---
_id: '4305'
abstract:
- lang: eng
  text: The common shrew (Sorex araneus) is subdivided into several karyotypic races
    in Britain. Two of these races meet near Oxford to form the "Oxford-Hermitage"
    hybrid zone. We present a model which describes this system as a "tension
    zone," i.e., a set of clines maintained by a balance between dispersal and
    selection against chromosomal heterozygotes. The Oxford and Hermitage races differ
    by Robertsonian fusions with monobrachial homology (kq, no versus ko), and so
    F1 hybrids between them would have low fertility. However, the acrocentric karyotype
    is found at high frequency within the hybrid zone, so that complex Robertsonian
    heterozygotes (kq no/q ko n) are replaced by more fertile combinations, such as
    (kq no/k q n o). This suggests that the hybrid zone has been modified so as to
    increase hybrid fitness. Mathematical analysis and simulation show that, if selection
    against complex heterozygotes is sufficiently strong relative to selection against
    simple heterozygotes, acrocentrics increase, and displace the clines for kq and
    no from the cline for ko. Superimposed on this separation is a tendency for the
    hybrid zone to move m favor of the Oxford (kq no) race. We compare the model with
    estimates of linkage disequilibrium and cline shape made from field data.
acknowledgement: 'This study was funded by grants from the Royal Society of London
  to J.B.S., and from the S.E.R.C., N.E.R.C. and the Darwin Trust to N.Barton. A.J.Reilly,
  Y.Luo, and S. J.Mercer provided unpublished data and D.Currie, A.E.Douglas, K.  S.Jackson,
  X.Lambin and D.Kapan made helpful comments on the manuscript. We appreciate our
  discussions with B. O.Bengtsson. '
article_processing_charge: No
article_type: original
author:
- first_name: Todd
  full_name: Hatfield, Todd
  last_name: Hatfield
- 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: Jeremy
  full_name: Searle, Jeremy
  last_name: Searle
citation:
  ama: Hatfield T, Barton NH, Searle J. A model of a hybrid zone between two chromosomal
    races of the common shrew (Sorex araneus). <i>Evolution; International Journal
    of Organic Evolution</i>. 1992;46(4):1129-1145. doi:<a href="https://doi.org/10.1111/j.1558-5646.1992.tb00624.x">10.1111/j.1558-5646.1992.tb00624.x</a>
  apa: Hatfield, T., Barton, N. H., &#38; Searle, J. (1992). A model of a hybrid zone
    between two chromosomal races of the common shrew (Sorex araneus). <i>Evolution;
    International Journal of Organic Evolution</i>. Wiley-Blackwell. <a href="https://doi.org/10.1111/j.1558-5646.1992.tb00624.x">https://doi.org/10.1111/j.1558-5646.1992.tb00624.x</a>
  chicago: Hatfield, Todd, Nicholas H Barton, and Jeremy Searle. “A Model of a Hybrid
    Zone between Two Chromosomal Races of the Common Shrew (Sorex Araneus).” <i>Evolution;
    International Journal of Organic Evolution</i>. Wiley-Blackwell, 1992. <a href="https://doi.org/10.1111/j.1558-5646.1992.tb00624.x">https://doi.org/10.1111/j.1558-5646.1992.tb00624.x</a>.
  ieee: T. Hatfield, N. H. Barton, and J. Searle, “A model of a hybrid zone between
    two chromosomal races of the common shrew (Sorex araneus),” <i>Evolution; International
    Journal of Organic Evolution</i>, vol. 46, no. 4. Wiley-Blackwell, pp. 1129–1145,
    1992.
  ista: Hatfield T, Barton NH, Searle J. 1992. A model of a hybrid zone between two
    chromosomal races of the common shrew (Sorex araneus). Evolution; International
    Journal of Organic Evolution. 46(4), 1129–1145.
  mla: Hatfield, Todd, et al. “A Model of a Hybrid Zone between Two Chromosomal Races
    of the Common Shrew (Sorex Araneus).” <i>Evolution; International Journal of Organic
    Evolution</i>, vol. 46, no. 4, Wiley-Blackwell, 1992, pp. 1129–45, doi:<a href="https://doi.org/10.1111/j.1558-5646.1992.tb00624.x">10.1111/j.1558-5646.1992.tb00624.x</a>.
  short: T. Hatfield, N.H. Barton, J. Searle, Evolution; International Journal of
    Organic Evolution 46 (1992) 1129–1145.
date_created: 2018-12-11T12:08:09Z
date_published: 1992-08-01T00:00:00Z
date_updated: 2022-03-15T14:49:26Z
day: '01'
doi: 10.1111/j.1558-5646.1992.tb00624.x
extern: '1'
external_id:
  pmid:
  - '28564402'
intvolume: '        46'
issue: '4'
language:
- iso: eng
main_file_link:
- url: http://www.jstor.org/stable/2409761
month: '08'
oa_version: Published Version
page: 1129 - 1145
pmid: 1
publication: Evolution; International Journal of Organic Evolution
publication_identifier:
  eissn:
  - 1558-5646
  issn:
  - 0014-3820
publication_status: published
publisher: Wiley-Blackwell
publist_id: '1759'
quality_controlled: '1'
status: public
title: A model of a hybrid zone between two chromosomal races of the common shrew
  (Sorex araneus)
type: journal_article
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 46
year: '1992'
...
---
_id: '4308'
acknowledgement: This work was supported by the Darwin Trust, NSF  grant BSR/866548,
  and SERC grant GR/E/08507. Valuable comments on the manuscript were received  from
  D. Currie, K. Dawson, K. S. Jackson, W. G. Hill,  M. Turelli, and an anonymous referee.
  I would particularly like to thank K. Dawson and the referee, for  pointing out
  the complexities involved in calculating  P(i, j; k), and J. F. Crow, for supplying
  detailed simulation results, and for his helpful comments on the draft of this paper.
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. On the spread of new gene combinations in the third phase of Wright’s
    shifting balance. <i>Evolution; International Journal of Organic Evolution</i>.
    1992;46(2):551-557.
  apa: Barton, N. H. (1992). On the spread of new gene combinations in the third phase
    of Wright’s shifting balance. <i>Evolution; International Journal of Organic Evolution</i>.
    Wiley-Blackwell.
  chicago: Barton, Nicholas H. “On the Spread of New Gene Combinations in the Third
    Phase of Wright’s Shifting Balance.” <i>Evolution; International Journal of Organic
    Evolution</i>. Wiley-Blackwell, 1992.
  ieee: N. H. Barton, “On the spread of new gene combinations in the third phase of
    Wright’s shifting balance,” <i>Evolution; International Journal of Organic Evolution</i>,
    vol. 46, no. 2. Wiley-Blackwell, pp. 551–557, 1992.
  ista: Barton NH. 1992. On the spread of new gene combinations in the third phase
    of Wright’s shifting balance. Evolution; International Journal of Organic Evolution.
    46(2), 551–557.
  mla: Barton, Nicholas H. “On the Spread of New Gene Combinations in the Third Phase
    of Wright’s Shifting Balance.” <i>Evolution; International Journal of Organic
    Evolution</i>, vol. 46, no. 2, Wiley-Blackwell, 1992, pp. 551–57.
  short: N.H. Barton, Evolution; International Journal of Organic Evolution 46 (1992)
    551–557.
date_created: 2018-12-11T12:08:10Z
date_published: 1992-04-01T00:00:00Z
date_updated: 2022-03-14T13:36:15Z
day: '01'
extern: '1'
intvolume: '        46'
issue: '2'
language:
- iso: eng
main_file_link:
- url: http://www.jstor.org/stable/2409871
month: '04'
oa_version: None
page: 551 - 557
publication: Evolution; International Journal of Organic Evolution
publication_identifier:
  eissn:
  - 1558-5646
  issn:
  - 0014-3820
publication_status: published
publisher: Wiley-Blackwell
publist_id: '1756'
quality_controlled: '1'
status: public
title: On the spread of new gene combinations in the third phase of Wright's shifting
  balance
type: journal_article
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 46
year: '1992'
...
---
_id: '3646'
abstract:
- lang: eng
  text: "We compare the pattern of morphological and electrophoretic variation in
    the hybrid zone between Bombina bombina and B. variegata across two transects:
    one near Cracow and one 200 km away, near Przemysl in southeastern Poland. Morphological
    variation across the Przemysl transect had been surveyed more than 50 years ago;
    though we found a significant shift at one site, there is no evidence for gross
    movement over this period. Morphological and electrophoretic changes coincide,
    and the average shape of the clines is the same across both transects. At the
    center, most of the change in frequency of six diagnostic allozymes occurs within
    w = 6.05 km (2-unit support limits 5.56-6.54 km). These steep gradients are generated
    not by selection on the allozymes themselves, but by associations with other loci:
    though these markers are unlinked, they are in strong linkage disequilibrium with
    each other [R = D/ = 0.22 (0.15-0.29) at the center]. Disequilibria are broken
    up as alleles diffuse away from the zone and flow into the new genetic background.
    The net barrier to the flow of genes from bombina into variegata, which is generated
    by these disequilibria, is B = 51 (22-81) km. The fitness of hybrids must be substantially
    reduced to produce such a barrier [W̄H/W̄P = 0.58 (0.54-0.68)], and this selection
    must be spread over many loci [N = 55 (26-88)]. Alleles introgress significantly
    less far than would be expected from the age of the zone and the estimated dispersal
    rate [σ = 0.99 (0.82-1.14) km gen.-1/2]: this implies selection of se = 0.37 (0.15-0.58)%
    on the enzymes themselves. There is weak but significant linkage disequilibrium
    well away from the center of the zone; this, together with the presence of parental
    and F1 genotypes, suggests some long-range migration. However, such migration
    is not likely to cause significant introgression.\r\n"
acknowledgement: This work was supported by grants from  the Royal Society, the Nuffield
  Foundation,  the University of London Central Research Fund, and the Polish Academy
  of Sciences (project MR-II.6). We also thank Dr. Jan Rafinski for help in collecting
  toads.
article_processing_charge: No
article_type: original
author:
- first_name: Jacek
  full_name: Szymura, Jacek
  last_name: Szymura
- 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: 'Szymura J, Barton NH. The genetic structure of the hybrid zone between the
    fire-bellied toads Bombina bombina and B. variegata: comparisons between transects
    and between loci. <i>Evolution</i>. 1991;45(2):237-261. doi:<a href="https://doi.org/10.1111/j.1558-5646.1991.tb04400.x">10.1111/j.1558-5646.1991.tb04400.x</a>'
  apa: 'Szymura, J., &#38; Barton, N. H. (1991). The genetic structure of the hybrid
    zone between the fire-bellied toads Bombina bombina and B. variegata: comparisons
    between transects and between loci. <i>Evolution</i>. Wiley-Blackwell. <a href="https://doi.org/10.1111/j.1558-5646.1991.tb04400.x">https://doi.org/10.1111/j.1558-5646.1991.tb04400.x</a>'
  chicago: 'Szymura, Jacek, and Nicholas H Barton. “The Genetic Structure of the Hybrid
    Zone between the Fire-Bellied Toads Bombina Bombina and B. Variegata: Comparisons
    between Transects and between Loci.” <i>Evolution</i>. Wiley-Blackwell, 1991.
    <a href="https://doi.org/10.1111/j.1558-5646.1991.tb04400.x">https://doi.org/10.1111/j.1558-5646.1991.tb04400.x</a>.'
  ieee: 'J. Szymura and N. H. Barton, “The genetic structure of the hybrid zone between
    the fire-bellied toads Bombina bombina and B. variegata: comparisons between transects
    and between loci,” <i>Evolution</i>, vol. 45, no. 2. Wiley-Blackwell, pp. 237–261,
    1991.'
  ista: 'Szymura J, Barton NH. 1991. The genetic structure of the hybrid zone between
    the fire-bellied toads Bombina bombina and B. variegata: comparisons between transects
    and between loci. Evolution. 45(2), 237–261.'
  mla: 'Szymura, Jacek, and Nicholas H. Barton. “The Genetic Structure of the Hybrid
    Zone between the Fire-Bellied Toads Bombina Bombina and B. Variegata: Comparisons
    between Transects and between Loci.” <i>Evolution</i>, vol. 45, no. 2, Wiley-Blackwell,
    1991, pp. 237–61, doi:<a href="https://doi.org/10.1111/j.1558-5646.1991.tb04400.x">10.1111/j.1558-5646.1991.tb04400.x</a>.'
  short: J. Szymura, N.H. Barton, Evolution 45 (1991) 237–261.
date_created: 2018-12-11T12:04:25Z
date_published: 1991-03-01T00:00:00Z
date_updated: 2022-03-02T15:50:09Z
day: '01'
doi: 10.1111/j.1558-5646.1991.tb04400.x
extern: '1'
external_id:
  pmid:
  - '28567861 '
intvolume: '        45'
issue: '2'
language:
- iso: eng
main_file_link:
- url: ' http://www.jstor.org/stable/2409660'
month: '03'
oa_version: None
page: 237 - 261
pmid: 1
publication: Evolution
publication_identifier:
  eissn:
  - 1558-5646
  issn:
  - 0014-3820
publication_status: published
publisher: Wiley-Blackwell
publist_id: '2737'
quality_controlled: '1'
scopus_import: '1'
status: public
title: 'The genetic structure of the hybrid zone between the fire-bellied toads Bombina
  bombina and B. variegata: comparisons between transects and between loci'
type: journal_article
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 45
year: '1991'
...
---
_id: '3648'
abstract:
- lang: eng
  text: 'We investigate the probability of fixation of a chromosome rearrangement
    in a subdivided population, concentrating on the limit where migration is so large
    relative to selection (m ≫ s) that the population can be thought of as being continuously
    distributed. We study two demes, and one- and two-dimensional populations. For
    two demes, the probability of fixation in the limit of high migration approximates
    that of a population with twice the size of a single deme: migration therefore
    greatly reduces the fixation probability. However, this behavior does not extend
    to a large array of demes. Then, the fixation probability depends primarily on
    neighborhood size (Nb), and may be appreciable even with strong selection and
    free gene flow (≈exp(-B·Nb) in one dimension, ≈exp(-B\cdotNb) in two dimensions).
    Our results are close to those for the more tractable case of a polygenic character
    under disruptive selection.'
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. The probability of fixation of a new karyotype in a continuous
    population. <i>Evolution</i>. 1991;45(3):499-517. doi:<a href="https://doi.org/10.1111/j.1558-5646.1991.tb04326.x">10.1111/j.1558-5646.1991.tb04326.x</a>
  apa: Barton, N. H., &#38; Rouhani, S. (1991). The probability of fixation of a new
    karyotype in a continuous population. <i>Evolution</i>. Wiley-Blackwell. <a href="https://doi.org/10.1111/j.1558-5646.1991.tb04326.x">https://doi.org/10.1111/j.1558-5646.1991.tb04326.x</a>
  chicago: Barton, Nicholas H, and Shahin Rouhani. “The Probability of Fixation of
    a New Karyotype in a Continuous Population.” <i>Evolution</i>. Wiley-Blackwell,
    1991. <a href="https://doi.org/10.1111/j.1558-5646.1991.tb04326.x">https://doi.org/10.1111/j.1558-5646.1991.tb04326.x</a>.
  ieee: N. H. Barton and S. Rouhani, “The probability of fixation of a new karyotype
    in a continuous population,” <i>Evolution</i>, vol. 45, no. 3. Wiley-Blackwell,
    pp. 499–517, 1991.
  ista: Barton NH, Rouhani S. 1991. The probability of fixation of a new karyotype
    in a continuous population. Evolution. 45(3), 499–517.
  mla: Barton, Nicholas H., and Shahin Rouhani. “The Probability of Fixation of a
    New Karyotype in a Continuous Population.” <i>Evolution</i>, vol. 45, no. 3, Wiley-Blackwell,
    1991, pp. 499–517, doi:<a href="https://doi.org/10.1111/j.1558-5646.1991.tb04326.x">10.1111/j.1558-5646.1991.tb04326.x</a>.
  short: N.H. Barton, S. Rouhani, Evolution 45 (1991) 499–517.
date_created: 2018-12-11T12:04:25Z
date_published: 1991-05-01T00:00:00Z
date_updated: 2022-03-02T10:37:19Z
day: '01'
doi: 10.1111/j.1558-5646.1991.tb04326.x
extern: '1'
external_id:
  pmid:
  - '28568824'
intvolume: '        45'
issue: '3'
language:
- iso: eng
main_file_link:
- url: http://www.jstor.org/stable/2409908
month: '05'
oa_version: None
page: 499 - 517
pmid: 1
publication: Evolution
publication_identifier:
  eissn:
  - 1558-5646
  issn:
  - 0014-3820
publication_status: published
publisher: Wiley-Blackwell
publist_id: '2735'
quality_controlled: '1'
status: public
title: The probability of fixation of a new karyotype in a continuous population
type: journal_article
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 45
year: '1991'
...
---
_id: '3653'
abstract:
- lang: eng
  text: 'Frequency-dependent selection on warning color can maintain narrow hybrid
    zones between unpalatable prey taxa. To measure such selection, we transferred
    marked Heliconius erato (Lepidoptera: Nymphalidae) in both directions across a
    10-km-wide hybrid zone between Peruvian races differing in color pattern. These
    experimental H. erato were released at four sites, along with control H. erato
    of the phenotype native to each site. Survival of experimental butterflies was
    significantly lower than that of controls at two sites and overall. Most selection,
    measured as differences in survival, occurred soon after release. Selection against
    foreign morphs was 52% (confidence limits: 25-71%) and was probably due to bird
    attacks on unusual warning-color morphs (more than 10% of the recaptures had beak
    marks). Since only three major loci determine the color-pattern differences, this
    suggests an average selection coefficient of 0.17 per locus, sufficient to maintain
    the narrow clines in H. erato.'
acknowledgement: We thank G.Lamas for sharing his knowledge of the Tarapoto hybrid
  zone;  M.A.Arboleda, H.Eeley, S.Knapp, M.Muedas, and J.Santisteban for their help
  in the field;  P.Donnelly and C.Smith for statistical advice; and S.Jones, S.Knapp,
  G.Lamas, and the reviewers for helpful comments on the manuscript. We are grateful
  to the Natural Environment Research Council, the Royal Society, and the Nuffield
  Foundation for funding this research.
article_processing_charge: No
article_type: original
author:
- first_name: James
  full_name: Mallet, James
  last_name: Mallet
- 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: Mallet J, Barton NH. Strong natural selection in a warning color hybrid zone.
    <i>Evolution</i>. 1989;43(2):421-431. doi:<a href="https://doi.org/10.2307/2409217
    ">10.2307/2409217 </a>
  apa: Mallet, J., &#38; Barton, N. H. (1989). Strong natural selection in a warning
    color hybrid zone. <i>Evolution</i>. Wiley-Blackwell. <a href="https://doi.org/10.2307/2409217
    ">https://doi.org/10.2307/2409217 </a>
  chicago: Mallet, James, and Nicholas H Barton. “Strong Natural Selection in a Warning
    Color Hybrid Zone.” <i>Evolution</i>. Wiley-Blackwell, 1989. <a href="https://doi.org/10.2307/2409217
    ">https://doi.org/10.2307/2409217 </a>.
  ieee: J. Mallet and N. H. Barton, “Strong natural selection in a warning color hybrid
    zone,” <i>Evolution</i>, vol. 43, no. 2. Wiley-Blackwell, pp. 421–431, 1989.
  ista: Mallet J, Barton NH. 1989. Strong natural selection in a warning color hybrid
    zone. Evolution. 43(2), 421–431.
  mla: Mallet, James, and Nicholas H. Barton. “Strong Natural Selection in a Warning
    Color Hybrid Zone.” <i>Evolution</i>, vol. 43, no. 2, Wiley-Blackwell, 1989, pp.
    421–31, doi:<a href="https://doi.org/10.2307/2409217 ">10.2307/2409217 </a>.
  short: J. Mallet, N.H. Barton, Evolution 43 (1989) 421–431.
date_created: 2018-12-11T12:04:27Z
date_published: 1989-01-01T00:00:00Z
date_updated: 2022-02-14T11:00:42Z
day: '01'
doi: '10.2307/2409217 '
extern: '1'
external_id:
  pmid:
  - '28568556 '
intvolume: '        43'
issue: '2'
language:
- iso: eng
main_file_link:
- url: https://www.jstor.org/stable/2409217?origin=crossref&seq=1#metadata_info_tab_contents
month: '01'
oa_version: None
page: 421 - 431
pmid: 1
publication: Evolution
publication_identifier:
  eissn:
  - 1558-5646
  issn:
  - 0014-3820
publication_status: published
publisher: Wiley-Blackwell
publist_id: '2730'
quality_controlled: '1'
scopus_import: '1'
status: public
title: Strong natural selection in a warning color hybrid zone
type: journal_article
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 43
year: '1989'
...
---
_id: '4309'
abstract:
- lang: eng
  text: Three methods for estimating the average level of gene flow in natural population
    are discussed and compared. The three methods are FST, rare alleles, and maximum
    likelihood. All three methods yield estimates of the combination of parameters
    (the number of migrants [Nm] in a demic model or the neighborhood size [4πDσ2]
    in a continuum model) that determines the relative importance of gene flow and
    genetic drift. We review the theory underlying these methods and derive new analytic
    results for the expectation of FST in stepping-stone and continuum models when
    small sets of samples are taken. We also compare the effectiveness of the different
    methods using a variety of simulated data. We found that the FST and rare-alleles
    methods yield comparable estimates under a wide variety of conditions when the
    population being sampled is demographically stable. They are roughly equally sensitive
    to selection and to variation in population structure, and they approach their
    equilibrium values at approximately the same rate. We found that two different
    maximum-likelihood methods tend to yield biased estimates when relatively small
    numbers of locations are sampled but more accurate estimates when larger numbers
    are sampled. Our conclusion is that, although FST and rare-alleles methods are
    expected to be equally effective in analyzing ideal data, practical problems in
    estimating the frequencies of rare alleles in electrophoretic studies suggest
    that FST is likely to be more useful under realistic conditions.
acknowledgement: This research has been supported in partv by grant 85-00258 from
  the National Science Foundation and by grants GR/C/9 1529 and GR/E/08507 from the
  Science and Engineering Research Council. We thank C. C. Cockerham and B. S. Weir
  for helpful discussions of this topic, C. Wehrhahn for bringing his method to our
  attention and for providing us with a copy of his program for estimating Nm, and
  J. Coyne, M. Nei, B. S. Weir, and an anonymous referee for comments on an earlier
  draft of this paper.
article_processing_charge: No
article_type: original
author:
- first_name: Montgomery
  full_name: Slatkin, Montgomery
  last_name: Slatkin
- 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: Slatkin M, Barton NH. A comparison of three methods for estimating average
    levels of gene flow. <i>Evolution; International Journal of Organic Evolution</i>.
    1989;43(7):1349-1368. doi:<a href="https://doi.org/10.1111/j.1558-5646.1989.tb02587.x
    ">10.1111/j.1558-5646.1989.tb02587.x </a>
  apa: Slatkin, M., &#38; Barton, N. H. (1989). A comparison of three methods for
    estimating average levels of gene flow. <i>Evolution; International Journal of
    Organic Evolution</i>. Wiley-Blackwell. <a href="https://doi.org/10.1111/j.1558-5646.1989.tb02587.x
    ">https://doi.org/10.1111/j.1558-5646.1989.tb02587.x </a>
  chicago: Slatkin, Montgomery, and Nicholas H Barton. “A Comparison of Three Methods
    for Estimating Average Levels of Gene Flow.” <i>Evolution; International Journal
    of Organic Evolution</i>. Wiley-Blackwell, 1989. <a href="https://doi.org/10.1111/j.1558-5646.1989.tb02587.x
    ">https://doi.org/10.1111/j.1558-5646.1989.tb02587.x </a>.
  ieee: M. Slatkin and N. H. Barton, “A comparison of three methods for estimating
    average levels of gene flow,” <i>Evolution; International Journal of Organic Evolution</i>,
    vol. 43, no. 7. Wiley-Blackwell, pp. 1349–1368, 1989.
  ista: Slatkin M, Barton NH. 1989. A comparison of three methods for estimating average
    levels of gene flow. Evolution; International Journal of Organic Evolution. 43(7),
    1349–1368.
  mla: Slatkin, Montgomery, and Nicholas H. Barton. “A Comparison of Three Methods
    for Estimating Average Levels of Gene Flow.” <i>Evolution; International Journal
    of Organic Evolution</i>, vol. 43, no. 7, Wiley-Blackwell, 1989, pp. 1349–68,
    doi:<a href="https://doi.org/10.1111/j.1558-5646.1989.tb02587.x ">10.1111/j.1558-5646.1989.tb02587.x
    </a>.
  short: M. Slatkin, N.H. Barton, Evolution; International Journal of Organic Evolution
    43 (1989) 1349–1368.
date_created: 2018-12-11T12:08:10Z
date_published: 1989-11-01T00:00:00Z
date_updated: 2022-02-10T09:44:53Z
day: '01'
doi: '10.1111/j.1558-5646.1989.tb02587.x '
extern: '1'
external_id:
  pmid:
  - '28564250 '
intvolume: '        43'
issue: '7'
language:
- iso: eng
main_file_link:
- url: http://www.jstor.org/stable/2409452
month: '11'
oa_version: None
page: 1349 - 1368
pmid: 1
publication: Evolution; International Journal of Organic Evolution
publication_identifier:
  eissn:
  - 1558-5646
  issn:
  - 0014-3820
publication_status: published
publisher: Wiley-Blackwell
publist_id: '1751'
quality_controlled: '1'
status: public
title: A comparison of three methods for estimating average levels of gene flow
type: journal_article
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 43
year: '1989'
...
---
_id: '4321'
abstract:
- lang: eng
  text: 'The fire-bellied toads Bombina bombina and B. variegata differ extensively
    in biochemistry, morphology, and behavior. We use a survey of five diagnostic
    enzyme loci across the hybrid zone near Cracow in Southern Poland to estimate
    the dispersal rate, selection pressures, and numbers of loci which maintain this
    zone. The enzyme clines coincide closely with each other and with morphological
    and mitochondrial DNA clines. Although the zone lies on a broad transition between
    environments suitable for bombina and variegata, the close concordance of diverse
    characters, together with increased aberrations and mortality in hybrids, suggest
    that the zone is maintained largely by selection against hybrids. There are strong
    “linkage disequilibria” between each pair of (unlinked) enzyme loci (R̄ = 0.129
    [2-unit support limits: 0.119–0.139]). These are probably caused by gene flow
    into the zone, and they give an estimate of dispersal (σ = 890 [790–940] m gen−½).
    The clines are sharply stepped, with most of the change occurring within 6.15
    (5.45–6.45) km, but with long tails of introgression on either side. This implies
    that the effective selection pressure on each enzyme marker (due largely to disequilibrium
    with other loci) is s* = 0.17 (0.159–0.181) at the center but that the selection
    acting directly on the enzyme loci is weak or zero (se < 0.0038). The stepped
    pattern implies a barrier to gene flow of 220 (48–415) km. This would substantially
    delay neutral introgression but would have little effect on advantageous alleles;
    the two taxa need not evolve independently. Strong selection is needed to maintain
    such a barrier: hybrid populations must have their mean fitness reduced by a factor
    of 0.65 (0.60–0.77). This selection must be spread over a large number of loci
    to account for the concordant patterns and the observed cline widths (N = 300
    [80–2,000]).'
acknowledgement: 'We are grateful to J. Mitton and W. P. Hall for their suggestions
  and help with earlier versions of the statistical analysis. The manuscript was much
  improved by the helpful comments of Dorothy Currie, Gunther Gollmann, Godfrey Hewitt,
  Julian MacLean, and Jim Mallet. Thanks are also due to Tina Tsang for her careful
  typing. This work was supported by  the Exchange Agreement between the Polish Academy
  of Sciences and the Royal Society, and by grants from the Polish Academy of Sciences
  (project MR-II/6), the Royal Society, the Nuffield Foundation, and the  Science
  and Engineering Research Council. '
article_processing_charge: No
article_type: original
author:
- first_name: Jacek
  full_name: Szymura, Jacek
  last_name: Szymura
- 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: Szymura J, Barton NH. Genetic analysis of a hybrid zone between the fire-bellied
    toads Bombina bombina and B. variegata, near Cracow in Southern Poland. <i>Evolution;
    International Journal of Organic Evolution</i>. 1986;40:1141-1159. doi:<a href="https://doi.org/10.1111/j.1558-5646.1986.tb05740.x">10.1111/j.1558-5646.1986.tb05740.x</a>
  apa: Szymura, J., &#38; Barton, N. H. (1986). Genetic analysis of a hybrid zone
    between the fire-bellied toads Bombina bombina and B. variegata, near Cracow in
    Southern Poland. <i>Evolution; International Journal of Organic Evolution</i>.
    Society for the Study of Evolution. <a href="https://doi.org/10.1111/j.1558-5646.1986.tb05740.x">https://doi.org/10.1111/j.1558-5646.1986.tb05740.x</a>
  chicago: Szymura, Jacek, and Nicholas H Barton. “Genetic Analysis of a Hybrid Zone
    between the Fire-Bellied Toads Bombina Bombina and B. Variegata, near Cracow in
    Southern Poland.” <i>Evolution; International Journal of Organic Evolution</i>.
    Society for the Study of Evolution, 1986. <a href="https://doi.org/10.1111/j.1558-5646.1986.tb05740.x">https://doi.org/10.1111/j.1558-5646.1986.tb05740.x</a>.
  ieee: J. Szymura and N. H. Barton, “Genetic analysis of a hybrid zone between the
    fire-bellied toads Bombina bombina and B. variegata, near Cracow in Southern Poland,”
    <i>Evolution; International Journal of Organic Evolution</i>, vol. 40. Society
    for the Study of Evolution, pp. 1141–1159, 1986.
  ista: Szymura J, Barton NH. 1986. Genetic analysis of a hybrid zone between the
    fire-bellied toads Bombina bombina and B. variegata, near Cracow in Southern Poland.
    Evolution; International Journal of Organic Evolution. 40, 1141–1159.
  mla: Szymura, Jacek, and Nicholas H. Barton. “Genetic Analysis of a Hybrid Zone
    between the Fire-Bellied Toads Bombina Bombina and B. Variegata, near Cracow in
    Southern Poland.” <i>Evolution; International Journal of Organic Evolution</i>,
    vol. 40, Society for the Study of Evolution, 1986, pp. 1141–59, doi:<a href="https://doi.org/10.1111/j.1558-5646.1986.tb05740.x">10.1111/j.1558-5646.1986.tb05740.x</a>.
  short: J. Szymura, N.H. Barton, Evolution; International Journal of Organic Evolution
    40 (1986) 1141–1159.
date_created: 2018-12-11T12:08:14Z
date_published: 1986-01-01T00:00:00Z
date_updated: 2022-01-31T15:31:37Z
day: '01'
doi: 10.1111/j.1558-5646.1986.tb05740.x
extern: '1'
intvolume: '        40'
language:
- iso: eng
month: '01'
oa_version: None
page: 1141 - 1159
publication: Evolution; International Journal of Organic Evolution
publication_identifier:
  eissn:
  - 1558-5646
  issn:
  - 0014-3820
publication_status: published
publisher: Society for the Study of Evolution
publist_id: '1724'
quality_controlled: '1'
status: public
title: Genetic analysis of a hybrid zone between the fire-bellied toads Bombina bombina
  and B. variegata, near Cracow in Southern Poland
type: journal_article
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 40
year: '1986'
...
---
_id: '3668'
abstract:
- lang: eng
  text: When two populations which differ at many loci meet, the degree of introgression
    of alleles across the boundary will depend on the selection acting on each locus
    (s), the rate of recombination between adjacent loci (r), and the number of loci
    involved (n). Simple scaling arguments suggest that the behavior of the system
    should depend on the ratio of selection to recombination (θ = s/r), and on n.
    This is borne out by mathematical analysis of two demes which exchange individuals
    at a low rate; when selection is stronger than recombination (θ > 1), the effective
    selection on each locus is comparable to the total selection over the whole genome
    (s* ∼ ns). When selection is weaker than recombination (θ < 1), the effective
    selection is much weaker, but is still stronger than the selection on each locus
    alone (s* \sim sn20 for small θ). When n is very large, these two regimes are
    separated by a sharp threshold at θ = 1. The results are extended to two taxa
    which meet in a continuous habitat; the effective selection pressure, which determines
    the width of the hybrid zone, behaves in the same way as for the simpler case
    above. Even when selection is weak compared to recombination, multilocus clines
    have a sharp step at their center, flanked by tails of introgression in which
    the alleles behave independently of each other. The set of clines acts as a barrier
    to gene flow, and it is shown that the barrier is strongest when selection is
    spread over many loci. The implications of the results for divergence and speciation
    are discussed.
acknowledgement: "I would like to thank G. Hewitt, J. Raper, M. Shaw, P. Oliver, M.
  Slatkin, J. Felsenstein, and D. J. Futuyma for their\r\n helpful comments. This
  work was partly supported by an SRC Post-Doctoral Fellowship."
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. Multilocus clines. <i>Evolution; International Journal of Organic
    Evolution</i>. 1983;37(3):454-471. doi:<a href="https://doi.org/10.2307/2408260">10.2307/2408260</a>
  apa: Barton, N. H. (1983). Multilocus clines. <i>Evolution; International Journal
    of Organic Evolution</i>. Society for the Study of Evolution. <a href="https://doi.org/10.2307/2408260">https://doi.org/10.2307/2408260</a>
  chicago: Barton, Nicholas H. “Multilocus Clines.” <i>Evolution; International Journal
    of Organic Evolution</i>. Society for the Study of Evolution, 1983. <a href="https://doi.org/10.2307/2408260">https://doi.org/10.2307/2408260</a>.
  ieee: N. H. Barton, “Multilocus clines,” <i>Evolution; International Journal of
    Organic Evolution</i>, vol. 37, no. 3. Society for the Study of Evolution, pp.
    454–471, 1983.
  ista: Barton NH. 1983. Multilocus clines. Evolution; International Journal of Organic
    Evolution. 37(3), 454–471.
  mla: Barton, Nicholas H. “Multilocus Clines.” <i>Evolution; International Journal
    of Organic Evolution</i>, vol. 37, no. 3, Society for the Study of Evolution,
    1983, pp. 454–71, doi:<a href="https://doi.org/10.2307/2408260">10.2307/2408260</a>.
  short: N.H. Barton, Evolution; International Journal of Organic Evolution 37 (1983)
    454–471.
date_created: 2018-12-11T12:04:31Z
date_published: 1983-05-01T00:00:00Z
date_updated: 2022-08-19T07:08:29Z
day: '01'
doi: 10.2307/2408260
extern: '1'
external_id:
  pmid:
  - '28563316 '
intvolume: '        37'
issue: '3'
language:
- iso: eng
main_file_link:
- url: http://www.jstor.org/stable/2408260
month: '05'
oa_version: None
page: 454 - 471
pmid: 1
publication: Evolution; International Journal of Organic Evolution
publication_identifier:
  eissn:
  - 1558-5646
  issn:
  - 0014-3820
publication_status: published
publisher: Society for the Study of Evolution
publist_id: '2715'
quality_controlled: '1'
status: public
title: Multilocus clines
type: journal_article
user_id: 3E5EF7F0-F248-11E8-B48F-1D18A9856A87
volume: 37
year: '1983'
...
---
_id: '4331'
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 structure of the hybrid zone in Uroderma bilobatum (Chiroptera:
    Phyllostomatidae). <i>Evolution</i>. 1982;36(4):863-866. doi:<a href="https://doi.org/10.1111/j.1558-5646.1982.tb05452.x">10.1111/j.1558-5646.1982.tb05452.x</a>'
  apa: 'Barton, N. H. (1982). The structure of the hybrid zone in Uroderma bilobatum
    (Chiroptera: Phyllostomatidae). <i>Evolution</i>. Wiley. <a href="https://doi.org/10.1111/j.1558-5646.1982.tb05452.x">https://doi.org/10.1111/j.1558-5646.1982.tb05452.x</a>'
  chicago: 'Barton, Nicholas H. “The Structure of the Hybrid Zone in Uroderma Bilobatum
    (Chiroptera: Phyllostomatidae).” <i>Evolution</i>. Wiley, 1982. <a href="https://doi.org/10.1111/j.1558-5646.1982.tb05452.x">https://doi.org/10.1111/j.1558-5646.1982.tb05452.x</a>.'
  ieee: 'N. H. Barton, “The structure of the hybrid zone in Uroderma bilobatum (Chiroptera:
    Phyllostomatidae),” <i>Evolution</i>, vol. 36, no. 4. Wiley, pp. 863–866, 1982.'
  ista: 'Barton NH. 1982. The structure of the hybrid zone in Uroderma bilobatum (Chiroptera:
    Phyllostomatidae). Evolution. 36(4), 863–866.'
  mla: 'Barton, Nicholas H. “The Structure of the Hybrid Zone in Uroderma Bilobatum
    (Chiroptera: Phyllostomatidae).” <i>Evolution</i>, vol. 36, no. 4, Wiley, 1982,
    pp. 863–66, doi:<a href="https://doi.org/10.1111/j.1558-5646.1982.tb05452.x">10.1111/j.1558-5646.1982.tb05452.x</a>.'
  short: N.H. Barton, Evolution 36 (1982) 863–866.
corr_author: '1'
date_created: 2018-12-11T12:08:18Z
date_published: 1982-07-01T00:00:00Z
date_updated: 2024-10-09T20:53:53Z
day: '01'
doi: 10.1111/j.1558-5646.1982.tb05452.x
extern: '1'
external_id:
  pmid:
  - '28568238'
intvolume: '        36'
issue: '4'
language:
- iso: eng
month: '07'
oa_version: None
page: 863 - 866
pmid: 1
publication: Evolution
publication_identifier:
  eissn:
  - 1558-5646
  issn:
  - 0014-3820
publication_status: published
publisher: Wiley
publist_id: '1705'
quality_controlled: '1'
status: public
title: 'The structure of the hybrid zone in Uroderma bilobatum (Chiroptera: Phyllostomatidae)'
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 36
year: '1982'
...
---
_id: '3670'
abstract:
- lang: eng
  text: The grasshopper Podisma pedestris includes two chromosomal races, which differ
    by a Robertsonian fusion involving the sex chromosome. The two races meet in a
    cline which runs for 100 km across the Alpes Maritimes in south-eastern France.
    An intensive study of the easternmost end of this cline shows that it is about
    800 m wide; the cline is not smooth, containing substantial spikes in chromosome
    frequency which might be due to sampling drift. Though the cline seems narrow,
    it is wide compared with the dispersal rate of the insect; a selective force of
    only 0.5% would be enough to maintain the cline. It is difficult to determine
    the nature of this force, but some evidence comes from the position of the cline,
    and from the presence of coincident clines at other loci. An estimate of the distribution
    of Podisma has been made, and the cline seems to follow, for the most part, a
    region of low population density, suggesting that it is maintained by hybrid unfitness.
    However, in the one region where the cline is relatively free to move, the XY
    race bulges forwards more than would be expected if hybrids are unfit. The observation
    of severe inviability in crosses between the races, though it is not associated
    with the chromosomal difference, also indicates that this cline is the result
    of some sort of genetic incompatibility.
acknowledgement: "Many thanks are due to the Hewitt  family (Elizabeth, Daniel, Matthew,
  and James), Bruce and Helen Halliday, Mike\r\n Shaw, Alan Jenyon, and Bob Williams
  for their help in collecting the grasshoppers;  to M. and Mme. Aviotti for their
  hospitality in Casterino; and to Marise East for her help in karyotyping the samples.
  The work was supported by a grant from the S.R.C. to G. Hewitt, and N. Barton was
  supported by a N.E.R.C. studentship."
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: Godfrey
  full_name: Hewitt, Godfrey
  last_name: Hewitt
citation:
  ama: Barton NH, Hewitt G. A chromosomal cline in the grasshopper Podisma pedestris.
    <i>Evolution; International Journal of Organic Evolution</i>. 1981;35(5):1008-1018.
    doi:<a href="https://doi.org/ 10.1111/j.1558-5646.1981.tb04966.x"> 10.1111/j.1558-5646.1981.tb04966.x</a>
  apa: Barton, N. H., &#38; Hewitt, G. (1981). A chromosomal cline in the grasshopper
    Podisma pedestris. <i>Evolution; International Journal of Organic Evolution</i>.
    Wiley-Blackwell. <a href="https://doi.org/ 10.1111/j.1558-5646.1981.tb04966.x">https://doi.org/
    10.1111/j.1558-5646.1981.tb04966.x</a>
  chicago: Barton, Nicholas H, and Godfrey Hewitt. “A Chromosomal Cline in the Grasshopper
    Podisma Pedestris.” <i>Evolution; International Journal of Organic Evolution</i>.
    Wiley-Blackwell, 1981. <a href="https://doi.org/ 10.1111/j.1558-5646.1981.tb04966.x">https://doi.org/
    10.1111/j.1558-5646.1981.tb04966.x</a>.
  ieee: N. H. Barton and G. Hewitt, “A chromosomal cline in the grasshopper Podisma
    pedestris,” <i>Evolution; International Journal of Organic Evolution</i>, vol.
    35, no. 5. Wiley-Blackwell, pp. 1008–1018, 1981.
  ista: Barton NH, Hewitt G. 1981. A chromosomal cline in the grasshopper Podisma
    pedestris. Evolution; International Journal of Organic Evolution. 35(5), 1008–1018.
  mla: Barton, Nicholas H., and Godfrey Hewitt. “A Chromosomal Cline in the Grasshopper
    Podisma Pedestris.” <i>Evolution; International Journal of Organic Evolution</i>,
    vol. 35, no. 5, Wiley-Blackwell, 1981, pp. 1008–18, doi:<a href="https://doi.org/
    10.1111/j.1558-5646.1981.tb04966.x"> 10.1111/j.1558-5646.1981.tb04966.x</a>.
  short: N.H. Barton, G. Hewitt, Evolution; International Journal of Organic Evolution
    35 (1981) 1008–1018.
date_created: 2018-12-11T12:04:32Z
date_published: 1981-09-01T00:00:00Z
date_updated: 2022-01-21T08:51:51Z
day: '01'
doi: ' 10.1111/j.1558-5646.1981.tb04966.x'
extern: '1'
external_id:
  pmid:
  - '28581059'
intvolume: '        35'
issue: '5'
language:
- iso: eng
main_file_link:
- url: http://www.jstor.org/stable/2407871
month: '09'
oa_version: None
page: 1008 - 1018
pmid: 1
publication: Evolution; International Journal of Organic Evolution
publication_identifier:
  eissn:
  - 1558-5646
  issn:
  - 0014-3820
publication_status: published
publisher: Wiley-Blackwell
publist_id: '2713'
quality_controlled: '1'
status: public
title: A chromosomal cline in the grasshopper Podisma pedestris
type: journal_article
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 35
year: '1981'
...