Theoretical Population BiologyThis is an RSS file. You can use it to subscribe to this data in your favourite RSS reader, such as GoogleReader, or to display this data on your own website or blog. Subscribe to this data using MyMedWorm.Subscribe to this data using GoogleReader.Subscribe to this data using Bloglines.Subscribe to this data using MyYahoo.

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Evolutionary consequences of a search image.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In conclusion, the formation of a search image causes the predator to control the prey densities such that the ratio of available prey is kept constant by the predator. PMID: 19917301 [PubMed - as supplied by publisher] (Source: Theoretical Population Biology)
Source: Theoretical Population Biology - November 13, 2009 Category: Biology Authors: van Leeuwen E, Jansen VA Tags: Theor Popul Biol Source Type: journals

Evolution of resistance and progression to disease during clonal expansion of cancer.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Inspired by previous work of Iwasa, Nowak, and Michor (2006), and Haeno, Iwasa, and Michor (2007), we consider an exponentially growing population of cancerous cells that will evolve resistance to treatment after one mutation or display a disease phenotype after two or more mutations. We prove results about the distribution of the first time when k mutations have accumulated in some cell, and about the growth of the number of type k cells. We show that our results can be used to derive the previous results about the tumor grown to a fixed size. PMID: 19896491 [PubMed - as supplied by publisher] (Source: Theoretical Population Biology)
Source: Theoretical Population Biology - November 4, 2009 Category: Biology Authors: Durrett R, Moseley S Tags: Theor Popul Biol Source Type: journals

The risk of competitive exclusion during evolutionary branching: Effects of resource variability, correlation and autocorrelation.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We present a single, comprehensible analytical result which summarizes most effects of environmental fluctuations on evolutionary branching driven by resource competition. Corroborating earlier findings, we show that branching may be delayed or impeded if the underlying resources have uncorrelated or negatively correlated responses to environmental fluctuations. There is also a strong impeding effect of positive environmental autocorrelation, which can be related to results from recent experiments on adaptive radiation in bacterial microcosms. In addition, we find that environmental fluctuations can lead to cycles of repea...
Source: Theoretical Population Biology - November 3, 2009 Category: Biology Authors: Johansson J, Ripa J, Kuckländer N Tags: Theor Popul Biol Source Type: journals

Spatially explicit neutral models for population genetics and community ecology: Extensions of the Neyman-Scott clustering process.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Spatially explicit models relating to plant populations have developed little since Felsenstein (1975) pointed out that if limited seed dispersal causes clustering of individuals, such models cannot reach an equilibrium. This paper aims to resolve this issue by modifying the Neyman-Scott cluster point process. The new point processes are dynamic models with random immigration, and the continuous increase in the clustering of individuals stops at some level. Hence, an equilibrium state is achieved, and new individual-based spatially explicit neutral coalescent models are established. By fitting the spatial structure at ...
Source: Theoretical Population Biology - October 19, 2009 Category: Biology Authors: Shimatani IK Tags: Theor Popul Biol Source Type: journals

Time to fixation in the presence of recombination.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We study the evolutionary dynamics of a haploid population of infinite size recombining with a probability r in a two locus model. Starting from a low fitness locus, the population is evolved under mutation, selection and recombination until a finite fraction of the population reaches the fittest locus. An analytical method is developed to calculate the fixation time T to the fittest locus for various choices of epistasis. We find that (1) for negative epistasis, T decreases slowly for small r but decays fast at larger r (2) for positive epistasis, T increases linearly for small r and mildly for large r (3) for compens...
Source: Theoretical Population Biology - October 16, 2009 Category: Biology Authors: Jain K Tags: Theor Popul Biol Source Type: journals

Fluctuation domains in adaptive evolution.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We derive an expression for the variation between parallel trajectories in phenotypic evolution, extending the well known result that predicts the mean evolutionary path in adaptive dynamics or quantitative genetics. We show how this expression gives rise to the notion of fluctuation domains-parts of the fitness landscape where the rate of evolution is very predictable (due to fluctuation dissipation) and parts where it is highly variable (due to fluctuation enhancement). These fluctuation domains are determined by the curvature of the fitness landscape. Regions of the fitness landscape with positive curvature, such as...
Source: Theoretical Population Biology - October 16, 2009 Category: Biology Authors: Boettiger C, Dushoff J, Weitz JS Tags: Theor Popul Biol Source Type: journals

Change and maintenance of variation in quantitative traits in the context of the Price equation.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, we use the Price equation to derive many such well-known results for the dynamics and equilibria of variances in a straightforward way and to develop them further. PMID: 19836408 [PubMed - as supplied by publisher] (Source: Theoretical Population Biology)
Source: Theoretical Population Biology - October 13, 2009 Category: Biology Authors: Zhang XS, Hill WG Tags: Theor Popul Biol Source Type: journals

Complex dynamics occur in a single-locus, multiallelic model of general frequency dependent selection.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We examine the characteristics of non-equilibrium dynamics produced by a simple well-known model of frequency-dependent selection at a single diploid locus. An examination of the parameter space of this "pairwise-interaction model" (PIM) revealed non-equilibrium dynamics for polymorphisms of 3, 4 and 5 alleles; both allele-frequency cycling and aperiodic trajectories were detected. We measured the number, cycle length and domains of attraction of the various attractors produced by the model. Domains of attraction tended to be smaller, and cycles longer, for systems with larger number of alleles. Fitnesses that parametr...
Source: Theoretical Population Biology - October 7, 2009 Category: Biology Authors: Trotter MV, Spencer HG Tags: Theor Popul Biol Source Type: journals

Diversity partitioning of Rao's quadratic entropy.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Many applications of diversity indices are only valid if they are first transformed into their equivalent number of species. These equivalent numbers of species can be multiplicatively partitioned into independent alpha, beta and gamma components, and can be formed into mathematically consistent similarity measures. The utility of beta diversity and similarity measures that incorporate information about the degree of ecological dissimilarity between species is becoming increasingly recognized. The concept of equivalent number of species is here extended to Rao's quadratic entropy, opening the way to methods of diversit...
Source: Theoretical Population Biology - October 6, 2009 Category: Biology Authors: Ricotta C, Szeidl L Tags: Theor Popul Biol Source Type: journals

Epistasis in a quantitative trait captured by a molecular model of transcription factor interactions.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
With technological advances in genetic mapping studies more of the genes and polymorphisms that underlie Quantitative Trait Loci (QTL) are now being identified. As the identities of these genes become known there is a growing need for an analysis framework that incorporates the molecular interactions affected by natural polymorphisms. As a step towards such a framework we present a molecular model of genetic variation in sporulation efficiency between natural isolates of the yeast, Saccharomyces cerevisiae. The model is based on the structure of the regulatory pathway that controls sporulation. The model captures the p...
Source: Theoretical Population Biology - October 6, 2009 Category: Biology Authors: Gertz J, Gerke JP, Cohen BA Tags: Theor Popul Biol Source Type: journals

Efficient maximum likelihood pedigree reconstruction.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A simple and efficient algorithm is presented for finding a maximum likelihood pedigree using microsatellite (STR) genotype information on a complete sample of related individuals. The computational complexity of the algorithm is at worst (O(n(3)2(n))), where n is the number of individuals. Thus it is possible to exhaustively search the space of all pedigrees of up to thirty individuals for one that maximizes the likelihood. A priori age and sex information can be used if available, but is not essential. The algorithm is applied in a simulation study, and to some real data on humans. PMID: 19781561 [PubMed - as sup...
Source: Theoretical Population Biology - September 21, 2009 Category: Biology Authors: Cowell RG Tags: Theor Popul Biol Source Type: journals

From discrete to continuous evolution models: A unifying approach to drift-diffusion and replicator dynamics.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We study the large population limit of the Moran process, under the assumption of weak-selection, and for different scalings. Depending on the particular choice of scalings, we obtain a continuous model that may highlight the genetic-drift (neutral evolution) or natural selection; for one precise scaling, both effects are present. For the scalings that take the genetic-drift into account, the continuous model is given by a singular diffusion equation, together with two conservation laws that are already present at the discrete level. For scalings that take into account only natural selection, we obtain a hyperbolic sin...
Source: Theoretical Population Biology - September 14, 2009 Category: Biology Authors: Chalub FA, Souza MO Tags: Theor Popul Biol Source Type: journals

Investigating the role of enemies in temporal dynamics: Differential sensitivity, competition and stable coexistence.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The impact on plants of herbivores and other pests varies greatly from year to year. Here we develop an analytical model of a temporal niche dynamic as a tool to examine how natural fluctuations in pest (enemy) levels may determine coexistence in competing annual plant species when one but not the other is affected by the pest. We show that the probability and speed with which the resistant drives out the sensitive species, coexists with it, or is driven out by its sensitive competitor depends on the cost of pest-resistance to the unaffected species, the frequency of high pest levels in the habitat and the competitive ...
Source: Theoretical Population Biology - September 13, 2009 Category: Biology Authors: Kelly CK, Bowler MG Tags: Theor Popul Biol Source Type: journals

A predator-prey refuge system: Evolutionary stability in ecological systems.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A refuge model is developed for a single predator species and either one or two prey species where no predators are present in the prey refuge. An individual's fitness depends on its strategy choice or ecotype (predators decide which prey species to pursue and prey decide what proportion of their time to spend in the refuge) as well as on the population sizes of all three species. It is shown that, when there is a single prey species with a refuge or the two prey species with no refuge compete only indirectly (i.e. there is only apparent competition between prey species), that stable resident systems where all individu...
Source: Theoretical Population Biology - September 10, 2009 Category: Biology Authors: Cressman R, Garay J Tags: Theor Popul Biol Source Type: journals

The effects of abrupt topography on plankton dynamics.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Plankton population dynamics in the upper layer of the ocean depends on upwelling processes that bring nutrients from deeper waters. In turn, these depend on the structure of the vertical velocity field. In coastal areas and in oceanic regions characterized by the presence of strong submarine topographic features, the variable bottom topography induces significant effects on vertical velocities and upwelling/downwelling patterns. As a consequence, large plankton and fish abundances are frequently observed above seamounts, canyons and steep continental shelves. In this work, the dynamics of an NPZ (nutrient-phytoplankto...
Source: Theoretical Population Biology - September 4, 2009 Category: Biology Authors: Zavala Sansón L, Provenzale A Tags: Theor Popul Biol Source Type: journals

Population dynamics of live-attenuated virus vaccines.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Viruses contained in live-attenuated virus vaccines (LAVV) can be transmitted between individuals, resulting in secondary or contact vaccinations. This fact has been exploited successfully in the use of the Oral Polio Vaccine (OPV) to better control wild-type polio viruses. In this work we analyze general LAVV vaccination models for infections that confer lifelong immunity. We consider both standard (continuous) vaccination strategies and pulse vaccination programs (where mass vaccination is carried out at regular intervals). For continuous vaccination, we provide a complete global analysis of a very general compartmen...
Source: Theoretical Population Biology - September 3, 2009 Category: Biology Authors: Wagner BG, Earn DJ Tags: Theor Popul Biol Source Type: journals

On the accuracy of a diffusion approximation to a discrete state-space Markovian model of a population.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The traditional Kolmogorov equations treat the size of a population as a discrete random variable. A model is introduced that extends these equations to incorporate environmental variability. Difficulties with this discrete model motivate approximating the population size as a continuous random variable through the use of diffusion processes. The set of cumulants for both the population size and the environmental factors affecting the population size characterize the population-environmental system. The evolution of this set, as predicted by the diffusion approximation, closely matches the corresponding predictions for...
Source: Theoretical Population Biology - August 20, 2009 Category: Biology Authors: Varughese MM Tags: Theor Popul Biol Source Type: journals

Central-place seed foraging and vegetation patterns.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We investigate how central-place seed foragers with a nest in the proximity of one or more seed sources determine the formation of different vegetation patterns. In particular, we discuss the ecological conditions that lead to the formation of hump-shaped (Janzen-Connell) patterns in a two-dimensional landscape. Our analysis shows that central-place predation can generate Janzen-Connell patterns even if predators' movement strategies are exclusively based on resource abundance, both in the single-plant/single-nest case and in a forest with several seed sources. We also show that social foraging may either promote or wo...
Source: Theoretical Population Biology - August 11, 2009 Category: Biology Authors: Mari L, Gatto M, Casagrandi R Tags: Theor Popul Biol Source Type: journals

Evolution under the multilocus Levene model without epistasis.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Evolution under the multilocus Levene model is investigated. The linkage map is arbitrary, but epistasis is absent. The geometric-mean fitness, w(rho), depends only on the vector of gene frequencies, rho; it is nondecreasing, and the single-generation change is zero only on the set, Lambda, of gametic frequencies at gene-frequency equilibrium. The internal gene-frequency equilibria are the stationary points of w(rho). If the equilibrium points rho^ of rho(t) (where t denotes time in generations) are isolated, as is generic, then rho(t) converges as t-->infinity to some rho^. Generically, rho(t) converges to a local ...
Source: Theoretical Population Biology - August 9, 2009 Category: Biology Authors: Nagylaki T Tags: Theor Popul Biol Source Type: journals

Polymorphism in the two-locus Levene model with nonepistatic directional selection.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
For the Levene model with soft selection in two demes, the maintenance of polymorphism at two diallelic loci is studied. Selection is nonepistatic and dominance is intermediate. Thus, there is directional selection in every deme and at every locus. We assume that selection is in opposite directions in the two demes because otherwise no polymorphism is possible. If at one locus there is no dominance, then a complete analysis of the dynamical and equilibrium properties is performed. In particular, a simple necessary and sufficient condition for the existence of an internal equilibrium and sufficient conditions for global...
Source: Theoretical Population Biology - August 3, 2009 Category: Biology Authors: Bürger R Tags: Theor Popul Biol Source Type: journals

The positive effects of negative interactions: can avoidance of competitors or predators increase resource sampling by prey?Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Spatial overlap between predators and prey is key to predicting their interaction strength and population dynamics. We constructed a spatially-explicit simulation model to explore how predator and prey behavioral traits and patterns of resource distribution influence spatial overlap between predators, prey, and prey resources. Predator and prey spatial association primarily followed the ideal free distribution. Departures from this model were intriguing, especially from the interactions of predator and prey behavior. When prey weakly avoided conspecifics, they associated more highly with resources when predators were p...
Source: Theoretical Population Biology - June 28, 2009 Category: Biology Authors: Bell AV, Rader RB, Peck SL, Sih A Tags: Theor Popul Biol Source Type: journals

An investigation of the relationship between innovation and cultural diversity.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this paper we apply reaction-diffusion models to explore the relationship between the rate of behavioural innovation and the level of cultural diversity. We investigate how both independent invention and the modification and refinement of established innovations impact on cultural dynamics and diversity. Further, we analyse these relationships in the presence of biases in cultural learning and find that the introduction of new variants typically increases cultural diversity substantially in the short term, but may decrease long-term diversity. Independent invention generally supports higher levels of cultural divers...
Source: Theoretical Population Biology - June 28, 2009 Category: Biology Authors: Kandler A, Laland KN Tags: Theor Popul Biol Source Type: journals

Multilocus genomics of outcrossing plant populations.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The structure and organization of natural plant populations can be understood by estimating the genetic parameters related to mating behavior, recombination frequency, and gene associations with DNA-based markers typed throughout the genome. We developed a statistical and computational model for estimating and testing these parameters from multilocus data collected in a natural population. This model, constructed by a maximum likelihood approach and implemented within the EM algorithm, is shown to be robust for simultaneously estimating the outcrossing rate, recombination frequencies and linkage disequilibria. The algo...
Source: Theoretical Population Biology - June 28, 2009 Category: Biology Authors: Hou W, Liu T, Li Y, Li Q, Li J, Das K, Berg A, Wu R Tags: Theor Popul Biol Source Type: journals

Perturbation expansions of multilocus fixation probabilities for frequency-dependent selection with applications to the Hill-Robertson effect and to the joint evolution of helping and punishment.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Natural populations are of finite size and organisms carry multilocus genotypes. There are, nevertheless, few results on multilocus models when both random genetic drift and natural selection affect the evolutionary dynamics. In this paper we describe a formalism to calculate systematic perturbation expansions of moments of allelic states around neutrality in populations of constant size. This allows us to evaluate multilocus fixation probabilities (long-term limits of the moments) under arbitrary strength of selection and gene action. We show that such fixation probabilities can be expressed in terms of selection coef...
Source: Theoretical Population Biology - June 28, 2009 Category: Biology Authors: Lehmann L, Rousset F Tags: Theor Popul Biol Source Type: journals

Population and prehistory III: Food-dependent demography in variable environments.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The population dynamics of preindustrial societies depend intimately on their surroundings, and food is a primary means through which environment influences population size and individual well-being. Food production requires labor; thus, dependence of survival and fertility on food involves dependence of a population's future on its current state. We use a perturbation approach to analyze the effects of random environmental variation on this nonlinear, age-structured system. We show that in expanding populations, direct environmental effects dominate induced population fluctuations, so environmental variability has lit...
Source: Theoretical Population Biology - June 17, 2009 Category: Biology Authors: Lee CT, Puleston CO, Tuljapurkar S Tags: Theor Popul Biol Source Type: journals

Alternative dynamical states in stage-structured consumer populations.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The population dynamics of a consumer population with an internal structure is investigated. The population is divided into juvenile and adult individuals that consume different resources and do not interfere with each other. Over a broad range of external conditions (varying mortality and different resource levels), alternative stable states exist. These population states correspond to domination of juveniles and domination of adults, respectively. When mortality is varied, hysteresis between the alternative states only occurs if juveniles have more resources than adults. In the opposite case the juvenile-dominated st...
Source: Theoretical Population Biology - June 9, 2009 Category: Biology Authors: Guill C Tags: Theor Popul Biol Source Type: journals

Antigenic distance and cross-immunity, invasibility and coexistence of pathogen strains in an epidemiological model with discrete antigenic space.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In models of pathogen interaction and evolution discrete genotypes in the form of bit strings may be mapped to points in a discrete phenotype space based on similarity in antigenic structure. Cross-immunity between strains, that is the reduction in susceptibility to strain A conferred to a host by infection with strain B, can then be defined for pairs of points in the antigenic space by a specified function. Analysis of an SIR type model shows that, if two strains are at equilibrium, the shape of the cross-immunity function has a strong influence on the invasion and coexistence of a third strain and, consequently, the ...
Source: Theoretical Population Biology - June 5, 2009 Category: Biology Authors: Adams B, Sasaki A Tags: Theor Popul Biol Source Type: journals

The evolution of juvenile-adult interactions in populations structured in age and space.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We study the evolution of a spatially structured population with two age classes using spatial moment equations. In the model, adults can either help juveniles by increasing their survival, or adopt a cannibalistic behaviour and consume juveniles. While cannibalism is the sole evolutionary outcome when the population is well-mixed, both cannibalism and parental care can be evolutionarily stable if the population is viscous. Our analysis allows us to make two main technical points. First, we present a method to define invasion fitness in class-structured viscous populations, which allows us to apply adaptive dynamics me...
Source: Theoretical Population Biology - June 5, 2009 Category: Biology Authors: Lion S, van Baalen M Tags: Theor Popul Biol Source Type: journals

Metapopulation extinction risk: Dispersal's duplicity.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Metapopulation extinction risk is the probability that all local populations are simultaneously extinct during a fixed time frame. Dispersal may reduce a metapopulation's extinction risk by raising its average per-capita growth rate. By contrast, dispersal may raise a metapopulation's extinction risk by reducing its average population density. Which effect prevails is controlled by habitat fragmentation. Dispersal in mildly fragmented habitat reduces a metapopulation's extinction risk by raising its average per-capita growth rate without causing any appreciable drop in its average population density. By contrast, dispe...
Source: Theoretical Population Biology - June 5, 2009 Category: Biology Authors: Higgins K Tags: Theor Popul Biol Source Type: journals

The vitality model: A way to understand population survival and demographic heterogeneity.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A four-parameter model describing mortality as the first passage of an abstract measure of survival capacity, vitality, is developed and used to explore four classic problems in demography: (1) medfly demographic paradox, (2) effect of diet restriction on longevity, (3) cross-life stage effects on survival curves and (4) mortality plateaus. The model quantifies the sources of mortality in these classical problems into vitality-dependent and independent parts, and characterizes the vitality-dependent part in terms of initial and evolving heterogeneities. Three temporal scales express the balance of these factors: a time...
Source: Theoretical Population Biology - June 2, 2009 Category: Biology Authors: Li T, Anderson JJ Tags: Theor Popul Biol Source Type: journals

An approximate likelihood for genetic data under a model with recombination and population splitting.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We describe a new approximate likelihood for population genetic data under a model in which a single ancestral population has split into two daughter populations. The approximate likelihood is based on the 'Product of Approximate Conditionals' likelihood and 'copying model' of Li and Stephens [Li, N., Stephens, M., 2003. Modeling linkage disequilibrium and identifying recombination hotspots using single-nucleotide polymorphism data. Genetics 165 (4), 2213-2233]. The approach developed here may be used for efficient approximate likelihood-based analyses of unlinked data. However our copying model also considers the effects ...
Source: Theoretical Population Biology - May 31, 2009 Category: Biology Authors: Davison D, Pritchard JK, Coop G Tags: Theor Popul Biol Source Type: journals

The conditional ancestral selection graph with strong balancing selection.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We present the results of computer simulations to support our heuristic mathematical results. We also present a more rigorous demonstration that the neutral conditional ancestral process converges to the Kingman coalescent in the limit as the mutation rate tends to infinity. PMID: 19371754 [PubMed - in process] (Source: Theoretical Population Biology)
Source: Theoretical Population Biology - May 31, 2009 Category: Biology Authors: Wakeley J, Sargsyan O Tags: Theor Popul Biol Source Type: journals

Site frequency spectra from genomic SNP surveys.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Genomic survey data now permit an unprecedented level of sensitivity in the detection of departures from canonical evolutionary models, including expansions in population size and selective sweeps. Here, we examine the effects of seemingly subtle differences among sampling distributions on goodness of fit analyses of site frequency spectra constructed from single nucleotide polymorphisms. Conditioning on the observation of exactly two alleles in a random sample results in a site frequency spectrum that is independent of the scaled rate of neutral substitution (theta). Other sampling distributions, including conditionin...
Source: Theoretical Population Biology - May 31, 2009 Category: Biology Authors: Ganapathy G, Uyenoyama MK Tags: Theor Popul Biol Source Type: journals

Karlin volume.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Authors: PMID: 19383508 [PubMed - in process] (Source: Theoretical Population Biology)
Source: Theoretical Population Biology - May 31, 2009 Category: Biology Tags: Theor Popul Biol Source Type: journals

Sam Karlin: a personal appreciation.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In the 1960s Karlin and Bodmer established an active programme in mathematical population genetics with NIH support that, in turn, supported the work of Ewens and Feldman with Karlin. Subsequently Karlin established a similar programme in Israel. The overall contributions of Karlin to population genetics and molecular biology are briefly reviewed from a personal perspective. PMID: 19496242 [PubMed - in process] (Source: Theoretical Population Biology)
Source: Theoretical Population Biology - May 31, 2009 Category: Biology Authors: Bodmer W Tags: Theor Popul Biol Source Type: journals

Sam Karlin and the stochastic theory of evolutionary population genetics.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Sam Karlin's role in the development of the stochastic theory of evolutionary population genetics is outlined, together with his work in developing BLAST theory. PMID: 19496243 [PubMed - in process] (Source: Theoretical Population Biology)
Source: Theoretical Population Biology - May 31, 2009 Category: Biology Authors: Ewens WJ Tags: Theor Popul Biol Source Type: journals

Polymorphism in multiallelic migration-selection models with dominance.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The evolution of the gene frequencies at a single multiallelic locus under the joint action of migration and viability selection with dominance is investigated. The monoecious, diploid population is subdivided into finitely many panmictic colonies that exchange adult migrants independently of genotype. Underdominance and overdominance are excluded. If the degree of dominance is deme independent for every pair of alleles, then under the Levene model, the qualitative evolution of the gene frequencies (i.e., the existence and stability of the equilibria) is the same as without dominance. In particular: (i) the number of d...
Source: Theoretical Population Biology - May 31, 2009 Category: Biology Authors: Nagylaki T Tags: Theor Popul Biol Source Type: journals

Allele fixation in a dynamic metapopulation: Founder effects vs refuge effects.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The fixation of mutant alleles has been studied with models assuming various spatial population structures. In these models, the structure of the metapopulation that we call the "landscape" (number, size and connectivity of subpopulations) is often static. However, natural populations are subject to repetitive population size variations, fragmentation and secondary contacts at different spatiotemporal scales due to geological, climatic and ecological processes. In this paper, we examine how such dynamic landscapes can alter mutant fixation probability and time to fixation. We consider three stochastic landscape dynamic...
Source: Theoretical Population Biology - May 20, 2009 Category: Biology Authors: Aguilée R, Claessen D, Lambert A Tags: Theor Popul Biol Source Type: journals

Sequential Markov coalescent algorithms for population models with demographic structure.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We analyse sequential Markov coalescent algorithms for populations with demographic structure: for a bottleneck model, a population-divergence model, and for a two-island model with migration. The sequential Markov coalescent method is an approximation to the coalescent suggested by McVean and Cardin, and by Marjoram and Wall. Within this algorithm we compute, for two individuals randomly sampled from the population, the correlation between times to the most recent common ancestor and the linkage probability corresponding to two different loci with recombination rate R between them. These quantities characterise the li...
Source: Theoretical Population Biology - May 8, 2009 Category: Biology Authors: Eriksson A, Mahjani B, Mehlig B Tags: Theor Popul Biol Source Type: journals

Structured coalescent processes from a modified Moran model with large offspring numbers.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Structured coalescent processes are derived for the finite island model under a migration mechanism that conserves the subpopulation sizes. The underlying population model is a modified Moran model in which the reproducing individual can have very many offspring with some probability. Convergence to a structured coalescent process results when assuming that migration follows a coalescent timescale which can be much shorter than the usual Wright-Fisher timescale. Three different limit processes are possible depending on the coalescent timescale, two of which allow multiple mergers of ancestral lines. The expected time t...
Source: Theoretical Population Biology - May 8, 2009 Category: Biology Authors: Eldon B Tags: Theor Popul Biol Source Type: journals

Accumulation of independent cultural traits.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In a species capable of (imperfect) social learning, how much culture can a population of a given size carry? And what is the relationship between the individual and the population? In the first study of these novel questions, here we develop a mathematical model of the accumulation of independent cultural traits in a finite population with overlapping generations. PMID: 19427878 [PubMed - as supplied by publisher] (Source: Theoretical Population Biology)
Source: Theoretical Population Biology - May 7, 2009 Category: Biology Authors: Strimling P, Sjöstrand J, Enquist M, Eriksson K Tags: Theor Popul Biol Source Type: journals

Persistence of structured populations in random environments.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Environmental fluctuations often have different impacts on individuals that differ in size, age, or spatial location. To understand how population structure, environmental fluctuations, and density-dependent interactions influence population dynamics, we provide a general theory for persistence for density-dependent matrix models in random environments. For populations with compensating density dependence, exhibiting "bounded" dynamics, and living in a stationary environment, we show that persistence is determined by the stochastic growth rate (alternatively, dominant Lyapunov exponent) when the population is rare. If ...
Source: Theoretical Population Biology - April 6, 2009 Category: Biology Authors: Benaïm M, Schreiber SJ Tags: Theor Popul Biol Source Type: journals

Drawing inferences about the coancestry coefficient.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The coancestry coefficient, also known as the population structure parameter, is of great interest in population genetics. It can be thought of as the intraclass correlation of pairs of alleles within populations and it can serve as a measure of genetic distance between populations. For a general class of evolutionary models it determines the distribution of allele frequencies among populations. Under more restrictive models it can be regarded as the probability of identity by descent of any pair alleles at a locus within a random mating population. In this paper we review estimation procedures that use the method of m...
Source: Theoretical Population Biology - April 1, 2009 Category: Biology Authors: Samanta S, Li YJ, Weir BS Tags: Theor Popul Biol Source Type: journals

A coalescent dual process in a Moran model with genic selection.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A coalescent dual process for a multi-type Moran model with genic selection is derived using a generator approach. This leads to an expansion of the transition functions in the Moran model and the Wright-Fisher diffusion process limit in terms of the transition functions for the coalescent dual. A graphical representation of the Moran model (in the spirit of Harris) identifies the dual as a strong dual process following typed lines backwards in time. An application is made to the harmonic measure problem of finding the joint probability distribution of the time to the first loss of an allele from the population and the...
Source: Theoretical Population Biology - March 30, 2009 Category: Biology Authors: Etheridge AM, Griffiths RC Tags: Theor Popul Biol Source Type: journals

Mutating away from your enemies: The evolution of mutation rate in a host-parasite system.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The rate at which mutations occur in nature is itself under natural selection. While a general reduction of mutation rates is advantageous for species inhabiting constant environments, higher mutation rates can be advantageous for those inhabiting fluctuating environments that impose on-going directional selection. Analogously, species involved in antagonistic co-evolutionary arms-races, such as hosts and parasites, can also benefit from higher mutation rates. We use modifier theory, combined with simulations, to investigate the evolution of mutation rate in such a host-parasite system. We derive an expression for the ...
Source: Theoretical Population Biology - March 30, 2009 Category: Biology Authors: M'gonigle LK, Shen JJ, Otto SP Tags: Theor Popul Biol Source Type: journals

Sex-specific spatio-temporal variability in reproductive success promotes the evolution of sex-biased dispersal.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Inbreeding depression, asymmetries in costs or benefits of dispersal, and the mating system have been identified as potential factors underlying the evolution of sex-biased dispersal. We use individual-based simulations to explore how the mating system and demographic stochasticity influence the evolution of sex-specific dispersal in a metapopulation with females competing over breeding sites, and males over mating opportunities. Comparison of simulation results for random mating with those for a harem system (locally, a single male sires all offspring) reveal that even extreme variance in local male reproductive succe...
Source: Theoretical Population Biology - March 19, 2009 Category: Biology Authors: Gros A, Poethke HJ, Hovestadt T Tags: Theor Popul Biol Source Type: journals

The limitation of species range: A consequence of searching along resource gradients.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Ecological modelers have long puzzled over the spatial distribution of species. The random walk or diffusive approach to dispersal has yielded important results for biology and mathematics, yet it has been inadequate in explaining all phenomenological features. Ranges can terminate non-smoothly absent a complementary shift in the characteristics of the environment. Also unexplained is the absence of a species from nearby areas of adequate, or even abundant, resources. In this paper, I show how local searching behavior - keyed to a density-dependent fitness - can limit the speed and extent of a species' spread. In contr...
Source: Theoretical Population Biology - March 17, 2009 Category: Biology Authors: Rowell JT Tags: Theor Popul Biol Source Type: journals

The rate at which asexual populations cross fitness valleys.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Complex traits often involve interactions between different genetic loci. This can lead to sign epistasis, whereby a set of mutations are individually deleterious or neutral but in combination confer a fitness benefit. In order to acquire the beneficial genotype, an asexual population must cross a fitness valley or plateau by first acquiring the deleterious or neutral intermediates. Here, we present a complete, intuitive theoretical description of the valley-crossing process across the full spectrum of possible parameter regimes. We calculate the rate at which a population crosses a fitness valley or plateau of arbitra...
Source: Theoretical Population Biology - March 12, 2009 Category: Biology Authors: Weissman DB, Desai MM, Fisher DS, Feldman MW Tags: Theor Popul Biol Source Type: journals

Optimization under frequency-dependent selection.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We consider a model of frequency-dependent selection, to which we refer as the Wildcard Model. A variety of more specific models, representing quite diverse biological situations, are covered by the Wildcard Model as particular cases. Two very different particular models that are subsumed by the Wildcard Model are the game theoretically motivated two-phenotype model of Lessard (1984), and the model of selection on a continuous trait due to intraspecific competition of [Bürger, R., 2005. A multilocus analysis of intraspecific competition and stabilizing selection on a quantitative trait. J. Math. Biol. 50 (4) 355-3...
Source: Theoretical Population Biology - March 12, 2009 Category: Biology Authors: Matessi C, Schneider KA Tags: Theor Popul Biol Source Type: journals

The impact of parasitoid emergence time on host-parasitoid population dynamics.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We investigate the effect of parasitoid phenology on host-parasitoid population cycles. Recent experimental research has shown that parasitised hosts can continue to interact with their unparasitised counterparts through competition. Parasitoid phenology, in particular the timing of emergence from the host, determines the duration of this competition. We construct a discrete-time host-parasitoid model in which within-generation dynamics associated with parasitoid timing is explicitly incorporated. We found that late-emerging parasitoids induce less severe, but more frequent, host outbreaks, independent of the choice of...
Source: Theoretical Population Biology - March 7, 2009 Category: Biology Authors: Cobbold CA, Roland J, Lewis MA Tags: Theor Popul Biol Source Type: journals