmentation mediates thermal habitat choice in ciliate microcosms

2020 ◽  
Vol 287 (1919) ◽  
pp. 20192818
Author(s):  
Estelle Laurent ◽  
Nicolas Schtickzelle ◽  
Staffan Jacob
Keyword(s):  
Habitat Fragmentation ◽  
Evolutionary Dynamics ◽  
Environmental Changes ◽  
Tetrahymena Thermophila ◽  
Habitat Choice ◽  
Emigration And Immigration ◽  
Dispersal Rate ◽  
Thermal Habitat ◽  
Twofold Increase ◽  
Dynamics Of Populations

Habitat fragmentation is expected to reduce dispersal movements among patches as a result of increased inter-patch distances. Furthermore, since habitat fragmentation is expected to raise the costs of moving among patches in the landscape, it should hamper the ability or tendency of organisms to perform informed dispersal decisions. Here, we used microcosms of the ciliate Tetrahymena thermophila to test experimentally whether habitat fragmentation, manipulated through the length of corridors connecting patches differing in temperature, affects habitat choice. We showed that a twofold increase of inter-patch distance can as expected hamper the ability of organisms to choose their habitat at immigration. Interestingly, it also increased their habitat choice at emigration, suggesting that organisms become choosier in their decision to either stay or leave their patch when obtaining information about neighbouring patches gets harder. This study points out that habitat fragmentation might affect not only dispersal rate but also the level of non-randomness of dispersal, with emigration and immigration decisions differently affected. These consequences of fragmentation might considerably modify ecological and evolutionary dynamics of populations facing environmental changes.

scholarly journals Enhanced propagation of motile bacteria on surfaces due to forward scattering

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Stanislaw Makarchuk ◽  
Vasco C. Braz ◽  
Nuno A. M. Araújo ◽  
Lena Ciric ◽  
Giorgio Volpe
Keyword(s):  
Biofilm Formation ◽  
Flat Surface ◽  
Experimental Studies ◽  
Forward Scattering ◽  
Bacterial Motility ◽  
Complex Environments ◽  
Natural Habitats ◽  
Near Surface ◽  
Propulsion Mechanism ◽  
Motile Bacteria

Abstract How motile bacteria move near a surface is a problem of fundamental biophysical interest and is key to the emergence of several phenomena of biological, ecological and medical relevance, including biofilm formation. Solid boundaries can strongly influence a cell’s propulsion mechanism, thus leading many flagellated bacteria to describe long circular trajectories stably entrapped by the surface. Experimental studies on near-surface bacterial motility have, however, neglected the fact that real environments have typical microstructures varying on the scale of the cells’ motion. Here, we show that micro-obstacles influence the propagation of peritrichously flagellated bacteria on a flat surface in a non-monotonic way. Instead of hindering it, an optimal, relatively low obstacle density can significantly enhance cells’ propagation on surfaces due to individual forward-scattering events. This finding provides insight on the emerging dynamics of chiral active matter in complex environments and inspires possible routes to control microbial ecology in natural habitats.

scholarly journals Eco‐evolutionary dynamics of range expansion

Ecology ◽  
2020 ◽  
Vol 101 (10) ◽  
Author(s):  
Tom E. X. Miller ◽  
Amy L. Angert ◽  
Carissa D. Brown ◽  
Julie A. Lee‐Yaw ◽  
Mark Lewis ◽  
...  
Keyword(s):  
Range Expansion ◽  
Evolutionary Dynamics

Demography-Dispersal Trait Correlations Modify the Eco-Evolutionary Dynamics of Range Expansion

2020 ◽  
Vol 195 (2) ◽  
pp. 231-246 ◽  
Author(s):  
Brad M. Ochocki ◽  
Julia B. Saltz ◽  
Tom E. X. Miller
Keyword(s):  
Range Expansion ◽  
Evolutionary Dynamics ◽  
Trait Correlations

scholarly journals Range expansion is associated with increased survival and fecundity in a long-lived bat species

2019 ◽  
Vol 286 (1906) ◽  
pp. 20190384 ◽  
Author(s):  
P.-L. Jan ◽  
L. Lehnen ◽  
A.-L. Besnard ◽  
G. Kerth ◽  
M. Biedermann ◽  
...  
Keyword(s):  
Life History ◽  
Population Growth ◽  
Range Expansion ◽  
Empirical Studies ◽  
Simulated Data ◽  
Adult Survival ◽  
Juvenile Survival ◽  
Average Growth ◽  
Population Growth Rates ◽  
Expanding Population

The speed and dynamics of range expansions shape species distributions and community composition. Despite the critical impact of population growth rates for range expansion, they are neglected in existing empirical studies, which focus on the investigation of selected life-history traits. Here, we present an approach based on non-invasive genetic capture–mark–recapture data for the estimation of adult survival, fecundity and juvenile survival, which determine population growth. We demonstrate the reliability of our method with simulated data, and use it to investigate life-history changes associated with range expansion in 35 colonies of the bat species Rhinolophus hipposideros . Comparing the demographic parameters inferred for 19 of those colonies which belong to an expanding population with those inferred for the remaining 16 colonies from a non-expanding population reveals that range expansion is associated with higher net reproduction. Juvenile survival was the main driver of the observed reproduction increase in this long-lived bat species with low per capita annual reproductive output. The higher average growth rate in the expanding population was not associated with a trade-off between increased reproduction and survival, suggesting that the observed increase in reproduction stems from a higher resource acquisition in the expanding population. Environmental conditions in the novel habitat hence seem to have an important influence on range expansion dynamics, and warrant further investigation for the management of range expansion in both native and invasive species.

scholarly journals Projecting marine developmental diversity and connectivity in future oceans

2020 ◽  
Vol 375 (1814) ◽  
pp. 20190450 ◽  
Author(s):  
Dustin J. Marshall ◽  
Mariana Alvarez-Noriega
Keyword(s):  
Evolutionary Dynamics ◽  
Marine Conservation ◽  
Theme Issue ◽  
Developmental Duration ◽  
Larval Phase ◽  
Marine Systems ◽  
Integrative Research ◽  
Research Perspectives ◽  
Species Groups ◽  
Dynamics Of Populations

Global change will alter the distribution of organisms around the planet. While many studies have explored how different species, groups and traits might be re-arranged, few have explored how dispersal is likely to change under future conditions. Dispersal drives ecological and evolutionary dynamics of populations, determining resilience, persistence and spread. In marine systems, dispersal shows clear biogeographical patterns and is extremely dependent on temperature, so simple projections can be made regarding how dispersal potentials are likely to change owing to global warming under future thermal regimes. We use two proxies for dispersal—developmental mode and developmental duration. Species with a larval phase are more dispersive than those that lack a larval phase, and species that spend longer developing in the plankton are more dispersive than those that spend less time in the plankton. Here, we explore how the distribution of different development modes is likely to change based on current distributions. Next, we estimate how the temperature-dependence of development itself depends on the temperature in which the species lives, and use this estimate to project how developmental durations are likely to change in the future. We find that species with feeding larvae are likely to become more prevalent, extending their distribution poleward at the expense of species with aplanktonic development. We predict that developmental durations are likely to decrease, particularly in high latitudes where durations may decline by more than 90%. Overall, we anticipate significant changes to dispersal in marine environments, with species in the polar seas experiencing the greatest change. This article is part of the theme issue ‘Integrative research perspectives on marine conservation’.

Experimenal analysis of in-plane strain on curved surfaces using transferring techniques

1978 ◽  
Vol 13 (2) ◽  
pp. 121-128 ◽  
Author(s):  
J Buitrago ◽  
A J Durelli ◽  
V J Parks
Keyword(s):  
Rigid Body ◽  
Finite Deformation ◽  
Flat Surface ◽  
Flexible Structures ◽  
Strain Analysis ◽  
Curved Surfaces ◽  
Double Curvature ◽  
Threshold Strain ◽  
Rigid Body Motions ◽  
Inside Out

A new grid-transferring technique is introduced that allows the strain analysis of flat or curved surfaces of single or double curvature. The technique consists of transferring a grid from the structure to a flat surface by means of a thin, adhesive, transparent ribbon. Information is obtained along a strip, or point-by-point when circles or rosettes are used. The technique is specially suitable for the solution of problems of finite deformation of flexible structures, and its threshold strain is about 0.004. As a verification of the new method, strains obtained on a disc under diametral compression are compared with results already given in the literature. As a general example of application, strains on the anticlastic surface of tubes with and without perforation, and turned inside out, are determined. The method is not influenced by rigid-body motions.

scholarly journals Selective signatures and high genome-wide diversity in traditional Brazilian manioc (Manihot esculenta Crantz) varieties

2021 ◽  
Author(s):  
Alessandro Alves-Pereira ◽  
Maria Imaculada Zucchi ◽  
Charles R. Clement ◽  
João Paulo Gomes Viana ◽  
José Baldin Pinheiro ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genetic Resources ◽  
Manihot Esculenta ◽  
Evolutionary Dynamics ◽  
Raw Material ◽  
Nucleotide Polymorphisms ◽  
Manihot Esculenta Crantz ◽  
Genome Wide ◽  
Neutral Genetic Diversity ◽  
Effective Use

Knowledge about crops' genetic diversity is essential to promote effective use and conservation of their genetic resources, because genetic diversity enables farmers to adapt their crops to specific needs and is the raw material for breeding efforts. Currently, manioc (Manihot esculenta ssp. esculenta) is one of the most important food crops in the world and has the potential to help achieve food security in the context of on-going climate changes. In this study we assessed the patterns of genome-wide diversity of traditional Brazilian manioc varieties conserved in the gene bank of the Luiz de Queiroz College of Agriculture, University of São Paulo. We used single nucleotide polymorphisms to evaluate the organization of genetic diversity and to identify selective signatures contrasting varieties from different biomes with samples of manioc's wild relative M. esculenta ssp. flabellifolia. We identified signatures of selection putatively associated with resistance genes, plant development and response to abiotic stresses. This presumed adaptive variation might have been important for the initial domestication and for the crop's diversification in response to cultivation in different environments. The neutral variation revealed high levels of genetic diversity within groups of varieties from different biomes and low to moderate genetic divergence among biomes. These results reflect the complexity of manioc's biology and its evolutionary dynamics under traditional cultivation. Our results exemplify how the smallholder practices contribute to the conservation of manioc's genetic resources, maintaining variation of potential adaptive significance and high levels of neutral genetic diversity.

Population Dynamics

2016 ◽  
Author(s):  
Andrew P. Hendry
Keyword(s):  
Population Dynamics ◽  
Environmental Change ◽  
Range Expansion ◽  
Phenotypic Variation ◽  
Evolutionary Dynamics ◽  
Final Analysis ◽  
Contemporary Evolution ◽  
Population Declines ◽  
Individual Fitness ◽  
The Difference

This chapter evaluates various methods for inferring how phenotypes/genotypes influence population dynamics, including extensions of the year-by-year tracking approach used in analyzing the eco-to-evo side of eco-evolutionary dynamics. It provides a detailed outline of the various possibilities, including complexities that move beyond population dynamics. The chapter examines how maladaptation resulting from environmental change might decrease individual fitness and contribute to population declines, range contractions, and extirpations. It considers the extent to which contemporary evolution helps to recover individual fitness and population size, which might then make the difference between persistence versus extirpation and range expansion versus contraction. A final analysis asks how phenotypic variation within populations and species influences population dynamics.

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