We analyse how migration from a large mainland influences genetic load and population numbers on an island, in scenario where fitness-affecting variants are unconditionally deleterious, decline with increasing load. Our analysis shows that can have qualitatively different effects, depending the total mutation target fitness effects of deleterious variants. In particular, we find populations exhibit Allee effect across wide range parameter combinations, when partially recessive, cycling...

Abstract We consider how the genetic architecture underlying locally adaptive traits determines strength of a barrier to gene flow in mainland-island model. Assuming general life cycle, we derive an expression for effective migration rate when local adaptation is due variation at many loci under directional selection on island, allowing arbitrary fitness and dominance effects across loci. show can be combined with classical single-locus diffusion theory accurately predict multilocus...

Adaptive introgression is common in nature and can be driven by selection acting on multiple, linked genes. We explore the effects of polygenic under infinitesimal model with linkage. This assumes that introgressing block has an effectively infinite number loci, each effect trait selection. The assumed to introgress directional within a native population genetically homogeneous. use individual-based simulations branching process framework compute various statistics block, how these depend...

Abstract Interspecific crossing experiments have shown that sex chromosomes play a major role in reproductive isolation between many pairs of species. However, their ability to act as barriers, which hamper interspecific genetic exchange, has rarely been evaluated quantitatively compared Autosomes. This genome-wide limitation gene flow is essential for understanding the complete separation species, and thus speciation. Here, we develop mainland-island model secondary contact hybridizing...

This article analyzes the conditions for local adaptation in a metapopulation with infinitely many islands under model of hard selection, where population size depends on fitness. Each island belongs to one two distinct ecological niches or habitats. Fitness is influenced by an additive trait which habitat-dependent directional selection. Our analysis based diffusion approximation and accounts both genetic drift demographic stochasticity. By neglecting linkage disequilibria, it yields joint...

We study how a block of genome with large number weakly selected loci introgresses under directional selection into genetically homogeneous population. derive exact expressions for the expected rate growth any fragment introduced during initial phase introgression, and show that single-locus variant is largely insensitive to its own additive effect, but depends instead on combined effect all within characteristic linkage scale. The highly correlated long-term introgression probability in...

This paper considers how polygenic local adaptation and reproductive isolation between hybridizing populations is influenced by linkage disequilibria (LD) loci, in scenarios where both gene flow genetic drift counteract selection. It shows that the combined effects of multi-locus LD on allele frequencies at selected loci heterozygosity neutral are predicted accurately incorporating (deterministic) effective migration rates into diffusion approximation (for loci) structured coalescent loci)....

Assortative mating is an important driver of speciation in populations with gene flow and predicted to evolve under certain conditions few‐locus models. However, the evolution assortment less understood for based on quantitative traits, which are often characterized by high genetic variability extensive linkage disequilibrium between trait loci. We explore this scenario a two‐deme model migration, considering single polygenic subject divergent viability selection across demes, as well...

Abstract A central issue in cell biology is the physico-chemical basis of organelle biogenesis intracellular trafficking pathways, its most impressive manifestation being Golgi cisternae. At a basic level, such morphologically and chemically distinct compartments should arise from an interplay between molecular transport chemical maturation. Here, we formulate analytically tractable, minimalist models, that incorporate this progression physical space, explore conditions for de novo We...

We study real space condensation in aggregation-fragmentation models where the total mass is not conserved, as phenomena like cloud formation and intracellular trafficking. scaling properties of system with influx outflux at boundaries using numerical simulations, supplemented by analytical results absence fragmentation. The found to undergo a phase transition an unusual condensate phase, characterized strong intermittency giant fluctuations mass. A related also occurs for biased movement...

This article analyzes how partial selfing in a large source population influences its ability to colonize new habitat via the introduction of few founder individuals. Founders experience inbreeding depression due partially recessive deleterious alleles as well maladaptation environment selection on number additive loci. I first introduce simplified version history model characterize mutation‐selection balance large, under involving multiple nonidentical then use individual‐based simulations...

Abstract We consider how the genetic architecture underlying locally adaptive traits determines strength of a barrier to gene flow in mainland-island model. Assuming general life cycle, we derive an expression for effective migration rate when local adaptation is due polygenic trait under directional selection on island, allowing arbitrary fitness and dominance effects across loci. show can be combined with classical single-locus diffusion theory accurately predict multilocus differentiation...

Motivated by the phenomenology of transport through Golgi apparatus cells, we study a multi-species model with boundary injection one species particle, interconversion between different and driven diffusive movement particles system chipping single particle from site. The is analysed in dimension using equations for currents. It found that, depending on rates various processes asymmetry hopping, may exist either steady phase, which average mass at each site attains time-independent value, or...

We consider how a population of N haploid individuals responds to directional selection on standing variation, with no new variation from recombination or mutation. Individuals have trait values z1,…,zN, which are drawn distribution ψ; the fitness individual i is proportional ezi. For illustration, we Laplace and Gaussian distributions, parametrised only by variance V0, show that for large N, there scaling limit depends single parameter NV0. When weak relative drift (NV0≪1), decreases...

Abstract Assortative mating and sexual selection are widespread in nature can play an important role speciation, through the buildup maintenance of reproductive isolation (RI). However, their contribution to genome-wide suppression gene flow during RI is rarely quantified. Here, we consider a polygenic ‘magic’ trait that divergently selected across two populations connected by migration, while also serving as basis assortative mating, thus generating on one or both sexes. We obtain...

ABSTRACT Interspecific crossing experiments have shown that sex chromosomes play a major role in reproductive isolation between many pairs of species. However, their ability to act as barriers, which hamper interspecific genetic exchange, has rarely been evaluated quantitatively compared Autosomes. This genome-wide limitation gene flow is essential for understanding the complete separation species, and thus speciation. Here, we develop mainland-island model secondary contact hybridizing...

Abstract Habitat fragmentation poses a significant threat to the persistence of populations, by generating increased genetic drift (and thus higher load) as well demographic stochasticity. Higher load causes population numbers decline, which reduces efficiency selection and further increases load, resulting in positive feedback may drive entire populations extinction. Here, we investigate this eco-evolutionary metapopulation, focusing on how extinction thresholds depend total rate...

Abstract This paper analyses the conditions for local adaptation in a metapopulation with infinitely many islands under model of hard selection, where population size depends on fitness. Each island belongs to one two distinct ecological niches or habitats. Fitness is influenced by an additive trait which habitat-dependent directional selection. Our analysis based diffusion approximation and accounts both genetic drift demographic stochasticity. By neglecting linkage disequilibria, it yields...

Abstract Adaptive introgression is common in nature and can be driven by selection acting on multiple, linked genes. We explore the effects of polygenic under infinitesimal model with linkage. This assumes that introgressing block has an effectively infinite number genes, each effect trait selection. The assumed to introgress directional within a native population genetically homogeneous. use individual-based simulations branching process approximation compute various statistics block, how...