scholarly journals Polymorphism from environmental heterogeneity: models are only robust if the heterozygote is close in fitness to the favoured homozygote in each environment

1985 ◽  
Vol 45 (3) ◽  
pp. 299-314 ◽  
Author(s):  
Rolf F. Hoekstra ◽  
R. Bijlsma ◽  
A. J. Dolman
Keyword(s):  
Habitat Selection ◽  
Temporal Variation ◽  
Experimental Evidence ◽  
Environmental Heterogeneity ◽  
Heterogeneous Environment ◽  
Partial Dominance ◽  
Favourable Allele

SummaryThe lack of robustness of models of the maintenance of polymorphism in a heterogeneous environment which has been pointed out by Maynard Smith & Hoekstra (1980), applies also to models based on habitat selection, on temporal variation and on density-regulated selection. Only if (partial) dominance ‘switches’ between environments such that the fitness of the heterozygote is always close to the favoured homozygote, is there reasonable robustness. This is true for all models considered. It is argued that there are good reasons for supposing that the favourable allele at a locus may show dominance, although the experimental evidence is still scanty.

scholarly journals Polymorphism in a varied environment: how robust are the models?

1980 ◽  
Vol 35 (1) ◽  
pp. 45-57 ◽  
Author(s):  
J. Maynard Smith ◽  
R. Hoekstra
Keyword(s):  
Habitat Selection ◽  
Narrow Range ◽  
Arithmetic Mean ◽  
Heterogeneous Environment ◽  
Simple Assumption ◽  
Partial Dominance ◽  
Protected Polymorphism ◽  
The Way

SUMMARYThis paper shows that a number of models of the maintenance of polymorphism in a heterogeneous environment, including those of Levene and Dempster, can be derived from a simple assumption about the way in which the numbers and kinds of individuals emerging from a niche depend on the number of eggs laid in it. It is shown that for such models, unless selective advantages per locus are large, protected polymorphism requires that the relative niche sizes lie in a narrow range. This lack of robustness applies also to models of stable polymorphism proposed by Clarke and by Stewart & Levin. Excluding models relaying on habitat selection or restricted migration, the only models which may escape this criticism are diploid models with partial dominance with respect to fitness, such as one proposed by Gillespie, in which in all niches the fitness of heterozygotes is higher than the arithmetic mean of the homozygotes.

scholarly journals GENETIC VARIATION IN A HETEROGENEOUS ENVIRONMENT. I. TEMPORAL HETEROGENEITY AND THE ABSOLUTE DOMINANCE MODEL

Genetics ◽  
1974 ◽  
Vol 78 (2) ◽  
pp. 757-770
Author(s):  
Philip W Hedrick
Keyword(s):  
Genetic Variation ◽  
Temporal Variation ◽  
Gene Frequency ◽  
Environmental Heterogeneity ◽  
Finite Population ◽  
Environmental Variation ◽  
Dominance Model ◽  
Infinite Population ◽  
The Absolute ◽  
Absolute Dominance

ABSTRACT The conditions for a stable polymorphism and the equilibrium gene frequency in an infinite population are compared when there is spatial or temporal environmental heterogeneity for the absolute dominance model. For temporal variation the conditions for stability are more restrictive and the equilibrium gene frequency is often at a low gene frequency. In a finite population, temporal environmental heterogeneity for the absolute dominance model was found to be quite ineffective in maintaining genetic variation and is often less effective than no selection at all. For comparison, the maximum maintenance for temporal variation is related to the overdominant model. In general, cyclic environmental variation was found to be more effective at maintaining genetic variation than where the environment varies stochastically. The importance of temporal environmental variation and the maintenance of genetic variation is discussed.

Temporal variation in habitat selection breaks the catch-22 of spatially contrasting predation risk from multiple predators

Oikos ◽  
2016 ◽  
Vol 126 (5) ◽  
pp. 624-632 ◽  
Author(s):  
Karen Lone ◽  
Atle Mysterud ◽  
Terje Gobakken ◽  
John Odden ◽  
John Linnell ◽  
...  
Keyword(s):  
Habitat Selection ◽  
Temporal Variation ◽  
Predation Risk ◽  
Multiple Predators ◽  
Catch 22

scholarly journals Effects of environmental heterogeneity and temporal variation on ecological relationships of vegetation in a seasonally dry tropical forest in Brazil

2020 ◽  
Vol 44 (3) ◽  
pp. 232-244
Author(s):  
Alisson Borges Miranda SANTOS ◽  
Nathalle Cristine Alencar FAGUNDES ◽  
Cléber Rodrigo de SOUZA ◽  
Vinicius Andrade MAIA ◽  
Wilder Bento da SILVA ◽  
...  
Keyword(s):  
Tropical Forest ◽  
Temporal Variation ◽  
Environmental Heterogeneity ◽  
Seasonally Dry Tropical Forest ◽  
Dry Tropical Forest ◽  
Seasonally Dry ◽  
Ecological Relationships

The Evolution of Recombination in a Heterogeneous Environment

Genetics ◽  
2000 ◽  
Vol 156 (1) ◽  
pp. 423-438 ◽  
Author(s):  
Thomas Lenormand ◽  
Sarah P Otto
Keyword(s):  
Spatial Heterogeneity ◽  
Selection Pressure ◽  
Environmental Heterogeneity ◽  
Directional Selection ◽  
Heterogeneous Environment ◽  
Single Population ◽  
Modifier Locus ◽  
Linkage Disequilibria ◽  
And Migration ◽  
Drift Models

Abstract Most models describing the evolution of recombination have focused on the case of a single population, implicitly assuming that all individuals are equally likely to mate and that spatial heterogeneity in selection is absent. In these models, the evolution of recombination is driven by linkage disequilibria generated either by epistatic selection or drift. Models based on epistatic selection show that recombination can be favored if epistasis is negative and weak compared to directional selection and if the recombination modifier locus is tightly linked to the selected loci. In this article, we examine the joint effects of spatial heterogeneity in selection and epistasis on the evolution of recombination. In a model with two patches, each subject to different selection regimes, we consider the cases of mutation-selection and migration-selection balance as well as the spread of beneficial alleles. We find that including spatial heterogeneity extends the range of epistasis over which recombination can be favored. Indeed, recombination can be favored without epistasis, with negative and even with positive epistasis depending on environmental circumstances. The selection pressure acting on recombination-modifier loci is often much stronger with spatial heterogeneity, and even loosely linked modifiers and free linkage may evolve. In each case, predicting whether recombination is favored requires knowledge of both the type of environmental heterogeneity and epistasis, as none of these factors alone is sufficient to predict the outcome.

Living with an engineer: fish metacommunities in dynamic patchy environments

2018 ◽  
Vol 69 (6) ◽  
pp. 883 ◽  
Author(s):  
Aneta Bylak ◽  
Krzysztof Kukuła
Keyword(s):  
Community Structure ◽  
Species Composition ◽  
Temporal Variation ◽  
Fish Species ◽  
Environmental Heterogeneity ◽  
Size Structure ◽  
Local Communities ◽  
Spatial And Temporal Variation ◽  
The Creation ◽  
Fish Species Composition

Different environmental preferences and dispersal abilities allow fish to coexist in local communities. In the present study we analysed the effects of engineering species on the community structure based on the example of the European beaver (Castor fiber) and mountainous European stream fish. We hypothesised that the creation of beaver impoundments increases environmental heterogeneity and causes a strong spatial and temporal variation in fish species composition and size structure. Finally, we placed these results in the context of the metacommunity theory. Our research was conducted over a large spatial scale, and over a relatively long (5-year) temporal scale. Data analysis revealed strong environmental gradients associated with stream size and increased environmental heterogeneity associated with the creation of beaver impoundments. The results also indicated strong spatial and temporal variation in fish species composition and size structure associated with this environmental heterogeneity. Although local communities changed over time, the main metacommunity characteristics remained constant. Fish must move and follow environmental changes for their populations and communities to persist in streams inhabited by beavers. Gaining a deeper understanding of the effects of the engineering species on fish community structure may help inform management and the conservation of stream ecosystems.

scholarly journals Fitness patterns and phenotypic plasticity in a spatially heterogeneous environment

1996 ◽  
Vol 68 (3) ◽  
pp. 241-248 ◽  
Author(s):  
Lev A. Zhivotovsky ◽  
Marcus W. Feldman ◽  
Aviv Bergman
Keyword(s):  
Environmental Heterogeneity ◽  
Genetic System ◽  
Quadratic Functions ◽  
Heterogeneous Environment ◽  
Mean And Variance ◽  
Haploid Population ◽  
The Mean ◽  
The Difference ◽  
Analytical Expressions ◽  
Special Case

SummaryWe analyse patterns of the means and variances of genotypic fitnesses across different niches in a randomly mating haploid population. The population inhabits a spatially heterogeneous environment where it is subject to mutation and weak multilocus additive selection, with different selection coefficients in different niches. Approximate analytical expressions are derived for the stationary mean and variance of genotypic fitnesses among the niches in terms of environmental and genetic parameters. As a special case, we analyse an environment described by a variable t, distributed among the niches with mean t* and variance D*, and quadratic decrease in correlation between environments as a function of the difference in values of t. If the niches have the same qualities, the mean and variance of genotypic fitnesses evolve to be quadratic functions of t that achieve their maximum and minimum, respectively, at t*. With unequal niche qualities, these are non-polynomial functions that attain their extrema at different, usually intermediate values of t, although the coefficient of variation of the genotypic fitnesses still attains its minimum near t*. The functions involve the total mutation rate, the contribution of the loci to genotypic fitnesses, and the frequency and quality distributions of the niches. Thus, for this relatively simple model the norms of reaction may be calculated in terms of the detailed properties of the environmental heterogeneity, and the genetic system.

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