---
_id: '4262'
abstract:
- lang: eng
text: Natural populations are structured spatially into local populations and genetically
into diverse ‘genetic backgrounds’ defined by different combinations of selected
alleles. If selection maintains genetic backgrounds at constant frequency then
neutral diversity is enhanced. By contrast, if background frequencies fluctuate
then diversity is reduced. Provided that the population size of each background
is large enough, these effects can be described by the structured coalescent process.
Almost all the extant results based on the coalescent deal with a single selected
locus. Yet we know that very large numbers of genes are under selection and that
any substantial effects are likely to be due to the cumulative effects of many
loci. Here, we set up a general framework for the extension of the coalescent
to multilocus scenarios and we use it to study the simplest model, where strong
balancing selection acting on a set of n loci maintains 2n backgrounds at constant
frequencies and at linkage equilibrium. Analytical results show that the expected
linked neutral diversity increases exponentially with the number of selected loci
and can become extremely large. However, simulation results reveal that the structured
coalescent approach breaks down when the number of backgrounds approaches the
population size, because of stochastic fluctuations in background frequencies.
A new method is needed to extend the structured coalescent to cases with large
numbers of backgrounds.
acknowledgement: "We thank B. Charlesworth, D. Charlesworth and F. Depaulis for valuable
discussion and criticism. We are also\r\ngrateful to an anonymous reviewer, who
pointed out an imprecision in the original manuscript. This work was\r\nsupported
by the BBSRC."
article_processing_charge: No
article_type: original
author:
- first_name: Nicholas H
full_name: Barton, Nicholas H
id: 4880FE40-F248-11E8-B48F-1D18A9856A87
last_name: Barton
orcid: 0000-0002-8548-5240
- first_name: Arcadio
full_name: Navarro, Arcadio
last_name: Navarro
citation:
ama: 'Barton NH, Navarro A. Extending the coalescent to multilocus systems: the
case of balancing selection. Genetical Research. 2002;79(2):129-139. doi:10.1017/S0016672301005493'
apa: 'Barton, N. H., & Navarro, A. (2002). Extending the coalescent to multilocus
systems: the case of balancing selection. Genetical Research. Cambridge
University Press. https://doi.org/10.1017/S0016672301005493'
chicago: 'Barton, Nicholas H, and Arcadio Navarro. “Extending the Coalescent to
Multilocus Systems: The Case of Balancing Selection.” Genetical Research.
Cambridge University Press, 2002. https://doi.org/10.1017/S0016672301005493.'
ieee: 'N. H. Barton and A. Navarro, “Extending the coalescent to multilocus systems:
the case of balancing selection,” Genetical Research, vol. 79, no. 2. Cambridge
University Press, pp. 129–139, 2002.'
ista: 'Barton NH, Navarro A. 2002. Extending the coalescent to multilocus systems:
the case of balancing selection. Genetical Research. 79(2), 129–139.'
mla: 'Barton, Nicholas H., and Arcadio Navarro. “Extending the Coalescent to Multilocus
Systems: The Case of Balancing Selection.” Genetical Research, vol. 79,
no. 2, Cambridge University Press, 2002, pp. 129–39, doi:10.1017/S0016672301005493.'
short: N.H. Barton, A. Navarro, Genetical Research 79 (2002) 129–139.
date_created: 2018-12-11T12:07:55Z
date_published: 2002-05-23T00:00:00Z
date_updated: 2023-06-06T11:23:19Z
day: '23'
doi: 10.1017/S0016672301005493
extern: '1'
external_id:
pmid:
- '12073551'
intvolume: ' 79'
issue: '2'
language:
- iso: eng
month: '05'
oa_version: None
page: 129 - 139
pmid: 1
publication: Genetical Research
publication_identifier:
issn:
- 0016-6723
publication_status: published
publisher: Cambridge University Press
publist_id: '1832'
quality_controlled: '1'
scopus_import: '1'
status: public
title: 'Extending the coalescent to multilocus systems: the case of balancing selection'
type: journal_article
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 79
year: '2002'
...
---
_id: '4276'
article_processing_charge: No
author:
- first_name: Nicholas H
full_name: Barton, Nicholas H
id: 4880FE40-F248-11E8-B48F-1D18A9856A87
last_name: Barton
orcid: 0000-0002-8548-5240
citation:
ama: Barton NH. Population genetics of multiple loci. Genetics Research.
2000;75(3):371-373. doi:10.1017/S0016672300239220
apa: Barton, N. H. (2000). Population genetics of multiple loci. Genetics Research.
Cambridge University Press. https://doi.org/10.1017/S0016672300239220
chicago: Barton, Nicholas H. “Population Genetics of Multiple Loci.” Genetics
Research. Cambridge University Press, 2000. https://doi.org/10.1017/S0016672300239220.
ieee: N. H. Barton, “Population genetics of multiple loci,” Genetics Research,
vol. 75, no. 3. Cambridge University Press, pp. 371–373, 2000.
ista: Barton NH. 2000. Population genetics of multiple loci. Genetics Research.
75(3), 371–373.
mla: Barton, Nicholas H. “Population Genetics of Multiple Loci.” Genetics Research,
vol. 75, no. 3, Cambridge University Press, 2000, pp. 371–73, doi:10.1017/S0016672300239220.
short: N.H. Barton, Genetics Research 75 (2000) 371–373.
date_created: 2018-12-11T12:07:59Z
date_published: 2000-06-01T00:00:00Z
date_updated: 2023-04-18T15:01:01Z
day: '01'
doi: 10.1017/S0016672300239220
extern: '1'
intvolume: ' 75'
issue: '3'
language:
- iso: eng
main_file_link:
- url: https://www.cambridge.org/core/journals/genetics-research/article/population-genetics-of-multiple-loci-by-f-b-christiansen-wiley-series-in-mathematical-and-computational-biology-ed-s-levin-john-wiley-sons-1999-isbn-0-471-979791-365-pages-price-80-hardback/9F9E954479B9FB87B0A07250AD6AAD9C
month: '06'
oa_version: None
page: 371 - 373
publication: Genetics Research
publication_identifier:
issn:
- 0016-6723
publication_status: published
publisher: Cambridge University Press
publist_id: '1814'
quality_controlled: '1'
status: public
title: Population genetics of multiple loci
type: review
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 75
year: '2000'
...
---
_id: '4271'
abstract:
- lang: eng
text: "Within hybrid zones that are maintained by a balance between selection and
dispersal, linkage disequilibrium is generated by the mixing of divergent populations.
This linkage disequilibrium causes selection on each locus to act on all other
loci, thereby steepening dines, and generating a barrier to gene flow. Diffusion
models predict simple relations between the strength of linkage disequilibrium
and the dispersal rate, σ, and between the barrier to gene flow, B, and the reduction
in mean fitness, W̄. The aim of this paper is to test the accuracy of these predictions
by comparison with an exact deterministic model of unlinked loci (r = 0.5). Disruptive
selection acts on the proportion of alleles from the parental populations (p,
q): W = exp[-S(4pq)(β)], such that the least fit genotype has fitness e(-S). Where
β << 1, fitness is reduced for a wide range of intermediate genotypes; where
β >> 1, fitness is only reduced for those genotypes close to p = 0.5. Even
with strong epistasis, linkage disequilibria are close to σ2p'(i)p'(j)/r(ij),
where p'(i), p'(j) are the gradients in allele frequency at loci i, j. The barrier
to gene flow, which is reflected in the steepening of neutral dines, is given
by B = ∫(-∞)(∞) (W̄(1/r̄)-1) dx, where r̄, the harmonic mean recombination rate
between the neural and selected loci, is here 0.5. This is a close approximation
for weak selection, but underestimates B for strong selection. The barrier is
stronger for small β, because hybrid fitness is then reduced over a wider range
of p. The widths of the selected dines are harder to predict: though simple approximations
are accurate for β = 1, they become inaccurate for extreme β because, then, fitness
changes sharply with p. Estimates of gene number, made from neutral dines on the
assumption that selection acts against heterozygotes, are accurate for weak selection
when β = 1; however, for strong selection, gene number is overestimated. For β
> 1, gene number is systematically overestimated and, conversely, when β <
1, it is underestimated.\r\n"
acknowledgement: We are grateful to Loeske Kruuk and Michael Turelli for their helpful
comments on the manuscript. N.B. was supported by grants GR3/11635 from the NERC
and GR/L10048 from the EPSRC, and by the Darwin Trust of Edinburgh. M.S. was supported
by a graduate student fellowship from the Yale Institute for Biospheric Studies.
article_processing_charge: No
article_type: original
author:
- first_name: Nicholas H
full_name: Barton, Nicholas H
id: 4880FE40-F248-11E8-B48F-1D18A9856A87
last_name: Barton
orcid: 0000-0002-8548-5240
- first_name: Max
full_name: Shpak, Max
last_name: Shpak
citation:
ama: Barton NH, Shpak M. The effects of epistasis on the structure of hybrid zones.
Genetical Research. 2000;75(2):179-198. doi:10.1017/S0016672399004334
apa: Barton, N. H., & Shpak, M. (2000). The effects of epistasis on the structure
of hybrid zones. Genetical Research. Cambridge University Press. https://doi.org/10.1017/S0016672399004334
chicago: Barton, Nicholas H, and Max Shpak. “The Effects of Epistasis on the Structure
of Hybrid Zones.” Genetical Research. Cambridge University Press, 2000.
https://doi.org/10.1017/S0016672399004334.
ieee: N. H. Barton and M. Shpak, “The effects of epistasis on the structure of hybrid
zones,” Genetical Research, vol. 75, no. 2. Cambridge University Press,
pp. 179–198, 2000.
ista: Barton NH, Shpak M. 2000. The effects of epistasis on the structure of hybrid
zones. Genetical Research. 75(2), 179–198.
mla: Barton, Nicholas H., and Max Shpak. “The Effects of Epistasis on the Structure
of Hybrid Zones.” Genetical Research, vol. 75, no. 2, Cambridge University
Press, 2000, pp. 179–98, doi:10.1017/S0016672399004334.
short: N.H. Barton, M. Shpak, Genetical Research 75 (2000) 179–198.
date_created: 2018-12-11T12:07:58Z
date_published: 2000-04-01T00:00:00Z
date_updated: 2023-04-19T09:58:36Z
day: '01'
doi: 10.1017/S0016672399004334
extern: '1'
external_id:
pmid:
- '10816975'
intvolume: ' 75'
issue: '2'
language:
- iso: eng
month: '04'
oa_version: None
page: 179 - 198
pmid: 1
publication: Genetical Research
publication_identifier:
issn:
- 0016-6723
publication_status: published
publisher: Cambridge University Press
publist_id: '1819'
quality_controlled: '1'
scopus_import: '1'
status: public
title: The effects of epistasis on the structure of hybrid zones
type: journal_article
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 75
year: '2000'
...
---
_id: '3623'
abstract:
- lang: eng
text: 'We present the theoretical background to a new method for measuring genetic
variation for total fitness in Drosophila. The method allows heterozygous effects
on total fitness of whole wild-type chromosomes to be measured under normal demography
with overlapping generations. The wild-type chromosomes are competed against two
balancer chromosomes (B1, B2, say), providing a standard genotype B1/B2 against
which variation in the fitness effects of the wild-type chromosomes can be assessed.
Fitness can be assessed in two ways: (i) at equilibrium of all three chromosomes
under heterozygote advantage, and (ii) during displacement of one balancer by
the other. Equilibrium with all three chromosomes present will be achieved only
if the wild-type homozygote is not too fit, and if the fitnesses of the three
heterozygotes are not too unequal. These conditions were not satisfied for any
of a sample of 12 lethal-bearing chromosomes isolated from a random-bred laboratory
population of Drosophila. At equilibrium, genotypic frequencies show low sensitivity
to changes in genotypic fitness. Furthermore, where all four genotypes are viable
and fertile, supplementary information from cages with only two chromosomes present
and from direct measurements of pre-adult viability are required to estimate fitnesses
from frequencies. The invasion method has the advantages of a greater sensitivity
and of not requiring further data to estimate fitnesses if the wild-type homozygote
is fertile. However, it requires that multiple samples be taken as the invasion
progresses. In a discrete generation model, generation time influences fitness
estimates from this method and is difficult to estimate accurately from the data.
A full age-structured model can also be applied to the data from both types of
experiment. For the invasion method, this gives fitness estimates close to those
from the discrete generation model.'
acknowledgement: This work was supported by grant GR31/G09821 from the BBSRC, and
by fellowships from the Darwin Trust of Edinburgh and the NERC. We are grateful
to the referees for their helpful comments on the manuscript.
article_processing_charge: No
article_type: original
author:
- first_name: Nicholas H
full_name: Barton, Nicholas H
id: 4880FE40-F248-11E8-B48F-1D18A9856A87
last_name: Barton
orcid: 0000-0002-8548-5240
- first_name: Linda
full_name: Patridge, Linda
last_name: Patridge
citation:
ama: Barton NH, Patridge L. Measuring fitness by means of balancer chromosomes.
Genetical Research. 2000;75(3):297-314. doi:10.1017/S0016672399004346
apa: Barton, N. H., & Patridge, L. (2000). Measuring fitness by means of balancer
chromosomes. Genetical Research. Cambridge University Press. https://doi.org/10.1017/S0016672399004346
chicago: Barton, Nicholas H, and Linda Patridge. “Measuring Fitness by Means of
Balancer Chromosomes.” Genetical Research. Cambridge University Press,
2000. https://doi.org/10.1017/S0016672399004346.
ieee: N. H. Barton and L. Patridge, “Measuring fitness by means of balancer chromosomes,”
Genetical Research, vol. 75, no. 3. Cambridge University Press, pp. 297–314,
2000.
ista: Barton NH, Patridge L. 2000. Measuring fitness by means of balancer chromosomes.
Genetical Research. 75(3), 297–314.
mla: Barton, Nicholas H., and Linda Patridge. “Measuring Fitness by Means of Balancer
Chromosomes.” Genetical Research, vol. 75, no. 3, Cambridge University
Press, 2000, pp. 297–314, doi:10.1017/S0016672399004346.
short: N.H. Barton, L. Patridge, Genetical Research 75 (2000) 297–314.
date_created: 2018-12-11T12:04:18Z
date_published: 2000-06-01T00:00:00Z
date_updated: 2023-05-02T12:09:23Z
day: '01'
doi: 10.1017/S0016672399004346
extern: '1'
external_id:
pmid:
- '10893866'
intvolume: ' 75'
issue: '3'
language:
- iso: eng
month: '06'
oa_version: None
page: 297 - 314
pmid: 1
publication: Genetical Research
publication_identifier:
issn:
- 0016-6723
publication_status: published
publisher: Cambridge University Press
publist_id: '2760'
quality_controlled: '1'
scopus_import: '1'
status: public
title: Measuring fitness by means of balancer chromosomes
type: journal_article
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 75
year: '2000'
...
---
_id: '3625'
abstract:
- lang: eng
text: 'This article outlines theoretical models of clines in additive polygenic
traits, which are maintained by stabilizing selection towards a spatially varying
optimum. Clines in the trait mean can be accurately predicted, given knowledge
of the genetic variance. However, predicting the variance is difficult, because
it depends on genetic details. Changes in genetic variance arise from changes
in allele frequency, and in linkage disequilibria. Allele frequency changes dominate
when selection is weak relative to recombination, and when there are a moderate
number of loci. With a continuum of alleles, gene flow inflates the genetic variance
in the same way as a source of mutations of small effect. The variance can be
approximated by assuming a Gaussian distribution of allelic effects; with a sufficiently
steep cline, this is accurate even when mutation and selection alone are better
described by the ''House of Cards'' approximation. With just two alleles at each
locus, the phenotype changes in a similar way: the mean remains close to the optimum,
while the variance changes more slowly, and over a wider region. However, there
may be substantial cryptic divergence at the underlying loci. With strong selection
and many loci, linkage disequilibria are the main cause of changes in genetic
variance. Even for strong selection, the infinitesimal model can be closely approximated
by assuming a Gaussian distribution of breeding values. Linkage disequilibria
can generate a substantial increase in genetic variance, which is concentrated
at sharp gradients in trait means.'
acknowledgement: This work was supported by the Darwin Trust of Edinburgh, and by
grants MMI09726 from the BBSRC}EPSRC and GR3}11635 from the NERC. I would like to
thank R. Lande and M. Slatkin for their comments on an earlier incarnation of this
article, and Mark Kirkpatrick, Loeske Kruuk and Michael Turelli for their comments
on this manuscript.
article_processing_charge: No
article_type: original
author:
- first_name: Nicholas H
full_name: Barton, Nicholas H
id: 4880FE40-F248-11E8-B48F-1D18A9856A87
last_name: Barton
orcid: 0000-0002-8548-5240
citation:
ama: Barton NH. Clines in polygenic traits. Genetical Research. 1999;74(3):223-236.
doi:10.1017/S001667239900422X
apa: Barton, N. H. (1999). Clines in polygenic traits. Genetical Research.
Cambridge University Press. https://doi.org/10.1017/S001667239900422X
chicago: Barton, Nicholas H. “Clines in Polygenic Traits.” Genetical Research.
Cambridge University Press, 1999. https://doi.org/10.1017/S001667239900422X.
ieee: N. H. Barton, “Clines in polygenic traits,” Genetical Research, vol.
74, no. 3. Cambridge University Press, pp. 223–236, 1999.
ista: Barton NH. 1999. Clines in polygenic traits. Genetical Research. 74(3), 223–236.
mla: Barton, Nicholas H. “Clines in Polygenic Traits.” Genetical Research,
vol. 74, no. 3, Cambridge University Press, 1999, pp. 223–36, doi:10.1017/S001667239900422X.
short: N.H. Barton, Genetical Research 74 (1999) 223–236.
date_created: 2018-12-11T12:04:18Z
date_published: 1999-12-01T00:00:00Z
date_updated: 2022-09-06T09:10:35Z
day: '01'
doi: 10.1017/S001667239900422X
extern: '1'
external_id:
pmid:
- '10689800 '
intvolume: ' 74'
issue: '3'
language:
- iso: eng
month: '12'
oa_version: None
page: 223 - 236
pmid: 1
publication: Genetical Research
publication_identifier:
issn:
- 0016-6723
publication_status: published
publisher: Cambridge University Press
publist_id: '2758'
quality_controlled: '1'
scopus_import: '1'
status: public
title: Clines in polygenic traits
type: journal_article
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 74
year: '1999'
...
---
_id: '3627'
abstract:
- lang: eng
text: When a favourable mutation sweeps to fixation, those genes initially linked
to it increase in frequency; on average, this reduces diversity in the surrounding
region of the genome. In the first analysis of this 'hitch-hiking' effect, Maynard-Smith
and Haigh followed the increase of the neutral allele that chanced to be associated
with the new mutation in the first generation, and assumed that the subsequent
increase was deterministic. Later analyses, based on either coalescence arguments,
or on diffusion equations for the mean and variance of allele frequency, have
also made one or both of these assumptions. In the early generations, stochastic
fluctuations in the frequency of the selected allele, and coalescence of neutral
lineages, can be accounted for correctly by following relationships between genes
conditional on the number of copies of the favourable allele. This analysis shows
that the hitch-hiking effect is increased because an allele that is destined to
fix tends to increase more rapidly than exponentially. However, the identity generated
by the selective sweep has the same form as in previous work, h[r/s] (2 Ns)(-2r/s),
where h[r/s] tends to 1 with tight linkage. This analysis is extended to samples
of many genes; then, genes may trace back to several families of lineages, each
related through a common ancestor early in the selective sweep. Simulations show
that the number and sizes of these families can (in principle) be used to make
separate estimates of r/s and Ns.
acknowledgement: S. P. Otto kindly supplied the simulation results shown in Fig. 1.
I would like to thank B. Charlesworth, A. Etheridge and S. P. Otto for their comments
on the manuscript. This work was supported by the Biotechnology and Biological Sciences
Research Council, and by the Darwin Trust of Edinburgh.
article_processing_charge: No
article_type: original
author:
- first_name: Nicholas H
full_name: Barton, Nicholas H
id: 4880FE40-F248-11E8-B48F-1D18A9856A87
last_name: Barton
orcid: 0000-0002-8548-5240
citation:
ama: Barton NH. The effect of hitch-hiking on neutral genealogies. Genetical
Research. 1998;72(2):123-133. doi:10.1017/S0016672398003462
apa: Barton, N. H. (1998). The effect of hitch-hiking on neutral genealogies. Genetical
Research. Cambridge University Press. https://doi.org/10.1017/S0016672398003462
chicago: Barton, Nicholas H. “The Effect of Hitch-Hiking on Neutral Genealogies.”
Genetical Research. Cambridge University Press, 1998. https://doi.org/10.1017/S0016672398003462.
ieee: N. H. Barton, “The effect of hitch-hiking on neutral genealogies,” Genetical
Research, vol. 72, no. 2. Cambridge University Press, pp. 123–133, 1998.
ista: Barton NH. 1998. The effect of hitch-hiking on neutral genealogies. Genetical
Research. 72(2), 123–133.
mla: Barton, Nicholas H. “The Effect of Hitch-Hiking on Neutral Genealogies.” Genetical
Research, vol. 72, no. 2, Cambridge University Press, 1998, pp. 123–33, doi:10.1017/S0016672398003462.
short: N.H. Barton, Genetical Research 72 (1998) 123–133.
date_created: 2018-12-11T12:04:19Z
date_published: 1998-10-01T00:00:00Z
date_updated: 2022-08-29T12:42:44Z
day: '01'
doi: 10.1017/S0016672398003462
extern: '1'
intvolume: ' 72'
issue: '2'
language:
- iso: eng
month: '10'
oa_version: None
page: 123 - 133
publication: Genetical Research
publication_identifier:
issn:
- 0016-6723
publication_status: published
publisher: Cambridge University Press
publist_id: '2756'
quality_controlled: '1'
scopus_import: '1'
status: public
title: The effect of hitch-hiking on neutral genealogies
type: journal_article
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 72
year: '1998'
...
---
_id: '4282'
article_processing_charge: No
author:
- first_name: Nicholas H
full_name: Barton, Nicholas H
id: 4880FE40-F248-11E8-B48F-1D18A9856A87
last_name: Barton
orcid: 0000-0002-8548-5240
citation:
ama: Barton NH. Genetics and analysis of quantitative traits. Genetical Research.
1998;72(1):73-73. doi:10.1017/S0016672398219732
apa: Barton, N. H. (1998). Genetics and analysis of quantitative traits. Genetical
Research. Cambridge University Press. https://doi.org/10.1017/S0016672398219732
chicago: Barton, Nicholas H. “Genetics and Analysis of Quantitative Traits.” Genetical
Research. Cambridge University Press, 1998. https://doi.org/10.1017/S0016672398219732.
ieee: N. H. Barton, “Genetics and analysis of quantitative traits,” Genetical
Research, vol. 72, no. 1. Cambridge University Press, pp. 73–73, 1998.
ista: Barton NH. 1998. Genetics and analysis of quantitative traits. Genetical Research.
72(1), 73–73.
mla: Barton, Nicholas H. “Genetics and Analysis of Quantitative Traits.” Genetical
Research, vol. 72, no. 1, Cambridge University Press, 1998, pp. 73–73, doi:10.1017/S0016672398219732.
short: N.H. Barton, Genetical Research 72 (1998) 73–73.
date_created: 2018-12-11T12:08:01Z
date_published: 1998-08-01T00:00:00Z
date_updated: 2022-08-24T13:36:46Z
day: '01'
doi: 10.1017/S0016672398219732
extern: '1'
intvolume: ' 72'
issue: '1'
language:
- iso: eng
month: '08'
oa_version: None
page: 73 - 73
publication: Genetical Research
publication_identifier:
issn:
- 0016-6723
publication_status: published
publisher: Cambridge University Press
publist_id: '1801'
status: public
title: Genetics and analysis of quantitative traits
type: review
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 72
year: '1998'
...
---
_id: '4291'
article_processing_charge: No
author:
- first_name: Nicholas H
full_name: Barton, Nicholas H
id: 4880FE40-F248-11E8-B48F-1D18A9856A87
last_name: Barton
orcid: 0000-0002-8548-5240
citation:
ama: 'Barton NH. The ecological detective: Confronting models with data. Genetical
Research. 1997;70(2):180-181.'
apa: 'Barton, N. H. (1997). The ecological detective: Confronting models with data.
Genetical Research. Cambridge University Press.'
chicago: 'Barton, Nicholas H. “The Ecological Detective: Confronting Models with
Data.” Genetical Research. Cambridge University Press, 1997.'
ieee: 'N. H. Barton, “The ecological detective: Confronting models with data,” Genetical
Research, vol. 70, no. 2. Cambridge University Press, pp. 180–181, 1997.'
ista: 'Barton NH. 1997. The ecological detective: Confronting models with data.
Genetical Research. 70(2), 180–181.'
mla: 'Barton, Nicholas H. “The Ecological Detective: Confronting Models with Data.”
Genetical Research, vol. 70, no. 2, Cambridge University Press, 1997, pp.
180–81.'
short: N.H. Barton, Genetical Research 70 (1997) 180–181.
date_created: 2018-12-11T12:08:04Z
date_published: 1997-10-01T00:00:00Z
date_updated: 2022-08-18T09:36:25Z
day: '01'
extern: '1'
intvolume: ' 70'
issue: '2'
language:
- iso: eng
main_file_link:
- url: https://www.cambridge.org/core/journals/genetics-research/article/ecological-detective-confronting-models-with-data-by-ray-hilborn-and-marc-mangel-princeton-university-press-1997-315xvii-pages-price-3000-cloth-1695-paper-isbn-0-691-03496-6-0-691-03497-4-pbk/AA6FCD668DFFAEF537C2674ECCFC8966
month: '10'
oa_version: None
page: 180 - 181
publication: Genetical Research
publication_identifier:
issn:
- 0016-6723
publication_status: published
publisher: Cambridge University Press
publist_id: '1790'
quality_controlled: '1'
status: public
title: 'The ecological detective: Confronting models with data'
type: review
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 70
year: '1997'
...
---
_id: '4290'
article_processing_charge: No
author:
- first_name: Nicholas H
full_name: Barton, Nicholas H
id: 4880FE40-F248-11E8-B48F-1D18A9856A87
last_name: Barton
orcid: 0000-0002-8548-5240
citation:
ama: Barton NH. Natural hybridization and evolution. Genetical Research.
1997;70(2):178-180.
apa: Barton, N. H. (1997). Natural hybridization and evolution. Genetical Research.
Cambridge University Press.
chicago: Barton, Nicholas H. “Natural Hybridization and Evolution.” Genetical
Research. Cambridge University Press, 1997.
ieee: N. H. Barton, “Natural hybridization and evolution,” Genetical Research,
vol. 70, no. 2. Cambridge University Press, pp. 178–180, 1997.
ista: Barton NH. 1997. Natural hybridization and evolution. Genetical Research.
70(2), 178–180.
mla: Barton, Nicholas H. “Natural Hybridization and Evolution.” Genetical Research,
vol. 70, no. 2, Cambridge University Press, 1997, pp. 178–80.
short: N.H. Barton, Genetical Research 70 (1997) 178–180.
date_created: 2018-12-11T12:08:04Z
date_published: 1997-10-01T00:00:00Z
date_updated: 2022-08-17T14:10:20Z
day: '01'
extern: '1'
intvolume: ' 70'
issue: '2'
language:
- iso: eng
month: '10'
oa_version: None
page: 178 - 180
publication: Genetical Research
publication_identifier:
issn:
- 0016-6723
publication_status: published
publisher: Cambridge University Press
publist_id: '1789'
status: public
title: Natural hybridization and evolution
type: review
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 70
year: '1997'
...
---
_id: '3635'
abstract:
- lang: eng
text: Experiments on Drosophila suggest that genetic recombination may result in
lowered fitness of progeny (a 'recombination load'). This has been interpreted
as evidence either for a direct effect of recombination on fitness, or for the
maintenance of linkage disequilibria by epistatic selection. Here we show that
such a recombination load is to be expected even if selection favours increased
genetic recombination. This is because of the fact that, although a modifier may
suffer an immediate loss of fitness if it increases recombination, it eventually
becomes associated with a higher additive genetic variance in fitness, which allows
a faster response to direction selection. This argument applies to mutation-selection
balance with synergistic epistasis, directional selection on quantitative traits,
and ectopic exchange among transposable elements. Further experiments are needed
to determine whether the selection against recombination due to the immediate
load is outweighed by the increased additive variance in fitness produced by recombination.
article_processing_charge: No
article_type: original
author:
- first_name: Brian
full_name: Charlesworth, Brian
last_name: Charlesworth
- first_name: Nicholas H
full_name: Barton, Nicholas H
id: 4880FE40-F248-11E8-B48F-1D18A9856A87
last_name: Barton
orcid: 0000-0002-8548-5240
citation:
ama: Charlesworth B, Barton NH. Recombination load associated with selection for
increased recombination. Genetical Research. 1996;67(1):27-41. doi:10.1017/S0016672300033450
apa: Charlesworth, B., & Barton, N. H. (1996). Recombination load associated
with selection for increased recombination. Genetical Research. Cambridge
University Press. https://doi.org/10.1017/S0016672300033450
chicago: Charlesworth, Brian, and Nicholas H Barton. “Recombination Load Associated
with Selection for Increased Recombination.” Genetical Research. Cambridge
University Press, 1996. https://doi.org/10.1017/S0016672300033450.
ieee: B. Charlesworth and N. H. Barton, “Recombination load associated with selection
for increased recombination,” Genetical Research, vol. 67, no. 1. Cambridge
University Press, pp. 27–41, 1996.
ista: Charlesworth B, Barton NH. 1996. Recombination load associated with selection
for increased recombination. Genetical Research. 67(1), 27–41.
mla: Charlesworth, Brian, and Nicholas H. Barton. “Recombination Load Associated
with Selection for Increased Recombination.” Genetical Research, vol. 67,
no. 1, Cambridge University Press, 1996, pp. 27–41, doi:10.1017/S0016672300033450.
short: B. Charlesworth, N.H. Barton, Genetical Research 67 (1996) 27–41.
date_created: 2018-12-11T12:04:21Z
date_published: 1996-02-01T00:00:00Z
date_updated: 2022-08-10T12:38:51Z
day: '01'
doi: 10.1017/S0016672300033450
extern: '1'
external_id:
pmid:
- '8919888 '
intvolume: ' 67'
issue: '1'
language:
- iso: eng
month: '02'
oa_version: None
page: 27 - 41
pmid: 1
publication: Genetical Research
publication_identifier:
issn:
- 0016-6723
publication_status: published
publisher: Cambridge University Press
publist_id: '2748'
quality_controlled: '1'
scopus_import: '1'
status: public
title: Recombination load associated with selection for increased recombination
type: journal_article
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 67
year: '1996'
...
---
_id: '3639'
abstract:
- lang: eng
text: 'A general representation of multilocus selection is extended to allow recombination
to depend on genotype. The equations simplify if modifier alleles have small effects
on recombination. The evolution of such modifiers only depends on how they alter
recombination between the selected loci, and does not involve dominance in modifier
effects. The net selection on modifiers can be found explicitly if epistasis is
weak relative to recombination. This analysis shows that recombination can be
favoured in two ways: because it impedes the response to epistasis which fluctuates
in sign, or because it facilitates the response to directional selection. The
first mechanism is implausible, because epistasis must change sign over periods
of a few generations: faster or slower fluctuations favour reduced recombination.
The second mechanism requires weak negative epistasis between favourable alleles,
which may either be increasing, or held in check by mutation. The selection (si)
on recombination modifiers depends on the reduction in additive variance of log
(fitness) due to linkage disequilibria (υ1 < 0), and on non-additive variance
in log (fitness) (V′2, V′3,.. epistasis between 2, 3.. loci). For unlinked loci
and pairwise epistasis, si = − (υ1 + 4V2/3)δr, where δr is the average increase
in recombination caused by the modifier. The approximations are checked against
exact calculations for three loci, and against Charlesworth''s analyses of mutation/selection
balance (1990), and directional selection (1993). The analysis demonstrates a
general relation between selection on recombination and observable components
of fitness variation, which is open to experimental test.'
article_processing_charge: No
article_type: original
author:
- first_name: Nicholas H
full_name: Barton, Nicholas H
id: 4880FE40-F248-11E8-B48F-1D18A9856A87
last_name: Barton
orcid: 0000-0002-8548-5240
citation:
ama: Barton NH. A general model for the evolution of recombination. Genetical
Research. 1995;65(2):123-144. doi:10.1017/S0016672300033140
apa: Barton, N. H. (1995). A general model for the evolution of recombination. Genetical
Research. Cambridge University Press. https://doi.org/10.1017/S0016672300033140
chicago: Barton, Nicholas H. “A General Model for the Evolution of Recombination.”
Genetical Research. Cambridge University Press, 1995. https://doi.org/10.1017/S0016672300033140.
ieee: N. H. Barton, “A general model for the evolution of recombination,” Genetical
Research, vol. 65, no. 2. Cambridge University Press, pp. 123–144, 1995.
ista: Barton NH. 1995. A general model for the evolution of recombination. Genetical
Research. 65(2), 123–144.
mla: Barton, Nicholas H. “A General Model for the Evolution of Recombination.” Genetical
Research, vol. 65, no. 2, Cambridge University Press, 1995, pp. 123–44, doi:10.1017/S0016672300033140.
short: N.H. Barton, Genetical Research 65 (1995) 123–144.
date_created: 2018-12-11T12:04:23Z
date_published: 1995-04-01T00:00:00Z
date_updated: 2022-06-24T11:54:10Z
day: '01'
doi: 10.1017/S0016672300033140
extern: '1'
external_id:
pmid:
- '7605514'
intvolume: ' 65'
issue: '2'
language:
- iso: eng
main_file_link:
- url: https://www.cambridge.org/core/journals/genetics-research/article/general-model-for-the-evolution-of-recombination/8CBDDF2DC779CF4B6AE9B461B80BB4AE
month: '04'
oa_version: None
page: 123 - 144
pmid: 1
publication: Genetical Research
publication_identifier:
issn:
- 0016-6723
publication_status: published
publisher: Cambridge University Press
publist_id: '2744'
quality_controlled: '1'
scopus_import: '1'
status: public
title: A general model for the evolution of recombination
type: journal_article
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 65
year: '1995'
...
---
_id: '3641'
abstract:
- lang: eng
text: The probability of fixation of a mutation with selective advantage s will
be reduced by substitutions at other loci. The effect of a single substitution,
with selective advantage S0016672300032857inline1, can be approximated as a sudden
reduction in the frequency of the favourable allele, by a fraction w = 1 −(s/S)r/s
(where r is the recombination rate). An expression for the effect of a given sequence
of such catastrophes is derived. This also applies to the ecological prxoblem
of finding the probability that a small population will survive, despite occasional
disasters. It is shown that if substitutions occur at a rate Δ, and are scattered
randomly over a genetic map of length R, then an allele is unlikely to be fixed
if its advantage is less than a critical value, Scrit = (π2/6)(2ΔS/(Rlog(S/s))).
This threshold depends primarily on the variance in fitness per unit map length
dueto substitutions, var(W)/R = 2ΔS/R. With no recombination, the fixation probability
can be calculated for a finite population. If Δ > s, it is of the same order
as for a neutral allele ( ≈ Δ/(2N(Δ−s))), whilst if S0016672300032857inline2,
fixation probability is much higher than for a neutral allele, but much lower
than in the absence of hitch-hiking S0016672300032857inline3. These results suggest
that hitch-hiking may substantially impede the accumulation of weakly favoured
adaptations.
article_processing_charge: No
article_type: original
author:
- first_name: Nicholas H
full_name: Barton, Nicholas H
id: 4880FE40-F248-11E8-B48F-1D18A9856A87
last_name: Barton
orcid: 0000-0002-8548-5240
citation:
ama: Barton NH. The reduction in fixation probability caused by substitutions at
linked loci. Genetical Research. 1994;64(3):199-208. doi:10.1017/S0016672300032857
apa: Barton, N. H. (1994). The reduction in fixation probability caused by substitutions
at linked loci. Genetical Research. Cambridge University Press. https://doi.org/10.1017/S0016672300032857
chicago: Barton, Nicholas H. “The Reduction in Fixation Probability Caused by Substitutions
at Linked Loci.” Genetical Research. Cambridge University Press, 1994.
https://doi.org/10.1017/S0016672300032857
.
ieee: N. H. Barton, “The reduction in fixation probability caused by substitutions
at linked loci,” Genetical Research, vol. 64, no. 3. Cambridge University
Press, pp. 199–208, 1994.
ista: Barton NH. 1994. The reduction in fixation probability caused by substitutions
at linked loci. Genetical Research. 64(3), 199–208.
mla: Barton, Nicholas H. “The Reduction in Fixation Probability Caused by Substitutions
at Linked Loci.” Genetical Research, vol. 64, no. 3, Cambridge University
Press, 1994, pp. 199–208, doi:10.1017/S0016672300032857 .
short: N.H. Barton, Genetical Research 64 (1994) 199–208.
date_created: 2018-12-11T12:04:23Z
date_published: 1994-12-01T00:00:00Z
date_updated: 2022-06-03T08:34:32Z
day: '01'
doi: '10.1017/S0016672300032857 '
extern: '1'
intvolume: ' 64'
issue: '3'
language:
- iso: eng
main_file_link:
- url: https://www.cambridge.org/core/journals/genetics-research/article/reduction-in-fixation-probability-caused-by-substitutions-at-linked-loci/458BBF3E7FE92E4EA6AFB2B000A98945
month: '12'
oa_version: None
page: 199 - 208
publication: Genetical Research
publication_identifier:
issn:
- 0016-6723
publication_status: published
publisher: Cambridge University Press
publist_id: '2742'
quality_controlled: '1'
scopus_import: '1'
status: public
title: The reduction in fixation probability caused by substitutions at linked loci
type: journal_article
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 64
year: '1994'
...
---
_id: '4303'
abstract:
- lang: eng
text: In a stably subdivided population with symmetric migration, the chance that
a favoured allele will be fixed is independent of population structure. However,
random extinction introduces an extra component of sampling drift, and reduces
the probability of fixation. In this paper, the fixation probability is calculated
using the diffusion approximation; comparison with exact solution of the discrete
model shows this to be accurate. The key parameters are the rates of selection,
migration and extinction, scaled relative to population size (S = 4Ns, M = 4Nm,
Λ = 4Nλ); results apply to a haploid model, or to diploids with additive selection.
If new colonies derive from many demes, the fixation probability cannot be reduced
by more than half. However, if colonies are initially homogeneous, fixation probability
can be much reduced. In the limit of low migration and extinction rates (M, Λ
1), it is 2s/{1 + (Λ/MS)(1 −exp(−S))}, whilst in the opposite limit (S 1), it
is 4sM/{Λ(Λ + M)}. In the limit of weak selection (M, Λ 1), it is 4sM/{Λ(Λ +
M)}. These factors are not the same as the reduction in effective population size
(Ne/N), showing that the effects of population structure on selected alleles cannot
be understood from the behaviour of neutral markers.
acknowledgement: This work was supported by grants from the SERC (GR/H/09928) and
NERC (GR/3/8002), and by the Darwin Trust of Edinburgh. Thanks are due to B. Nürnberger
for convincing me that population structure does reduce fixation probability, to
M. Whitlock for discussions on calculations of effective population size, and to
W. G. Hill, P. Keightley and the anonymous referees for their comments.
article_processing_charge: No
article_type: original
author:
- first_name: Nicholas H
full_name: Barton, Nicholas H
id: 4880FE40-F248-11E8-B48F-1D18A9856A87
last_name: Barton
orcid: 0000-0002-8548-5240
citation:
ama: Barton NH. The probability of fixation of a favoured allele in a subdivided
population. Genetics Research. 1993;62(2):149-158. doi:10.1017/S0016672300031748
apa: Barton, N. H. (1993). The probability of fixation of a favoured allele in a
subdivided population. Genetics Research. Cambridge University Press. https://doi.org/10.1017/S0016672300031748
chicago: Barton, Nicholas H. “The Probability of Fixation of a Favoured Allele in
a Subdivided Population.” Genetics Research. Cambridge University Press,
1993. https://doi.org/10.1017/S0016672300031748.
ieee: N. H. Barton, “The probability of fixation of a favoured allele in a subdivided
population,” Genetics Research, vol. 62, no. 2. Cambridge University Press,
pp. 149–158, 1993.
ista: Barton NH. 1993. The probability of fixation of a favoured allele in a subdivided
population. Genetics Research. 62(2), 149–158.
mla: Barton, Nicholas H. “The Probability of Fixation of a Favoured Allele in a
Subdivided Population.” Genetics Research, vol. 62, no. 2, Cambridge University
Press, 1993, pp. 149–58, doi:10.1017/S0016672300031748.
short: N.H. Barton, Genetics Research 62 (1993) 149–158.
date_created: 2018-12-11T12:08:09Z
date_published: 1993-10-01T00:00:00Z
date_updated: 2022-03-23T15:41:32Z
day: '01'
doi: 10.1017/S0016672300031748
extern: '1'
intvolume: ' 62'
issue: '2'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://www.cambridge.org/core/journals/genetics-research/article/probability-of-fixation-of-a-favoured-allele-in-a-subdivided-population/3257B4AEC7044AFE40436C2DC15FBC4C#article
month: '10'
oa: 1
oa_version: None
page: 149 - 158
publication: Genetics Research
publication_identifier:
issn:
- 0016-6723
publication_status: published
publisher: Cambridge University Press
publist_id: '1762'
quality_controlled: '1'
scopus_import: '1'
status: public
title: The probability of fixation of a favoured allele in a subdivided population
type: journal_article
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 62
year: '1993'
...
---
_id: '4302'
article_processing_charge: No
author:
- first_name: Nicholas H
full_name: Barton, Nicholas H
id: 4880FE40-F248-11E8-B48F-1D18A9856A87
last_name: Barton
orcid: 0000-0002-8548-5240
citation:
ama: Barton NH. Review of "The causes of molecular evolution"
by J.H. Gillespie. Genetical Research. 1993;62(1):77-85. doi:10.1017/S001667230003158X
apa: Barton, N. H. (1993). Review of "The causes of molecular evolution"
by J.H. Gillespie. Genetical Research. Cambridge University Press. https://doi.org/10.1017/S001667230003158X
chicago: Barton, Nicholas H. “Review of "The Causes of Molecular Evolution"
by J.H. Gillespie.” Genetical Research. Cambridge University Press, 1993.
https://doi.org/10.1017/S001667230003158X
.
ieee: N. H. Barton, “Review of "The causes of molecular evolution"
by J.H. Gillespie,” Genetical Research, vol. 62, no. 1. Cambridge University
Press, pp. 77–85, 1993.
ista: Barton NH. 1993. Review of "The causes of molecular evolution"
by J.H. Gillespie. Genetical Research. 62(1), 77–85.
mla: Barton, Nicholas H. “Review of "The Causes of Molecular Evolution"
by J.H. Gillespie.” Genetical Research, vol. 62, no. 1, Cambridge University
Press, 1993, pp. 77–85, doi:10.1017/S001667230003158X .
short: N.H. Barton, Genetical Research 62 (1993) 77–85.
date_created: 2018-12-11T12:08:08Z
date_published: 1993-01-01T00:00:00Z
date_updated: 2022-03-23T16:05:31Z
day: '01'
doi: '10.1017/S001667230003158X '
extern: '1'
intvolume: ' 62'
issue: '1'
language:
- iso: eng
main_file_link:
- url: https://www.cambridge.org/core/journals/genetics-research/article/causes-of-molecular-evolution-by-john-h-gillespie-oxford-university-press-1992-336-pages-price-2500-isbn-0-19-506883-1/FF2B56D0B883F340BEC4E3C068F89F6C
month: '01'
oa_version: None
page: 77 - 85
publication: Genetical Research
publication_identifier:
issn:
- 0016-6723
publication_status: published
publisher: Cambridge University Press
publist_id: '1763'
quality_controlled: '1'
status: public
title: Review of "The causes of molecular evolution" by J.H. Gillespie
type: review
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 62
year: '1993'
...
---
_id: '3643'
abstract:
- lang: eng
text: 'We investigate the establishment and spread of new adaptive peaks within
Wright''s ‘shifting balance’. The third phase of the ‘shifting balance’ involves
a kind of group selection, since demes in which a superior peak has been established
contain more individuals, and so send out more migrants. We assume that population
size, N, increases with mean fitness, , according to the exponential relation,
. Here, k is a measure of the weakness of density-dependent regulation, and equals
the inverse of the regression of log (fitness) on log(N). In the island model,
we find that just as with soft selection (k = 0), two distinct types of behaviour
exist: group selection makes no qualitative difference. With low numbers of migrants,
demes fluctuate almost independently, and only one equilibrium exists. With large
numbers of migrants, all the demes evolve towards the same adaptive peak, and
so the whole population can move towards one or other of the peaks. Group selection
can be understood in terms of an effective mean fitness function. Its main consequence
is to increase the effect of selection relative to drift (Ns), and so increase
the bias towards the fitter peak. However, this increased bias depends on the
ratio between k and the deme size (k/N), and so is very small when density-dependence
is reasonably strong.'
acknowledgement: 'This work was supported by the Darwin Trust, by a Science and Engineering
Research Council grant (GR/E/08507), and by an SERC Visiting Fellowship to S.Rouhani. '
article_processing_charge: No
article_type: original
author:
- first_name: Shahin
full_name: Rouhani, Shahin
last_name: Rouhani
- first_name: Nicholas H
full_name: Barton, Nicholas H
id: 4880FE40-F248-11E8-B48F-1D18A9856A87
last_name: Barton
orcid: 0000-0002-8548-5240
citation:
ama: Rouhani S, Barton NH. Group selection and the “shifting balance.” Genetical
Research. 1993;61(2):127-136. doi:10.1017/S0016672300031232
apa: Rouhani, S., & Barton, N. H. (1993). Group selection and the “shifting
balance.” Genetical Research. Cambridge University Press. https://doi.org/10.1017/S0016672300031232
chicago: Rouhani, Shahin, and Nicholas H Barton. “Group Selection and the ‘Shifting
Balance.’” Genetical Research. Cambridge University Press, 1993. https://doi.org/10.1017/S0016672300031232.
ieee: S. Rouhani and N. H. Barton, “Group selection and the ‘shifting balance,’”
Genetical Research, vol. 61, no. 2. Cambridge University Press, pp. 127–136,
1993.
ista: Rouhani S, Barton NH. 1993. Group selection and the ‘shifting balance’. Genetical
Research. 61(2), 127–136.
mla: Rouhani, Shahin, and Nicholas H. Barton. “Group Selection and the ‘Shifting
Balance.’” Genetical Research, vol. 61, no. 2, Cambridge University Press,
1993, pp. 127–36, doi:10.1017/S0016672300031232.
short: S. Rouhani, N.H. Barton, Genetical Research 61 (1993) 127–136.
date_created: 2018-12-11T12:04:24Z
date_published: 1993-04-01T00:00:00Z
date_updated: 2022-03-30T08:28:54Z
day: '01'
doi: 10.1017/S0016672300031232
extern: '1'
intvolume: ' 61'
issue: '2'
language:
- iso: eng
main_file_link:
- url: https://www.cambridge.org/core/journals/genetics-research/article/group-selection-and-the-shifting-balance/CFDE26EA7125957545F9A0AA37755BC4
month: '04'
oa_version: None
page: 127 - 136
publication: Genetical Research
publication_identifier:
issn:
- 0016-6723
publication_status: published
publisher: Cambridge University Press
publist_id: '2740'
quality_controlled: '1'
scopus_import: '1'
status: public
title: Group selection and the 'shifting balance'
type: journal_article
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 61
year: '1993'
...
---
_id: '3644'
abstract:
- lang: eng
text: "Wright proposed that there is a ' shifting balance' between selection within
demes, random drift, and selection between demes at different 'adaptive peaks'.
We investigate the establishment and spread of new adaptive peaks, considering
a chromosome rearrangement, and a polygenic character under disruptive selection.
When the number of migrants (Nm) is small, demes fluctuate independently, with
a bias towards the fitter peak. When Nm is large, the whole population can\r\nmove
to one of two stable equilibria, and so can be trapped near the lower peak. These
two regimes are separated by a sharp transition at a critical Nm of order 1. Just
below this critical point, adaptation is most efficient, since the shifting balance
greatly increases the proportion of demes that reach the global optimum. This
is so even if one peak is only slightly fitter than the other (AWx \\/N), and
for both strong and weak selection (Ns <§ 1 or Ns > 1). Provided that Nm\r\nvaries
sufficiently gradually from place to place, the fitter peak can be established
in regions where Nm « 1, and can then spread through the rest of the range. Our
analysis confirms Wright's argument that if selection, migration and drift are
of the same order, the ' shifting balance' leads to efficient evolution towards
the global optimum."
article_processing_charge: No
article_type: original
author:
- first_name: Nicholas H
full_name: Barton, Nicholas H
id: 4880FE40-F248-11E8-B48F-1D18A9856A87
last_name: Barton
orcid: 0000-0002-8548-5240
- first_name: Shahin
full_name: Rouhani, Shahin
last_name: Rouhani
citation:
ama: Barton NH, Rouhani S. Adaptation and the “shifting balance.” Genetical Research.
1993;61(1):57-74. doi:10.1017/S0016672300031098
apa: Barton, N. H., & Rouhani, S. (1993). Adaptation and the “shifting balance.”
Genetical Research. Cambridge University Press. https://doi.org/10.1017/S0016672300031098
chicago: Barton, Nicholas H, and Shahin Rouhani. “Adaptation and the ‘Shifting Balance.’”
Genetical Research. Cambridge University Press, 1993. https://doi.org/10.1017/S0016672300031098 .
ieee: N. H. Barton and S. Rouhani, “Adaptation and the ‘shifting balance,’” Genetical
Research, vol. 61, no. 1. Cambridge University Press, pp. 57–74, 1993.
ista: Barton NH, Rouhani S. 1993. Adaptation and the ‘shifting balance’. Genetical
Research. 61(1), 57–74.
mla: Barton, Nicholas H., and Shahin Rouhani. “Adaptation and the ‘Shifting Balance.’”
Genetical Research, vol. 61, no. 1, Cambridge University Press, 1993, pp.
57–74, doi:10.1017/S0016672300031098
.
short: N.H. Barton, S. Rouhani, Genetical Research 61 (1993) 57–74.
date_created: 2018-12-11T12:04:24Z
date_published: 1993-02-01T00:00:00Z
date_updated: 2022-03-30T08:18:58Z
day: '01'
doi: '10.1017/S0016672300031098 '
extern: '1'
intvolume: ' 61'
issue: '1'
language:
- iso: eng
main_file_link:
- url: https://www.cambridge.org/core/journals/genetics-research/article/adaptation-and-the-shifting-balance/2E15452B3AFCA97E77743E0C7E108064
month: '02'
oa_version: None
page: 57 - 74
publication: Genetical Research
publication_identifier:
issn:
- 0016-6723
publication_status: published
publisher: Cambridge University Press
publist_id: '2739'
quality_controlled: '1'
scopus_import: '1'
status: public
title: Adaptation and the 'shifting balance'
type: journal_article
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 61
year: '1993'
...
---
_id: '4314'
abstract:
- lang: eng
text: 'Polygenic variation can be maintained by a balance between mutation and stabilizing
selection. When the alleles responsible for variation are rare, many classes of
equilibria may be stable. The rate at which drift causes shifts between equilibria
is investigated by integrating the gene frequency distribution W2N II (pq)4N mu-1.
This integral can be found exactly, by numerical integration, or can be approximated
by assuming that the full distribution of allele frequencies is approximately
Gaussian. These methods are checked against simulations. Over a wide range of
population sizes, drift will keep the population near an equilibrium which minimizes
the genetic variance and the deviation from the selective optimum. Shifts between
equilibria in this class occur at an appreciable rate if the product of population
size and selection on each locus is small (Ns alpha 2 less than 10). The Gaussian
approximation is accurate even when the underlying distribution is strongly skewed.
Reproductive isolation evolves as populations shift to new combinations of alleles:
however, this process is slow, approaching the neutral rate (approximately mu)
in small populations.'
article_processing_charge: No
article_type: original
author:
- first_name: Nicholas H
full_name: Barton, Nicholas H
id: 4880FE40-F248-11E8-B48F-1D18A9856A87
last_name: Barton
orcid: 0000-0002-8548-5240
citation:
ama: Barton NH. The divergence of a polygenic system under stabilising selection,
mutation and drift. Genetical Research. 1989;54(1):59-78. doi:10.1017/S0016672300028378
apa: Barton, N. H. (1989). The divergence of a polygenic system under stabilising
selection, mutation and drift. Genetical Research. Cambridge University
Press. https://doi.org/10.1017/S0016672300028378
chicago: Barton, Nicholas H. “The Divergence of a Polygenic System under Stabilising
Selection, Mutation and Drift.” Genetical Research. Cambridge University
Press, 1989. https://doi.org/10.1017/S0016672300028378.
ieee: N. H. Barton, “The divergence of a polygenic system under stabilising selection,
mutation and drift,” Genetical Research, vol. 54, no. 1. Cambridge University
Press, pp. 59–78, 1989.
ista: Barton NH. 1989. The divergence of a polygenic system under stabilising selection,
mutation and drift. Genetical Research. 54(1), 59–78.
mla: Barton, Nicholas H. “The Divergence of a Polygenic System under Stabilising
Selection, Mutation and Drift.” Genetical Research, vol. 54, no. 1, Cambridge
University Press, 1989, pp. 59–78, doi:10.1017/S0016672300028378.
short: N.H. Barton, Genetical Research 54 (1989) 59–78.
date_created: 2018-12-11T12:08:12Z
date_published: 1989-08-01T00:00:00Z
date_updated: 2022-02-09T14:18:28Z
day: '01'
doi: 10.1017/S0016672300028378
extern: '1'
external_id:
pmid:
- '2806907'
intvolume: ' 54'
issue: '1'
language:
- iso: eng
main_file_link:
- url: https://www.cambridge.org/core/journals/genetics-research/article/divergence-of-a-polygenic-system-subject-to-stabilizing-selection-mutation-and-drift/95DF5B589A5C32376F1AAEE99F3200D8
month: '08'
oa_version: None
page: 59 - 78
pmid: 1
publication: Genetical Research
publication_identifier:
eissn:
- 1469-5073
issn:
- 0016-6723
publication_status: published
publisher: Cambridge University Press
publist_id: '1741'
quality_controlled: '1'
scopus_import: '1'
status: public
title: The divergence of a polygenic system under stabilising selection, mutation
and drift
type: journal_article
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 54
year: '1989'
...
---
_id: '4322'
abstract:
- lang: eng
text: A method is developed for calculating the probability of establishment of
an allele which is favoured in some places, but not others, in a large subdivided
population. This method is quite general, and could be used to calculate the chance
that any system which is linear near an absorbing boundary will move away from
that boundary. The results are applied to a population distributed along one dimension.
Only mutants which arise within a distance σ/ √2s of the region in which they
are favoured stand an appreciable chance of establishment. The net chance of establishment
of mutations distributed randomly across the habitat will be decreased by gene
flow if selection against them is sufficiently strong. However, if the mutations
are only weakly deleterious outside some limited region, gene flow may increase
the net chance of establishment.
acknowledgement: "This work was supported by a grant from the Science and Engineering
Research Council (GR/D/91529). Shahin\r\nRouhani supplied the proof that no positive
solution to (6) exists when all eigenvalues are negative (Appendix);\r\nM. Slatkin,
M. Turelli, T. Nagylaki and he also gave helpful comments on the manuscript."
article_processing_charge: No
article_type: original
author:
- first_name: Nicholas H
full_name: Barton, Nicholas H
id: 4880FE40-F248-11E8-B48F-1D18A9856A87
last_name: Barton
orcid: 0000-0002-8548-5240
citation:
ama: Barton NH. The probability of establishment of an advantageous mutation in
a subdivided population. Genetical Research. 1987;50(1):35-40. doi:10.1017/S0016672300023314
apa: Barton, N. H. (1987). The probability of establishment of an advantageous mutation
in a subdivided population. Genetical Research. Cambridge University Press.
https://doi.org/10.1017/S0016672300023314
chicago: Barton, Nicholas H. “The Probability of Establishment of an Advantageous
Mutation in a Subdivided Population.” Genetical Research. Cambridge University
Press, 1987. https://doi.org/10.1017/S0016672300023314.
ieee: N. H. Barton, “The probability of establishment of an advantageous mutation
in a subdivided population,” Genetical Research, vol. 50, no. 1. Cambridge
University Press, pp. 35–40, 1987.
ista: Barton NH. 1987. The probability of establishment of an advantageous mutation
in a subdivided population. Genetical Research. 50(1), 35–40.
mla: Barton, Nicholas H. “The Probability of Establishment of an Advantageous Mutation
in a Subdivided Population.” Genetical Research, vol. 50, no. 1, Cambridge
University Press, 1987, pp. 35–40, doi:10.1017/S0016672300023314.
short: N.H. Barton, Genetical Research 50 (1987) 35–40.
date_created: 2018-12-11T12:08:15Z
date_published: 1987-01-01T00:00:00Z
date_updated: 2022-02-03T10:16:16Z
day: '01'
doi: 10.1017/S0016672300023314
extern: '1'
external_id:
pmid:
- '3653687 '
intvolume: ' 50'
issue: '1'
language:
- iso: eng
month: '01'
oa_version: None
page: 35 - 40
pmid: 1
publication: Genetical Research
publication_identifier:
eissn:
- 1469-5073
issn:
- 0016-6723
publication_status: published
publisher: Cambridge University Press
publist_id: '1725'
quality_controlled: '1'
scopus_import: '1'
status: public
title: The probability of establishment of an advantageous mutation in a subdivided
population
type: journal_article
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 50
year: '1987'
...
---
_id: '3660'
abstract:
- lang: eng
text: "The maintenance of polygenic variability by a balance between mutation and
stabilizing selection has been analysed using two approximations: the ‘Gaussian’
and the ‘house of cards’. These lead to qualitatively different relationships
between the equilibrium genetic variance and the parameters describing selection
and mutation. Here we generalize these approximations to describe the dynamics
of genetic means and variances under arbitrary patterns of selection and mutation.
We incorporate genetic drift into the same mathematical framework.\r\nThe effects
of frequency-independent selection and genetic drift can be determined from the
gradient of log mean fitness and a covariance matrix that depends on genotype
frequencies. These equations describe an ‘adaptive landscape’, with a natural
metric of genetic distance set by the covariance matrix. From this representation
we can change coordinates to derive equations describing the dynamics of an additive
polygenic character in terms of the moments (means, variances, …) of allelic effects
at individual loci. Only under certain simplifying conditions, such as those derived
from the Gaussian and house-of-cards approximations, do these general recursions
lead to tractable equations for the first few phenotypic moments. The alternative
approximations differ in the constraints they impose on the distributions of allelic
effects at individual loci. The Gaussian-based prediction that evolution of the
phenotypic mean does not change the genetic variance is shown to be a consequence
of the assumption that the allelic distributions are never skewed. We present
both analytical and numerical results delimiting the parameter values consistent
with our approximations."
article_processing_charge: No
article_type: original
author:
- first_name: Nicholas H
full_name: Barton, Nicholas H
id: 4880FE40-F248-11E8-B48F-1D18A9856A87
last_name: Barton
orcid: 0000-0002-8548-5240
- first_name: Michael
full_name: Turelli, Michael
last_name: Turelli
citation:
ama: Barton NH, Turelli M. Adaptive landscapes, genetic distance, and the evolution
of quantitative characters. Genetical Research. 1987;49(2):157-174. doi:10.1017/S0016672300026951
apa: Barton, N. H., & Turelli, M. (1987). Adaptive landscapes, genetic distance,
and the evolution of quantitative characters. Genetical Research. Cambridge
University Press. https://doi.org/10.1017/S0016672300026951
chicago: Barton, Nicholas H, and Michael Turelli. “Adaptive Landscapes, Genetic
Distance, and the Evolution of Quantitative Characters.” Genetical Research.
Cambridge University Press, 1987. https://doi.org/10.1017/S0016672300026951.
ieee: N. H. Barton and M. Turelli, “Adaptive landscapes, genetic distance, and the
evolution of quantitative characters,” Genetical Research, vol. 49, no.
2. Cambridge University Press, pp. 157–174, 1987.
ista: Barton NH, Turelli M. 1987. Adaptive landscapes, genetic distance, and the
evolution of quantitative characters. Genetical Research. 49(2), 157–174.
mla: Barton, Nicholas H., and Michael Turelli. “Adaptive Landscapes, Genetic Distance,
and the Evolution of Quantitative Characters.” Genetical Research, vol.
49, no. 2, Cambridge University Press, 1987, pp. 157–74, doi:10.1017/S0016672300026951.
short: N.H. Barton, M. Turelli, Genetical Research 49 (1987) 157–174.
date_created: 2018-12-11T12:04:29Z
date_published: 1987-04-01T00:00:00Z
date_updated: 2022-02-04T10:54:31Z
day: '01'
doi: 10.1017/S0016672300026951
extern: '1'
intvolume: ' 49'
issue: '2'
language:
- iso: eng
main_file_link:
- url: https://www.cambridge.org/core/journals/genetics-research/article/adaptive-landscapes-genetic-distance-and-the-evolution-of-quantitative-characters/25C2D277AC7554F805D67F6C32579549
month: '04'
oa_version: None
page: 157 - 174
publication: Genetical Research
publication_identifier:
eissn:
- 1469-5073
issn:
- 0016-6723
publication_status: published
publisher: Cambridge University Press
publist_id: '2723'
quality_controlled: '1'
scopus_import: '1'
status: public
title: Adaptive landscapes, genetic distance, and the evolution of quantitative characters
type: journal_article
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 49
year: '1987'
...
---
_id: '4324'
abstract:
- lang: eng
text: The maintenance of polygenic variation through a balance between mutation
and stabilizing selection can be approximated in two ways. In the ‘Gaussian’ approximation,
a normal distribution of allelic effects is assumed at each locus. In the ‘House
of Cards’ approximation, the effect of new mutations is assumed to be large compared
with the spread of the existing distribution. These approximations were developed
to describe models where alleles may have a continuous range of effects. However,
previous analyses of models with only two alleles have predicted an equilibrium
variance equal to that given by the ‘House of Cards’ approximation. These analyses
of biallelic models have assumed that, at equilibrium, the population mean is
at the optimum. Here, it is shown that many stable equilibria may coexist, each
giving a slight deviation from the optimum. Though the variance is given by the
‘House of Cards’ approximation when the mean is at the optimum, it increases towards
a value of the same order as that given by the ‘Gaussian’ approximation when the
mean deviates from the optimum. Thus, the equilibrium variance cannot be predicted
by any simple model, but depends on the previous history of the population.
acknowledgement: Thanks are due to J. Felsenstein, J. Gillespie, S. Rouhani, M. Slatkin,
and M. Turelli for stimulating discussions, and for their comments on the manuscript.
This work was sup- ported by a travel grant from the Royal Society, and by a research
grant from the SERC
article_processing_charge: No
article_type: original
author:
- first_name: Nicholas H
full_name: Barton, Nicholas H
id: 4880FE40-F248-11E8-B48F-1D18A9856A87
last_name: Barton
orcid: 0000-0002-8548-5240
citation:
ama: Barton NH. The maintenance of polygenic variation through a balance between
mutation and stabilising selection. Genetical Research. 1986;47(3):209-216.
doi:10.1017/S0016672300023156
apa: Barton, N. H. (1986). The maintenance of polygenic variation through a balance
between mutation and stabilising selection. Genetical Research. Cambridge
University Press. https://doi.org/10.1017/S0016672300023156
chicago: Barton, Nicholas H. “The Maintenance of Polygenic Variation through a Balance
between Mutation and Stabilising Selection.” Genetical Research. Cambridge
University Press, 1986. https://doi.org/10.1017/S0016672300023156.
ieee: N. H. Barton, “The maintenance of polygenic variation through a balance between
mutation and stabilising selection,” Genetical Research, vol. 47, no. 3.
Cambridge University Press, pp. 209–216, 1986.
ista: Barton NH. 1986. The maintenance of polygenic variation through a balance
between mutation and stabilising selection. Genetical Research. 47(3), 209–216.
mla: Barton, Nicholas H. “The Maintenance of Polygenic Variation through a Balance
between Mutation and Stabilising Selection.” Genetical Research, vol. 47,
no. 3, Cambridge University Press, 1986, pp. 209–16, doi:10.1017/S0016672300023156.
short: N.H. Barton, Genetical Research 47 (1986) 209–216.
date_created: 2018-12-11T12:08:15Z
date_published: 1986-06-01T00:00:00Z
date_updated: 2022-01-31T14:31:48Z
day: '01'
doi: 10.1017/S0016672300023156
extern: '1'
external_id:
pmid:
- '3744046'
intvolume: ' 47'
issue: '3'
language:
- iso: eng
month: '06'
oa_version: None
page: 209 - 216
pmid: 1
publication: Genetical Research
publication_identifier:
eissn:
- 1469-5073
issn:
- 0016-6723
publication_status: published
publisher: Cambridge University Press
publist_id: '1718'
quality_controlled: '1'
status: public
title: The maintenance of polygenic variation through a balance between mutation and
stabilising selection
type: journal_article
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 47
year: '1986'
...